Recruitment of Colorado Potato Beetles (Coleoptera: Chrysomelidae) to Solanaceous Hosts in the Field

Field recruitment on 10 solanaceous plant species by adult Colorado potato beetles, Leptinotarsa decemlineata (Say), and their oviposition, was investigated by frequent collection of adults and eggs from replicated Latin-square plots over 5 yr in Michigan, Maine, and Massachusetts. Preferred plants for adults were potato, Solanum tuberosum L.; bitter nightshade, Solanum dulcamara L., and buffalobur, Solanum rostratum Dunal; eggplant and horsenettle, Solanum melongena L. and Solanum carolinense L., were of intermediate rank in recruitment of adults. The remaining species (tomato, Lycopersicon esculentum L.; black nightshade, Solanum nigrum L.; silverleaf nightshade, Solanum eleaegnifolium Cavanilles; groundcherry, Physalis heterophylla Nees; jimsonweed, Datura stramonium L.) were not preferred. Adult recruitment and oviposition changed over the season and differed from site to site, but was not influenced by the host-plant origin of recruited adults. Daily collections of adults in Massachusetts in 1991 showed four distinct periods of adult recruitment. These differed in relative importance depending on whether plots were near or distant to previous and current year's potato fields. Early overwintered recruitment was highest and relatively less different between near and distant plots, reflecting the importance of flight during this period. Late overwintered recruitment was mostly by short-distance dispersal of adults that had already fed on potato plants, based on oviposition of collected females. Summer females also appeared to be previously fed, and their recruitment to distant plots suggested dispersal mostly by flight. Prediapause dispersal resulted in recruitment mostly to plots a short distance from potato fields. Reproduction, as measured by egg masses per adult, increased over the season, with summer adults showing the highest egg mass-adult ratio. Recruitment 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.