The use of <i>Bacillus thuringiensis kurstaki</i> for managing gypsy moth populations under the Slow the Spread Program, 1996-2010, relative to the distributional range of threatened and endangered species

Abstract

The Slow the Spread Program operates along the expanding population front of the gypsy moth, from Minnesota to North Carolina. The primary objective of the program is to eliminate newly-founded colonies that form ahead of the leading edge to reduce the gypsy moth's rate of spread and delay the costs associated with infestation and outbreaks. Although the majority of areas under the STS Program are treated with control methods specific to the gypsy moth, commercial formulations of Bacillus thuringiensis var. kurstaki (Btk) are the second most used tactic. Bacillus thuringiensis kurstaki can directly affect other Lepidoptera, as well as indirectly affect species that depend on Lepidoptera for pollination services or as a food source. Because of these nontarget effects, proposed treatment areas are always reviewed by the U.S. Department of Interior - Fish and Wildlife Service as well as state agencies that are responsible for the conservation of threatened and endangered species to ensure that government programs to control gypsy moth are not likely to have an adverse effect. In this report, we used a variety of sources to compile a spatial database of the historical distributional ranges of 21 threatened and endangered species that occur within the STS management area. We then quantified the area of overlap between areas treated with Btk under the STS Program from 1996 to 2010 and the distributional ranges of these species to evaluate the use of Btk with regard to federal and state management guidelines.