Antifeedant Activity and Active Ingredients Against Plutella xylostella from Momordica charantia Leaves

With the bioguided fractionation of the ethanol extracts from the leaves of Momordica charantia, we obtained two most active compounds against the feeding of the diamondback moth, Plutella xylostella larvae. The antifeedant activity of momordicine I and momordicine II against the second and the third instar larvae of Plutella xylostella were tested using leaf discs of cabbage in the laboratory. The results showed that momordicin I and momordicin II had significant antifeedant activity on the larvae of P. xylostella, and momordicin II was more active than momordicin I. The concentrations for 50% antifeedant effects (AFC50) of momordicin II against the second and the third instar larvae of P. xylostella were 76.69 and 116.24 μg mL−1, whereas that of momordicin I was 144.08 and 168.42 μg mL−1, respectively. In addition, momordicin I and momordicin II had significant inhibitive effect on the rate of weight gain and survival of P. xylostella larvae.