Kruttika’s work on the bacterial communities of butterflies is now out in the journal Royal Society Open Science! This was our first large butterfly project, and it was a lot of fun. We collaborated with Krushnamegh Kunte for this project. We chased butterflies, learned to identify different species, and combed through different host plants to find camouflaged larvae and pupae. Then we got back to the lab, and brainstormed our way through molecular work and microbiome analysis.
Butterflies start their life as a tiny egg, giving rise to a hungry caterpillar that ravenously feeds on plant leaves (solid food). The caterpillar morphs through a non-feeding pupal stage to emerge as an adult butterfly that feeds only on nectar and other fluids. We predicted that this dramatic dietary and developmental transformation should result in very different bacterial communities across life stages of each butterfly species. Surprisingly, we found this pattern in only a few butterfly species. This suggested that though all butterflies undergo dramatic dietary and developmental transition, the associated bacterial communities do not change in the same manner across different hosts. Across different butterfly species, dietary variation was strongly associated with distinct bacterial communities. Surprisingly, larvae (which are relatively specialized on single host plants) showed relatively similar microbiomes, whereas more generalist adults (which feed on nectar from many flowers) harboured distinct bacterial communities. Thus, adult butterflies seem to impose a stronger filter on their gut communities. Overall, our results suggest that butterflies have not evolved strong associations with their gut microbes, despite large dietary and developmental variation.
For more about butterflies and their bacteria, read the paper!