A POSSIBLE MECHANISM FOR THE PHYSIOLOGICAL SUPPRESSION OF CONSPECIFICEGGS AND LARVAE FOLLOWING SUPERPARASITISM BY SOLITARY ENDOPARASITOIDS

Competition for possession of a host by internal solitary parasitoids has been attributed to physical combat and physiological suppression, but the mechanisms that result in what has been referred to as physiol ogical suppression is poorly understood. Some insights are provided by the studies reported here using the solitary endoparasitoid, Campolet is sonorensis (Cameron). Embryos of C. sonorensis less than ten hours old rarely hatch in various artificial media; while embryos twenty hou rs or older generally hatch. These results suggest that young embryos in which the embryonic membranes have not yet formed are only able to develop in a narrow range of environments represented by the nonparasi ted hemolymph. In contrast. embryos in which the embryonic membranes a n formed are able to develop in a wide range of environments represent ed by parasitized hemolymph which has been shown by a number of studie s to change. These ideas were given support by studies reported here, where young and older eggs were incubated singly or paired. We suggest the general changes in the hemolymph of a parasitized host become unf avorable for the development of newly oviposited eggs. (C) 1998 Elsevi er Science Ltd. All rights reserved.