|KUMAR, DEEPAK - University Of Southern Mississippi
|ADAMSON, STEVEN - University Of Southern Mississippi
|KARIM, SHAHID - University Of Southern Mississippi
Submitted to: Insect Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 11/7/2016
Publication Date: N/A
Interpretive Summary: We sequenced the genomes of bacteria species residing inside the bodies of male and female spotted wing Drosophila (SWD) flies, major invasive fruit fly pests of fruit and berry crops worldwide. Our survey of microbial genomes or "microbiomes" in these gnat-sized flies identified pathogens known to cause insect disease. These included Serratia spp. and Rickettsiella popilliae, cellular pathogens known to kill insects that come into contact with wet soil. SWD also carried the bacterium Geobacillus stearothermophilis, a heat tolerant microbe that causes food spoilage and may be involved in the rapid decay of infested berries. SWD also carries symbiotic bacteria, which may produce antibiotic substances and enzymes useful to adult flies and their offspring. Interestingly, 32% of the microbes carried by SWD were largely sex-specific, indicating that males and females visit very different habitats during the course of their lifespan.
Technical Abstract: Complete surveys of insect endosymbionts including species of economic importance have until recently been hampered by a lack of high-throughput genetic assays. We used 454-pyrosequencing of the 16S rRNA gene amplicon of adult spotted wing Drosophila (SWD) Drosophila suzukii (Matsumura) from southern Mississippi to survey entire microbial communities of this economically important fly pest attacking rabbiteye blueberry. The bacterial community of Mississippi SWD, in part, was similar to that of SWD on California cherries and largely (>90%) composed of two phyla, Firmicutes and Proteobacteria. Notable or predominant bacterial species included Serratia spp. and Rickettsiella popilliae, intracellular entomopathogens, Geobacillus stearothermophilis, a heat tolerant soil bacterium responsible for food spoilage, and Pseudomonas putida, a saprotrophic soil bacterium with antifungal activity. Because we sampled each fly’s entire body, SWD harbored a much larger and diverse microbiome than previously reported for California populations. We also corroborate the existence of a core gut microbiome for SWD consisting of species of Tatumella, Gluconobacter, and Acetobacter, which accounted for less than 1% of total reads for this fly species’ entire internal microbiome. Both sexes of SWD shared 26 species of bacteria (68% of detectable microbiota) in roughly equal proportions with 12 bacterial species remaining sex-specific or dominant in a particular sex. Overall, SWD males harbored a more diverse microbiota (Shannon-Weaver Diversity Index, male H’ = 1.0784), yet contained fewer unique species when compared with females (2 spp. unique to males versus 6 spp. unique to females, female H’ = 0.9998). Such sex-specific community structure in endomicrobiota implies males travel or reside in microhabitats different from those of females.