Divergence of Cultivable Bacteria Associated with Larvae and Adult Bactrocera dorsalis (Diptera: Tephritidae) Laboratory-Reared Strains

Insects entertain intricate and mutualistic relationship with an array of microorganisms, which significantly influence their fitness, ecology and evolution. In recent decades, there has been increasing interest toward studying the effects of microbiome on many host insects (Dipterans, Lepidopterans, and Coleopterans). Studies so far realized indicate that gut microbiome contribute to host nutritional ecology, defense, immunity and lifespan.

Bactrocera dorsalis (Tephritidae: Diptera) is a polyphagous fruit fly which attacks a huge variety of fruits and vegetables worldwide and has been placed as a quarantine species by many countries. To investigate the specific functions of the gut endosymbionts, it is a prerequisite to know the composition of gut bacterial communities whose manipulation will help to decipher their ecological relevance. Here, we used the culture-dependent technique to isolate and identify gut bacteria from B. dorsalis at different developmental stages. The results revealed 11 bacterial species from the third instar larvae, 18 and 12 from female and male populations, respectively. These bacteria were assigned to six families, namely, Enterobacteriaceae, Enterococcaceae, Staphylococcaceae, Streptococcaceae, Micrococcaceae and Bacillaceae. Bacterial species from these families were differentially represented in various samples, except Klebsiella oxytoca , Enterobacter cloacae, Pantoea dispers and Enterococcus faecalis that were detected at all developmental stages. Overall, Enterobacteriaceae was the most dominant family in females and third instar larvae accounting for 57.89% and 26.32%, respectively, while Enterococcaceae was dominant in males with 75% of the total bacterial taxa. These results suggest that B. dorsalis possesses a huge variety of cultivable bacteria that could be used to explore their specific functions on host physiology and fitness.