Flexible female choice in haplo-diploid predatory mites Phytoseiulus persimilis

Abstract: Predatory mites such as Phytoseiulus persimilis Athias-Henriot (Acari: Phytoseiidae)are sexually reproducing and, because of their specialization on patchily distributed herbivorousspider mites, living in groups. Depending on the number of group foundresses, groups may becomposed of individuals having various degrees of genetic relatedness, from siblings to nonkin.Such circumstances should select for sophisticated mate discrimination abilities byfemales. Choosing a genetically compatible mate of the same species is important to ensureproduction of viable healthy progeny. Excessive inbreeding, that is, mating with too closerelatives, commonly results in fitness loss because of increased homozygosity levels and, at theother pole, also extreme outbreeding may be unfavorable if it breaks up favorable genecomplexes. Therefore, sexually reproducing organisms should be selected for an optimalbalance between in- and out-breeding and an ability to assess the genetic distance of potentialmates. Accordingly, many organisms evolved inbreeding avoidance mechanisms such as kinrecognition. Here, we tested the mate choice of predatory mite females P. persimilis from twodifferent populations, Sicily and Greece. We performed three experiments on mate choice,based on the combined predictions of optimal outbreeding and (k)inbreeding theories, inpredatory mites P. persimilis. Virgin females were presented to binary choices between brothersand distant kin (same population) or non-kin (other population). Females of Greece but notSicily preferred unfamiliar brothers to familiar brothers. Females of both origins preferreddistant kin to unfamiliar and familiar brothers but preferred unfamiliar brothers to non-kin.Females of Sicily but not Greece preferred familiar brothers to non-kin. Overall, this studysuggests that females flexibly base their mate preferences on the available mate options andachievable direct and indirect fitness benefits.