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Abstract:
It has been shown that gut microbes are very important for the behavior and development of Drosophila, as the beneficial microbes are involved in the identification of suitable feeding and oviposition places. However, in what way these associated gut microbes influence the fitness-related behaviors of Drosophila melanogaster remains unclear. Here we show that D. melanogaster exhibits different behavioral preferences towards gut microbes. Both adults and larvae were attracted by the headspace of Saccharomyces cerevisiae and Lactobacillus plantarum, but were repelled by Acetobacter malorum in behavioral assays, indicating an olfactory mechanism involved in these preference behaviors. While the attraction to yeast was governed by olfactory sensory neurons expressing the odorant co-receptor Orco, the observed behaviors towards the other microbes still remained in flies lacking this co-receptor. By experimentally manipulating the microbiota of the flies, we found that flies did not strive for a diverse microbiome by e.g. increasing their preference towards gut microbes that they had not experienced previously. Instead, in some cases the flies even increased preference for the microbes they were reared on. Furthermore, exposing Drosophila larvae to all three microbes promoted Drosophila’s development while only exposure to S. cerevisiae and A. malorum resulted in the development of larger ovaries and in increased egg numbers the flies laid in an oviposition assay. Thus our study provides a better understanding of how gut microbes affect insect behavior and development, and offers an ecological rationale for preferences of flies for different microbes in their natural environment.
