Gut microbiota facilitates the adaptation of <i>Apolygus lucorum</i> (Hemiptera: Miridae) to its host plant

The mirid bug, Apolygus lucorum Meyer-Dür, is a significant pest in cotton (Gossypium hirsutum L.) cultivation. Previous studies have shown that gut microbiota plays a crucial role in insect adaptation to host plants. However, the gut microbiota of A. lucorum and its role in insect adaptation remains unclear. In this study, we investigated the gut microbiota of A. lucorum and their contributions to the growth performance of the mirids on cotton plants. We analyzed gut microbial compositions of field-collected (FCAL) and laboratory-reared (LRAL) A. lucorum populations. High-throughput sequencing of the 16S rRNA gene revealed distinct gut microbial community structures between the two populations, with Delftia and Serratia serving as the dominant gut bacteria in the FCAL and LRAL populations, respectively. We confirmed that Delftia sp. W1 and Serratia marcescens R1 facilitate the growth of A. lucorum on cotton. The A. lucorum exhibits retarded growth on cotton by removal of these two strains, and its growth performance is restored upon recolonization with these strains. The capabilities of both strains in protein degradation are evident, with S. marcescens R1 exhibiting the most pronounced degradation ability. This study reveals the crucial role of gut microbiota in A. lucorum's adaptation to cotton. We identified two strains from the gut microbiota which contribute to protein digestion in A. lucorum. Our findings contribute to understanding the interaction mechanisms among insects, symbiotic bacteria, and plants, facilitating the development of insect symbiotic microbial resources.