Simple SummaryHyphantria cuneais a cosmopolitan quarantine pest that can sustain on a wide range of host plants. However, the role of the digestive physiology ofH. cunealarvae 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 ofH. cunea. Furthermore,H. cunealarvae 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 ofH. cunealarvae.AbstractDigestive physiology mediates the adaptation of phytophagous insects to host plants. In this study, the digestive characteristics ofHyphantria cunealarvae feeding preferences on different host plants were investigated. The results showed that the body weight, food utilization, and nutrient contents ofH. cunealarvae 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 ofH. cunealarvae significantly decreased in all host plant groups. Furthermore, theH. cuneacomprised 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 ofH. cuneato multiple host plants, and the compensatory effect of digestive physiology is an important counter-defense strategy implemented byH. cuneato resist plant defense factors, especially the insect digestive enzyme inhibitors.