Comparative Transcriptomic Analysis Reveals Adaptation Mechanisms of Bean Bug Riptortus pedestris to Different Food Resources

SIMPLE SUMMARY: The bean bug Riptortus pedestris causes a significant decrease in soybean production and economic losses. To understand how these bugs adapt to different parts of the soybean plant, we studied their gut transcriptomic changes when feeding on soybean leaves, beans, and pods. We discovered that when they fed on pods and beans, there was a notable increase in the expression of digestive enzymes like cathepsins, serine proteases, and lipases. On the other hand, when the bugs consumed soybean leaves, detoxification enzymes, such as ABC transporters and 4-coumarate-CoA ligase, showed higher expression levels. These findings suggest that the dynamic regulation of digestive and detoxification enzymes enables bean bugs to successfully feed on various soybean tissues. ABSTRACT: The bean bug, Riptortus pedestris (Hemiptera: Heteroptera), poses a significant threat to soybean production, resulting in substantial crop losses. Throughout the soybean cultivation period, these insects probe and suck on various parts of plants, including leaves, pods, and beans. However, the specific mechanisms by which they adapt to different food resources remain unknown. In this study, we conducted gut transcriptomic analyses of R. pedestris fed with soybean leaves, pods, and beans. A total of 798, 690, and 548 differently expressed genes (DEGs) were monitored in G—pod vs. G—leaf (comparison of insect feeding on pods and leaves), G—bean vs. G—leaf (comparison of insect feeding on beans and leaves), and G—pod vs. G—bean (comparison of insect feeding on pods and beans), respectively. When fed on pods and beans, there was a significant increase in the expression of digestive enzymes, particularly cathepsins, serine proteases, and lipases. Conversely, when soybean leaves were consumed, detoxification enzymes, such as ABC transporters and 4-coumarate-CoA ligase, exhibited higher expression. Our findings indicate that R. pedestris dynamically regulates different metabolic pathways to cope with varying food resources, which may contribute to the development of effective strategies for managing this pest.