Abstract: In order to study the bioactivities of ethanol extracts from Phytolacca americana, Citrus maxima peels and Macleaya cordata against the larvaes of Dioryctria splendidella preliminarily in laboratory, contact toxicity, antifeedant activities and body weight gains of D. splendidella larvaes were determined after treated with 3 ethanol extracts. The results indicated that 3 ethanol extracts with different concentration had some bioactivities against the larvae of D. splendidella, and the higher the extracted concentrations, the more obvious of the bioactivities to the larvaes were. When the concentration of Citrus maxima peels extracts was 100 mg/mL, there were the strongest bioactivities. The contact toxicity corrected mortality, antifeedant rate and growth inhibiting rate reached to 80.00%, 99.28%, and 96.32%, respectively. The control effect in the forest was 55.70%, the same as the pesticides thiacloprid. The ethanol extracts from Phytolacca americana had the lowest bioactivities, but the corrected mortality of ethanol extracts being high concentration were more than 70%, antifeedant rates and growth inhibiting rates were more than 90%.

Key words: Ethanol extracts, Dioryctria splendidella, Contact toxicity, Antifeedant activities, Growth inhibition