Submitted to: Journal of Economic Entomology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: May 11, 1998
Publication Date: N/A
Interpretive Summary: The gypsy moth is one of the most important pests of hardwood trees in the northeastern United States, and millions of dollars are spent each year to control this pest. Because of concern over the use of currently-available pesticides, which can affect many insect species that are not considered pests, there is a need for a control agent that is specific to the gypsy moth. The gypsy moth virus product, Gypchek, kills only the gypsy moth, but it is not commercially available. If available, this product could be used by arborists as an environment-friendly spray to treat residential trees that are under attack by the gypsy moth. Different doses and formulations of Gypchek applied by a truck-mounted hydraulic sprayer were tested in this two-year study. Significant larval reduction and foliage protection were obtained at the currently-recommended dose of 10^12 PIB (polyhedral inclusion bodies) per 100 gallons and also at one-tenth of this dose. The addition of a sunscreen, which increases the cost of the treatment, did not improve the effectiveness of the formulation. By demonstrating that Gypchek can be used effectively by arborists to control gypsymoths, the results of this study will help promote interest in the development of a commercial Gypchek product. The information from this study will be used to develop recommendations for the use of Gypchek by gypsy moth managers, arborists, and government agencies.
Gypchek, a registered microbial insecticide for aerial and ground-based application against the gypsy moth, was field-tested in 1996 and 1997 at two doses (10^11 and 10^12 polyhedral inclusion bodies(PIB) per 379 liters [100 gallons]) and with and without a sunscreen. Treatments were applied to overstory oak trees with a truck-mounted hydraulic sprayer. Larval mortality was significantly greater, and larval density was significantly lower, on treated trees than on untreated trees. Defoliation was significantly reduced by the treatments in 1996, but not in 1997, when overall gypsy moth population density dropped to very low levels. Mortality was significantly higher among larvae treated atthe higher dose in 1996, but there was no significant dose effecton larval density or defoliation. Mortality, density, and defoliation were not dose-dependent in the 1997 test. The addition of sunscreen did not have a significant effect on any of the measured parameters in 1996 or 1997. The level of control with the high dose Gypchek treatment was not significantly different from that achieved with an application of Bacillus thuringiensis at 36 billion international units (BIU) per 379 liters. These results suggest that Gypchek can be used effectively as a ground-based or arborist-applied gypsy moth control agent, and that it may be possible to achieve acceptable levels of foliage protection at a 10^11 PIB dose and without the addition of a sunscreen.