ADULT FEEDING AND LIFETIME REPRODUCTIVE SUCCESS IN THE PARASITOID APHYTIS-MELINUS

The diet of adult females of the parasitoid Aphytis melinus DeBach (Hy menoptera: Aphelinidae) includes host insects and sugar-rich foods suc h as nectar and honeydew. We compared the contributions of host feedin g to longevity and fecundity in A. melinus females in the presence and in the absence of honey meals. First, we assessed the longevity of fe males that were not allowed to oviposit. While the longevity of female s fed honey was significantly increased by host feeding (median ages w ere 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 exce ed 3 days for any individual and there was no effect of host feeding o n longevity in this group. In the second set of experiments, we assess ed the fecundity and longevity of females allowed to oviposit. We cond ucted two experiments, one in which honey was continuously available, and one in which honey was not available. In both experiments, daily o bservations were made of females that were either allowed to host feed or manually prevented from host feeding. In the presence of honey, ho st feeding significantly increased both fecundity and longevity, and i n the absence of honey, parasitoids died within 2 days and host feedin g had no significant effect on either fecundity or longevity. The life time 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 fecun dity of honey-fed females. In the last experiment, we compared the rat e 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 resor ption was detected in honey-fed females over this time period, starved females resorbed approximately 9 eggs. Thus, the availability of a su gar-rich food interacts strongly with host feeding in influencing long evity and fecundity and has a strong direct effect on egg resorption.