PROACTIVE MANAGEMENT FOR SUSTAINABLE RANGELAND PRODUCTION
Location: Range and Livestock Research
Title: Nucler Polyhedrosis Virus as a Biological Control Agent for Malacosoma americanum (Lepidoptera: Lasiocampidae)
Submitted to: Journal of Applied Entomology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: January 8, 2010
Publication Date: February 1, 2010
Citation: Progar, R.A., Rinella, M.J., Fekedulegn, D., Butler, L. 2010. Nucler Polyhedrosis Virus as a Biological Control Agent for Malacosoma americanum (Lepidoptera: Lasiocampidae). Journal of Applied Entomology 134:641-646.
Interpretive Summary: The eastern tent caterpillar not only damages trees, but has also been found to cause abortion in horses. This research tested a biological control method for the eastern tent caterpillar using a naturally occurring virus. First, the virus was propagated in caterpillar larvae. Then a viral pesticide was formulated and applied to leaves on which caterpillar larvae were feeding under natural conditions. Young larvae were killed by the virus when applied at high concentrations while older larvae were resistant to the virus. Although it would not be desirable to completely eradicate the eastern tent caterpillar, the virus may be used in areas where caterpillar populations are large enough to warrant control.
In addition to damaging trees, the eastern tent caterpillar, (Malacosoma americanum (F.)) is implicated in early fetal loss and late-term abortion in horses. In a field study, we evaluated the potential biological control of eastern tent caterpillar using eastern tent caterpillar nuclear polyhedrosis virus (ETNPV), a naturally occurring virus that is nearly species specific. Egg masses were collected and hatched in the laboratory then second instar larvae were inoculated and the virus propagated in vivo. The following year, a viral pesticide was formulated using 72% distilled water, 25% molasses, 1% folic acid, 2% Rhoplex B-60 A® as a spreader-sticker, and a measured quantity of viral polyhedra. Virus concentrations of 104, 106 and 108 polyhedral inclusion bodies (PIB)/ml were applied to foliage on which second, third and fourth instar caterpillars were feeding. The larval colonies were collected and the surviving caterpillars counted. Treatment means were compared via 95% bootstrap confidence intervals. The data indicate fourth instar caterpillars are fairly resistant to the virus. Alternatively, third instar caterpillars are somewhat susceptible to the virus and second instar caterpillars are highly susceptible, but only at the highest concentration tested. Our data indicate ETNPV can be propagated, harvested and refined for formulation as a biological control of eastern tent caterpillar. Its use on this insect may be merited in circumstances where landowners and managers want to deter outbreaks and maintain low endemic population levels.