Abstract: The alcohol active extract from the plant Daphne genkwa is a strong antifeedant to Abraxas miranda, Pieris rapae. The experiments were carried out with P. rapae to find the mechanism affected by the active extract. The activities of various digest digest enzymes except trehalase, both in epithelium and lumen of mid-gut, were enhanced by the extract when they were compared to the control. The reason causing the enhancing activity of the digest enzyme may be that the extract stimulates the epithelium cells to secrete a super-amount of digest enzyme to degrade or combined the extract to coothe or wipe out the poison. So a great quantity of energy and amino acid are consumed. Another reason is probably a number of sulphur-contaming amino acids are depleted owing to secrete large amounts of trypsin and chymotryspin, resulting in imbalance of amino acids, and causing the anti-nutritional effects.

Key words: Daphne genkwa, Digest enzyme, Pieris rapae