Direct and trans-generational effects of male and female gut microbiota in <i>Drosophila melanogaster</i>

Abstract

There is increasing evidence of the far-reaching effects of gut bacteria on physiological and behavioural traits, yet the fitness-related consequences of changes in the gut bacteria composition of sexually interacting individuals remain unknown. To address this question, we manipulated the gut microbiota of fruit flies, <i>Drosophila melanogaster</i>, by monoinfecting flies with either <i>Acetobacter pomorum</i> (<i>AP</i>) or <i>Lactobacillus plantarum</i> (<i>LP</i>)<i>.</i> Re-inoculated individuals were paired in all treatment combinations. <i>LP-</i>infected males had longer mating duration and induced higher short-term offspring production in females compared with <i>AP</i>-infected males. Furthermore, females of either re-inoculation state mated with <i>AP-</i>infected males were more likely to have zero offspring after mating, suggesting a negative effect of <i>AP</i> on male fertility<i>.</i> Finally, we found that the effects of male and female gut bacteria interacted to modulate their daughters', but not sons' body mass, revealing a new trans-generational effect of parental gut microbiota. In conclusion, this study shows direct and trans-generational effects of the gut microbiota on mating and reproduction.