6. Insects to watch in 2008 - Part I - Winter cutworm
Christina DiFonzo, Entomology
Last season was exciting (for an entomologist) because of the discovery of three new potential field crop insect pests in Michigan. This week, I will cover one of these pests, winter cutworm. In the future spring issues, I will discuss the remaining new potential pests, Asiatic garden beetle and western bean cutworm, and talk about some of the other insects that could be found in high numbers in 2008.
Last fall, northern Michigan experienced an outbreak of Noctua pronuba, the greater yellow underwing moth. Noctua pronuba caterpillars (Howard Russell from MSU Diagnostic Services calls them winter cutworms) remain active well into the fall. In 2007, they fed on alfalfa, winter wheat, and lawns, moved en-masse across roads and into homes, and sickened pets. These caterpillars made it through the winter and may feed again this spring.
Noctua pronuba is one of the most common Noctuid moths in Europe, where it is a frequent garden pest. It is related to the pest cutworms we find in field crops. The first N. pronuba moths in North America were found in Nova Scotia in 1979. How it got into North America, we dont know. But adults are strong night fliers and the larval (caterpillar) host range is broad, including strawberry, tomato, potato, carrot, cabbage, beet, lettuce, grape and grasses. Thus this insect spread rapidly across Canada, into the eastern United States. In Michigan, the first adult moths were collected in 1998. Moths are now common around lights in the evening between June and October. Literature says there is one generation per year, although based on the extended adult flight, the single generation is not well-synchronized or perhaps there are two generations.
Although N. pronuba moths are somewhat common, a N. pronuba larval outbreak was not something we anticipated in 2007. Prior to that time, homeowners typically reported caterpillars to the MSU Diagnostic Clinic or MSU Extension offices as a curiosity. This is because of N. pronubas unusual ability to remain active under very cold conditions, even crawling on the snow in winter (thus Howards name winter cutworm).
In early October 2007, Norm Myers, an MSU Extension county director from Oceana County, sent in the first email about large numbers of caterpillars to MSU Diagnostic Services. After that, things got crazy. In October and November 2007, commercial fields of alfalfa, winter wheat and rye cover crop were heavily damaged in northern Michigan counties of Alpena, Lake, Oceana, Osceola, and Wexford. As far as we know, this was the first reported economic injury to field crops by this cutworm in North America. Caterpillars moved as a wave between fields, leaving a path of destruction as they crawled. In mid-October, Jerry Lindquist, Osceola County MSUE, reported massive numbers of caterpillars in fields: The farmer noticed them after he picked up some recently cut third cutting round-baled hay and saw the larvae dropping out of the bales Once the field was cut he noticed them moving in mass across the road and he said the tractor tires were actually starting to spin because of the slippery larvae covered pavement.
In November, a grower from Posen clocked the cutworms at eight inches per minute crossing his road. Some alfalfa and small grain fields were treated, using armyworm thresholds as a guide.
Caterpillars also consumed lawns and crawled around homes in large numbers. On October 23, a distraught homeowner emailed Howard: my home, garage and pole barn are being invaded by caterpillars. They are in the grass by the thousands. I feel like I'm in a "B" movie.
Things took a strange turn when reports of sick pets came in the following month. On November 12, Mary Dunckel, MSUE Alpena County, reported I was in the veterinarian's office Friday and while at the counter paying, a woman came running in with a bag. She was completely frantic, as her dog had just vomited up the contents of the bag. Yup, you guessed it.... 40-50 Noctua pronuba!
Marys observations were confirmed by a few days later by Jerry Lindquist: A black lab in the Midland area was vomiting blood, went off of feed, and after a week was passing whole cutworms in her stool. The veterinarian diagnosed it as a potential parasite problem, sent a stool sample to Cornell's Parasite Diagnostic Lab and they identified it as armyworm. The dog owner called me after a TV news spot on cutworms and I am quite sure cutworms are what the dog ate.
Reports of cutworm infestation and feeding continued into December. Even in January and February, caterpillars emerged on warm days on the snow.
Will this outbreak carry over into this spring? We arent sure. Thus far, Howard and I have not received calls about waves of caterpillars marching across fields, but its still early. As the temperature warms and alfalfa, wheat and lawns green up, I expect to see increased activity in northern Michigan. The caterpillars themselves will be obvious on warm days, since they are 1-3 inches in length and active. On cooler days, they may hide at the base of plants. Signs of early feeding may appear as fields not greening up as expected.
As far as management, since this is the first widespread report of economic crop damage in the United States due to winter cutworm, there arent thresholds or guidelines specifically for this insect. However, this insect acts like armyworm, so a good bet is to use armyworm thresholds as a guide: alfalfa = 4 or more per foot of row; winter wheat and hay = 4 or more per sq. foot. Last fall, caterpillars were reported crawling on warm afternoons and also coming out on warm evening. Thus treating in mid-afternoon on a warm day would increase the chance that caterpillars will crawl across freshly-treated foliage. Growers and homeowners sprayed with various pyrethroids as well as Sevin last fall, and reported good control with all products.
Based on what we know about the life cycle, I am making an educated guess that caterpillars will pupate in early May, so that corn and soybean planted in northern counties will not be at risk of damage. However, observations on caterpillar numbers, movement and damage are welcome to myself or Howard to increase our understanding of this insect.
Howard and I wish to thank MSU Extension educators Ben Bartlett, Jim Breinling, Mary Dunckel, Duke Elsner, Jerry Lindquist, Norm Myers, Jill ODonnel and Sheri Pollington who kept track of winter cutworm last fall and sent us such entertaining reading material.
Here are some additional resources on winter cutworm and caterpillar identification
Please do not let the outcome of this Farm Bill be the destruction of existing Research Title funding. If you cannot find ways to enhance funding, I urge you to at least protect the current land-grant funding baseline.
There is a tremendous stake for the land-grant system in a positive outcome. We need you and all of your faculty, staff, graduate students, and outside supporters to make these calls and emails!
Thanks, as always, for your assistance.
PLEA TO FARM BILL CONFEREES:
DO NOT KILL THE AGRICULTURAL RESEARCH BASELINE
Based on limited available information, we are of the understanding that the tentative agreements reached by House and Senate Agriculture Committee staff on the Research Title of the Farm Bill will, if ratified by the Conferees, result in three significant fiscal impacts regarding agricultural research:
1. It eliminates current law Initiative for Future Agriculture and Food Systems (IFAFS) funding a net loss in the Farm Bill of $1.6 billion in budget authority ($1.244 billion in budget outlays)
2. It creates two or three new targeted mandatory research programs for specialty crops, organics, and energy. No figures are available but the total is approximately $200 million over five years.
3. It terminates these targeted programs in 2012. This will result in ZERO dollars in the Committee baseline for agricultural research in FY 2012 and the future.
This course of action would be a huge step backwards for the federal commitment to agriculture, nutrition, energy and related research with permanent negative repercussions far beyond the five year life of the Farm Bill.
REPEALS MORE THAN $1.2 BILLION (OUTLAYS) IN MANDATORY AG RESEARCH FUNDING: The tentative agreement would abandon funding for the IFAFS program provided in current law in the amount of $200 million per year for eight fiscal years (2010 through 2017). This would repeal $1.6 BILLION in mandatory research budget authority (and $1.244 Billion in outlays) over the 10 year budget baseline of the bill.
TARGETED RESEARCH FUNDS ARE NOT A SUBSTITUTE: While the tentative agreement reportedly includes some mandatory funding targeted to specialty crops, organics, and renewable energy, the total amount of new mandatory research funds made available are more than ONE BILLION DOLLARS LESS THAN CURRENT LAW.
KILLS LONG TERM COMMITMENT TO AG RESEARCH BY REPEALING PERMANENT LAW BUDGET BASELINE: Not only does the tentative agreement specifically terminate IFAFS funds beginning immediately, it would eliminate the new, targeted funds in FY 2012. This means that the budget baseline for all of these agriculture research priorities will be ZERO when the next Farm Bill is written in 2012. Specialty crops research baseline = ZERO. Renewable energy research baseline = ZERO. Organics research baseline = ZERO. IFAFS research baseline = ZERO. This would reverse more than 10 years of effort in building the budget baseline for agricultural, nutrition, renewable energy, and related research.