Gut microbiome composition of Trichoptera larvae across functional feeding groups: a case study from the Provo River, Utah, USA.

Diet is known to be a major factor in the gut microbiome of many groups of insects. Larvae from the insect order Trichoptera have varied feeding behaviors, encompassing all functional feeding groups, making them an excellent group for studying the links between diet and gut microbe community variation. However, no previous study has examined these links in caddisflies. Here, we characterize the gut microbiome composition of four caddisfly genera belonging to four different functional feeding groups over two sampling periods using 16S metabarcoding. We found that the sampling date had the strongest influence on gut microbiome variation. Host functional feeding groups and phylogeny also influenced gut community composition; however, improved sampling is necessary to confirm this relationship. Our preliminary results point to interesting differences among larvae from different feeding groups and suggest future areas for research, including performing species-level identification of the caddisfly larvae, using more taxa within and between functional feeding groups, using temporal and larval stage-matched replicates, assessing the degree of microbiome residency in caddisfly guts, and performing deeper sequencing.