Effects of Mating Status and Parasitoid Density on Superparasitism and Offspring Fitness in <I>Tiphodytes gerriphagus</I> (Hymenoptera: Scelionidae)

Abstract

Laboratory experiments investigated the effects of mating status and wasp density on frequency of superparasitism, development time, longevity, and fecundity of offspring of the egg parasitoid Tiphodytes gerriphagus Marchal. When individual females searched a patch over a 24-h period the number of probes per egg from mated wasps was higher than that from unmated wasps, but there was no difference in number of larvae found per egg during dissections. When groups of 5 females searched a patch together, both number of probes per egg and number of larvae per egg increased significantly compared with that of individual females. Superparasitism occurred most frequently when eggs were simultaneously exposed to 5 females, and mated groups of females superparasitized more frequently than unmated groups (frequencies of 78.1 and 62.9%, respectively). Development time of wasps in superparasitized eggs was longer than that of wasps in singly parasitized eggs. Longevity of adult male parasitoids was not affected by having come from superparasitized eggs, but female longevity was decreased significantly. Mated and unmated females showed no significant differences in fecundity, regardless of whether they had emerged from superparasitized or singly parasitized eggs.