A survey of Wolbachia, Spiroplasma and other bacteria in parthenogenetic and non-parthenogenetic phasmid (Phasmatodea) species

The ecological and genetic mechanisms that determine Phasmatodea reproductive biology are poorly understood. The order includes standard sexual species, but also many others that display distinct types of parthenogenesis (tychoparthenogenesis, automixis, apomixis, etc.), or both systems facultatively. In a preliminary survey, we analysed Wolbachia and Spiroplasma infection in 244 individuals from 28 species and 24 genera of stick insects by bacterial 16S rRNA gene amplification. Our main aim was to determine whether some of the bacterial endosymbionts involved in distinct reproductive alterations in other arthropods, including parthenogenesis and male killing, are present in phasmids. We found no Wolbachia infection in any of the phasmid species analysed, but confirmed the presence of Spiroplasma in some sexual, mixed and asexual species. Phylogenetic analysis identified these bacterial strains as belonging to the Ixodetis clade. Other bacteria genera were also detected. The possible role of these bacteria in Phasmatodea biology is discussed.