Optimal Egg Distribution Among Host Patches for Parasitoids Subject to Attack by Hyperparasitoids

Abstract

Using an aphid-parasitoid-hyperparasitoid system as an example, we study the optimal oviposition strategy of a parasitoid whose offspring are subject to attack by hyperparasitoids. We assume that hyperparasitoids, which search aphid colonies for aphids that have been infected by parasitoids, decide to leave a colony when they have searched some fixed number of aphids consecutively without finding an infected one. We use a simulation model to investigate how many hosts the parasitoid should infect per colony to maximize the long-term average rate of producing eclosing offspring. We consider three different variables and deal with them one at a time: (1) N = the number of aphids in a colony, (2) H = the average number of perparasitoids visiting each colony, and (3) tau = the parasitoid travel time between colonies. The optimal number of aphids to infect in a colony is sometimes much less than the total number of aphids available. The optimal number of aphids to infect within a colony decreases with a decrease in the colony size, with an increase in the average number of perparasitoid visits, and with a decrease in travel time between aphid colonies.