Gut bacteria in potato tuberworm (Phthorimaea operculella) populations are dominated by Enterococcus spp. and these play a significant role in carbohydrate metabolism and host growth

The pivotal role of gut microbiota in maintaining the insect host’s well-being has been extensive researched. Here, our research objective was to determine the microbes in the gut of larvae of the potato tuberworm (Phthorimaea operculella) and to investigate the role they play in the host development, metabolism, gut structure integrity and immune deficiency (Imd). Shotgun metagenomics sequencing from specimens collected in major potato-producing regions in China, and principal coordinate analysis revealed that the geographic location explained much of the variance in bacterial composition, but Enterococcus mundtii was dominant in all samples. KEGG analysis demonstrated that carbohydrate metabolism was the major function of the P. operculella’s gut microbiome. Subsequently, with the use of artificial diet supplemented with antibiotics, the gut microbes were removed, especially the bacteria of the Enterococcus genus were significantly decreased. Typically, insects fed with antibiotics showed a lower carbohydrate metabolism, survival rate, longer developmental period and poorer fecundity. Metabolomics analysis also confirmed that the antibiotics treatment had a striking impact on the metabolic profile in the gut, especially for starch degradation. In addition, the gut homeostasis with its microbiota composition, metabolism and gut structure was damaged in the antibiotics-treated insects. In summary, our data provide evidence that a complex interaction exists between the microbiome of the gut and the metabolism and structure integrity of the host insect, which is essential for its growth and development. These findings enhance our comprehension of the microbiota's function in insects and facilitate the advancement of environmentally friendly management strategies for this pest.