Adult feeding and lifetime reproductive success in the parasitoid Aphytis melinus

Abstract The diet of adult females of the parasitoid Aphytis melinus DeBach (Hymenoptera: Aphelinidae) includes host insects and sugar‐rich foods such as nectar and honeydew. We compared the contributions of host feeding to longevity and fecundity in A. melinus females in the presence and in the absence of honey meals. First, we assessed the longevity of females that were not allowed to oviposit. While the longevity of females fed honey was significantly increased by host feeding (median ages were 30.5 days for host‐fed females and 17 days for females not allowed to host feed), the lifespan of parasitoids not fed honey did not exceed 3 days for any individual and there was no effect of host feeding on longevity in this group. In the second set of experiments, we assessed the fecundity and longevity of females allowed to oviposit. We conducted two experiments, one in which honey was continuously available, and one in which honey was not available. In both experiments, daily observations were made of females that were either allowed to host feed or manually prevented from host feeding. In the presence of honey, host feeding significantly increased both fecundity and longevity, and in the absence of honey, parasitoids died within 2 days and host feeding had no significant effect on either fecundity or longevity. The lifetime fecundity of females fed honey but not hosts exceeded the initial egg complement by 60% on average. Approximately one host per day was used for host feeding whether honey was supplied or not, and each host‐feeding meal contributed approximately 3.9 eggs to the lifetime fecundity of honey‐fed females. In the last experiment, we compared the rate of egg resorption over a 36‐h period in A. melinus females that were deprived of hosts and either fed honey or starved. While no egg resorption was detected in honey‐fed females over this time period, starved females resorbed approximately 9 eggs. Thus, the availability of a sugar‐rich food interacts strongly with host feeding in influencing longevity and fecundity and has a strong direct effect on egg resorption.