Assessing superparasitism with a model combining the functional response and the egg distribution of parasitoids

Abstract

A model for superparasitism in insect parasitoids is developed. This model combines the study of superparasitism in terms of distribution of eggs among hosts (for a given number of hosts) and in terms of functional response (number of hosts attacked for a varying number of hosts available). Thus, it gives a synthetic treatment of problems that had been previously handled with separate models (e.g., Bakkeret al. (1972) on one hand and Arditi (1983) on the other hand). The combined model involves several parameters, among which important ones are the propensity to superparasitise, δ, and the average handling times spent on healthy and parasitised hosts, Th and Tp. Special cases are those of an indiscriminate parasitoid (δ=1 and Tp=Th) and of a “predator-like” parasitoid (δ=0 and Tp=0).