Prevalence of Wolbachia in 10 Tenebrionidae stored-product insects and spatiotemporal infection dynamics in Tribolium confusum (Jaquelin Du Val) (Coleoptera: Tenebrionidae)

Abstract

Insect symbionts Wolbachia used for pest population control has focused on vector pest species and agricultural insects while rare reports in Chinese stored-product insect samples. In this paper, we surveyed the prevalence of Wolbachia using a PCR detection method in ten Tenebrionidae stored-product insects. Subsequently, the spatiotemporal Wolbachia infection dynamics in Tribolium confusum and Wolbachia elimination patterns using tetracycline treatment were investigated in detail by TaqMan® probe real-time quantitative PCR, and host reproductive fitness parameters were compared. T. confusum was the only Wolbachia infected species in all the surveyed species. Wolbachia infection density consistently increased with the development of T. confusum and plateaued at 3.7 × 107 wsp copies per individual insect at the young adult stage. Wolbachia densities in females were higher than that in males with a significant difference at the pupae stage and varied among different tissues and organs. Uninfected female beetles were completely incapable of producing mature progenies when crossed with Wolbachia infected males. Embryogenesis and egg hatch rate were specifically inhibited after Wolbachia elimination, while other traits, including the number of eggs, pupation rate and sex ratio, remained unaffected by tetracycline treatment. Our results show that the TaqMan® probe qPCR is a reliable detection method for quantifying the density of Wolbachia as compared to qualitative detection of wsp gene by PCR and relatively quantified by real-time qPCR. The fitness results indicated that Wolbachia infection was not an obligate symbiont and benefited the host confused flour beetle. Keywords: Wolbachia, Tenebrionidae, Tribolium spp., Stored product insects, Endosymbiont, Infection density, Tetracycline