Two Apriona Species Sharing a Host Niche Have Different Gut Microbiome Diversity.

The adaptability of herbivorous insects to toxic plant defense compounds is partly related to the structure of the gut microbiome. To overcome plant resistance, the insect gut microbiome should respond to a wide range of allelochemicals derived from dietary niches. Nevertheless, for sibling herbivorous insect species, whether the gut microbiome contributes to success in food niche competition is unclear. Based on 16S rDNA high-throughput sequencing, the gut microbiomes of two Apriona species that share the same food niche were investigated in this study to determine whether the gut microbiome contributes to insect success in food-niche competition. Our observations indicated that the gut microbiome tended to play a part in host niche competition between the two Apriona species. The gut microbiome of Apriona swainsoni had many enriched pathways that can help degrade plant toxic secondary compounds, including xenobiotic biodegradation and metabolism, terpenoid and polyketide metabolism, and secondary metabolite biosynthesis. Meanwhile, A. swainsoni hosted a much greater variety of microorganisms and had more viable bacteria than A. germari. We conclude that gut microbes may influence the coevolution of herbivores and host plants. Gut bacteria may not only serve to boost nutritional relationships, but may also play an important role in insect food niche competition.