Environmental and genetic determinants of ovicide in parasitic wasp Bracon hebetor

Abstract

Superparasitism occurs when a parasitoid lays a second dutch of eggs on a host previously parasitized by herself or a conspecific. Ovidde refers to a parasitoid destroying an ^H«ring dutch of eggs on a parasitized host before laying a second clutch. We investigated environmental and genetic determinants of ovidde in the parasitic wasp Bracon hebetor. Characterization of egglaying behavior revealed that B. hebetor commits ovidde during the host examination phase of oviposition. The temporal costs of ovidde were found to be relatively small for females that experienced low rates of host encounter, whereas the costs of ovidde increased for females that experienced a high rate of host encounter. Individual wasps committed ovidde on conspecifically parasitized hosts more frequently than on self-parasiti zed hosts. Manipulation experiments suggested that B. hebetor females learn about their environment while foraging and commit ovidde on die basis of die travel time between successive hosts. Significant differences were also found in oviddal behavior among laboratory and field populations of B. hebetor. The implications of our results for dutch size theory and die evolution of ovidde are discussed. Key words: Bracon hebetor, competition, foraging, infantidde, ovidde, parasitoid, reproduction, superparasitism. [Behav Ecol 8:647-654 (1997)] M