Absence of complementary sex determination in twoLeptopilinaspecies (Figitidae, Hymenoptera) and a reconsideration of its incompatibility with endosymbiont‐induced thelytoky

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Abstract
Complementary sex determination (CSD) is a widespread sex determination mechanism in haplodiploid Hymenoptera. Under CSD, sex is determined by the allelic state of one or multiple CSD loci. Heterozygosity at one or more loci leads to female development, whereas hemizygosity of haploid eggs and homozygosity of diploid eggs results in male development. Sexual (arrhenotokous) reproduction normally yields haploid male and diploid female offspring. Under asexual reproduction (thelytoky), diploidized unfertilized eggs develop into females. Thelytoky is often induced by bacterial endosymbionts that achieve egg diploidization by gamete duplication. As gamete duplication leads to complete homozygosity, endosymbiont‐induced thelytokous reproduction is presumed to be incompatible with CSD, which relies on heterozygosity for female development. Previously, we excluded CSD in fourAsobara(Braconidae) species and proposed a two‐step mechanism forWolbachia‐induced thelytoky inAsobara japonica. Here, we conclusively reject CSD in two cynipid wasp species,Leptopilina heterotomaandLeptopilina clavipes. We further show that thelytoky inL. clavipesdepends onWolbachiatiter but that diploidization and feminization steps cannot be separated, unlike inA. japonica. We discuss what these results reveal about the sex determination mechanism ofL. clavipesand the presumed incompatibility between CSD and endosymbiont‐induced thelytoky in the Hymenoptera.
Funding Information
  • China Scholarship Council (201506300038)

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