Single-locus complementary sex determination absent in Heterospilus prosopidis (Hymenoptera: Braconidae)

Abstract

In the haplodiploid Hymenoptera, haploid males arise from unfertilized eggs, receiving a single set of maternal chromosomes while diploid females arise from fertilized eggs and receive both maternal and paternal chromosomes. Under single-locus complementary sex determination (sl-CSD), sex is determined by multiple alleles at a single locus. Sex locus heterozygotes develop as females, while hemizygous and homozygous eggs develop as haploid and diploid males, respectively. Diploid males, which are inviable or sterile in almost all cases studied, are therefore produced in high frequency under inbreeding or in populations with low sex allele diversity. CSD is considered to be the ancestral form of sex determination within the Hymenoptera because members of the most basal taxa have CSD while some of the more derived groups have other mechanisms of sex determination that produce the haplo-diploid pattern without penalizing inbreeding. In this study, we investigated sex determination in Heterospilus prosopidis Viereck, a parasitoid from a relatively primitive subfamily of the Braconidae, a hymenopteran family having species with and without CSD. By comparing sex ratio and mortality patterns produced by inbred and outbred females, we were able to rule out sl-CSD as a sex determination mechanism in this species. The absence of sl-CSD in H. prosopidis was unexpected given its basal phylogenetic position in the Braconidae. This and other recent studies suggest that sex determination systems in the Hymenoptera may be evolutionary labile. Heredity (2005) 95, 228-234.

Experimental Support for Multiple-Locus Complementary Sex Determination in the Parasitoid Cotesia vestalis

“…The braconid genus Cotesia could provide a valuable system for comparative studies because it comprises species with presumed sl-CSD (C. glomerata), ml-CSD (C. vestalis), and no CSD (C. sesamiae, C. flavipes) (Gu and Dorn 2003;Niyibigira et al 2004a,b;Zhou et al 2006;de Boer et al 2007a,b). A similar diversity of sex determining systems can be found more broadly in the Braconidae as well (Beukeboom et al 2000;Wu et al 2005;van Wilgenburg et al 2006). Another interesting group is the ant family, Formicidae, because many species are believed to have sl-CSD (van Wilgenburg et al 2006), but it appears to be absent in the inbreeding ant Cardiocondyla batesii (Schrempf et al 2006).…”

Absence of Complementary Sex Determination in the Parasitoid Wasp Genus Asobara (Hymenoptera: Braconidae)

“…Absence of diploid males is crucial but no conclusive evidence for absence of CSD, because diploid males could be inviable [23], [27], [47]. If diploid males do not survive, both female offspring number and brood size are expected to decrease over inbreeding generations, since diploid male production comes at the cost of female production under CSD.…”

Applied evolutionary ecology of insects of the subfamily Bruchinae (Coleoptera: Chrysomelidae)

“…Alternatively, parasitoids (e.g., a trichogrammatid egg parasitoid Uscana, larval-pupal parasitoids, pteromalid Dinarmus, Anisopteromalus, an eupelmid Eupelmus, and a braconid Heterospilus; e.g., Southgate, 1979;Steffan, 1981;Fujii and Wai, 1990;Mitsunaga and Fujii, 1999;Schmale et al, 2001;Tuda et al, 2001;Kobayashi et al, 2003;Jaloux et al, 2004;Tuda and Shimada, 2005;Wu et al, 2005;Vamosi, Hollander and Tuda, unpublished) and plant extracts (e.g., Lambert, 1985;Rahman, 1990) have been actively explored for biological control (see Huis, 1991 for review). In addition to biological and botanical control, controlled temperature (e.g., Rahman, 1990), mechanical control (e.g., Quentin et al, 1991), controlled atmosphere (e.g., Oosthuzien and Schmidth, 1942) and radiation (e.g., Kiyoku and Tsukuda, 1968;Hossain et al, 1972;Reddy et al, 2006) have been proposed as effective control methodology (see also Highley et al, 1994).…”