Partial characterization of digestive enzymes in the larvae of the fall armyworm, Spodoptera frugiperda..

The fall armyworm (FAW), Spodoptera frugiperda is one of the most destructive pests of corn in Egypt and over all the world. FAW has a wide range of host due to the variation in its digestive enzymes. In the current study, the digestive enzymes including trypsin, chymotrypsin, papain and alpha-amylase were partially characterized in the different larval stages of the fall armyworm (FAW). Serine proteases were found to have higher activity compared to cysteine and alpha-amylase enzymes. The first and fourth instar larvae found have elevated enzymes activity compared to other larval stages. FAW digestive enzymes show stability at wide range of temperatures and pHs. Kinetic studies revealed that chymotrypsin enzyme exhibited highest Vmax value followed by trypsin, alpha-amylase and papain enzymes. On the other hand, papain enzyme showed higher affinity with its substrate followed by chymotrypsin, trypsin and alpha-amylase showed low substrate affinity. The results of the current study provide essential knowledge about the composition, feature and activity of digestive enzymes of FAW that can be used to design effective management program based on distribution of digestive enzymes.