The microbiota ofDrosophila suzukiiinfluences the larval development ofDrosophila melanogaster

Abstract

Microorganisms play a central role in the biology of vinegar flies such asDrosophila suzukiiandDrosophila melanogaster: serving as a food source to both adults and larvae, and influencing a range of traits including nutrition, behavior, and development. The niches utilized by the fly species partially overlap, as do the microbiota that sustain them, and interactions among these players may drive the development of crop diseases. To learn more about how the microbiota of one species may affect the other, we isolated and identified microbes from field-caughtD. suzukii, and then characterized their effects onD. melanogasterlarval development time in the laboratory. We found that theD. suzukiimicrobiota consistently included both yeasts and bacteria. It was dominated by yeasts of the genusHanseniaspora, and bacteria from the families Acetobacteraceae and Enterobacteriaceae. RaisingD. melanogasterunder gnotobiotic conditions with each microbial isolate individually, we found that some bacteria promoted larval development relative to axenic conditions, but most did not have a significant effect. In contrast, nearly all the yeasts tested significantly accelerated larval development. The one exception wasStarmerella bacillaris, which had the opposite effect: significantly slowing larval developmental rate. We investigated the basis for this effect by examining whetherS. bacillariscells could sustain larval growth, and measuring the survival ofS. bacillarisand other yeasts in the larval gut. Our results suggestS. bacillarisis not digested byD. melanogasterand therefore cannot serve as a source of nutrition. These findings have interesting implications for possible interactions between the twoDrosophiliaspecies and their microbiota in nature. Overall, we found that microbes isolated fromD. suzukiipromoteD. melanogasterlarval development, which is consistent with the model that infestation of fruit byD. suzukiican open up habitat forD. melanogaster. We propose that the microbiome is an important dimension of the ecological interactions betweenDrosophilaspecies.