LARVAL COMPETITION AMONG THREE HYMENOPTEROUS PARASITE SPECIES ON MULTIPARASITIZED HOUSEFLY (DIPTERA) PUPAE
AbstractOnly one parasite species survived on most housefly (Musca domestica L.) pupae multiparasitized by any two of Nasonia vitripennis (Walk.), Muscidifurax zaraptor K. & L., or Spalangia cameroni Perk. N. vitripennis and M. zaraptor were both intrinsically superior to S. cameroni if the attacks on the hosts by their females preceded, were simultaneous with, or followed by up to 48 hours those by females of S. cameroni. N. vitripennis was intrinsically superior to M. zaraptor if its attack preceded that by M. zaraptor by at least 24 hours; M. zaraptor survived when it oviposited before N. vitripennis; and neither species was consistently superior to the other when their attacks were simultaneous or that by N. vitripennis closely preceded that by M. zaraptor. N. vitripennis often survived on multiparasitized hosts because of its rapid development and rapid and thorough host utilization which caused its rivals to starve. In contrast, M. zaraptor’s success was a consequence of its prédation on eggs and larvae of its competitors and to a lesser extent its moderately rapid development and host utilization. S. cameroni was usually intrinsically inferior to both of the other species because, in spite of being predaceous on their larvae, it developed much more slowly and seldom attacked their eggs. The significance of these qualitative characteristics in insect parasites used in biological control programmes is discussed.