POPULATION BEHAVIOR AND ADULT FEEDING CAPABILITY IN LEPIDOPTERA

Population behavior in Lepidoptera is increasingly being shown to corr elate with life-system or intrinsic factors. Two examples of such fact ors are larval gregariousness (and associated egg clustering) and over wintering stage (and associated larval feeding phenology). Adult feedi ng capability, also an intrinsic factor has received scant attention i n Lepi- doptera population studies. It varies from species that are in capable of feeding to species that feed daily or hourly Because adult feeding capability determines reproductive duration, it could affect v ulnerability to mortality agents during a critical period and thereby influence population behavior. Using comparative methodology, I tested whether long-term population density and variability are related to a dult feeding capability Test data were published density records for > 200 species in 16 families during 10-60 yr in Canada, the United Kingd om, and Germany, with species assigned to low, medium, and high classe s of adult feeding capability Mean logarithmic population densities, a s well as standard deviations, were inversely related to degree of adu lt feeding capability. I also indirectly explored history of phenotypi c variation through evolutionary time in the 3 intrinsic factors. Resu lts suggested that adult feeding capability diverged earlier and was e volutionarily tracked by larval gregariousness and overwintering stage . Among 29 phylogenetically independent lineages of outbreak Lepidopte ra, there was a significant association with low adult feeding capabil ity. Study results lead to the conclusion that adult feeding capabilit y is a primary intrinsic factor that influences population behavior mo re than has hitherto been recognized.