Food, ground cover, and Colorado potato beetle (Coleoptera: Chrysomelidae) dispersal in late summer

Abstract

Factors that affect adult Colorado potato beetle, Leptinotarsa decemlineata (Say), dispersal before overwintering were examined in field studies. Test plots were established next to a planting of potatoes that served as a source of beetles to test the effects of food type and depth of straw mulch on adult dispersal. Beetle numbers above ground and in the plots during September, number in the soil within plots during late autumn and winter, and number emerging from the plots during spring were measured. In both years of the study and by each measure of beetle abundance, straw mulch had no impact on beetle dispersal but food source did. Availability of foliage as food resulted in a larger number of beetles in the plot, both on plants before overwintering and in the soil, than did potato tubers. Mulch depth had no impact on overwintering depth of beetles in the soil or average date of emergence in the spring. If concentrated in space, beetles might be controlled more efficiently by chemical or nonchemical means, such as propane flaming or manipulation of the soil environment. This study demonstrates that adult dispersal of Colorado potato beetles could be manipulated to concentrate the adults in space before and during overwintering.