Beyond sex allocation: the role of mating systems in sexual selection in parasitoid wasps

Abstract

Despite the diverse array of mating systems and life histories which characterise the parasitic Hymenoptera,sexual selection and sexual conict in this taxon have been somewhat overlooked. For instance, parasitoidmating systems have typically been studied in terms of how mating structure affects sex allocation. In thepast decade, however, some studies have sought to address sexual selection in the parasitoid wasps moreexplicitly and found that, despite the lack of obvious secondary sexual traits, sexual selection has the potentialto shape a range of aspects of parasitoid reproductive behaviour and ecology. Moreover, various characteristicsfundamental to the parasitoid way of life may provide innovative new ways to investigate different processesof sexual selection. The overall aim of this review therefore is to re-examine parasitoid biology with sexualselection in mind, for both parasitoid biologists and also researchers interested in sexual selection and theevolution of mating systems more generally. We will consider aspects of particular relevance that have alreadybeen well studied including local mating structure, sex allocation and sperm depletion. We go on to review whatwe already know about sexual selection in the parasitoid wasps and highlight areas which may prove fruitfulfor further investigation. In particular, sperm depletion and the costs of inbreeding under chromosomal sexdetermination provide novel opportunities for testing the role of direct and indirect benets for the evolutionof mate choice.