The Optimal Clutch Size of Insects When Many Females Oviposit Per Patch

When more than one female insect oviposits on the same patch of larval food, the optimal clutch size depends not only on the number of other females that oviposit but also on the form of larval competition within patches. I use models to show that, depending on the type of larval competition, the evolutionarily stable clutch size can either decrease or increase as more females oviposit per patch. The models predict decreases in the evolutionarily stable clutch size with increasing numbers of females ovipositing per patch when larval competition causes rapid mortality at high densities, and they predict increases in the evolutionarily stable clutch size when larval competition is more benign. I also give examples of both extremes of larval competition by analyzing data from the literature for 10 insect species.