Insect-associated bacterial communities in an alpine stream

The roles of macroinvertebrate and microbial communities in stream ecosystems are recognized to be important to energy flow and nutrient cycling. While the linkages of these major groups of aquatic organisms have not been thoroughly investigated, determining how they interact is particularly important for understanding the mechanisms and potential evolutionary relationships that contribute to ecosystem processes, such as organic matter decomposition. We evaluated the microbiomes of several aquatic insect species differing in trophic ecology and belonging to different functional feeding groups at two sites along an Italian Alpine river with different elevation and environmental characteristics, one located above the tree line and the other in a forested environment. We found that the internal microbial communities of the different species significantly varied in taxonomic and functional composition and could be used to classify samples to both species and environment. We demonstrated that functional differences existed between the microbiota of different insect species with variable feeding behaviors, and that species differences were more important, in this context, than environmental or habitat conditions. These results provide new information on how the microbiomes of aquatic insects may potentially be influenced by their hosts and habitat conditions in Alpine streams.