FITNESS CONSEQUENCES OF SUPERPARASITISM AND MECHANISM OF HOST DISCRIMINATION IN THE STEMBORER PARASITOID COTESIA FLAVIPES

The fitness consequences of superparasitism and the mechanism of host discrimination in Cotesia flavipes, a larval parasitoid of concealed s temborer larvae was investigated. Naive females readily superparasitiz ed and treated the already parasitized host as an unparasitized host b y allocating the same amount of eggs as in an unparasitized host. Howe ver, there was no significant increase in the number of emerging paras itoids from superparasitized hosts due to substantial mortality of par asitoid offspring in superparasitized hosts. Furthermore, the developm ental time of the parasitoids in a superparasitized host was significa ntly longer than in a singly parasitized host and the emerging progeny were significantly smaller (body length and head width). Naive female s entered a tunnel in which the host was parasitized 4 h previously an d accepted it for oviposition. Experienced females (oviposition experi ence in unparasitized host) refused to enter a tunnel with a host para sitized by herself or by another female. In experiments where the tunn el and/or host was manipulated it was demonstrated that the female lea ves a mark in the tunnel when she parasitizes a host. The role of patc h marking in C. flavipes is discussed in relation to the ecology of th e parasitoid.