Microbiomes of a specialist caterpillar are consistent across different habitats but also resemble the local soil microbial communities.

We found that the monophagous caterpillars collected from fields located more than 100 km apart were all dominated by a single Ralstonia. The remainder of the bacterial communities that were present resembled the local microbial communities in the soil in which the host plant was growing. Our findings provide an example of a caterpillar that has just a few key associated bacteria, but that also contains a community of low abundant bacteria characteristic of soil communities.