OVIPOSITION RESTRAINT OF MUSCIDIFURAX ZARAPTOR (HYMENOPTERA: PTEROMALIDAE) ON PARASITIZED HOUSEFLY PUPAE

Abstract

Females of Muscidifurax zaraptor K. & L. oviposit on unparasitized housefly (Musca domestica L.) pupae in preference to those attacked by M. zaraptor, Nasonia vitripennis (Walk.), or Spalangia cameroni Perk. (Hymenoptera: Pteromalidae). The discrimination against parasitized houseflies is greatest in the case of those attacked by M. zaraptor and least for those parasitized by S. cameroni. Discrimination is based on differences between unparasitized and parasitized pupae that the female parasites detect after they pierce the pupae with the ovipositor. Death of parasitized hosts, or a change resulting directly therefrom, is not responsible for the differences. The fact that hosts pierced at or near the original drilling site are more likely to be rejected than those attacked elsewhere supports the hypothesis that a ’venom’ injected by the female parasites during oviposition diffuses throughout the host and is responsible for oviposition restraint.