Impact of the mate-finding Allee effect on the competitiveness of diploid versus haplodiploid parasitoids: A theoretical approach

Insect parasitoids can either be diploid, and require mating prior to ovipositing, or haplodiploid, in which case females can produce male offspring through parthenogenesis. In small or low-density populations, parasitoid females might face a mate-finding Allee effect, that is they might not be able to find a male to mate with. Incidences of low-densities populations may be frequent in parasitoid due to the host-parasitoid interaction, which can lead to cycling dynamics, or because of their use in biological control where they might be introduced in small numbers. The ability of virgin haplodiploid females to produce offspring might favor them when confronted with mate-finding difficulties. Using modeling tool to simulate a host-parasitoid dynamics, we investigated whether haplodiploidy confers a competitive advantage over diploidy in parasitoid populations undergoing mate-finding Allee effect. Our results suggest that the Allee effect impacts parasitoid dynamics by inducing competitive exclusion between diploid and haplodiploid parasitoids. Haplodiploidy is favored when mate-finding difficulties are strong.