FOOD, GROUND COVER, AND COLORADO POTATO BEETLE (COLEOPTERA, CHRYSOMELIDAE) DISPERSAL IN LATE SUMMER

Factors that affect adult Colorado potato beetle, Leptinotarsa decemli neata (Say), dispersal before overwintering were examined in field stu dies. 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 dep th 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 spri ng were measured. In both years of the study and by each measure of be etle abundance, straw mulch had no impact on beetle dispersal but food source did. Availability of foliage as food resulted in a larger numb er of beetles in the plots, both on plants before overwintering and in the soil than did potato tubers. Mulch depth had no impact on overwin tering depth of beetles in the soil or average date of emergence in th e spring. If concentrated in space, beetles might be controlled more e fficiently by chemical or nonchemical means, such as propane flaming o r manipulation of the soil environment. This study demonstrates that a dult dispersal of Colorado potato beetles could be manipulated to conc entrate the adults in space before and during overwintering.