Parasitism by Trophotylenchulus floridensis Raski, 1957 was studied on roots of sand pine (Pinus clausa [Chapm.] Vasey). Different life stages of the nematode were observed to be covered by dark, spherical, brittle, capsule-like structures which protruded from the root surface. The mature capsule enveloped a single sedentary female with a gelatinous matrix containing an average of 76 (44-117) eggs. The capsule was composed of a single layer of cells which appeared to be of plant origin. The anterior end of the nematode was embedded superficially in the root tissue where it created a feeding site comprised of a small number of discrete stelar parenchyma cells with dense cytoplasm and enlarged nuclei and nucleoli. The nematode also infected slash pine, Pinus elliottii, loblolly pine, P. taeda, red oak, Quercus falcata, post oak, Q. stellada, and sweet gum, Liquidambar styraciflua, in four different locations in central Florida. The taxonomic relationship between Tr. floridensis and Tylenchulus spp. is discussed. Based on differences in the tail and lip regions, position of the excretory pore, type of obesity and especially in the mode of plant parasitism, the genus Trophotylenchulus Raski, 1957 is upheld, and the transfer of Tylenchulus clavicaudatus Colbran, 1966, Ty. rnangenoti Luc, 1957, and Ty. obscurus Colbran, 1961 to Trophotylenchulus is proposed.
pine; citrus nematode; histopathology; taxonomy
Soaking potato tuber pieces for 15 min in 8,000 μg/ml of oxamyl just before planting reduced the number of Globodera rostochiensis cysts that developed on potato roots, but this treatment was phytotoxic. Five foliar applications of 1.12 kg a.i./ha of oxamyl or carbofuran at 10-day intervals beginning when 90% of the plants had emerged suppressed increase in G. rostochiensis densities. Similar foliar applications of phenamiphos were ineffective in controlling G. rostochiensis. Soil applications (in the row at planting) of aldicarb, carbofuran, phenamiphos, ethoprop, and oxamyl at 5.6 kg a.i./ha reduced the numbers of white females that developed on potato roots, but only those treatments involving aldicarb and oxamyl suppressed G. rostochiensis population increase. Combined soil and foliar treatments did not provide any advantage over soil treatment alone, as soil applications of 5.6 kg a.i./ha alone were equal to, or better than, combined soil (3.4 kg a.i./ha) and foliar (2.2 kg a.i./ha) applications in controlling G. rostochiensis.
chemical control; Globodera rostochiensis; seed treatments; soil treatments; foliar treatments
Heterodera mediterranea completes embryogenic development in 15-18 days at 24 ± 2 C. On olive and pistachio seedlings the postembryogenic development was completed in 42-50 days at 24-30 C. Juveniles and adults have semiendoparasitic habits and do not penetrate completely into the root tissue. This cyst forming nematode has been detected only on Olea europaea, Pistacia lentiscus, and P. vera. Syncytia formation and disorder of root stelar structure are the main anatomical changes induced by the parasite.
cyst nematode; embryogenesis; histopathology; Oleo europaea; Pistacia lentiscus; P. vera; host range
Verutus volvingentis Esser, 1981 deposits eggs in the rhizosphere without a gelatinous matrix. Ecdysis was not observed to occur in the egg. Spicular primordia in the rectal area of a second-stage larva were well defined. One larva increased in width from 28.2 μm to a maximum of 51.7 μm after 176.5 hours of feeding, prior to the second ecdysis. It then decreased steadily in width to 33.3 μm, at which time it had molted to a fully developed male. Males leave the third-stage larval integument embedded in the root following final ecdysis. The unique feature of female development was the occurrence of large vaginal primordial cells. Male and female development took from 6 to 15 days and 17 days, respectively.
Diodia virginiana; life cycle
In laboratory tests, larvae of the Colorado potato beetle (CPB), Leptinotarsa decemlineata (Say), and the sugarbeet wireworm (SBW), Limonius californicus (Mannerheim), were exposed to the nematodes Steinernema feltiae Filipjev (Mexican strain) (= Neoaplectana carpocapsae) and S. glaseri Steiner in soil. S. feltiae caused significantly higher mortality in SBW larvae than did S. glaseri, but both nematode species were equally effective against CPB larvae. The minimum concentration of S. feltiae for 100% mortality of CPB larvae after 13 days was 157 nematodes/cm² of soil, and the LC₅₀ based on 6-day mortality was 47.5 nematodes/cm²; in contrast, 100% mortality of SBW larvae was not achieved with even the highest concentration tested, 393 nematodes/cm². CPB adults emerging from nematode-contaminated soil were not infected. In field cage tests, S. feltiae applied to the soil surface at the rates of 155 and 310 nematodes/cm² soil caused 59% and 71% mortality, respectively, of late-fourth-instar spring-generation CPB, and 28% and 29% mortality, respectively, of SBW. No infection was obtained when larvae of summer generation CPB and SBW were placed in the same cages approximately 6 weeks after nematodes were applied to the soil. Inundative soil applications of S. feltiae, though cost prohibitive at present, were effective in reducing caged CPB and SBW field populations.
Leptinotarsa decemlineata; Limonious californicus; control; soil application; entomogenous nematodes
Replicated field and greenhouse experiments were used to evaluate the effect of tomato, cabbage, cucumber, carrot, Amaranthus hybridus, and pepper on growth and fecundity of Meloidogyne spp., particularly M. javanica. In the field tests, tomato, cucumber, and carrot favored population increases of Meloidogyne spp., while Amaranthus, pepper, and cabbage limited them. Some cropping sequences that included crops from the latter group had a suppressive effect on population growth. Thus, of the 36 cropping sequences that were investigated, the following kept the pests in check: tomato-pepper; tomato-Amaranthus; cabbage-pepper; Amaranthus-pepper; carrot-cabbage; pepper-pepper; pepper-Amaranthus; and Amaranthus-pepper. In the greenhouse tests, tomato, cucumber, and carrot had a high number of galls per 50 cm of root, large, conspicuous galls and egg masses, and a high number of larvae per egg mass. Thus, they were highly susceptible. Cabbage and Amaranthus were unsuitable hosts as reflected in the absence of galls or a low number per 50 cm of root. small size of galls and egg masses, and few progeny on the subsequent crop of pepper. The length of time required for eggs to hatch on different hosts varied considerably and is thought to be a significant factor in infection of hosts.
rotations; pest management
Four nonfumigant nematicides applied three times during the wet season were used to study dosage sequence and nematicide effectiveness. Control of Helicotylenchus multicinctus (Cobb) Thorne and Meloidogyne javanica (Treub) Chitwood increased plantain (Musa AAB) yields. The nematicide (aldicarb, carbofuran, oxamyl, and miral) performance and yield response varied with dosage sequences. Applications of 2, 3, and 2 g ai/tree in March, July, and October (sequence I), respectively, gave greater control of M. javanica than did applications of 3, 2, and 2 g ai/tree in March, June, and September (sequence II), respectively. However, the high initial dose sequence was effective against H. multicinctus. Persistence of the different nematicides differed over the 14-month experimental period. Miral, aldicarb, and carbofuran were the most effective treatments against either species by the end of the wet and dry seasons. Dry season residual nematode populations were significantly lower in nematicide treated than in control plots. Yield increases over controls were 96.9, 90.1, 78.4, and 70.1% for carbofuran applied by sequence II, aldicarb by II and I, and oxantyl by II, respectively. Nematode populations directly fluctuated with rainfall and dropped to low (H. multicinctus) or to undetectable (M. javanica juveniles) levels during the dry season. Of the two nematodes studied, the more serious pest to plantain was H. multicinctus; it was tolerant to drought and survived the dry season in untreated soils.
chemical control; Musa AAB. spiral nematode; root-knot nematode; nematode-rainfall-dose interrelationships; population dynamics; survival
chemical control; insecticides; development; screening; mode of action
Egg hatch of Meloidogyne exigua was significantly inhibited in 14 days pretreatment with aldicarb, ethoprop, or carbofnran at concentrations higher than 0.1 μg/ml; these eggs were found to delay hatch in 19 days posttreatment in ethoprop. Aldicarb and carbofuran solutions at concentrations greater than 0.1 μg/ml significantly decreased the motility and the life span of the second-stage juveniles; aldicarb was more toxic than carbofuran to the nematode. In a field test, aldicarb (Temik 10G), ethoprop (Mocap 10G), and carbofuran (Furadan 5G and Furadan Liquid 350F) significantly decreased M. exigua populations.
Coffea arabica; chemical control; hatching; motility; mortality; nematicides
The life history and feeding habits of Lasioseius scapulatus, an ascid predator and potential biocontrol agent of nematodes, was examined. Reproduction was asexual, and the life cycle was 8-10 days at room temperature. Life history consisted of the egg, protonymph, deutonymph, and adult. Both nymphal stages and the adult captured and consumed nematodes. Two fungal genera and eight genera of nematodes were suitable food sources. Second-stage root-knot nematode juveniles were eaten, but eggs and adult females were not. The mite fed voraciously on nematodes and drastically reduced Aphelenchus avenae populations in vitro. It is suggested that mites are of considerable importance in the ecology of certain nematodes.
Mesostigmata: Ascidae; biological control; predation; Meloidogyne
pest management; symposium
Ethylene production was determined in excised tomato (Lycopersicon esculentum) root cultures of Meloidogyne javanica susceptible and resistant cultivars infected with M. javanica. Uninfected cultivars produced very low amounts of ethylene. Relatively high amounts of ethylene were produced by the infected susceptible cultivars. Peak production of 1.6 n moles * g root⁻¹ * h¹⁻ occurred between 9 and 16 days after inoculation (DAI). The period of high ethylene production coincided with that of rapid increase in gall weight. Low amounts of ethylene were also released by the infected resistant cultivar between 9 and 12 DAI, which follows the hypersensitivity reaction. Ethylene production in infected intact plants during the period of rapid gall growth was twice as much as in uninfected plants during the same time. Exposing excised root cultures to 0.5 or l0 ppm ethylene accelerated the rate of increase in gall weight of M. javanica infected roots. In contrast, overall root growth was inhibited by these treatments, compared to infected roots which were not exposed to ethylene.
physiology; growth; inhibition; interactions; host-parasite relations
First, second, third, early and late fourth-instar larvae, and pupae of Aedes aegypti were infected with Romanomerrais culicivorax and reared at 20, 25, and 30 C. An increase in the ratio of male to female nematodes was observed with increase in host age at the time of infection at each temperature. The number of pupal and late fourth-instar infections was low, but R. culicivorax continued to develop in adult A. aegypti. Since male nematodes were recovered from both male and female hosts infected as late fourth instars or pupae, the sex of the host did not influence the sex of the nematode.
sex determination; temperature; entomogenus nematode; biological control
reproduction; modeling; tolerance
The genus Nagelus (Thorne and Malek, 1968) Siddiqi, 1979 is modified and a new species from Alaska is described. The combination of scanning electron microscopy and light microscopy permits the characterization of Nagelus spp. as having a broadly oval face pattern, no longitudinal striations on the lip region, deirids surrounded by six incisures, and an irregularly tapering tail with a large hyaline region. Nagelus leptus (Allen, 1955) Siddiqi, 1979, N. alpensis Doucet and Luc, 1981, N. camelliae (Kheiri, 1972) Siddiqi, 1979, N. jamelensis (Nesterov, 1973) Siddiqi, 1979, and N. obscurus (Allen, 1955) n. comb. are retained on this basis. Nagelus borealis n. sp. is characterized by a styler length of 30 μm or more, an irregularly scalloped perioral disc, and a proportionately larger basal bulb. Nagelus abalosi (Doucet, 1978) Doucet. 1980 and N. virginalis (Doucet, 1978) Doucet, 1980 are synonymized with N. leptus. Nine other species from Nagelus are transferred to Merlinius Siddiqi, 1970.
Merliniinae; taxonomy; Tylenchorhynchidae; scanning electron microscopy
biocontrol; Catenaria; Harposporium anguillulae; Monacrosporium cianopagum
allelopathy; biological control
Sugar beet (Beta vulgaris L. cv. Monogerm C.S.F. 1971) seeds sown into Vineland fine sandy loam, infested with 15,500 H. schachtii juveniles/pot, showed little growth during an 11-week test in the greenhouse. Seedlings transplanted at 2, 4, and 6 weeks of age had 32, 30, and 31% less top weight and 71, 68, and 59% less root weight, respectively, compared to controls grown in nematode-free soil. Nematode reproduction in both direct-seeded and transplanted sugar beets was limited and related to root weight. Shoot/root ratios were increased by the nematodes in all nematode-infected beets compared to those grown in soil without nematodes. In contrast to seeding or transplanting sugar beets into nematode-infested Vineland fine sandy loam, an inoculation of Beverly fine sandy loam supporting 0 (seeds), 2-, 4-, and 6-week-old sugar beet seedlings with 7,400 juveniles/pot, followed by 11 weeks of growth in the growth-room, resulted in top weight losses of only 13, 3, 18, and 15% and losses in root weight of 44, 38, 36, and 38%, respectively. Nematode reproduction was high and all shoot/root ratios were increased by the nematode compared to the noninoculated controls. These experiments have shown that sugar beets sown into nematode-infested soil are damaged much more heavily by H. schachtii juveniles than seeds inoculated with the nematode immediately following sowing. Results indicate that an increase in tolerance of sugar beets to attack by H. schachtii does not occur beyond the first 2 weeks of growth and that transplanting damage lowers the tolerance of seedlings to nematode attack.
sugar beet cyst nematode; age tolerance; transplanting damage; host-parasite relationship
Stage-specific differences in wheat germ agglutinin (WGA) binding saccharides were demonstrated between the surfaces of the eggs, L1 larvae, young aduhs, and old adults of Caenorhabditis elegans. The WGA binding was to n-acetylglucosamine groups but not to terminally linked n-acetylneuraminic acids. An age-related decrease in WGA binding occurred in adults, supporting previous findings of a decrease in net negative cuticle surface charge during aging.
¹²⁵I wheat germ agglutinin; development
Influence of Meloidogyne hapla on estahlishnrent and maturity of Heterodera schachtii in sugarbeet was studied. Results indicated that when the majority of M. hapla were in second, third, or fourth larval stages within plants prior to H. schachtii inoculation, growth and development of the latter was retarded. However, when M. hapla reached the young female stage prior to inoculation of H. schachtii, establishment and development of the latter was greatly enhanced. As M. hapla reached maturity before and after egg production prior to H. schachtii inoculation, establishment and growth of the latter was progressively decreased. In each instance, M. hapla developed independently and matured at the same rate as in plants inoculated with only M. hapla. Usually ratios of total soluble carbohydrates to reducing carbohydrates were lower, but not significantly different, in plants receiving both nematodes as compared to other treatments.
northern root-knot nematodes; sugarbeet nematodc; sugarbeet; interrelationships; carbohydrates; predisposition
Extracts from compost infested with Caenorhabditis elegans suppressed mycelial growth of Agaricus brunnescens. An extract from uninfested compost also inhibited mycelial growth but to a lesser degree. The critical role of compost bacteria and/or other compost micro-organisms is implicated by these results.
free-living nematodes; mushrooms; leachate
The location of carbohydrate moieties on the outer cuticle of Xiphinema index was examined by electron microcopy using several different reagents: a) The periodic acid-thiosemicarbazide-silver proteinate reaction was used as a general stain for carbohydrates. In sectioned material it stained the canal system and deeper layers of the cuticle as well as the outer surface, b) Cationized ferritin at pH 2.5, which identifies carboxyl and sulfate groups, was used to identify sialic acid residues and also labelled parts of the canal system, c) Ferritin-goat anti rabbit IgG coupled to a DNP ligand was used to label either sialyl or galactosyl/N-acetyl-D-galactosaminyl residues, d) Ferritin hydrazide, a new reagent, was used for the ultrastructural localization of glyco-conjugates. Reagents c) (with appropriate antisera) and d) were applied only to the outer surfaces of the cuticle; they showed that sialic acid residues were concentrated mainly on the outer body wall of the head, the lips, oral opening, amphid apertures, and outer surface of protruded odontostyles. Ferritin distribution was not altered by pretreatment with neurantinidase. Galactose oxidase treatments revealed galactose/N-acetyl-D-galactosamine residues along the entire body wall. These results confirmed earlier findings obtained by fluorescence microscopy.
outer cuticle surface; cuticular canal system; sialic acid; galactose; electron microscopy; cryoultramicrotomy; cationized ferritin; ferritin hydrazide
allelopathy; biological control
attraction; biological control; dispersal; entomogenous nematodes; nematode movements