LOCATION AND ABUNDANCE OF ADULT COLORADO POTATO BEETLES (COLEOPTERA, CHRYSOMELIDAE) FOLLOWING POTATO HARVEST

Colorado potato beetle, Leptinotarsa decemlineata (Say), population bi ology was investigated after Irish potatoes, Solanum tuberosum (L.), w ere harvested in eastern North Carolina. The abundance of adult Colora do potato beetles following potato harvest was estimated by taking mor e than 450 visual transects in 45 commercial potato fields in July and August, 1993 and 1994. Few second- and third-generation Colorado pota to beetle egg masses and larvae, volunteer potato plants and wild host s such as horsenettle, S. carolinense L., were encountered, suggesting that Colorado potato beetle generations produced after potatoes are h arvested in June and early July do not contribute significantly to the overall overwintering population. Location and abundance of overwinte ring adult Colorado potato beetles within the soil in fields previousl y planted in potato were determined. Densities of overwintering adults in soil along field edges were greater than those within fields prior to emergence in the spring, suggesting that adults moved toward field edges to overwinter. However, given that the area within potato field s was much greater than the area along field edges, the estimated tota l number of overwintering adults within fields was greater than along the edges. In light of these results, tillage at different times betwe en crop production seasons was evaluated for its effect on overwinteri ng Colorado potato beetle survival, but was found to have little effec t. (C) 1997 Elsevier Science Ltd.