Home > Journals > Journal of Economic Entomology > Volume 106 > Issue 2
Journal of Economic Entomology
VOL. 106 · NO. 2 | April 2013
RAPID COMMUNICATION (1)
APICULTURE AND SOCIAL INSECTS (6)
ARTHROPODS IN RELATION TO PLANT DISEASE (3)
BIOLOGICAL AND MICROBIAL CONTROL (5)
COMMODITY TREATMENT AND QUARANTINE ENTOMOLOGY (2)
ECOLOGY AND BEHAVIOR (9)
FIELD AND FORAGE CROPS (10)
FOREST ENTOMOLOGY (2)
HORTICULTURAL ENTOMOLOGY (5)
HOUSEHOLD AND STRUCTURAL INSECTS (1)
INSECTICIDE RESISTANCE AND RESISTANT MANAGEMENT (5)
MEDICAL ENTOMOLOGY (2)
MOLECULAR ENTOMOLOGY (2)
PLANT RESISTANCE (6)
SAMPLING AND BIOSTATISTICS (1)
STORED-PRODUCT (3)
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VIEW ALL ABSTRACTS +
Correction. Discrimination of Reproductive Forms of Thrips tabaci (Thysanoptera: Thripidae) by PCR with Sequence Specific Primers
Journal of Economic Entomology 106 (2), (1 April 2013) https://doi.org/10.1603/029.106.0201
The Case for a Generic Phytosanitary Irradiation Dose of 400 Gy for Lepidoptera That Infest Shipped Commodities as Pupae
Guy J. Hallman, Andrew G. Parker, Carl M. Blackburn
Journal of Economic Entomology 106 (2), 525-532, (1 April 2013) https://doi.org/10.1603/EC12429
KEYWORDS: phytosanitary treatment, quarantine Pest, ionizing radiation, phytosanitation
Read Abstract +
The pros and cons of a generic phytosanitary irradiation dose against all Lepidoptera pupae on all commodities are discussed. The measure of efficacy is to prevent the F1 generation from hatching (F1 egg hatch) when late pupae are irradiated. More data exist for this measure than for others studied, and it is also commercially tenable (i.e., prevention of adult emergence would require a high dose not tolerated by fresh commodities). The dose required to prevent F1 egg hatch provides a liberal margin of security for various reasons. A point at issue is that correctly irradiated adults could be capable of flight and thus be found in survey traps in importing countries resulting in costly and unnecessary regulatory action. However, this possibility would be rare and should not be a barrier to the adoption of this generic treatment. The literature was thoroughly examined and only studies that could reasonably satisfy criteria of acceptable irradiation and evaluation methodology, proper age of pupae, and adequate presentation of raw data were accepted. Based on studies with 34 species in nine families, we suggest an efficacious dose of 400 Gy. However, large-scale confirmatory testing (≥30,000 individuals) has only been reported for one species. A dose as low as 350 Gy might suffice if results of more large-scale studies were available or the measure of efficacy were extended beyond prevention of F1 egg hatch, but data to defend measures of efficacy beyond F1 egg hatch are scarce and more would need to be generated.
RAPID COMMUNICATION
First-Generation Megacopta cribraria (Hemiptera: Plataspidae) Can Develop on Soybeans
A. I. Del Pozo-Valdivia, D. D. Reisig
KEYWORDS: Megacopta cribraria, soybean, first-generation, rearing, life table
Megacopta cribraria (F.) (Hemiptera: Plataspidae) was first reported in 2009 near Atlanta, GA. The insect undergoes two generations per year. The first-generation is reported mainly in kudzu during May and June, with the second establishing on both kudzu and soybean during July and August. A greenhouse study was conducted to determine the suitability of two legumes as hosts for first generation M. cribraria. First generation M. cribraria successfully developed on caged potted soybean plants. Conversely, snap beans were not a suitable host under the conditions of this study. A range of 45–50 d was needed to transition from the egg to adult on soybean plants. Although this study was limited to the greenhouse, kudzu may not be an obligate host for the development of first-generation M. cribraria. An important implication of this finding is the establishment for this pest on spring-planted soybean and for the possible expanded geographic range for this pest beyond that of kudzu.
APICULTURE AND SOCIAL INSECTS
Identification of a Distinct Lineage of Cacopsylla chinensis (Hemiptera: Psyllidae) in Japan on the Basis of Two Mitochondrial DNA Sequences
H. Katoh, H. Inoue, F. Kuchiki, Y. Ide, N. Uechi, T. Iwanami
KEYWORDS: Cacopsylla chinensis, cytochrome oxidase I, 16s rDNA
Psyllids are a menacing pests of pears (Pyrus spp.) grown in temperate and subtropical regions of the world, including Taiwan and China. Pear psyllids belong to the large genus Cacopsylla (Psyllidae: Psyllinae). Among the 28 psyllid species that infest pear trees, Cacopsylla chinensis (Yang and Li, 1981) is considered the most harmful. Two psyllid outbreaks involving exotic species affected Japanese pear (Pyrus pyiifolia variety culta) orchards in the Saga Prefecture in July and November 2011. The psyllids were morphologically identical to the summer and winter forms of C. chinensis. In this study, we performed DNA sequence analysis of the mitochondrial cytochrome oxidase I-leucine tRNA-cytochrome oxidase II (COI-tRNALeu-COII) and 16S rDNA regions to elucidate the phylogenetic relationships among 82 summer-form psyllids, five winter-form psyllids from several orchards in Japan, and those reported from Taiwan and China. The sequences of the COI-tRNALeu-COII and 16S rDNA regions were identical among all 87 psyllids from Japan, regardless of summer/winter forms or orchards in Saga, Japan. Comparison of nucleotide sequences and phylogenetic analysis differentiated Japanese psyllids from the Taiwanese and Chinese C. chinensis isolates, with ≈8 and 7% nucleotide difference in the COII-RNALeu-COII and 16S rDNA regions, respectively. The results suggest that C. chinensis possess a high level of genetic variability and that the psyllids responsible for the outbreak in Saga, Japan belong to a distinct lineage of C. chinensis.
Variation in Alfalfa Leafcutting Bee (Hymenoptera: Megachilidae) Reproductive Success According to Location of Nests in United States Commercial Domiciles
Theresa L. Pitts-Singer
KEYWORDS: Megachile rotundata, Megachilidae, alfalfa, pollination, reproduction
The alfalfa leafcutting bee, Megachile rotundata F., is used extensively to pollinate alfalfa for seed production in western North America. However, it usually is not possible to sustain bee populations in the United States. In the managed pollination system, variable microenvironments are experienced by developing M. rotundata during the nesting season that may influence bee reproductive success. In this study, bee cells were produced in a small alfalfa field and collected from domiciles according to nesting boards and different portions of boards. Examination of cells showed that the production of live overwintering prepupae, diseased larvae, other dead eggs and larvae, and cells attacked by natural enemies varied according to board orientations and positions, and portions of the boards. Northeast-facing board samples were significantly heavier and had more pollen balls and chalkbrood compared with southwest-facing boards. Lower boards in stacks had significantly more chalkbrood than upper boards. Outer portions of boards had significantly more live prepupae and less chalkbrood than middle and inner portions, and outer and middle portions had less summer-emerging bees. These results suggest that reproductive success could be altered by changing the orientation of boards within domiciles or changing the designs of domiciles. To accurately assess the quality of bee populations managed in the commercial loose cell system, a sample of bees should be taken from a pooled sample from all boards in each domicile. Each domicile sample should then be evaluated according to its proportional contribution to the whole field's progeny production (e.g., by weight or volume).
Too Much Work, Not Enough Tarsi: Group Size Influences Bombus impatiens (Hymenoptera: Apidae) Worker Reproduction with Implications for Sublethal Pesticide Toxicity Assessments
A. E. Gradish, C. D. Scott-Dupree, A. D. McFarlane, A. J. Frewin
KEYWORDS: Bombus, pesticide, pollinator, behavior, queen-less
As bumble bees may routinely forage on pesticide-treated plants, it is imperative to apply pesticides that pose minimal risk. Identifying such reduced-risk pesticides requires toxicity tests using biologically relevant and standardized exposure methods. Our goal was to develop a functional and reliable queen-less micro-colony method for determining the sublethal effects of pesticides on Bombus impatiens Cresson, a species for which further toxicity assessments are needed. Originally developed using Bombus terrestris (L.), this method involves isolating three workers and allowing them to establish and maintain a colony. The workers and brood can then be exposed to pesticides and various effects measured simultaneously. Our preliminary work indicated that B. impatiens workers were unable to reproduce under the micro-colony conditions developed for B. terrestris. In the current study, we focused on the potential role of group size in B. impatiens worker reproduction by placing groups of three or five sister workers together and assessing their ability to establish a colony and rear males to adulthood. While both groups oviposited and produced males, significantly more males emerged from micro-colonies of five workers. We conclude that group size affects B. impatiens worker reproduction, and this effect in bumble bees varies interspecifically. In the context of toxicity testing, we recommend the use of at least five B. impatiens workers in micro-colonies to ensure a level of reproduction that allows the detection of potential sublethal changes to reproduction or development.
Fate of Dermally Applied Miticides Fluvalinate and Amitraz Within Honey Bee (Hymenoptera: Apidae) Bodies
Neil Kirk Hillier, Elisabeth H. Frost, Dave Shutler
KEYWORDS: miticides, Amitraz, tau-fluvalinate, honey bees, Varroa destructor
Varroa mites, Varroa destructor Anderson & Trueman, are economically important pests of honey bees. Varroa mites are principally controlled within honey bee colonies using miticides. However, despite their importance in managing mite populations for apiculture, potential effects of miticides on honey bees are poorly understood. Using gas chromatography-flame ionization detection, we investigated concentrations, over variable time frames and within different body regions, of two commonly used miticides, tau-fluvalinate and amitraz, after dermal exposure to honey bees. We also quantified mortality of honey bees exposed to each miticide at both a low and high dose. Significant differences were observed in distributions of miticides among body regions. Within honey bee body parts, tau-fluvalinate was more readily absorbed and decreased in concentration more rapidly than amitraz. Mortality increased with higher dosages of miticides, and at higher dosages mortality was greater from fluvalinate than from amitraz. For individual honeybees, our results for rate of breakdown suggest that fluvalinate may be the preferred miticide for apiculturists, whereas our mortality results suggest that amitraz may be preferable. Either choice must be weighed against geographic variation in varroa resistance to each pesticide and attendant costs of parasitism.
Associations of Parameters Related to the Fall of Varroa destructor (Mesostigmata: Varroidae) in Russian and Italian Honey Bee (Hymenoptera: Apidae) Colonies
Thomas E. Rinderer, Lilia I. De Guzman, Amanda M. Frake
KEYWORDS: Varroa destructor, Russian honey bee, mite fall, grooming behavior, Varroa resistance
Varroa destructor (Anderson and Truman) trapped on bottom boards were assessed as indirect measurements of colony mite populations and mite fall in colonies of Russian and Italian honey bees using 29 candidate measurements. Measurements included damaged and nondamaged younger mites, damaged and nondamaged older mites, fresh mites and all mites, each as a proportion of total mites in the colonies and as a proportion of all trapped mites or all trapped fresh mites. Regression analyses were used to determine the relationships of these candidate measurements to the number of mites in the colonies. The largest positive regressions were found for trapped younger mites (Y) and trapped fresh mites (F). Measurments of Y and F across time could be used to estimate mite population growth for the purposes of selective breeding. The largest negative regressions with colony mites were observed for: trapped older mites/trapped mites (O/T), trapped older mites/trapped younger mites (O/Y), and trapped injured older mites/injured mites (IO/I). O/T and O/Y are significantly higher for Russian honey bee colonies suggesting that they are related to at least some of the mechanisms used by Russian honeybee to resist Varroa population growth. O/T and O/Y have strong negative relationships with colony mites for both Russian honey bee and Italian colonies suggesting that both strains possibly could be selected for reduced colony mites using O/T or O/Y.
Intended Release and Actual Retention of Alfalfa Leafcutting Bees (Hymenoptera: Megachilidae) for Pollination in Commercial Alfalfa Seed Fields
KEYWORDS: alfalfa-seed production, Medicago sativa, Megachile rotundata, Megachilidae, pollination
Low, medium, and high stocking densities (15,000; 30,000; and 45,000–50,000 bees per acre, respectively) of Megachile rotundata (F.) (Hymenoptera: Megachilidae), the alfalfa leafcutting bee, were released over 4 yr in three research plots of Utah alfalfa, Medicago sativa L. (Fabaceae), planted at seed-production rates. A low percentage of bees (46–79% of released) survived the incubation and field-emergence processes; of those bees, the number of females that established at the nesting sites was 25–100%. Of the three field sites, one site consistently retained more females and produced more completed nests than the other sites, all of which usually had poor female establishment and progeny production. In addition, floral resources were depleted over time, but many flowers remained unvisited over the season. Nest production decreased over time, as numbers of flowers and female bees declined. Significant positive relationships were found between the intended stocking densities and 1) the number of females that actually survived incubation and field emergence and 2) the number of females that established nests. The number of females that established nests was positively affected by the number of females that survived to emerge in the field. The percentage of females that established was not significantly affected by the intended number of released bees, countering a prediction that the release of fewer bees would allow more females to establish nests and achieve high reproductive success. For growers, it may be more frugal to use modest numbers of M. rotundata for pollination, because many of the bees at medium and high stocking densities do not nest in grower-provided bee boards.
ARTHROPODS IN RELATION TO PLANT DISEASE
Second Generation Peanut Genotypes Resistant to Thrips-Transmitted Tomato Spotted Wilt Virus Exhibit Tolerance Rather Than True Resistance and Differentially Affect Thrips Fitness
Anita Shrestha, Rajagopalbabu Srinivasan, Sivamani Sundaraj, Albert K. Culbreath, David G. Riley
KEYWORDS: Frankliniella fusca, Tospovirus, resistant genotypes, peanut
Spotted wilt disease caused by Tomato spotted wilt virus (TSWV) (family Bunyaviridae; genus Tospovirus) is a major constraint to peanut (Arachis hypogaea L.) production in the southeastern United States. Reducing yield losses to TSWV has heavily relied on planting genotypes that reduce the incidence of spotted wilt disease. However, mechanisms conferring resistance to TSWV have not been identified in these genotypes. Furthermore, no information is available on how these genotypes influence thrips fitness. In this study, we investigated the effects of newly released peanut genotypes (Georganic, GA-06G, Tifguard, and NC94022) with field resistance to TSWV and a susceptible genotype (Georgia Green) on tobacco thrips, Frankliniella fusca (Hinds), fitness, and TSWV incidence. Thrips-mediated transmission resulted in TSWV infection in both TSWV-resistant and susceptible genotypes and they exhibited typical TSWV symptoms. However, some resistant genotypes had reduced viral loads (fewer TSWV N-gene copies) than the susceptible genotype. F. fusca larvae acquired TSWV from resistant and susceptible genotypes indicating that resistant genotypes also can serve as inoculum sources. Unlike resistant genotypes in other crops that produce local lesions (hypersensitive reaction) upon TSWV infection, widespread symptom development was noticed in peanut genotypes. Results indicated that the observed field resistance in peanut genotypes could be because of tolerance. Further, fitness studies revealed some, but not substantial, differences in thrips adult emergence rates and developmental time between resistant and susceptible genotypes. Thrips head capsule length and width were not different when reared on different genotypes.
Use of Fluorescence, a Novel Technique to Determine Reduction in Bemisia tabaci (Hemiptera: Aleyrodidae) Nymph Feeding When Exposed to Benevia and Other Insecticides
Rachel Cameron, Edward B. Lang, I. Billy Annan, Hector E. Portillo, Juan M. Alvarez
KEYWORDS: fluorescein sodium salt, Cyazypyr, cyantraniliprole, imidacloprid, spirotetramat
The sweet potato whitefly, Bemisia tabaci (Gennadius), is an economically important pest in the United States and other countries. Growers in many places rely on the use of insecticides to reduce populations of B. tabaci. However, insecticides may take a few days to cause B. tabaci mortality and some do not reduce feeding before death. Earlier reduction of feeding of whiteflies would decrease the physiological effects on plants, reduce the production of sooty mold and potentially reduce the transmission of viruses. Measuring the reduction in feeding after the exposure of B. tabaci to an insecticide has proven difficult. This series of laboratory experiments demonstrate the usefulness of fluorescence in determining B. tabaci feeding cessation. Fluorescein sodium salt is systemically transported in the xylem from the roots to the plant leaves and absorbed by B. tabaci nymphs feeding on these plants. Nymphs start fluorescing shortly after the cotton plant root system is submerged in the fluorescein sodium salt. Using this novel technique, the effect of three insecticides with different modes of action, cyantraniliprole, imidacloprid, and spirotetramat on B. tabaci was evaluated and compared to determine reduction in feeding. Results indicate that B. tabaci nymphs feeding on a plant treated with Benevia have a significant reduction of feeding when compared with nymphs feeding on plants treated with imidacloprid or spirotetramat. Both Benevia and spirotetramat caused significant nymphal mortality by 48 h after exposure. This novel technique will be useful to demonstrate the feeding cessation or reduction in feeding produced by different insecticides in several sucking insect groups.
Natural Phytoplasma Infection of Four Phloem-Feeding Auchenorrhyncha Across Vineyard Agroecosystems in Central-Eastern Italy
L. Landi, N. Isidoro, P. Riolo
KEYWORDS: Auchenorrhyncha, grapevine yellows, feeding-medium assay, phytoplasma seasonal variation, phytoplasma-insect relationships
The seasonal variations of grapevine yellow phytoplasma were investigated in four phloem-feeding planthopper and leafhopper species that are vectors of plant disease agents. In total, 1,148 wild specimens were collected from three vineyard agroecosystems in the Marche region (central-eastern Italy), from May to September 2008, and analyzed using polymerase chain reactionrestriction fragment-length polymorphism methods. Of 525 Euscelis lineolatus Brullé, 25.1% were positive for aster yellow phytoplasma (16SrI-C, 16SrI-B subgroups) and stolbur phytoplasma (16SrXII-A subgroup; Vergilbungskrankheit type I [VK-I]). Of 368 Hyalesthes obsoletus Signoret, 19.3% were positive for the 16SrXII-A subgroup (VK-I, VK-II; mainly according to their host plant). Of 146 Neoaliturus fenestratus (Herrich-Schäffer), 15.1% were positive for the 16SrI-C and 16SrI-B subgroups, and 7.3% of 109 Psammotettix alienus (Dahlbom) were positive for the 16SrI-B subgroup. The total inoculation efficiency in the feeding medium assays was 57.1% for P. alienus, 44.7% for E. lineolatus, 44.4% for N. fenestratus and 33.9% for H. obsoletus. All of the phytoplasma subgroups identified in the insect bodies were also detected in their feeding media. Detection of stolbur phytoplasma in E. lineolatus feeding media strengthens the hypothesis that it is a candidate vector of Bois noir disease causal agent. The phytoplasma subgroups detected in the Auchenorrhyncha species showed variations according to season and/or vineyard agroecosystem. This study highlights the different specificities of these phytoplasma-Auchenorrhyncha species relationships, and suggests a primary role of the entire vineyard agroecosystem in the epidemiology of grapevine yellow phytoplasma diseases.
BIOLOGICAL AND MICROBIAL CONTROL
Bacillus thuringiensis Insecticidal Crystal Proteins Affect Lifespan and Reproductive Performance of Helicoverpa armigera and Spodoptera exigua Adults
Ying Zhang, Yan Ma, Pin-Jun Wan, Li-Li Mu, Guo-Qing Li
KEYWORDS: Helicoverpa armigera, Spodoptera exigua, Bt toxin, lifespan, reproductive performance
Being delivered as sprays or expressed in plant, Bacillus thuringiensis (Bt) crystalline proteins (Cry toxins) display insecticidal activities against numerous Lepidopteran, Dipteran, and Coleopteran larvae. Comparative study of toxicities of Bt Cry toxins between larvae and adults may afford important new insights into the interactions of the toxins with receptor proteins in host insect, and represent intriguing targets for the control of insect pests. However, the effectiveness of Bt Cry toxins in insect adults has paid less attention. In the present article, the effectiveness of Cry1Ac and Cry1Ca on lifespans and reproductive performance of Helicoverpa armigera (Hübner) and Spodoptera exigua (Hübner) adults were evaluated by in vivo experiments. Considering transgenic plants express modified, truncated versions of cry genes yielding active toxin fragment, we used activated Bt toxins at the concentration of 500, 100, and 20 µg/ml in a 10% sucrose aquous solution. At the highest concentration, Cry1Ac and Cry1Ca shortened 48.1 and 48.9% of H. armigera female lifespan, and 43.5 and 38.5% of S. exigua female lifespan, and they reduced 37.8 and 40.3%, and 50.5 and 47.4% of H. armigera and S. exigua male lifespans respectively. Bt toxins negatively affected copulation. Exposure to 500 µg/ml of Cry1Ac and Cry1Ca greatly reduced 50.0 and 46.8%, and 58.7 and 57.3% spermatophore acceptance by H. armigera and S. exigua females, respectively. Similarly, Cry1Ac and Cry1Ca exposure decreased 40.0 and 50.3%, and 61.3 and 60.0% of spermatophore transfer by H. armigera and S. exigua males, respectively. Moreover, exposure females rather than males to 500 µg/ml of Cry1Ac and Cry1Ca significantly dropped 57.5 and 57.5% of the number of eggs laid by H. armigera, and 35.4 and 45.8% of the number of egg masses deposited by S. exigua. In contrast, both Cry1Ac and Cry1Ca did not negatively influence the egg hatchability. At the middle and the lowest concentrations, however, the biological effects of Cry1Ac and Cry1Ca on lifespans and reproductive performance partially or completely disappeared.
Interactions Among Bt Maize, Entomopathogens, and Rootworm Species (Coleoptera: Chrysomelidae) in the Field: Effects on Survival, Yield, and Root Injury
Jennifer L. Petzold—Maxwell, Stefan T. Jaronski, Eric H. Clifton, Mike W. Dunbar, Mark A. Jackson, Aaron J. Gassmann
KEYWORDS: Diabrotica barberi, Diabrotica virgifera virgifera, Heterorhabditis, Metarhizium, Steinernema
A 2 yr field study was conducted to determine how a blend of entomopathogens interacted with Bt maize to affect mortality of Diabrotica spp. (Coleoptera: Chrysomelidae), root injury to maize (Zea maize L.) and yield. The blend of entomopathogens included two entomopathogenic nematodes, Steinernema carpocapsae Weiser and Heterorhabditis bacteriophora Poinar, and one entomopathogenic fungus, Metarhizium brunneum (Metschnikoff) Sorokin. Bt maize (event DAS59122–7, which produces Bt toxin Cry34/35Ab1) decreased root injury and survival of western corn rootworm (Diabrotica virgifera virgifera LeConte) and northern corn rootworm (Diabrotica barberi Smith & Lawrence) but did not affect yield. During year 1 of the study, when rootworm abundance was high, entomopathogens in combination with Bt maize led to a significant reduction in root injury. In year 2 of the study, when rootworm abundance was lower, entomopathogens significantly decreased injury to non-Bt maize roots, but had no effect on Bt maize roots. Yield was significantly increased by the addition of entomopathogens to the soil. Entomopathogens did not decrease survival of corn rootworm species. The results suggest that soil-borne entomopathogens can complement Bt maize by protecting roots from feeding injury from corn rootworm when pest abundance is high, and can decrease root injury to non-Bt maize when rootworm abundance is low. In addition, this study also showed that the addition of entomopathogens to soil contributed to an overall increase in yield.
Host Egg Age of Leptoglossus occidentalis (Heteroptera, Coreidae) and Parasitism by Gryon pennsylvanicum (Hymenoptera, Platygastridae)
Giuseppino Sabbatini Peverieri, Paola Furlan, Daniele Benassai, Sarah Caradonna, Ward B. Strong, Pio Federico Roversi
KEYWORDS: Western conifer seed bug, egg-parasitoid, biological control, host age
Leptoglossus occidentalis Heidemann (Heteroptera, Coreidae) is native to Western North America and is a serious pest for seed production of conifers. The pest was accidentally introduced into Europe in the 1990s. Since then, seed loss has been recorded in Pinuspinea (L.) forests, with a negative impact on the commercial production of pine nuts. Classical biological control of this pest in P. pinea stands is an attractive proposition. Previous work showed that the egg-parasitoid Gryon pennsylvanicum (Ashmead) (Hymenoptera, Platygastridae) had promising life history traits in laboratory studies using L. occidentalis eggs as host. In the present work, the effect of host egg age on parasitization rate was evaluated in the laboratory, using choice and no-choice tests. Host eggs ranged in age from <24 h to within a day of hatching. Results showed that parasitization rate, juvenile survival rate, sex ratio, and longevity of female G. pennsylvanicum were not significantly affected by the age of the host eggs. However, egg-parasitoid development time was longer in older host eggs, and females were smaller than those that developed in younger host eggs. Parasitization behaviors (drumming, oviposition, and marking) were not affected by the age of the host. G. pennsylvanicum females tended to parasitize all available host eggs within a cluster before moving to a new cluster, without displaying a preferences for host egg age. The ability to exploit host eggs of any age class improves the prospect of successful classical biological control using this egg-parasitoid.
Fitness Improvement of Mass-Reared Sterile Males of Ceratitis capitata (Vienna 8 strain) (Diptera: Tephritidae) After Gut Enrichment with Probiotics
Heithem Hamden, Meriem M'Saad Guerfali, Selma Fadhl, Mouldi Saidi, Claude Chevrier
KEYWORDS: probiotic, medfly, irradiation, sterile insect technique, sperm
Successful mass rearing is crucial for sterile insect technique programs. It has been shown that the sterilizing process using gammaradiation results in damage to midgut tissue, cellular organelles, and gut microbiota of flies. This can be responsible for the inferiority of sterile males compared with wild males. A bacteria-enhanced diet could contribute to the improvement of the fly's fitness. We investigated ways of increasing the competitiveness of mass-reared Mediterranean fruit fly, Ceratitis capitata (Wiedemann) sterile males. We tested the hypothesis that the addition of beneficial bacteria to the larvae's diet would lead to a significant increase in their levels in the gut of the sterile adults and consequently improve their size and fitness. As expected, enriching the diet of mass-rearing Vienna-8 strain larvae with beneficial bacteria (Klebsiella pneumonia, Enterobacter spp., and Citrobacter freundii) resulted in increase in the number of Enterobacteriacae communities inhabiting the male's gut and a subsequent significant increase in the size of males and other morphometric traits and enhanced sexual performance of males at emergence.
Biological Control Agent of Larger Black Flour Beetles (Coleoptera: Tenebrionidae): A Nuisance Pest Developing in Cotton Gin Trash Piles
Christian Nansen, Bryan Stokes, Jacob James, Patrick Porter, Elson J. Shields, Terry Wheeler, William G. Meikle
KEYWORDS: Steinernema carpocapsae, entomopathogenic nematodes, Steinernematidae, integrated pest management, Tenebrionidae
The larger black flour beetles, Cynaeus angustus (LeConte) (Coleoptera: Tenebrionidae), feeds on saprophytic fungi found in gin trash piles and occasionally becomes a nuisance pest in adjacent homes and businesses. The potential of Steinernema carpocapsae 'NY 001,' as a potential control agent of larger black flour beetle under experimental conditions was examined with particular reference to the importance of soil moisture content. Without prospects of insecticides being labeled for control of larger black flour beetle in gin trash, the data presented here support further research into applications of entomopathogenic nematodes underneath gin trash piles as a way to minimize risk of larger black flour beetle populations causing nuisance to nearby homes and businesses.
COMMODITY TREATMENT AND QUARANTINE ENTOMOLOGY
Freezing as a Treatment to Prevent the Spread of Hypothenemus hampei (Coleoptera: Curculionidae), in Coffee
Robert G. Hollingsworth, Eric B. Jang, Peter A. Follett
KEYWORDS: Hypothenemus hampei, coffee berry borer, Hawaii, green coffee, Freezing
Coffee berry borer, Hypothenemus hampei (Ferrari) is the most serious insect pest of coffee around the world. Although it is already present in most of the world's major coffee growing regions, it is important to delay further spread and to prevent reintroductions that might include hyperparasites or improve the genetic base of existing populations. Green coffee is shipped around the world for custom blending and roasting and such shipments carry the risk of spreading H. hampei. We used heavily infested coffee berries as a surrogate for green coffee to test the freezing tolerance of H. hampei. After freezing, all life stages of H. hampei were dissected from coffee berries and mortality was assessed. Counting all life stages, >15,000 insects were measured in this study. A temperature of approximately -15°C (range, -13.9 to -15.5) for 48 h provided 100% control of all life stages. A logit regression model predicted ≤1 survivor in a million for treatments of -20°C for 5 d or -15°C for 6 d. A freezing treatment for green coffee might be more economical and acceptable compared with fumigation with methyl bromide, especially for small-scale and organic growers and millers in Hawaii who ship green coffee beans to other islands for custom roasting. Freezing treatments could also be used to kill H. hampei in coffee seeds before export with minimal effects on seed germination if coffee seeds are first dried to critical water content levels in accordance with published methods.
PCR-RFLP Analysis for Identification of Tetranychus Spider Mite Species (Acari: Tetranychidae)
Makoto Arimoto, Masaru Satoh, Ryuji Uesugi, Masahiro Osakabe
KEYWORDS: Tetranychus, ITS, ribosomal DNA, PCR-restriction fragment-length polymorphism, species identification
A polymerase chain reaction (PCR)-restriction fragment length polymorphism (PCR-restriction fragment-length polymorphism)-based method for species identification was applied to 14 Tetranychus spider mite species, which were dominant species intercepted at Japanese import plant quarantine. We sequenced the internal transcribed spacer (ITS) region of the nuclear ribosomal DNA (rDN A), which included the partial ends of the 18S and 28S ribosomal RNA genes, 5.8S ribosomal RNA gene, and two internal transcribed spacers (ITS1 and ITS2) for 15 populations of the 14 species. We analyzed the recognition sites of four restriction endonucleases, which had been proposed for discrimination of Japanese Tetranychus species, and constructed a scheme for Tetranychus species identification by PCR-restriction fragment-length polymorphism. We then applied the scheme to 245 individuals from 199 populations, most of them were from foreign countries. As a result, all 14 species were correctly identified using PCR-restriction fragment-length polymorphism. This demonstrates the usefulness of the PCR-restriction fragment-length polymorphism method for the worldwide identification of Tetranychus species.
ECOLOGY AND BEHAVIOR
Effects of Carbaryl-Bran Bait on Trap Catch and Seed Predation by Ground Beetles (Coleoptera: Carabidae)
Dennis J. Fielding, Linda S. Defoliart, Aaron M. Hagerty
KEYWORDS: grasshopper bait, Alaska, high-latitude agriculture, Insecta, Conservation Reserve Program
Carbaryl-bran bait is effective against grasshoppers without many impacts on nontarget organisms, but ground beetles (Coleoptera: Carabidae) may be susceptible to these baits. Carabids are beneficial in agricultural settings as predators of insect pests and weed seeds. Carabid species and their consumption of weed seeds have not been previously studied in agricultural settings in Alaska. This study examined the effect of grasshopper bran bait on carabid activity-density, as measured by pitfall trap catches, and subsequent predation by invertebrates of seeds of three species of weed. Data were collected in fallow fields in agricultural landscape in the interior of Alaska, near Delta Junction, in 2008 and 2010. Bait applications reduced ground beetle activity-density by over half in each of 2 yr of bait applications. Seed predation was generally low overall (1–10%/ wk) and not strongly affected by the bait application, but predation of lambsquarters (Chenopodium album L.) seed was lower on treated plots in 1 yr (340 seeds recovered versus 317 seeds, on treated versus untreated plots, respectively). Predation of dandelion (Taraxacum officinale G. H. Weber ex Wiggers) seeds was correlated with ground beetle activity-density in 1 yr, and predation of dragonhead mint (Dracocephalum parvifolium Nutt.) seed in the other year. We conclude that applications of carbaryl-bran bait for control of grasshoppers will have only a small, temporary effect on weed seed populations in high-latitude agricultural ecosystems.
Demography and Randomized Life Table Statistics for Peach Twig Borer Anarsia lineatella (Lepidoptera: Gelechiidae)
Petros Damos
KEYWORDS: Anarsia lineatella, life table, demographic parameter, intrinsic rate of increase, actuarial mathematics
This work studies for first time the effect of constant temperatures (15, 20, 25, 30 and 35°C) on the demography of Anarsia lineatella Zeller (Lepidoptera: Gelechiidae) based on jackknife and bootstrap randomization methods. Male and female longevity was substantially reduced at the higher temperatures in contrast to intermediate and lower temperatures. According to a second order polynomial regression function, high correlations were observed between temperatures and the age of first reproduction as well as temperature and oviposition times. Net reproductive rate was highest at 25°C and 74.172, while the intrinsic rate of increase displayed its highest values at 30°C and was estimated to be 0.238. Birth rate and finite capacity of increase were higher at 30°C and estimated to be 0.235 and 1.268, respectively. Mean generation time and doubling time varied significantly with temperature and the shortest mean generation and doubling time was obtained at 30°C (25.566 and 2.909 d respectively). Life expectancy had its lowest value 10.3 d at 25°C, whereas cohorts that were maintained at 20 and 15°C increased their life expectation approximately three to sixfold.
Colonization of the Biomass Energy Crop Miscanthus by the Three Aphid Species, Aphis fabae, Myzus persicae, and Rhopalosiphum padi
Q. Coulette, A. Couty, P. Lasue, C. Rambaud, A. Ameline
KEYWORDS: host plant suitability, Miscanthus sacchariflorus, Aphididae, electrical penetration graph, phytovirus
Miscanthus is a perennial C4-grass that has received much interest as a potential biomass crop in Europe. However, little is known about the consequences of its introduction in terms of impact on the local agroecosytem. In this context, laboratory experiments were conducted to investigate the potential colonization of this new exotic plant species by three of the main aphid pest species of common crops in Picardie, northern France. In host preference experiments, the two polyphagous aphid species studied, Aphis fabae (Scop) and Myzus persicae (Sulzer), exhibited an exclusive preference for their host plant, whereas the cereal specialist Rhopalosiphum padi (L.) showed no preference between its host plant and miscanthus. When assessed by electrical penetration graph technique, plant tissue probing activity by all three species always was characterized by pathway phases including potential drops that are typically associated to the transmission of noncirculative viruses. Phloem ingestion was observed in 5% of the polyphagous aphid individuals tested and in 20% of the R. padi tested. Aphids kept in clip-cages on miscanthus had a low survival rate and were unable to reproduce. These results demonstrate that miscanthus is not a suitable host for these three main aphid pest species but could act as a potential host for some viruses transmitted in a noncirculative manner and also in a circulative nonpropagative manner. The use of miscanthus as a barrier crop to limit the flow of aphid vectors and their phytoviruses is discussed.
Laboratory Evaluation of the Flight Ability of Female Autographa nigrisigna (Lepidoptera: Noctuidae), Measured by Actograph and Flight Mill
Aoi Hashiyama, Masashi Nomura, Jun Kurihara, Goro Toyoshima
KEYWORDS: Autographa nigrisigna, flight ability, actograph, flight mill
Autographa nigrisigna (Lepidoptera: Noctuidae) is the target species of the mating disruptant for vegetables, Confuser V. However, emergence of A. nigrisigna does not decrease in the Confuser V treated vegetable fields. As one of the reasons for this phenomenon, migration of mated females into the Confuser V treated area were considered. Thus, we studied the flight ability of female A. nigrisigna by using computer-interfaced actograph and flight mill devices. Flight measurements for mated and unmated individuals 4- to 6-d-old were recorded for 24 h. The results of the actograph assay revealed that mated females moved more actively than unmated females, possibly because of their oviposition behavior. Both the flight duration and flight range, which were measured by the flight mill device, decreased continuously with age and did not show a significant difference between mated and unmated females through the ages from 4 to 6 d. This result indicates that mating status did not directly affect the flight duration or range. From our experiments, it was suggested that females maintain physical energy after mating at the same level as before mating and then mated females locomote more actively around the host plants for oviposition. These speculations are discussed in relation to the control of A. nigrisigna by mating disruption.
Mating Compatibility Among Four Pest Members of the Bactrocera dorsalis Fruit Fly Species Complex (Diptera: Tephritidae)
M. K. Schutze, A. Jessup, I. Ul-Haq, M.J.B Vreysen, V. Wornoayporn, M. T. Vera, A. R. Clarke
KEYWORDS: oriental fruit fly, prezygotic compatibility, sexual isolation
Bactrocera dorsalis (Hendel), Bactrocera papayae Drew & Hancock, Bactrocera philippinensis Drew & Hancock, and Bactrocera carambolae Drew & Hancock are pest members within the B. dorsalis species complex of tropical fruit flies. The species status of these taxa is unclear and this confounds quarantine, pest management, and general research. Mating studies carried out under uniform experimental conditions are required as part of resolving their species limits. These four taxa were collected from the wild and established as laboratory cultures for which we subsequently determined levels of prezygotic compatibility, assessed by field cage mating trials for all pair-wise combinations. We demonstrate random mating among all pair-wise combinations involving B. dorsalis, B. papayae, and B. philippinensis. B. carambolae was relatively incompatible with each of these species as evidenced by nonrandom mating for all crosses. Reasons for incompatibility involving B. carambolae remain unclear; however, we observed differences in the location of couples in the field cage for some comparisons. Alongside other factors such as pheromone composition or other courtship signals, this may lead to reduced interspecific mating compatibility with B. carambolae. These data add to evidence that B. dorsalis, B. papayae, and B. philippinensis represent the same biological species, while B. carambolae remains sufficiently different to maintain its current taxonomic identity. This poses significant implications for this group's systematics, impacting on pest management, and international trade.
Sperm Storage and Sperm Competition in the Helicoverpa armigera (Lepidoptera: Noctuidae)
Shuo Yan, Huiting Li, Jing Zhang, Jialin Zhu, Qingwen Zhang, Xiaoxia Liu
KEYWORDS: Helicoverpa armigera, sperm transfer, polyandry, mating history, sperm competition
The mechanism of reproductive behavior and sperm competition strategy in Helicoverpa armigera (Hübner) has been an interesting topic for quite some time. In the current study, sperm motility pattern and sperm competition in H. armigera were investigated. The majority of apyrene and eupyrene sperm from spermatophore were simultaneously transferred to spermatheca 2 h after copulation. During 3–24 h after copulation, the amounts of apyrene and eupyrene sperm both sharply decreased and only approximately one seventh of one ejaculate remained stable. We used highly variable microsatellite loci to survey 13 families with a total of 379 offspring (mean 29.2 per family). In 8 of 13 families, all offspring were assigned to the last male, and 85.9% of offspring were sired by the last male in total. The possible mechanism of sperm competition in H. armigera encompassed the combined effects of both relatively fixed volume of sperm storage by females and the displacement of sperm from the formerly mated males. This study provides insight into the mechanism underlying sperm precedence in H. armigera, and it is important for potential control of the cotton bollworm.
The Influence of Insecticides and Vegetation in Structuring Formica Mound Ant Communities (Hymenoptera: Formicidae) in Maine Lowbush Blueberry
Beth Choate, Francis A. Drummond
KEYWORDS: Formica sp, insecticide toxicity, mound-building ants, blueberry
Assessing the influence of new, reduced-risk insecticides on natural enemies within agroecosystems is essential to developing integrated pest management strategies. Three species of mound-building Formica ants are abundant throughout Maine lowbush blueberry fields (Formica, exsectoides Forel, F. glacialis Wheeler, and F. ulkei Emery). All three species have been described in the literature as predaceous, with research demonstrating that F. exsectoides preys on major pest insects of lowbush blueberry. The objectives of this study were to determine the impact of common-use and newly introduced insecticides on Formica sp. ant communities in lowbush blueberry fields. Laboratory assays indicated that the commonly applied insecticide phosmet is toxic to F. exsectoides, even after 8 d of field weathering (P < 0.05). Species comparisons indicated that susceptibility varied with exposure to residues in the field. However, some of the reduced-risk biorational insecticides, such as acetamiprid, had little effect on survival of all three species. Abundance of each species in the field varied with lowbush blueberry pesticide-use strategy and amount of nonblueberry vegetation. Both F. exsectoides and F. glacialis were most abundant in organic fields; however, overall F. glacialis was the most abundant in fields of all management types. Field surveys support laboratory results suggesting that phosmet is highly toxic to these species and influences their spatial pattern. Manipulation of the crop to conserve natural enemies in lowbush blueberry is difficult because the crop is not planted; therefore, we must look closely at the incorporation of low toxicity insecticides with natural enemies to efficiently control pest insects.
Performance of Methyl Eugenol Matrix Toxicant Combinations Under Field Conditions in Hawaii and California for Trapping Bactrocera dorsalis (Diptera:Tephritidae)
Eric B. Jang, Amanda Ramsey, Lori. A. Carvalho
KEYWORDS: monitoring traps, methyl eugenol, polymer matrix, toxicant, spinosad
The oriental fruit fly, Bactrocera dorsalis (Hendel) is a major pest of many fruit crops worldwide. Current detection programs by federal and state agencies in the United States use a grid of traps consisting of liquid methyl eugenol (lure) and naled (toxicant) applied to cotton wicks and hung inside the trap. In recent years efforts have been made to incorporate these chemicals into various solid-type matrices that could be individually packaged to reduce human exposure to the chemicals and improve handling. New solid formulations containing methyl eugenol and either naled or dichlorovinyl dimethyl phosphate toxicants were compared with the standard formulations on cotton wicks in large scale field evaluation in Hawaii. Two reduced risk toxicants (spinosad and Rynaxypyr) were also evaluated. In one test the solid lure-toxicant-matrix combinations were sent to California to be weathered under California climate conditions and then sent back to Hawaii for evaluation. The polymer matrices with lure and toxicant were found to be as attractive as baited wicks and have the same longevity of attraction regardless of being weathered in Hawaii or in California. The new ingestible toxicants were also effective, although further testing of these ingestible lure toxicant matrix products is necessary.
Tapachula-7, a New Genetic Sexing Strain of the Mexican Fruit Fly (Diptera: Tephritidae): Sexual Compatibility and Competitiveness
Dina Orozco, J. Salvador Meza, Silvia Zepeda, Eduardo Solís, J. Luis Quintero-Fong
KEYWORDS: Anastrepha ludens, Tapachula-7, sterile insect technique, genetic sexing, sexual behavior
A new genetic sexing strain of the Mexican fruit fly, Anastrepha ludens (Loew), was evaluated in tests of sexual behavior to determine its possible application using the sterile insect technique. Tests in field cages measuring time to sexual maturity, compatibility with wild flies, and competitiveness were compared between the genetic sexing strain, Tapachula-7, and the mass-reared standard bisexual strain. The results indicated that the onset of sexual maturity was similar for both laboratory strains. Males from the Tapachula-7 strain do not differ from the standard bisexual strain in compatibility and competitiveness with wild insects. The results indicate that the release of Tapachula-7 males in the field would be viable in programs that use the sterile insect technique for the control of the Mexican fruit fly.
Ricinus communis and Jatropha curcas (Euphorbiaceae) Seed Oil Toxicity Against Atta sexdens rubropilosa (Hymenoptera: Formicidae)
E. C. Alonso, D.Y.A.C. Santos
KEYWORDS: leaf-cutting ant, Atta sexdens rubropilosa, castor oil, physic nut, seed lipid
Leaf-cutting ants are the main herbivores in the New World tropics. Although the toxicity of seed oils against these ants has been poorly investigated, previous results revealed that seed oils exert considerable toxic activity against these insects. This paper analyzes the toxic action and deterrent properties of castor oil, Ricinus communis L., and physic nut oil, Jatropha curcas L., against workers of the leaf-cutting ant Atta sexdens rubropilosa reared in laboratory. Toxic effect was analyzed by feeding insects artificial diets supplemented with different oil concentrations and direct contact with the two oils. Deterrent activity was assessed by measuring the frequency of attendance to diets during the first 48 h of the ingestion bioassay. Castor oil at 10 and 30 mg/ml and physic nut oil at 5, 10, and 30 mg/ml were toxic by ingestion. In the direct contact bioassay, toxicity was observed for physic nut oil at 0.1 and 0.2 mg/ml, whereas castor oil exerted toxic effects only when the highest concentration was applied. Also, castor oil had a more pronounced deterrent effect against the leaf-cutting ant, compared with physic nut oil. Methods to apply these oils to control these insects are discussed.
Microscopic Analysis of Spodoptera frugiperda (Lepidoptera: Noctuidae) Embryonic Development Before and After Treatment with Azadirachtin, Lufenuron, and Deltamethrin
Alicely A. Correia, Valéria Wanderley-Teixeira, Álvaro A. C. Teixeira, José V. Oliveira, Gabriel G. A. Gonçalves, Marília G. S. Cavalcanti, Fábio A. Brayner, Luiz C. Alves
KEYWORDS: egg, embryology, fall armyworm, insecticide, morphology
The botanical insecticides, growth regulators, and pyrethroids have an effect on the biology of Spodoptera frugiperda (Smith). However, no emphasis has been given to the effect of these insecticides on embryonic development of insects, in histological level. Thus, this research aimed to examine by light and scanning electron microscopy S. frugiperda eggs and to describe the embryonic development, before and after immersion treatment, using commercial concentrations and lower concentrations than commercial ones, of the compounds lufenuron (Match), azadirachtin (AzaMax), and deltamethrin (Decis-positive control). For light microscopy semithin sections of eggs were used, and for scanning electron microscopy, images of the surface of eggs, treated and untreated with insecticides. The morphological characteristics of S. frugiperda eggs, in general, were similar to those described in the literature for most of the insects in the order Lepidoptera. Spherical eggs slightly flattened at the poles, with chorion, yolk, vitelline membrane, and embryo formation. In both microscopic analysis, we observed that insecticides acted immediately and independent of concentration, resulting absence, or incomplete embryo, presented yolk granules widely dispersed, without vitellophage formation, chorion disintegration, disorganized blastoderm, presenting vacuoles, yolk region with amorphous cells, and formation of completely uncharacterized appendages. Thus, we conclude that the compounds lufenuron and azadirachtin interfere on S. frugiperda embryonic development.
Synthetic Pesticides in Agro-Ecosystems: Are they as Detrimental to Nontarget Invertebrate Fauna as We Suspect?
Sommer Jenkins, Ary A. Hoffmann, Stuart Mccoll, Angelos Tsitsilas, Paul A. Umina
KEYWORDS: pesticide, nontarget, mortality, invertebrate, agro-ecosystems
Broad-spectrum pesticides used to protect field crops and pastures from invertebrate pests are frequently reported to reduce populations of nontarget fauna, but there is often little relevant field data. Nonetheless, this notion is used to promote the adoption of more selective pesticides with less impact on nontarget invertebrates, including beneficial insects. Selective pesticides are not widely available for broad-acre grain crops and pastures in southern Australia; however, several options available in other industries could be compatible with these agricultural systems. In this study, the impact of broad-spectrum pesticides and several selective pesticides on nontarget invertebrate fauna was assessed in five field trials in wheat and canola fields. Despite extensive sampling over short and medium timeframes, few treatment effects on nontarget groups were detected. In cases where broad-spectrum pesticides were detrimental, patterns were often inconsistent among nontarget groups and between field trials. In contrast, the pest species, Hatotydeus destructor Tucker and Penthateus spp., were effectively controlled by the broad-spectrum treatments and less effectively by the selective pesticides. The inconsistent and relatively small impact of broad-spectrum pesticides on some nontarget invertebrates demonstrates that caution is required when extrapolating from laboratory-based assessments routinely used to assess the impacts of pesticides to field conditions in agriculture.
Laboratory Bioassays to Estimate the Lethal and Sublethal Effects of Various Insecticides and Fungicides on Deraeocoris brevis (Hemiptera: Miridae)
K. G. Amarasekare, P. W. Shearer
KEYWORDS: biological control, generalist predator, pear psylla, lethal and sublethal effect, reduced-risk insecticide
This laboratory bioassay focused on lethal and sublethal effects of five insecticides (chlorantraniliprole, cyantraniliprole, spinetoram, novaluron, and lambda-cyhalothrin) and two fungicide treatments (sulfur and a mixture of copper hydroxide and mancozeb) on the predatory mired bug, Deraeocoris brevis (Uhler) (Hemiptera: Miridae) using second instars and adult males and females. Formulated pesticides were tested using concentrations that were equivalent to the high label rate (1x) (high rate) and 1/10th of that amount (0.1x) (low rate) dissolved in 378.5 liters of water. Lambda-cyhalothrin was highly toxic to D. brevis nymphs and adults at both rates, whereas both rates of novaluron were highly toxic to nymphs. Cyantraniliprole, chlorantraniliprole, and novaluron were less toxic to adults, and chlorantraniliprole and spinetoram were less toxic to nymphs. Both rates of spinetoram caused significant mortality to adults. Fecundity of adult females was affected negatively by the high rates of either novaluron or spinetoram, whereas the fertility was affected only by the high rate of novaluron. The high rate of spinetoram reduced survival of nymphs. Adults treated with spinetoram had reduced longevity. Cyantraniliprole caused some mortality to nymphs and affected their survival. Both rates of sulfur were toxic to nymphs and affected emergence to adults. The mixture of copper hydroxide and mancozeb was less toxic to D. brevis. Neither adult longevity nor sex ratio was affected by the fungicides. The r values for D. brevis treated with lambda-cyhalothrin, novaluron, spinetoram, and sulfur were low, indicating that these products may have negative impact on population growth.
FIELD AND FORAGE CROPS
Further Studies on Wireworm Management in Canada: Damage Protection Versus Wireworm Mortality in Potatoes
Robert S. Vernon, Willem G. Van Herk, Markus Clodius, Chantelle Harding
KEYWORDS: wireworm, Potato, damage, mortality, recovery
The efficacy of various insecticides and application methods in protecting potatoes from wireworm (Agriotes obscurus L.) damage as well as reducing wireworm populations was studied over 5 yr in Agassiz, British Columbia. Protection from wireworm damage was measured by the number of blemishes to daughter tubers, and effects on wireworm populations were measured by sampling soil around seed potatoes and/or by bait traps the following spring. Organophosphates registered for wireworm control in the United States and/or Canada (phorate and chlorpyrifos), significantly reduced blemishes to tubers by, respectively, 92.2 and 90.2%, and populations of large (≥9 mm long = 'resident') wireworms by 83.4 and 71.0% relative to controls. Similar reductions in smaller (<9 mm long = 'neonate') wireworms were also observed. Neonicotinoids (imidacloprid, clothianidin, and thiamethoxam) tested as seed piece treatments at ≈12.5 g active ingredient/100 kg potato seed reduced blemishes by, respectively, 19.1, 71.6, and 90.6%, but resident wireworms were only reduced by, respectively, 22.0, 29.1, and 51.8%. Significant mortality of neonates was not observed with any neonicotinoid treatment. With the possible exception of thiamethoxam, where significant reduction in resident wireworms occurred, it is likely that the blemish protection provided without significant wireworm mortality with imidacloprid and clothianidin treatments was because of long-term wireworm intoxication followed by population recovery. The phenyl pyrazole, fipronil, applied as an in-furrow spray reduced blemishes by 94.3%, and resident wireworm populations could not be detected in plots the following spring. Neonates were reduced by 93.3%, indicating excellent residual control had occurred with fipronil. These studies indicate that tuber protection by fipronil and currently registered organophosphates is likely because of significant early season mortality of wireworms, whereas neonicotinoids generally provide control through long-term morbidity without high levels of mortality occurring.
Application of a Frequency Distribution Method for Determining Instars of the Beet Armyworm (Lepidoptera: Noctuidae) from Widths of Cast Head Capsules
Y. Chen, S. J. Seybold
KEYWORDS: Spodoptera exigua (Hübner), nitrogen, instar determination method, Kernel Density Estimation
Instar determination of field-collected insect larvae has generally been based on the analysis of head capsule width frequency distributions or bivariate plotting, but few studies have tested the validity of such methods. We used head capsules from exuviae of known instars of the beet armyworm, Spodoptera exigua (Hübner) (Lepidoptera: Noctuidae), to determine the larval instars with the frequency distribution method and Dyar's rule. Head capsule widths of S. exigua ranged from 0.313 to 1.446 mm. The number of instars from the analytical method matched that from the observed data. Based on misclassification rules derived from nonlinear least square fitting of the head capsule width data, the theoretical misclassification rates ranged from 0.62 to 1.92%. Comparing the theoretical distribution to the observed data, the observational misclassification probabilities ranged from 1.18 to 3.03%. There were also 10 head capsules, eight third instars and two fourth instars, not classified into any of the known instars based on the theoretical distributions. Dyar's growth ratios of successive instars ranged from 1.41 to 1.65, and those based on the observed data and theoretical distribution were similar. Both approaches yielded a linear relationship between the natural logarithm of the mean head capsule width and the instar number, which indicates full representation of the larval instars. The results demonstrated that the frequency distribution-based method was robust, although we recommend caution when using such methods to classify head capsules into specific instar classes. Application of computer algorithms should also be accompanied by visual inspection to determine instars from the frequency distribution.
Effects of Aldicarb and Neonicotinoid Seed Treatments on Twospotted Spider Mite on Cotton
J. F. Smith, A. L. Catchot, F. R. Musser, J. Gore
KEYWORDS: thiamethoxam, imidacloprid, acephate, aldicarb, soil-applied insecticides
Twelve field experiments and one laboratory experiment were conducted to determine the effects of furrow applied aldicarb and seed treatments of thiamethoxam, imidacloprid, Avicta (thiamethoxam abamectin), Aeris (imidacloprid thiodicarb), and acephate on twospotted spider mite, Tetranychus urticae Koch, on cotton, Gossypium hirsutum L. For the field experiments, data were pooled across all experiments for analysis. Aeris, thiamethoxam, and imidacloprid treatments resulted in twospotted spider mite densities greater than those in the untreated check, aldicarb, and acephate treatments. However, cotton treated with Avicta (thiamethoxam abameetin) had 34% fewer mites than other neonicotinoid seed treatments when infestations occurred near cotyledon stage. Untreated check and aldicarb treatments had the lowest mite densities. Only aldicarb reduced mite densities below that in the untreated check. In a laboratory trial, the fecundity of twospotted spider mite was measured. While neonicotinoid seed treatments increased mite densities in the field, they did not increase fecundity in the laboratory experiment. Foliar applied thiamethoxam slightly elevated average fecundity in the laboratory experiment. Increased use of neonicotinoid seed treatments instead of furrow applied aldicarb is likely at least partly responsible for recent increased twospotted spider mite infestations in seedling cotton across the mid-south.
Injury and Interplant Compensation for Southwestern Corn Borer (Lepidoptera: Crambidae) Infestations in Field Corn
S. Steckel, S. D. Stewart
KEYWORDS: corn, southwestern corn borer, Diatraea grandiosella, refuge, compensation
Growers that plant Bacillus thuringiensis (Bt) Berliner corn (Zea mays L.) hybrids are required to plant non-Bt corn for resistance management. Refuge in a bag (RIB) is an emerging approach for resistance management where, for some hybrids having multiple Bt traits for a target species, the refuge is planted as a blend of Bt and non-Bt corn. Studies were conducted to evaluate how southwestern corn borer (Diatraea grandiosella Dyar), when infested at different densities and growth stages, affected the yield of infested, non-Bt plants and neighboring Bt plants. Infesting non-Bt corn plants with southwestern corn borer larvae caused significant injury. Both the number of larvae infested on plants and the timing of these infestations affected the number of kernels per ear, total kernel weight, and the weight of individual kernels. Infestation timing was more important than the number of larvae inoculated onto plants, with pretassel infestations causing more yield loss. There was little compensation by Bt plants that were adjacent to infested plants. Thus, the risk of yield loss from stalk tunneling larvae in a refuge in a bag scenario should be directly proportional to the percentage of non-Bt plants and the level of yield loss observed in these non-Bt plants. Because current refuge in a bag systems have five or 10% non-Bt corn plants within the seed unit, the likelihood of substantial yield losses from infestations of corn boring larvae is remote given our results, especially for infestations that occur after silking has begun.
Evaluation of Corn Hybrids Expressing Cry34Ab1/Cry35Ab1 and Cry3Bb1 Against the Western Corn Rootworm (Coleoptera: Chrysomelidae)
P. L Prasifka, D. M. Rule, N. P. Storer, S. P. Nolting, W. H. Hendrix
KEYWORDS: transgenic corn, Diabrotica virgifera virgifera, Event MON 89034, Event MON 88017, resistance management
Studies were conducted across nine U.S. states, over 5 yr, to characterize the efficacy of transgenic corn (Zea mays L.) hybrids producing insecticidal proteins derived from Bacillus thuringiensis (Bt) for control of western corn rootworm, Diabrotica virgifera virgifera Le Conte. Hybrids tested had the same genetic background, contained one of two single events (DAS-59122-7 expressing Cry34Ab1/Cry35Ab1 or MON 88017 expressing Cry3Bb1) or a pyramid consisting of both rootworm-active events (SmartStax traits) and were compared with a non-Bt near isoline. Frequency analyses of root feeding data showed that hybrids containing both events sustained less root damage (0–3 node injury scale) than hybrids containing either event alone. The levels of root protection provided by MON 88017 and DAS-59122-7 were not different from each other. Efficacy was also evaluated based on consistency of protection, based on the proportion of plants with root ratings of either ≤0.25 or <1.00 on the node injury scale. The combination of two modes of action in SmartStax provided greater product consistency over a single mode of action at the 0.25 level and all hybrids producing Bt proteins provided equally high consistency at the 1.00 level. Overall these data show single and multiple mode of action hybrids provided high, consistent protection over the past 5 yr across the trial geography; however, pyramiding the rootworm Bt events provided greater and more consistent root protection. These findings also support that pyramided traits like SmartStax (Cry3Bb1 Cry34Ab1/Cry35Ab1) remain a viable strategy for delaying resistance to either trait.
Evaluation of Pest Vulnerability of 'Benning' Soybean Value Added and Insect Resistant Near Isogenic Lines
Michelle Samuel—Foo, John N. All, H. Roger Boerma
KEYWORDS: Glycine max, insect resistance, value added traits, defoliation
Crop enhancement with value added traits may affect vulnerability to insects, and evaluating the susceptibility levels of the various value added traits in elite germplasm would aid in developing integrated pest management strategies. During 2007–2008, five 'Benning' soybean (Glycine max (L.) Merr) lines with different value added nutritional traits and four insect resistant quantitative trait loci (QTL) lines were evaluated in an effort to determine their pest vulnerability under artificial and natural insect pest populations. The lines showed variable susceptibility to lepidopterous insect pests classified as defoliators and stem feeders in replicated greenhouse and field tests. The study was carried out in Athens and Midville, GA. The green cloverworm (Hypena scabra (F.)) was the most common lepidopteran defoliator occurring in the fields. Other caterpillar pests found included the soybean looper (Pseudoplusia includens (Walker)), the bollworm (Helicoverpa zea (Boddie)), and the velvetbean caterpillar (Anticarsia gemmatalis (Hübner)). Data indicated that there was no significantly increased pest susceptibility among the value added cultivais with improved nutritional qualities, with the insect resistant quantitative trait loci lines Benning M and Benning MGH consistently being less susceptible to lepidopterous (Noctuidae) leaf injury.
An Injury Equivalency System for Establishing a Common Economic Threshold for Three Species of Rice Planthoppers (Hemiptera: Delphacidae) in Taiwan
Shou-Horng Huang, Ching-Huan Cheng, Chiou-Nan Chen, Wen-Jer Wu
KEYWORDS: rice, Oryza sativa, rice planthopper, feeding guild, injury equivalency
The economic threshold (ET) for multiple pest species that share the same injury type on host plants (feeding guild) has been proposed for decision-making in integrated management framework of many defoliating insect pests. However, only a few consider agricultural pests with sucking mouthparts. This study presents the first injury equivalency system for the feeding guild made up of three rice (Oryza sativa L.) planthopper (Hemiptera: Delphacidae) species—Nilaparvata lugens (Stål), Sogatella furcifera (Harváth), and Laodelphax striatellus (Fallén)—by using relative amount of honeydew excretion of each species. The intraspecific injury equivalent coefficient was determined; this coefficient provides an exchange rate for different developmental stages in a species. N. lugens was chosen as the standard species to obtain interspecific injury equivalents for other individuals in the guild, allowing estimates of total guild injury feasible. For extension purposes, the injury equivalency was simplified by pooling all nymphs and adults in the guild to mitigate the potential confusion resulting from uncertainty of instars or wing form. A matrix of ETs established on previous studies and incorporating changes of management cost and rice price was used and served as a control decision guide for the guild samples. The validity of the proposed injury equivalency system was tested using several field data sets, and the results are generally promising and meaningfully elevate the accuracy of estimating combined injury and damage to rice, suggesting that the proposed system is a better integrated pest management decision-making system compared with conventional practices.
Factors Affecting Pheromone-Baited Trap Capture of Male Coleophora deauratella, an Invasive Pest of Clover in Canada
Boyd A. Mori, Maya L. Evenden
KEYWORDS: Coleophora deauratella, monitoring, clover, pheromone-baited traps
Coleophora deauratella Leinig and Zeller (Lepidoptera: Coleophoridae) is an invasive pest of red clover, Trifolium pratense L. (Fabeles: Fabaceae), grown for seed in Canada. A pheromone-based monitoring program to determine the presence and seasonal activity of adult C. deauratella would be a valuable tool for growers because larvae are difficult to sample due to their internal feeding behavior. We conducted field experiments to evaluate several pheromone-baited trap characteristics, including pheromone lure substrate, trap type, trap color, lure longevity, trap height, and field position. The type of substrate that pheromone was released from and lure age did not affect trap capture of male C. deauratella. Moth capture in nonsaturating green Unitraps was significantly higher than Diamond or Wing traps when inspected at 2-wk intervals. Multi-colored Unitraps caught significantly more male C. deauratella than Diamond, and Wing traps when inspected at weekly intervals. Trap color did not influence C. deauratella capture, but by-catch of bumblebees, Bombus spp., was greatest in yellow and white colored Unitraps. Traps placed 35 cm above the soil surface captured more male C. deauratella than those placed at 1 m above or at ground level regardless of trap position within the field. Green Unitraps baited with either gray or red rubber septa lures placed 35 cm above the soil surface and 5 m from the field edge should be used to monitor C. deauratella. These characteristics optimize pheromone-baited trap performance and reduce by-catch of beneficial insects, and should be incorporated into a C. deauratella pheromone-monitoring program.
Permeability Barriers to Embryo Cryopreservation of Pectinophora gossypiella (Lepidoptera: Gelechiidae)
Arun Rajamohan, Joseph P. Rinehart, Stephen P. Foster, Roger A. Leopold
KEYWORDS: Pectinophora gossypiella, pink bollworm moth, cryopreservation, embryos, permeabilization
The aim of this study was to develop a method to cryopreserve the embryos of the pink bollworm moth, Pectinophora gossypiella (Saunders). Previously developed dipteran cryopreservation protocols were not directly adaptable to use with the embryos of this lepidopteran species. Physiochemical and electron microscope observations revealed substantial differences in the structure of the chorion, wax layer, and vitelline membrane complex when comparing the cryopreservable embryonic stages of P. gossypiella and dipteran embryos. Thus, the initial steps dealing with dechorionation and permeabilization were ineffective and had to be altered. Exposure to the sodium hypochlorite-based chorion removal step decreased P. gossypiella embryo viability to a very low level. Survival increased and permeability was evident when an alkane wash was used as the first step in the procedure. After the alkane treatment with a surfactant yielded the maximum exchange of cryoprotectant with water as evidenced by a significant lowering of the supercooling point of the cryoprotectant-loaded embryos. The remainder of the cryopreservation and storage recovery protocol for P. gossypiella was similar to those developed for dipteran embryos. Survival of recovered, hatched embryos to adulthood was ≈7%.
Impact of Twospotted Spider Mite (Acari: Tetranychidae) Duration of Infestation on Cotton Seedlings
W. S. Scott, A. Catchot, J. Gore, F. Musser, D. Cook
KEYWORDS: Tetranychus urticae, twospotted spider mite, cotton, yield
The yield response of cotton, Gossypium hirsulum L., to twospotted spider mite, Tetranychus urticae Koch, duration of infestation during the seedling stage was measured at Starkville and Stoneville, MS, during 2010 and 2011. The treatments included a noninfested control, infestations lasting for 7, 14, 21, or 28 d, and a season long infested control. Twospotted spider mites from a greenhouse colony were inoculated on all of the infested cotton plots during the three-leaf stage. Applications of miticides were made to terminate infestations at the desired timings for each treatment. Twospotted spider mite densities and injury ratings were determined for each treatment at the end of the infestation period and yield was measured at the end of the season. Twospotted spider mite densities and injury rating significantly increased as duration of infestation increased. Significant differences in yield were observed between treatments. These data suggest infestations initiated at the three-leaf cotton growth stage with population densities at a minimum of 0.39 mites/cm2 existing >14 d could result in reduction of cotton yields.
FOREST ENTOMOLOGY
First Report of Endoclita signifer (Lepidoptera: Hepialidae) as a New Pest on Eucalyptus
Xiu-Hao Yang, Yong-Hui Yu, Yao-Jun Wu, Jiang-Lin Qin, You-Qing Luo
KEYWORDS: Endoclita signifier, Eucalyptus, forest pest, life cycle, morphology
Endoclita signifier Walker (Lepidoptera: Hepialidae) has become a new wood borer pest in Eucalyptus plantations in southern China. This article documents survey results of its geographic distribution and host plant range in Guangxi and its morphological measurements, life cycle and behavior. In total, 83 Eucalyptus growing counties were surveyed. E. signifier was found in 59 counties. Host plants included 31 species in 16 families and 24 genera. Four Eucalyptus hybrid species were recorded as its host plant with E. grandis × E. urophyllo and E. urophylla × E. grandis infested the heaviest. The infestation of Eucalyptus trees 1–2 yr old was heavier than that of older trees. Most individuals of E. signifier took 1 yr to complete a generation, overwintering as larvae in tunnels in wooden stems, and pupating in February of the following year. Adults emerge, mate, and lay eggs in April, and the eggs hatch in late April or early May. Adult emergence peaks between 17:00–18:59 hours. Mating flights last under 30 min at dusk and the copulation duration was 24 h. Moths were large, weighting and average of 3.4 g. Eggs and newly hatched larvae were very small, weighing only 0.127 ± 0.001 mg and 0.093 ± 0.017 mg, respectively. The larvae have two distinct development stages. One stage spends 1–2 mo living in the forest litter, the second stage then moves to woody stems where it feeds for ≈10 mo. Larvae start boring into hosts between June and November, mainly in July and August. This study indicated that E. signifier, a highly polyphagous native species, has shifted host to exotic Eucalyptus and can cause significant damage to plantations.
The Within-Season and Between-Tree Distribution of Imidacloprid Trunk-Injected Into Acer platanoides (Sapindales: Sapindaceae)
Todd A. Ugine, Sana Gardescu, Ann E. Hajek
KEYWORDS: Acer platanoides, neonicotinoid, imidacloprid, distribution, translocation
Norway maple trees, Acer platanoides L. (Sapindales: Sapindaceae), that were trunk-injected with imidacloprid as part of an Asian longhorned beetle eradication program, were used to study the temporal and between-tree distribution of imidacloprid in twigs from June through September. The effect of injection time during spring on imidacloprid residues across the summer season and the distribution of imidacloprid in twig bark versus twig xylem were also investigated. Overall, we observed a significant decline in imidacloprid concentrations within each plant part sampled across the study period, although the 19 trees used in the study varied greatly in the pattern of imidacloprid residues over time. The concentration of imidacloprid in twig bark per dry mass was approximately two times higher than that of the twig xylem (means ± SD of 1.21 ± 2.16 ppm vs. 0.63 ± 1.08 ppm imidacloprid, respectively). The majority (>50%) of whole twig, twig bark and twig xylem samples from injected trees contained <1 ppm imidacloprid and 37% of twig samples contained 0 ppm. Maximum values were 9 ppm for whole twigs from trunk-injected trees, 12 ppm imidacloprid for twig bark, and 5 ppm for twig xylem. Leaves, sampled only in September, had much higher imidacloprid residues than twigs collected at the same time; the majority (53%) of leaf samples contained >5 ppm imidacloprid, with a maximum of 49 ppm. The concentrations of imidacloprid in whole twigs, twig bark, and twig xylem were highly correlated, and levels in leaves were correlated with imidacloprid levels in whole twigs.
HORTICULTURAL ENTOMOLOGY
Host Susceptibility of Citrus Cultivars to Queensland Fruit Fly (Diptera: Tephritidae)
A. C. Lloyd, E. L. Hamacek, D. Smith, R. A. Kopittke, H. Gu
KEYWORDS: Bactrocera tryoni, citrus, host susceptibility, field infestation
Citrus crops are considered to be relatively poor hosts for Queensland fruit fly, Bactrocera tryoni (Froggatt), as for other tephritid species. Australian citrus growers and crop consultants have reported observable differences in susceptibility of different citrus cultivars under commercial growing conditions. In this study we conducted laboratory tests and field surveys to determine susceptibility to B. tryoni of six citrus cultivars [(Eureka lemon (Citrus limon (L.) Osbeck); Navel and Valencia oranges (C. sinensis (L.) Osbeck); and Imperial, Ellendale, and Murcott mandarins (C. reticulata Blanco)]. The host susceptibility of these citrus cultivars was quantified by a Host Susceptibility Index, which is defined as the number of adult flies produced per gram of fruit infested at a calculated rate of one egg per gram of fruit. The HSI was ranked as Murcott (0.083) > Imperial (0.052) ≥ Navel (0.026) ≥ Ellendale (0.020) > Valencia (0.008) ≥ Eureka (yellow) (0.002) > Eureka (green) (0). Results of the laboratory study were in agreement with the level of field infestation in the four citrus cultivars (Eureka lemon, Imperial, Ellendale, and Murcott mandarins) that were surveyed from commercial orchards under baiting treatments against fruit flies in the Central Burnett district of Queensland. Field surveys of citrus hosts from the habitats not subject to fruit fly management showed that the numbers of fruit flies produced per gram of fruit were much lower, compared with the more susceptible noncitrus hosts, such as guava (Psidium guajava L.), cherry guava (P. littorale Raddi), mulberry (Morus nigra L.), loquat (Eriobotrya japonica (Thunb.) Lindl.), and pear (Pyrus communis L.). Therefore, the major citrus crops commercially cultivated in Australia have a relatively low susceptibility to B. tryoni, with Eureka lemons being a particularly poor host for this tephritid fruit fly.
The Development of an Economic Threshold for Nasonovia ribisnigri (Hemiptera: Aphididae) on Lettuce in Central Spain
Ignacio Morales, Beatriz María Diaz, Alfonso Hermoso De Mendoza, Miguel Nebreda, Alberto Fereres
KEYWORDS: aphid damage, lettuce crop, economic threshold, edibility
This study reports economic thresholds for the lettuce aphid Nasonovia ribisnigri (Mosley), based exclusively on cosmetic damage, that is, presence or absence of aphids at harvest time. Field trials were conducted in La Poveda Experimental Farm, Madrid (Spain) during autumn (2004 and 2005) and spring (2005 and 2006). Plants were arranged in plots and just before the formation of lettuce hearts they were infested with different densities of N. ribisnigri. Two days later, half of each plot was treated with tau-fluvalinate (Klartan24AF) and the other half remained as an untreated control. Economic thresholds were obtained from nonlinear regressions calculated between the percentage of commercial plants at the end of the crop cycle for both, treated and untreated semiplots, and the different initial densities of N. ribisnigri per plant. Two criteria were used to consider a commercial lettuce plant: a conservative estimate (0 aphids/plant) and a lax one (<5 aphids/plant). Thus, an economic threshold was established for each season and criterium. The economic thresholds that were obtained with the most and least conservative criteria were in spring 0.06 and 0.12 aphids per plant, and in autumn 0.07 and 0.13 aphids per plant, respectively. These results show that to avoid cosmetic damage, insecticide sprays are required when a very low aphid density is detected in lettuce seedlings soon after transplant.
Predictive Modelling of Adult Emergence in a Polyphagous Eucolaspis (Chrysomelidae: Eumolpinae) Leaf Beetle
P.R.C. Doddala, S. A. Trewick, D. J. Rogers, M. A. Minor
KEYWORDS: bronze beetle, Chrysomelidae, degree-day, phenology model, temperature
Eucolaspis sp. "Hawke's Bay" (Chrysomelidae: Eumolpinae) is a pest that inflicts huge economic loss in many organic apple (Malus domestica Borkh.) orchards in New Zealand. The timing of control methods for this pest has been shown to be crucial for success. To aid in planning control programs, we studied threshold temperature and degree-days required for the development of Eucolaspis sp. "Hawke's Bay" pupae and modeled adult emergence in the field. Pupal development was observed at three constant temperatures. Pupae required 237.0 ± 21.67 degree-days above lower threshold temperature of 4.7°C ± 0.89°C to develop into adults. The emergence of adults was modeled with these thermal values and the model was tested for accuracy with field data. The model performed well with a precision of ±4 d. The proposed phenology model has wide applicability in monitoring and planning pest control measures.
Yield-Based Economic Thresholds for Grape Berry Moth (Lepidoptera: Tortricidae) in Juice Grapes
Craig R. Roubos, Keith S. Mason, Luís A. F. Teixeira, Rufus Isaacs
KEYWORDS: Paralobesia viteana, grape, economic injury level, integrated pest management
A 3-yr field study was conducted at commercial juice grape (Vitis labrusca L.) vineyards to develop an economic injury level (EIL) for grape berry moth, Paralobesia viteana (Clemens) (Lepidoptera: Tortricidae) and to determine patterns of cluster injury. Infestation of grape clusters by P. viteana was measured biweekly from bloom until harvest, and fruit was sampled immediately before harvest to determine the yield and level of fruit injury by this pest. Comparison of fruit infestation at each sampling date to that found just before harvest revealed stronger relationships over time, and by early August at least 50% of the variation in preharvest infestation was accounted for by previous infestation. Grape yield declined with increasing infestation by P. viteana, allowing calculation of the EIL at which the value of yield lost to infestation equaled the cost of insecticide applications to prevent the infestation. Using two scenarios of pest control programs based on pyrethroid or diamide insecticides, the EILs were calculated to be 9.9 and 17.7% of clusters damaged, respectively. For use in juice grape vineyard integrated pest management programs, we propose using 5 and 10% damaged clusters at harvest as action thresholds for further testing in field trials to evaluate sampling plans and the use of thresholds to guide vineyard pest management decision-making under different insecticide scenarios.
Species Composition, Monitoring, and Feeding Injury of Stink Bugs (Heteroptera: Pentatomidae) in Blackberry
S. A. Brennan, O. E. Liburd, J. E. Eger, E. M. Rhodes
KEYWORDS: blackberry, stink bug, Euschistus spp., injury, monitoring
Blackberry (Rubus spp.) production in Florida has increased >100% within the past two decades, and several insect pests, including stink bugs (Heteroptera: Pentatomidae), have been observed feeding on this crop. The objectives for this study were to determine the stink bug species present in blackberry; to develop monitoring tools for stink bugs in blackberry; and to describe feeding injury to blackberries by Euschistus quadrator Rolston, a relatively new stink bug pest to Florida, that has spread throughout the state. In a field survey, E. quadrator was the most abundant stink bug species, followed by Euschistus servus Say, Euschistus obscurus (Palisot de Beauvois), Thyanta custator (F.), Proxys punctulatus (Palisot de Beauvois), and Podisus maculiventris Say. Yellow pyramid traps caught more stink bugs than tube traps with or without the addition of Euschistus spp. pheromone lures. There were no statistical differences between traps baited with a Trécé Pherocon Centrum lure, a Suterra Scenturion lure, and an unbaited trap. These results were supported by Y-tube olfactometer assays with E. quadrator where there were no differences between pheromone baited lures and a control. Injury to berries caused by E. quadrator adults and third instars was similar, and both adults and third instars fed more on green berries compared with turning berries. In addition, adults fed more on green berries compared with ripe fruit. The most common injury to green berries was discoloration. In contrast, misshapen drupelets were commonly seen on turning and ripe berries. The potential for managing stink bugs in blackberries to prevent them from reaching damaging levels is discussed.
Tomato Spotted Wilt Virus Infection Reduces the Fitness of a Nonvector Herbivore on Pepper
Huipeng Pan, Gong Chen, Fei Li, Qingjun Wu, Shaoli Wang, Wen Xie, Baiming Liu, Baoyun Xu, Youjun Zhang
KEYWORDS: tomato spotted wilt virus, Bemisia tabaci, nonvector herbivore, fitness
Plant pathogens and insect herbivores often share hosts under natural conditions. Hence, pathogen-induced changes in a host plant can affect the herbivore and vice versa. Even though plant viruses are ubiquitous in the field, little is known about plant-mediated interactions between viruses and nonvector herbivores. Here we tested whether the performance of the sweet potato whitefly, Bemisia tabaci (Gennadius) biotype Q, was altered when raised on pepper infected with Tomato spotted wilt virus (TSWV). TSWV infection reduced B. tabaci fecundity and longevity and increased B. tabaci developmental time but did not affect the insect's survival or female body lengths. Our results demonstrate that TSWV infection can decrease the fitness of B. tabaci biotype Q on pepper plants.
HOUSEHOLD AND STRUCTURAL INSECTS
Asymmetrical Behavioral Response Towards Two Boron Toxicants Depends on the Ant Species (Hymenoptera: Formicidae)
Francisco Sola, Agustina Falibene, Roxana Josens
KEYWORDS: ant, boric acid, sodium borate, feeding, bait
Urban ants are a worldwide critical household pests, and efforts to control them usually involve the use of alimentary baits containing slow-acting insecticides. A common toxicant used is boron, either as borax or boric acid. However, the presence of these compounds can affect the consumption of baits by reducing their acceptance and ingestion. Moreover, as feeding motivation varies widely, according not only to food properties but also to colony conditions, bait consumption might be diminished further in certain situations. In this study, we compared the feeding response of ants toward two boron toxic baits (boric acid and borax) in low motivation situations that enhance any possible phago-deterrence the baits may produce. Most studies investigating bait ingestion evaluate whole nests or groups of ants; here, we analyzed the individual ingestion behavior and mortality of the Argentine ant, Linepithema humile (Mayr), and the carpenter ant, Camponotus mus (Roger), for two boron baits, to detect which compound generates a higher rejection in each of these species. Although these two species have similar feeding habits, our results showed that ants under low motivation conditions reduced the acceptance and consumption of the toxic baits asymmetrically. While L. humile mostly rejected the borax, C. mus rejected the boric acid. These results denote the importance of considering the preference of each species when developing a pest management strategy.
INSECTICIDE RESISTANCE AND RESISTANT MANAGEMENT
Evaluation of Cytochrome P450 Activity in Field Populations of Cydia pomonella (Lepidoptera: Tortricidae) Resistant to Azinphosmethyl, Acetamiprid, and Thiacloprid
L. B. Cichón, J. Soleño, O. L. Anguiano, S.A.S. Garrido, C. M. Montagna
KEYWORDS: codling moth, neonate, insecticide resistance, diagnostic concentration
The Rio Negro and Neuquén Valley is the most important apple and pear growing region in Argentina. Cydia pomonella L. (Lepidoptera: Tortricidae), the main fruit-tree pest is being controlled by azinphosmethyl (AzMe), acetamiprid (Acet), and thiacloprid (Thia) among other insecticides. The objective of this study was to evaluate the response of neonate larvae of codling moth to these three insecticides and on the role of cytochrome P450 monooxygenase in their toxicity. All field populations presented significantly lower mortality to a discriminating concentration (DC) of Acet and AzMe. In addition, 13 of the 14 populations showed significantly lower mortality to DC of Thia. Most of the field populations (71%) showed significantly higher 7-ethoxycoumarine O-deethylase activity compared with the laboratory-susceptible strain. While positive significant correlation (r = 0.59) was found between Thia and AzMe mortalities at the DC level, no significant correlations were detected between Acet and Thia (r = 0.35) or Acet and AzMe (r = 0.12). However, Acet and Thia mortalities were significantly correlated to the percentage of individuals exhibiting 7-ethoxycoumarine O-deethylase activity activities higher than the mean upper 95% confidence limit of the susceptible strain (r = -0.52 and r = -0.63, respectively).
Implementation of an Indoxacarb Susceptibility Monitoring Program using Field-Collected German Cockroach Isolates from the United States
Ameya D. Gondhalekar, Clay W. Scherer, Raj K. Saran, Michael E. Scharf
KEYWORDS: indoxacarb, gel bait, insecticide resistance, resistance monitoring, German cockroach
Indoxacarb, a sodium channel-blocking insecticide, has been in widespread use for German cockroach control in the United States since 2006. A two-tiered indoxacarb susceptibility monitoring strategy was previously developed as a first step toward determining indoxacarb susceptibility levels in German cockroach field populations. This strategy entails: (tier 1) testing field-collected populations in vial bioassays at two diagnostic concentrations; and (tier 2) testing populations at three diagnostic doses in oral (feeding) bioassays with treated bait matrix. In the current study the two-tiered technique was implemented to evaluate field (n = 14) and susceptible laboratory (n = 2) strains collected from 13 different U.S. locations. Our hypothesis was that at least some of the field-collected populations would display significant survivorship in both bioassays relative to susceptible laboratory populations. In agreement with this hypothesis, significantly reduced susceptibility was detected in 13 and 7 field strains with vial and feeding bioassays, respectively. In general, the lower number of strains displaying reduced susceptibility in feeding bioassays (seven strains) supports previous findings that indoxacarb is more toxic via ingestion. Although these findings suggest a reduced risk for resistance selection via feeding on indoxacarb-containing baits, they also suggest a need for proactive resistance management with respect to both spray and bait products.
Development of Insecticide Resistance in Field Populations of Brevicoryne brassicae (Hemiptera: Aphididae) in Pakistan
Mushtaq Ahmad, Shamim Akhtar
KEYWORDS: Brevicoryne brassicae, insecticide resistance, organophosphate, pyrethroid, neonicotinoid
Cabbage aphid Brevicoryne brassicae (L.) (Hemiptera: Aphididae) is a serious pest of crucifers in Pakistan. After incidences of poor control by recommended insecticides, the current study was undertaken to find out the status of insecticide resistance in Pakistani B. brassicae. Apterous adult aphids were bioassayed from 2006 to 2010 for their response to 12 insecticides using an adult immersion method. No or very low levels of resistance was found to endosulfan; and the organophosphates: chlorpyrifos and profenofos. Resistance to methomyl; emamectin benzoate; the pyrethroids: cypermethrin, lambdacyhalothrin, bifenthrin and deltamethrin; and the neonicotinoids: imidacloprid, acetamiprid, and thiamethoxam; increased progressively in concurrence with their regular use on vegetables. B. brassicae resistance to these insecticides remained very low to low in 2007 and 2008, but then it increased to moderate to high levels in 2009 (except cypermethrin and bifenthrin) and 2010. Under heavy infestations of this aphid, the application of insecticides having no, very low and low resistance is recommended in rotation.
Wide Spread Cross Resistance to Pyrethroids in Aedes aegypti (Diptera: Culicidae) from Veracruz State Mexico
Adriana E. Flores, Gustavo Ponce, Brenda G. Silva, Selene M. Gutierrez, Cristina Bobadilla, Beatriz Lopez, Roberto Mercado, William C. Black
KEYWORDS: Aedes aegypti, pyrethroids, insecticide resistance, cross-resistance
Seven F1 strains of Aedes aegypti (L.) were evaluated by bottle bioassay for resistance to the pyrethroids d-phenothrin, permethrin, deltamethrin, λ-cyalothrin, bifenthrin, cypermethrin, á-cypermethrin, and z-cypermethrin. The New Orleans strain was used as a susceptible control. Mortality rates after a 1 h exposure and after a 24 h recovery period were determined. The resistance ratio between the 50% knockdown values (RRKC50) of the F1 and New Orleans strains indicated high levels of knockdown resistance. The RRKC50 with α-cypermethrin varied from 10 to 100 among strains indicating high levels of knockdown resistance. Most of the strains had moderate resistance to (d-phenothrin. Significant but much lower levels of resistance were detected for λ-cyalothrin, permethrin, and cypermethrin. For z-cypermethrin and bifenthrin, only one strain exhibited resistance with RRKC50 values of 10- and 21-fold, respectively. None of the strains showed RRKC50 >10 with deltamethrin, and moderate resistance was seen in three strains, while the rest were susceptible. Mosquitoes from all strains exhibited some recovery from all pyrethroids except d-phenothrin. Regression analysis was used to analyze the relationship between RRKC50 and RRKC50. Both were highly correlated (R2 = 0.84-0.97) so that the slope could be used to determine how much additional pyrethroid was needed to ensure lethality. Slopes ranged from 0.875 for d-phenothrin (RRLC50 RRKC50) to 8.67 for ë-cyalothrin (∼8.5-fold more insecticide needed to kill). Both RRLC50 and RRKC50 values were highly correlated for all pyrethroids except bifenthrin indicating strong cross-resistance. Bifenthrin appears to be an alternative pyrethroid without strong cross-resistance that could be used as an alternative to the current widespread use of permethrin in Mexico.
Toxicities and Synergistic Effects of Several Insecticides Against the Oriental Fruit Fly (Diptera: Tephritidae)
Jing-Jing Wang, Dong Wei, Wei Dou, Fei Hu, Wei-Feng Liu, Jin-Jun Wang
KEYWORDS: Bactrocera dorsalis, toxicity, synergist, carboxylesterases
The oriental fruit fly, Bactrocera dorsalis (Hendel), is a serious insect pest that causes large losses to orchards globally. In this study, we conducted experiments to investigate the susceptibility of two populations (Kunming of Yunnan and Dongguan of Guangdong province) of B. dorsalis to nine insecticides. Bioassay results demonstrated that fipronil was the most effective insecticide, followed by phoxim, abamectin, triazophos, β-cypermethrin, chlorpyrifos, deltamethrin, malathion, and imidacloprid against the Kunming of Yunnan province population, with LD50 values that ranged from 1.55 to 187.48 ng/ fly. For the Dongguan of Guangdong province population, fipronil was also most toxic, followed by triazophos, phoxim, chlorpyrifos, abamectin, deltamethrin, β-cypermethrin, malathion, and imidacloprid, with LD50 values from 2.07 to 439.11 ng/fly. The addition of synergists triphenyl phosphate, piperonyl butoxide, and diethyl maleate yielded different levels of synergistic effects on different insecticides against each population. However, the synergistic effects on the nine insecticides against the two populations are different. The treatment of a sublethal dose (LD20) of λ-cypermethrin together with three synergists could induce increased specific activity of carboxylesterases at the beginning of exposure, followed by a decline within 24 h. The specific activity of carboxylesterases was higher in the fat body, midgut, and Malpighian tubules, suggesting these are important tissues for detoxification. Overall, the data developed in this study provide useful information for designing an insecticide management strategy for controlling this insect in the field.
MEDICAL ENTOMOLOGY
Identification of Volatile Compounds from a Food-Grade Vinegar Attractive to House Flies (Diptera: Muscidae)
Kun Qian, Junwei J. Zhu, Steve R. Sims, David B. Taylor, Xiaopeng Zeng
KEYWORDS: attractant compounds, vinegar, Musca domestica
A commercial vinegar product (ChinKiang) was found to be highly attractive to adult house flies, Musca domestica L. Field experiments on a Nebraska dairy demonstrated that traps baited with vinegar and brown sugar captured more house flies than those baited with other house fly attractants. Solid phase microextraction was used in the field to collect volatiles from the vinegar bait. Seven compounds were identified as, acetic acid, furfural, butanoic acid, isovaleric acid, hexanoic acid, 2-phenylethanol, and p-cresol. Electroantennograms showed that the seven vinegar components elicited significant responses from antennae of female and male house flies. Bioassays indicated that the vinegar blend of the seven volatile components were more attractive than any of the individual components. Field evaluations demonstrated that traps baited with the synthetic seven component blend caught as many flies as those baited with vinegar. This is the first detailed report of house fly attractants from vinegar. The vinegar volatile compounds identified in this study will be useful for the development of less objectionable alternatives to the fetid, manure mimicking volatiles currently used in commercial fly bait systems, especially those designed for use in indoor environments.
No Sex-Related Differences in Mortality in Bed Bugs (Hemiptera: Cimicidae) Exposed to Deltamethrin, and Surviving Bed Bugs Can Recover
Mark F. Feldlaufer, Kevin R. Ulrich, Matthew Kramer
KEYWORDS: bed bug, Cimex lectularius, deltamethrin, sex-specific mortality
Exposure of a pyrethroid-susceptible strain of bed bugs, Cimex lectularius L. (Hemiptera: Cimicidae) to varying concentrations of deltamethrin for 24 h indicated no significant difference in mortality between males, females, and nymphs at 24 nor at 168 h postexposure when bed bugs were removed to untreated surfaces at 24 h. In addition, many bed bugs classified as morbid or moribund at 24 h and removed to untreated surfaces at this time, recovered by 336 h (2 wk) and were capable of feeding when given the opportunity. Adult female bed bugs that survived were able to lay eggs and the resulting nymphs blood-fed. By contrast, all bed bugs classified as morbid or moribund at 24 h that remained on deltamethrin-treated surfaces for 336 h either died or were still classified as morbid or moribund at the end of this time. No bed bugs classified as morbid or moribund blood-fed when given the opportunity at 2 wk, regardless of whether they remained on the treated surfaces or were removed to untreated surfaces. A power analysis demonstrated we would have detected even moderate differences in mortality between males and females, had differences existed. Therefore, using males exclusively in efficacy assays is a suitable strategy to preserve females for laboratory colony purposes. Results also indicated there is little reason to assess efficacy beyond 1 wk, even when bed bugs are exposed for only 24 h.
MOLECULAR ENTOMOLOGY
Genetic and Cytogenetic Characterization of Genetic Sexing Strains of Bactrocera dorsalis and Bactrocera cucurbitae (Diptera: Tephritidae)
A. Zacharopoulou, G. Franz
Journal of Economic Entomology 106 (2), 995-1003, (1 April 2013) https://doi.org/10.1603/EC12379
KEYWORDS: Bactrocera dorsalis, Bactrocera cucurbitae, polytene chromosome, genetic sexing strain, Tephritidae
In the current study, we performed genetic and cytogenetic analyses of two genetic sexing strains (GSSs), one for Bactrocera dorsalis s.s. and one for melon fly, Bactrocera Cucurbitae Coquillett, the first such strains ever constructed in these species. In both strains, the genetic sexing mechanism is based on a pupal color dimorphism (white or brown) and is the result of a reciprocal translocation between the Y chromosome and the autosome bearing the white pupae (wp) locus. Based on genetic analysis and cytological data on mitotic metaphases and larval salivary gland polytene chromosomes, we succeeded in mapping the autosome breakpoints in the two Y-autosome translocations even though the Y chromosome is not visible in polytene nuclei. We show that polytene chromosomes can be used in cytogenetic analyses toward the development of genetic control methods in these pest species. The results of the genetic analysis are in full agreement with the cytological description of the strains.
Genetic Variation in Bactericera cockerelli (Hemiptera: Triozidae) from Mexico
Beatriz Lopez, Susana Favela, Gustavo Ponce, Rahim Foroughbakhch, Adriana E. Flores
Journal of Economic Entomology 106 (2), 1004-1010, (1 April 2013) https://doi.org/10.1603/EC12258
KEYWORDS: Homoptera, Psyllidae, genetic differentiation, molecular marker, ISSR
Bactericera cockerelli (Sulc) is a significant pest of several solanacious crops in Mexico and the United States since 1970. In 2001 significant outbreaks of outstanding importance were observed for the first time in areas where infestations of this insect were historically rare. Molecular studies revealed that this was because of the development of a new biotype of B. cockerelli that had become adapted to south-western United States, further demonstrating that this genetic differentiation was reflected in the survival, development cycle, fertility, and growth rate of both the native biotype as well as the one recently reported. To determine genetic variation in populations of B. cockerelli from Mexico, inter simple sequence repeat were used. Results showed that populations of B. cockerelli from central and northeastern Mexico (Guanajuato, Morelos, Estado de Mexico, and Nuevo Leon states) are genetically similar, meanwhile B. cockerelli from northwest, southwest, and southeast of the country (Sinaloa, Michoacan, and Oaxaca states) are genetically distinct from each other and from the rest of the populations included in the study.
PLANT RESISTANCE
Chemical Characteristics of Normal, Woolly Apple Aphid-Damaged, and Mechanically Damaged Twigs of Six Apple Cultivars, Measured in Autumn Wood
Hong-Xu Zhou, Xi-Cun Wang, Yi Yu, Xiu-Mei Tan, Zai-Quan Cheng, An-Sheng Zhang, Xing-Yuan Men, Li-Li Li
KEYWORDS: Eriosoma lanigerum (Hausmann), apple cultivars, autumn shoots, physiological indices, resistance to insect
Chemical characteristics of normal, woolly apple aphid-damaged, and mechanically damaged twigs of six apple cultivars: Red Fuji, Golden Delicious, Qinguan, Zhaojin108, Starkrimson, and Red General, were examined in autumn wood to provide a better understanding of factors related to cultivar resistance to the woolly apple aphid, Eriosoma lanigerum (Hausmann). Chemical measures examined included soluble sugars, soluble proteins and amino acids, total phenolics, and polyphenol oxidase (that enhances the resistance of plants to insects) and superoxide dismutase, peroxidase, and catalase (that degrade waste products in plants). Soluble sugar, protein, and amino acid contents in normal (undamaged) twigs of Red Fuji, aphid-susceptible cultivar, were higher than in mechanically damaged and aphid-damaged twigs. Total phenolic compounds, an important group of defensive compounds against aphids, increased by 30.5 and 6.0% in mechanically damaged twigs of Qinguan and Zhaojin 108, respectively, and decreased by 21.7 and 16.1% in aphid-damaged twigs of Red Fuji and Red General, respectively. Compared with normal twigs, in aphid-damaged twigs, superoxide dismutase, peroxidase, and polyphenol activity all decreased in Red Fuji. The resistance of some apple cultivars to woolly apple aphid during the growth of autumn shoots was related to several of the physiological indices we monitored. The thin epidermis of callus tissue over healed wounds showed increased susceptibility to the attack by woolly apple aphid. Apple cultivar Qinguan with the highest level of resistance to woolly apple aphid in autumn had increased in amino acid, total phenolic compound levels, and enzyme activity after aphid feeding.
Nutritional Indices and Midgut Enzymatic Activity of Phthorimaea operculella (Lepidoptera: Gelechiidae) Larvae Fed Different Potato Germplasms
S. M. Mansouri, G. Nouri Ganbalani, S. A. A. Fathi, B. Naseri, J. Razmjou
KEYWORDS: Phthorimaea operculella, potato germplasms, nutritional indices, digestive enzymes
The effect of 10 potato cultivars and clones on the feeding and digestion of Phthorimaea operculella (Zeller) larvae was evaluated using larval nutritional indices and enzymatic activities. Studies were based on nutritional indices from larvae reared at 25 ± 1°C, 65 ± 5% relative humidity, and in complete darkness. The results of nutritional indices showed that conversion efficiency of ingested and digested food in the larvae at the fourth instar was the highest in Savalan cultivar at rates of 22.30 ± 0.39 and 32.87 0 ± 0.69%, respectively, and the lowest were recorded on Morene at rates of 15.83 0 ± 0.35 and 21.99 0 ± 0.58%, respectively. Among the different potato germplasms tested in the study, the highest proteolytic and amylolytic activities of the larvae, at optimal pH were in Morene with records of 8.204 0 ± 0.296 U/mg and 0.071 0 ± 0.0004 mU/mg, respectively; and the lowest were recorded in larvae fed on Savalan at 2.740 0 ± 0.131 U/mg and 0.028 0 ± 0.0001 mU/mg, respectively. It is concluded that Morene was the most unsuitable host for P. operculella.
Segregation and Efficacy of the cry1Ia1 Gene for Control of Potato Tuberworm in Four Populations of Cultivated Potato
David S. Douches, Joseph J. Coombs, Kimberly J. Felcher, Matthew Zuehlke, Walter Pett, Zsofia Szendrei, Johan Brink
KEYWORDS: Bacillus thuringiensis, Bt, Solanum tuberosum, Phthorimaea operculella, transgenic
The potato (Solanum tuberosum L.) cultivar 'SpuntaG2' contains a single copy of the Bacillus thuringiensis (Bt) cry1Ia1 gene and controls potato tuberworm (Phthorimaea operculella Zeller, Lepidoptera: Gelechiidae). Two potato cultivars and two breeding lines were crossed with SpuntaG2 creating four populations used to study cry1Ia1 segregation and efficacy. The cry1Ia1 gene segregated in each of the four populations with a 1:1 ratio. All progeny that were polymerase chain reaction positive for the cry1Ia1 gene had no surviving larvae and no leaf mining in detached leaf assays after 72 h. These results support previous evidence that SpuntaG2 carries a single copy of the cry1Ia1 gene and that transmission of the transgene from parent to progeny is not restricted and follows expected Mendelian segregation ratios. Based on detached leaf assays, the efficacy of the cry1Ia1 gene is retained through sexual transmission. If the SpuntaG2 cry1Ia1 insertion event is deregulated for commercial use, SpuntaG2 could be used for conventional breeding and the progeny carrying the SpuntaG2 event would also be available for commercial use.
Response of Russian Wheat Aphid Resistance in Wheat and Barley to Four Diuraphis (Hemiptera: Aphididae) Species
Gary J. Puterka, Scott J. Nicholson, Michael J. Brown, R. W. Hammon
KEYWORDS: plant resistance, Native species, wheat pests, cross resistance
Three Diuraphis species, Diuraphis frequens (Walker), Diuraphis mexicana (McVicar Baker), and Diuraphis tritici (Gillette), were known to exist in the United States before the 1986 appearance of the Russian wheat aphid, Diuraphis noxia Kurdjumov. The Russian wheat aphid soon became a significant pest of wheat although other endemic Diuraphis species were known to infest wheat. Wheat and barley entries resistant and susceptible to Russian wheat aphid biotype 2 were evaluated against all four Diuraphis species to determine their host interrelationships. Leaf chlorosis, leaf roll, leaf number, plant height, and infestation levels were assessed 21 d after the plants were infested by aphids in a no-choice caged environment. D. mexicana was unable to survive on wheat by 21 d after infestation and effects on the plant damage variables were negligible. D. frequens survived at low levels on resistant and susceptible plant entries and had a low impact on plant damage and growth. Russian wheat aphid biotype 2 and D. tritici were damaged most wheat and barley lines except the Russian wheat aphid biotype 2-resistant wheat lines containing genes from Dn7, STARS 2414-11, and CI2401; and resistant barley containing genes from STARS 9577B and 9301B. Russian wheat aphid biotype 2 and D. tritici reduced the growth of resistant plants by 25–50% and susceptible entries by 65–75%. Reductions at this level are typical under no-choice studies but resistant cultivars do not have these reductions under field conditions. The Russian wheat aphid biotype 2 resistant wheat lines would be effective in managing both wheat pest species.
Evaluation of Late Vegetative and Reproductive Stage Soybeans for Resistance to Soybean Aphid (Hemiptera: Aphididae)
T. J. Prochaska, L. M. Pierson, E.L.L. Baldin, T. E. Hunt, T. M. Heng-Moss, J. C. Reese
KEYWORDS: host plant resistance, tolerance, Aphis glycines
The soybean aphid, Aphis glycines Matsmura, has become the most significant soybean [Glycine max (L.) Merrill] insect pest in the north central soybean production region of North America. The objectives of this research were to measure selected genotypes for resistance to the soybean aphid in the later vegetative and reproductive stages under field conditions, and confirm the presence of tolerance in KS4202. The results from 2007 to 2011 indicate that KS4202 can support aphid populations with minimal yield loss at levels where significant yield loss would be expected in most other genotypes. The common Nebraska cultivar, 'Asgrow 2703′, appears to show signs of tolerance as well. None of the yield parameters were significantly different between the aphid infested and noninfested treatments. Based on our results, genotypes may compensate for aphid feeding in different ways. Asgrow 2703 appears to produce a similar number of seeds as its noninfested counterpart, although the seeds produced are slightly smaller. Field evaluation of tolerance in KS4202 indicated a yield loss of only 13% at 34,585–53,508 cumulative aphid-days, when 24–36% yield loss would have been expected.
Tolerance to Feeding Damage by Cotton Fleahopper (Hemiptera: Miridae) Among Genotypes Representing Adapted Germplasm Pools of United States Upland Cotton
Allen E. Knutson, Karthik D. Mekala, C. Wayne Smith, Carlos Campos
KEYWORDS: Pseudatomoscelis seriatus, cotton fleahopper, Gossypium hirsutum, plant resistance
Cotton fleahopper [Pseudatomoscelis seriatus (Reuter)] (Hemiptera: Miridae) is one of the most damaging insect pests of cotton (Gossypium hirsutum L.) in Texas and Oklahoma because of their feeding on small floral buds which are termed squares. Damage to early season squares can reduce yield, delay crop maturity and increase the risk of crop loss because of late season insect pests and adverse weather. Insecticide applications are the only control tactic. The objectives of this study were to determine the tolerance to cotton fleahopper injury to squares among upland cotton genotypes representing the adapted germplasm pools and breeding lines available to cotton breeders in the United States and to evaluate leaf hairiness as a resistant trait. Results of the choice and no-choice trials indicated that four entries, 'Stoneville 474', 'Suregrow 747', 'Deltapine 50', and 'TAM 96WD-22 h', were more tolerant to cotton fleahopper injury relative to the other 11 entries. In choice trials, cotton fleahopper density was significantly correlated with the density of trichomes on leaves, bracts and stems. However, there was no correlation between cotton fleahopper density and percent square damage in the choice trials, suggesting that in some genotypes the response to feeding injury is mediated by host plant resistance factors expressed as tolerance. Results of the no-choice studies also indicate that some genotypes express tolerance to cotton fleahopper feeding.
SAMPLING AND BIOSTATISTICS
Analyzing Blends of Herbivore-Induced Volatile Organic Compounds with Factor Analysis: Revisiting "Cotton Plant, Gossypium hirsutum L., Defense in Response to Nitrogen Fertilization"
Yigen Chen
KEYWORDS: multivariate statistical analysis, principal component analysis, Tritrophic interaction, VOCs
Many herbivorous, predaceous, and parasitic insects use constitutive and herbivore-induced volatile organic compounds (VOCs) to locate their respective host plant, prey, and hosts. Multivariate statistical tools (e.g., factor analysis) are recognized increasingly as an appropriate approach for analyzing intercorrelated data such as presence/absence or quantities of VOCs. One challenge of implementing factor analysis is determining how many new variables (factors) to retain in the final analysis. I demonstrate a method proposed by Johnson and Wichern to mitigate this problem by using VOC data published in Chen et al. The advantage of using loading (or weight) transformation in interpretation of new variables was also illustrated in the example. Factor analysis found similar nitrogen fertilization effects on VOC production as those in Chen et al. Similarities were 1) nitrogen fertilization interacted with herbivore damage status on VOC production: at low nitrogen (42 ppm) level, beet armyworm, Spodoptera exigua (Hübner) (Lepidoptera: Noctuidae), damage elicited increases in VOC production, whereas at high nitrogen (196 ppm) VOC production was suppressed; 2) nitrogen fertilization did not affect limonene, α-pinene, and β-pinene production. The seven individual VOCs significantly affected by nitrogen fertilization in Chen et al. were (Z)-3-hexenal, (E)-2-hexenal, (E)-β-farnesene, (E)-4,8-dimethyl-1,3,7-nonatriene (DMNT), α-bergamotene, γ-bisabolene, and bisabolol, of which only three ((E)-β-farnesene, γ-bisabolene, and bisabolol) weighed heavily on factor 1 in the current study.
STORED-PRODUCT
Effect of Storage and Insect Infestation on the Mineral and Vitamin Contents of Wheat Grain and Flour
S. Keskin, H. Ozkaya
KEYWORDS: Sitophilus granarius L., insect infestation, storage, mineral, vitamin
The objective of this study was to evaluate how storage and Sitophilus granarius L. infestation affects mineral and vitamin (thiamin and riboflavin) contents of wheat grain and flour obtained from the wheat. Wheat samples were infested with nonsexed S. granarius at a rate of two adults per kilogram, and stored for 6 mo at 30 ± 1°C and 70 ± 5% relative humidity. Every 30 d, samples of wheat were collected and evaluated for insect population, mineral, thiamin, and riboflavin contents. Flour milled from these wheat samples was also evaluated for mineral, thiamin, and riboflavin contents. None of the analyses performed on the uninfested wheat and flour samples showed any noticeable change during the storage period. The insect population of the infested wheat samples increased during the storage period. The ratio of the mineral contents to dry matter significantly increased in the infested wheat and flour samples during the infestation period, whereas thiamin and riboflavin contents considerably decreased. The feeding habits of S. granarius and the distribution of minerals and vitamins in the wheat grain caused the changes observed in the levels of these compounds. The effects of infestation were greatest in the latter stages, during which the insect population increased greatly.
Efficacy of a Combination of Beta-Cyfluthrin and Imidacloprid and Beta-Cyfluthrin Alone for Control of Stored-Product Insects on Concrete
Christos G. Athanassiou, Nickolas G. Kavallieratos, Frank H. Arthur, James E. Throne
KEYWORDS: cyfluthrin, imidacloprid, binary combinations, surface treatment
The insecticidal effect of Temprid, a formulation that contains beta-cyfluthrin and imidacloprid, was tested on concrete for control of seven stored-product insect species: the rusty grain beetle, Cryptolestes ferrugineus (Stephens); the sawtoothed grain beetle, Oryzaephilus surinamensis (L.); the red flour beetle, Tribolium castaneum (Herbst); the confused flour beetle, T. confusum Jacquelin du Val; the hide beetle, Dermestes maculatus (DeGeer); and the psocids Liposcelis bostrychophila Badonnel and L. paeta Pearman. Temprid, which contains 10.5% beta-cyfluthrin and 21% imidacloprid, was tested at the rate of 17.2 ml of formulation/4.1 liters of water/100 m2. Adults were exposed for 4, 8, 14, and 24 h, and then daily for 7 d, on untreated dishes or dishes treated with Temprid. In the untreated dishes, mortality of C. ferrugineus and O. surinamensis was lower when food was present, but food did not affect mortality of the other species. Presence of food did not affect mortality of any of the species tested in the treated dishes. C. ferrugineus, O. surinamensis, and the two psocid species were very susceptible to Temprid, with mortality of 97–100% after 7 d of exposure. In contrast, D. maculatus, T. castaneum, and T. confusum were tolerant to Temprid, as mortality did not exceed 57, 25, and 17%, respectively, at the 7-d exposure. A separate series of similar bioassays with Tempo, a formulation that contains 11.8% beta-cyfluthrin alone, which was applied at the same dose rate as Temprid, was conducted using O. surinamensis and T. castaneum as the target insect species, and results showed that Tempo was at least as effective as Temprid. Our results indicate that the simultaneous use of beta-cyfluthrin with imidacloprid is not more effective on concrete than beta-cyfluthrin alone, and efficacy of both formulations varies with the target species.
Determining Host Suitability of Pecan for Stored-Product Insects
A. A. Shufran, P. G. Mulder, M. E. Payton, K. A. Shufran
KEYWORDS: pecan, stored-product pests, Plodia interpunctella, Oryzaephilus surinamensis
A no-choice test was performed to determine survival and reproductive capacity of stored-product insect pests on pecan, Carya illinoensis (Wangenheim) Koch. Insects used were Indianmeal moth, Plodia interpunctella (Hübner) (Lepidoptera: Pyralidae); sawtoothed grain beetle, Oryzaephilus surinamensis (L.) (Coleoptera: Cucujidae); red flour beetle, Tribolium castaneum (Herbst) (Coleoptera: Tenebrionidae); lesser grain borer, Rhyzopertha dominica (F.) (Coleoptera: Bostrichidae); and rusty grain beetle, Cryptolestes ferrugineus (Stephens) (Coleoptera: Laemo-phloeidae). Fifty adults of each beetle species or 10 reproductive pairs of P. interpunctella adults were placed in 0.5-liter containers with either whole-shell pecans, cracked-shell pecans, randomly selected in-shell pecans, pecan nutmeats, cracked wheat, or glass beads and held at 28°C, 60–70% relative humidity, and 16:8 (L:D) photoperiod for 2,4,6, and 8 wk. Four replications of each insect-diet-interval combination were performed. Larvae of P. interpunctella, O. surinamensis, T. castaneum, C. ferrugineus, and adult P. interpunctella and O. surinamensis developed on cracked and nutmeat pecan diets. R. dominica did not complete reproduction on pecans. Knowledge that these pests can reproduce on stored pecan will assist pecan growers, accumulators, and storage facilities in preventing insect outbreaks on their product.