Effects of food deprivation, body size, and egg load on the mating behavior of female Japanese beetles, Popillia japonica Newman (Coleoptera Scarabaeidae)

Abstract

Female condition may play an important role in the mating frequency of species that mate at foraging areas. For example, in species where feeding females are more easily encountered or less resistant to mating than females that are performing other activities, low energy levels could increase mating activity. We studied the relationship between female condition and mating activity in the Japanese beetle, Popillia japonica (Coleoptera Scarabaeidae) in a laboratory study. We altered condition by depriving some females of food for one day and comparing their mating behavior to well-fed females. Our results showed that the effect of nutritional condition on mating behavior only became apparent when we considered female body size and fecundity status: well-fed, relatively large females, well-fed, relatively fecund females, and unfed, relatively small females mated more frequently than their counterparts. These patterns may be a result of food deprivation altering the costs and benefits of mating for females of different body sizes and egg loads, and perhaps reflect a need for females that are about to oviposit needing to maximize their food intake.