Phenoloxidase, an effective bioactivity target for botanical insecticide screening from green walnut husks

Phenoloxidase, a critical enzyme in insects, may serve as a promising target in botanical insecticide development. In an effort to identify active ingredients with insecticidal properties in green walnut husks, juglone and plumbagin were isolated from the chloroform extract using phenoloxidase as bioactive target with the IC₅₀ of 0.247 g/L and 0.256 g/L, respectively. After an artificial diet feeding of the juglone or plumbagin, more than 50% corrected mortality in stomach toxicity form was observed in Pieris rapae Linne larvae and Helicoverpa armigera Hübner larvae at the concentration ≥0.01 g/L, the LC₅₀ of juglone and plumbagin for two kinds of insects were determined as 0.012, 0.011 and 0.022, 0.030 g/L, respectively. This research indicated the significance of PO as bioactive target in pesticides identification and also shed light on the development of phenoloxidase inhibitor as promising botanical insecticides in the future.