Comparison of gut bacterial communities and their associations with host diets in four fruit borers

Microbiota that live in the gut of insects have a wide range of effects on host nutrition, physiology, and behavior. They may shape the adaptation of their hosts to different habitats and lifestyles. To characterize the gut microbiota of fruit borers comprehensively, we compared bacterial communities among Grapholita molesta, Conogethes punctiferalis, Carposina sasakii, and Cydia pomonella, which are serious lepidopteran pests. We selected G. molesta as a representative pest to more explicitly test the influence of host dietary niche on the insect gut microbiome, and compared the bacterial microbial communities of G. molesta fed different diets (peach shoots and apple) using Illumina high-throughput sequencing technology.

The results show that Proteobacteria and Firmicutes are dominant in their gut microbiota. The C. sasakii had the highest richness values and G. molesta (shoot-feeding) had the highest diversity, whereas C. pomonella and G. molesta (fruit-feeding) had the lowest bacterial richness and diversity, respectively. The ANOSIM analysis revealed significant differences in the structure of gut microbiota among different insects. In addition, G. molesta with a different feeding diet had significant differences in gut microbiota composition. PICRUSt analysis indicated that most functional prediction categories were related to metabolism.

Our results show that gut microbiota composition is affected significantly not only by host species but also host diets. An enhanced understanding of these herbivore-associated microbial symbionts is essential for understanding the biology and ecology of the host insect, and may offer new possibilities to improve integrated pest-management strategies for efficient control of fruit borers. © 2019 Society of Chemical Industry.