Some Factors that Reduce the Reproductive Rate of Nasonia vitripennis (Walk.) at High Adult Population Densities

Abstract

AbstractReproductive rate of the parasite Nasonia vitripennis (Walk.) on pupae of the housefly, Musca domestica L., measured by the number of mature progeny produced per female in 18 hours, decreased with increasing parasite:host ratios. This decrease resulted partly because each female laid fewer eggs, and partly because of increased larval mortality caused by superparasitism. The average number of eggs laid per female was reduced because the parasites wasted relatively more time drilling into unsuitable (i.e. parasitized and previously drilled) hosts on which they subsequently laid few or no eggs; and because the females interfered more with each other while ovipositing. Incidence of superparasitism was greater at higher parasite:host ratios because, in spite of increased interference among the females, there were more simultaneous attacks by two or more females on each fly pupa.