RECRUITMENT OF COLORADO POTATO BEETLES (COLEOPTERA, CHRYSOMELIDAE) TOSOLANACEOUS HOSTS IN THE FIELD

Field recruitment on 10 solanaceous plant species by adult Colorado po tato beetles, Leptinotarsa decemlineata (Say), and their oviposition, was investigated by frequent collection of adults and eggs from replic ated Latin-square plots over 5 yr in Michigan, Maine, and Massachusett s. Preferred plants for adults were potato, Solanum tuberosum L.; bitt er nightshade, Solanum dulcamara L., and buffalobur, Solanum rostratum Dunal; eggplant and horsenettle, Solanum melongena L. and Solanum car olinense L., were of intermediate rank in recruitment of adults. The r emaining species (tomato, Lycopersicon esculentum L,; black nightshade , Solanum nigrum L.; silverleaf nightshade, Solanum eleaegnifolium Cav anilles; groundcherry, Physalis heterophylla Nees; jimsonweed, Datura stranonium L.) were not preferred. Adult recruitment and oviposition c hanged over the season and differed from site to site, but was not inf luenced by the host-plant origin of recruited adults. Daily collection s of adults in Massachusetts in 1991 showed four distinct periods of a dult recruitment. These differed in relative importance depending on w hether plots were near or distant to previous and current year's potat o fields. Early overwintered recruitment was highest and relatively le ss different between near and distant plots, reflecting the importance of flight during this period. Late overwintered recruitment was mostl y by short-distance dispersal of adults that had already fed on potato plants, based on oviposition of collected females. Summer females als o appeared to be previously fed, and their recruitment to distant plot s suggested dispersal mostly by flight. Prediapause dispersal resulted in recruitment mostly to plots a short distance from potato fields. R eproduction, as measured by egg masses per adult, increased over the s eason, with summer adults showing the highest egg mass-adult ratio. Re cruitment of adults and their oviposition in the field were positively associated with no-choice assays of fecundity and larval survival in the laboratory using the same plant species, but with relatively more rejection of intermediate-ranked hosts in the field.