Some Mechanisms That Affect the Sex Ratio ofNasonia vitripennis(Walk.) (Hymenoptera: Pteromalidae) Reared From Superparasitized Housefly Pupae

Abstract

AbstractFemaleNasonia vitripennis(Walk.) parasitizing housefly (Musca domesticaL.) pupae produce a smaller percentage of female progeny at high parasite:host ratios than at lower ones because they fertilize a smaller percentage of their eggs (in this species unfertilized eggs produce male progeny), and because more female than male larvae die on superparasitized hosts. The adult females fertilize relatively fewer eggs at high than at low parasite:host ratios for two reasons. First, they encounter relatively more previously attacked hosts, on which they lay a smaller percentage of fertilized eggs than on previously unattacked ones; second, they more often encounter other female parasites while ovipositing, and this interference reduces the percentage of fertilized eggs they lay.