Oviposition and host‐feeding patterns in Aphelinus asychis (Hymenoptera: Aphelinidae) at different aphid densities

Abstract

Abstract. 1. The patterns of host‐feeding and oviposition were examined in Aphelinus asychis Walker, which had been provided with second‐instar pea aphids as hosts. 2. Female wasps responded to increasing host density (between one and forty aphids for 24 h) with an increasing tendency to oviposit rather than to feed. Superparasitism occurred at all aphid densities, even when unparasitized aphids were available. 3. Aphids intended for feeding were paralysed and died. Wasps did not feed on and oviposit in the same aphid. 4. Feeding to satiation lasted between 4 min and 42 min. Females that had starved for ≰18 h generally deposited one or more eggs before feeding again, while the reverse was true in wasps that had starved for 21 h. 5. The host‐feeding behaviour of A. asychis is determined by a female's nutritional status. At low rates of host encounter, the anhydropic eggs may be resorbed. This reproductive strategy conforms to the destructive non‐concurrent type among the Hymenoptera. Copyright © 1990, Wiley Blackwell. All rights reserved