Spodoptera littoralis is a highly polyphagous pest that attacks numerous important crops in the world and causes substantial economic losses to agricultural production. In the present study, the effects of different leafy vegetables, including Purslane, Chives, Parsley, Basil, Dill, Coriander, and Mint, were investigated on feeding responses and enzymatic activities of S. littoralis under laboratory conditions. Furthermore, the total contents of the three major secondary metabolites (phenolics, anthocyanins, and flavonoids) in the studied vegetables were determined. Our findings showed that the lowest and the highest approximate digestibility were on Basil and Purslane, respectively. The highest values of efficiency of conversion of ingested and digested food were achieved in larvae fed on Chives and Coriander, respectively, whereas the lowest values were recorded after feeding on Purslane. The highest and lowest relative growth rates were in larvae reared on Dill and Purslane, respectively. Furthermore, the highest amylolytic and proteolytic activities were in larvae fed with Coriander and Dill, respectively, while the lowest activities of these enzymes were on Purslane. In addition, correlation analysis revealed significant correlations between feeding characteristics and enzymatic activity of S. littoralis with biochemical compounds of the studied leafy vegetables. Our results suggest that Coriander is a suitable host, while Purslane displayed tolerance traits against S. littoralis, which can be used in sustainable management programs aiming to reduce chemical inputs.
Keywords: Egyptian cotton leafworm; IPM; leafy vegetables; nutritional physiology; secondary metabolites.