No evidence of parthenogenesis‐inducing bacteria involved in T hripoctenus javae thelytoky: an unusual finding in C halcidoidea

• Published in: Entomologia experimentalis et applicata 2016-09, Vol.160 (3), p.292-301
• Main Authors: Monti, Maurilia M., Nugnes, Francesco, Gualtieri, Liberata, Gebiola, Marco, Bernardo, Umberto
• Format: Article
• Language: English
• ISSN: 0013-8703; 1570-7458
• DOI: 10.1111/eea.12477

All H ymenoptera have a haplodiploid mode of sex determination. Although most species reproduce by arrhenotokous parthenogenesis, there are many thelytokous species, in which unfertilized eggs develop into diploid females. Thelytoky can be genetic or due to microbial infection. In the large C halcidoidea superfamily, thelytokous parthenogenesis is almost always associated with infection of endosymbionts of the genera W olbachia , C ardinium , and R ickettsia . T hripoctenus javae ( G irault) ( H ymenoptera: E ulophidae) is a larval parasitoid of the greenhouse thrips H eliothrips haemorrhoidalis ( B ouché) ( T hysanoptera: T hripidae), an important worldwide pest. Both the host and its parasitoid reproduce by thelytokous parthenogenesis. The main goal of this study was to test whether endosymbiotic bacteria, either those known to induce thelytokous parthenogenesis or other sex‐manipulators, are responsible for thelytoky of two geographically distinct populations of T . javae . We used sequencing of ribosomal ITS 2 and 28S‐D2 and mitochondrial COI genes to molecularly characterize the two populations, antibiotic and heat treatments, and FISH of ovaries, for thelytoky studies. It was impossible to revert thelytokous individuals back to sexual reproduction and no evidence of bacterial infection was found in parthenogenetic T . javae females. This makes T . javae the second chalcidoid in which thelytokous reproduction appears not to be associated with the presence of bacterial endosymbionts.