The effect of superparasitism by Aphidius smithi (Hymenoptera: Aphidiidae) on the food budget of the pea aphid, Acyrthosiphon pisum (Homoptera: Aphididae)

Abstract

The food budget of diet-fed, second-instar pea aphids when superparasitized by Aphidius smithi was similar to that of single-parasitized aphids. Aphids containing two parasite eggs or embryos consumed less diet and grew at a slower rate than did healthy controls. Feeding, assimilation, and growth increased significantly after the parasite larva(e) had hatched from the trophamnion. During the late stages of parasite larval development, host growth was increased by 133% and honeydew excretion by 146% over control values. During the same period, parasitized aphids converted ingested and digested food, respectively, with 66% and 86% greater efficiency than did controls. These increases were higher than in single-parasitized aphids, perhaps as a result of the larger number of teratocytes present in superparasitized hosts.