Bacterial communities of the reproductive organs of virgin and mated common bedbugs,Cimex lectularius

1. Microbes associated with reproductive organs of animals are either sexually transmitted or opportunistic. Both can affect host defence, immunity, and future colonisation with other microbes. There are only few studies on the microbiota of reproductive organs in insects and how they are affected by copulation. 2. This study examines the bacterial communities associated with reproductive organs in the common bedbug Cimex lectularius, a well-established insect model for the effects of microbes on male and female reproduction. Combining a metagenomic approach with a controlled mating scheme, we found 31 sequence variants (SVs) across 55 organ samples, with on average three SVs in each sample. Male and female reproductive organs harboured distinct bacterial communities in terms of present SVs. 3. Using a community ecology approach, we found three potential indications of sexual transmission of bacteria in the common bedbug: (i) copulation increased the similarity of the communities of male and female organs; (ii) mated individuals harboured bacteria that were found in non-mated individuals of the opposite sex but not in non-mated individuals of the same sex; and (iii) bacterial communities showed a high SV turnover between non-mated and mated individuals, suggesting a mating-induced replacement of bacteria. 4. Our findings show that the community ecology approach is useful to examine the bacterial dynamics on reproductive organs, especially when combined with studies that quantify the frequency of transmission and/or estimate the effect of the transmitted microbes on the host immune system and the host endosymbionts.