Digestive Characteristics of Hyphantria cunea Larvae on Different Host Plants

SIMPLE SUMMARY: Hyphantria cunea is a cosmopolitan quarantine pest that can sustain on a wide range of host plants. However, the role of the digestive physiology of H. cunea larvae in regulating its multi-host adaptation has not been reported. Herein, we found that α-amylase and trypsin played an important role in nutrient metabolism and host adaptation of H. cunea. Furthermore, H. cunea larvae had highly adaptable compensatory mechanisms for digestion in response to insect digestive enzyme inhibitors. The findings reveal that digestive physiology mediates the multi-host adaptation of H. cunea larvae. ABSTRACT: Digestive physiology mediates the adaptation of phytophagous insects to host plants. In this study, the digestive characteristics of Hyphantria cunea larvae feeding preferences on different host plants were investigated. The results showed that the body weight, food utilization, and nutrient contents of H. cunea larvae feeding on the high-preference host plants were significantly higher than those feeding on the low-preference host plants. However, the activity of larval digestive enzymes in different host plants presented an opposite trend, as higher α-amylase or trypsin activity was observed in the group feeding on the low-preference host plants than that feeding on the high-preference host plants. Upon treatment of leaves with α-amylase and trypsin inhibitors, the body weight, food intake, food utilization rate, and food conversion rate of H. cunea larvae significantly decreased in all host plant groups. Furthermore, the H. cunea comprised highly adaptable compensatory mechanisms of digestion involving digestive enzymes and nutrient metabolism in response to digestive enzyme inhibitors. Taken together, digestive physiology mediates the adaptation of H. cunea to multiple host plants, and the compensatory effect of digestive physiology is an important counter-defense strategy implemented by H. cunea to resist plant defense factors, especially the insect digestive enzyme inhibitors.