Mode-of-action of microbial symbiont regulation by Drosophila

Revealing the mechanisms underlying the interactions between larvae and their microbial environment is key to understanding the drivers of Drosophila melanogaster survival and might provide insights into host-microbe evolution. Given that larval survival can be affected by different microbial community composition in different ways, it is hypothesized that larvae possess strategies to manipulate the growth and composition of the microbiota on their developmental substrate. Previous observations have shown that Drosophila larvae do influence growth and community composition of yeast and filamentous fungi. We hypothesize that beyond the simple physical presence of insects, larvae might exert additional influence on their microbial symbionts by releasing bioactive compounds into their environment, such as antimicrobial peptides. We conducted experiments monitoring the growth of different yeast species isolated from D. melanogaster lab populations in the presence and absence of larval excretions. Preliminary results indicate that larval excretions can selectively benefit certain yeast species, suggesting that D. melanogaster larvae may emit signaling compounds that modulate the microbial composition of their environment. Although the mechanisms and implications of varied growth responses to larval excretions need to be investigated further, these findings imply that larvae may possess the capacity for selective management of their microbial symbionts.