ADAPTIVE SUPERPARASITISM AND PATCH TIME ALLOCATION IN SOLITARY PARASITOIDS - THE INFLUENCE OF THE NUMBER OF PARASITOIDS DEPLETING A PATCH

An ESS model that predicts more superparasitism and longer patch times with an increasing number of searching parasitoids in a patch, was tested in experiments with Leptopilina heteroloma, a solitary larval parasitoid of Drosophila. The observed egg distributions and patch times were in quantitative agreement with the predictions of the model; oviposition and patch time decisions are clearly influenced by the number of conspecifics in the patch. Both in the model and in the experiment patch quality was kept constant (the number of hosts and the patch area per parasitoid were kept constant). The model predicted and the experiments showed that parasitoids gain less offspring per unit of time when searching a patch together: superparasitism leads to mutual interference. No self-superparasitism should have occurred when parasitoids searched alone. This prediction was only met with females that had been kept in isolation in the days before the experiment; when stored in groups of four, self-superparasitism did occur. This indicates an ability of the parasitoids to assess the probability of future superparasitism by conspecifics. © 1990, Brill. All rights reserved.