The Effect of Egg Limitation on Stability in Insect Host-Parasitoid Population Models

Abstract

1. We investigate the potential effects of parasitoid egg limitation on host-parasitoid population dynamics. We define a parasitoid as egg-limited if a shortage of eggs means that at some time she cannot utilize an opportunity to oviposit. 2. We develop models which consider the differing physiologies of pro-ovigenic and synovigenic parasitoids to investigate the potential consequences of egg limitation. Pro-ovigenic parasitoids emerge with their full complement of mature eggs. Synovigenic parasitoids also emerge with some eggs, but can mature more later in life. 3. The models indicate that egg limitation in pro-ovigenic parasitoids has no effect on stability. This result is independent of the egg load distribution in newly emerged parasitoids, and of the maximum number of eggs with which a female emerges. In synovigenic models, however, egg limitation is found to be destabilizing, though the reduction in stability is decreased by (i) an increase in egg load at emergence, and (ii) a decrease in the 'latent' time required for egg maturation and gut emptying following a host meal. The latent period, during which time the full gut precludes feeding on hosts, differs from a conventional handling time in that host attacks (via oviposition) are still possible if the female has mature eggs. The maximum ovary storage capacity of females in a synovigenic parasitoid population has no effect on stability.