Comparative analysis of bacterial communities in olive psyllids, Euphyllura straminea and Euphyllura pakistanica expose proteobacteria dominance

Abstract Insect–bacteria symbiont associations can be found in almost all insect orders which supply an array of physiological and ecological benefits to the host insect. Plant sap‐feeding insects, including psyllids, have developed symbiotic relationships with a variety of bacteria to compensate nitrogen‐poor diets. In this study, we determined the bacterial composition of two olive psyllid pest species, Euphyllura straminea and Euphyllura pakistanica (Hemiptera: Aphalaridae), using 16S rRNA gene sequence and qPCR analyses. Proteobacteria, including Alphaproteobacteria, Gammaproteobacteria and Betaproteobacteria, composed the primary bacterial structures of the psyllids. Alphaproteobacteria were the dominant bacterial group in E. straminea, while Gammaproteobacteria composed the main portion of the bacterial structure in E. pakistanica. The primary endosymbiont, Carsonella, was detected in both psyllids and Arsenophonus with high prevalence was the main secondary endosymbiont. Interestingly, we observed high titres of Wolbachia in E. straminea compared with E. pakistanica, which revealed a negative correlation between Wolbachia and Carsonella and Arsenophonus titres. Our results show that the limited core microbiota of olive psyllids is similar while the abundance of each bacterial symbiont can vary in different species. A possible role of Wolbachia in modulating bacterial composition in the psyllids was also suggested. There is the potential to utilize symbionts for developing pest control strategies by reducing the insect host's fitness such as targeting essential endosymbionts, transferring symbionts between species and parthenogenesis. Our results can be used as a basis for further research towards the implementation of novel strategies in symbiont‐based biological control of the olive psyllids.