1. ¹Laboratory of Entomology, Wageningen University, 6700EH, Wageningen, The Netherlands
2. ²Department of Entomology, University of California, Riverside, CA 92521, USA

Correspondence: R Stouthamer, Department of Entomology, University of California, Riverside, CA 92521, USA. E-mail: richard.stouthamer@ucr.edu

³Current address: Department of Entomology, University of California, Riverside, CA 92521, USA

Received 26 April 2004; Accepted 30 September 2004; Published online 3 November 2004.

Abstract

A lepidopteran egg parasitoid species Telenomus nawai consists of two distinct populations with different reproductive modes. One is a completely thelytokous population consisting of females only, whereas the other displays arrhenotokous reproduction where fertilized eggs develop into diploid females and unfertilized eggs into haploid males. Thelytoky in T. nawai is caused by a bacterial symbiont, the parthenogenesis-inducing (PI) Wolbachia. Recent theoretical studies have shown that when a PI-Wolbachia is spreading in a population, mutations that allow uninfected females to produce more male offspring will spread rapidly eventually becoming fixed. The consequence of such a mutation is that sexual reproduction is no longer successful in infected females. Here we determine the genetic basis of the females' inability to reproduce sexually by introgressing the genome of a thelytokous line into an arrhenotokous line. The results suggest that the mutations are recessive and inherited either as a single-locus major gene with some modifiers, or as two partially linked loci.