Parthenogenesis‐inducing microorganisms in Aphytis (Hymenoptera: Aphelinidae)

Abstract

Production of males in uniparental lines of two species in the parasitic wasp genus Aphytis was induced by rifampicin, and male sexual functioning was determined. Wolbachia-specific 16S rDNA primers were used in a PCR in order to: (1) assess correlation between thelytokous reproduction and the presence of Wolbachia; (2) detect the loss of Wolbachia DNA in uniparental A. lingnanensis following antibiotic treatments, with or without the presence of a host; and (3) clone and sequence part of the Wolbachia 16S rDNA from the uniparental Aphytis species for phylogenetic studies. Males produced viable sperm that was transferred to the female spermatheca following mating. However, sperm failure to effect egg fertilization resulted in all-male progeny. Wolbachia were found in the two uniparental (A. lingnanensis and A. diaspidis) but not in the two biparental (A. lingnanensis and A. melinus) Aphytis lines tested. They can be detected in wasps up to 7 days following antibiotic treatments, regardless of the presence of host. The 16S rDNA for the symbionts in the two Aphytis species is virtually identical, and is most closely related to the Wolbachia found in Muscidifurax uniraptor (Pteromalidae).

The diversity of inherited parasites of insects: the male-killing agent of the ladybird beetle Coleomegilla maculata is a member of the Flavobacteria

“…Cytoplasmic incompatibility is subtle : the condensation of the paternal chromosome set of an uninfected female through (it is considered) products placed in sperm by infected males (Breeuwer & Werren, 1990). Parthogenesis induction is similarly associated with this bacterial clade (Stouthamer et al, 1993 ;Zchori-Fein et al, 1995 ;Pijls et al, 1996). It is similarly subtle, this time involving a manipulation of the early mitotic division in haploid (male) individuals (Stouthamer & Kazmer, 1994).…”

“…So far, parthenogenesis induction and cytoplasmic incompatibility have been observed to be associated with bacteria of one clade : the alpha proteus-like bacterium Wolbachia (Stouthamer et al, 1993 ;Van Meer et al, 1995 ;Zchori-Fein et al, 1995 ;Pijls et al, 1996). On the other hand, in the three cases where male-killing agents have been identified, bacteria from two different eubacterial groups have been observed : a member of the Gram positives (a Spiroplasma) in Drosophila willistoni (Hackett et al, 1985), and members of the Gram-negative proteobacteria in Nasonia itripennis (bacterium : Arsenophonus nasoniae) (Werren et al, 1986 ;Gherna et al, 1991) and Adalia bipunctata (bacterium : a member of the genus Rickettsia) (Werren et al, 1994 ;.…”

Neutral and selection-driven decay of sexual traits in asexual stick insects

“…Tests for trait decay in asexually produced males have been conducted in hymenopterans with endosymbiont-induced parthenogenesis [37,41,42], where males are produced by asexual females cured of their endosymbionts [43]. With few exceptions [44], these males appear fully functional, produce viable sperm [37,41,45,46] and sometimes even father similar numbers of offspring as sexual males [47,48] when mated to females from related sexual strains or species. Only in exceptional instances, notably in 'ancient' asexuals, has male functionality appeared to have decayed, as suggested by the lack of sperm in the darwinulid males [49] and the production of non-functional spermatophores by males in the oribatid mites [20].…”

Wolbachia-induced reproductive parasitism and applications

“…If a 100% occurrence is assumed, parthenogenesis as well as feminization doubles the potential transmission of Wolbachia to the offspring. Interestingly, all currently documented cases of Wolbachiainduced parthenogenesis are found only within haplodiploid species belonging to Thysanoptera (Arakaki et al 2001), Acari (Weeks and Breeuwer 2001) and Hymenoptera (Stouthamer et al 1993, Zchori-Fein et al 1995. Haplodiploidy describes the development of (diploid) females from fertilized eggs, while (haploid) males develop from unfertilized eggs.…”