Insecticidal activities of extracts from Buddleja albiflora Hemsl. against four kinds of pests.

The insecticidal activities of the extraction fractions, which were obtained by soaking the powder of Buddleja albiflora H. with 95% ethanol and then treated with petroleum ether, ethyl acetate and butanol, against three kinds of pests of Lepidoptera and Tetranychus cinnabarinus B. were tested. The results showed that the petroleum and ethyl acetate extracts possessed considerable activities to all testing pests. The antifeedant rates of ethyl acetate extracts against 3rd instar larvae of Plutella xylostella L. during 24 h and 4th instar larvae of Pieris rapae L. during 48 h were 94.22% and 83.94%, respectively. The median antifeedant concentration (AFC50) was 2.4185 mg·mL-1 against Mythimna separata W. during 24 h and the median-lethal concentration (LC50) was 0.2108 mg·mL-1 against T. cinnabarinus. The antifeedant rates of petroleum ether extracts against 3rd instar larvae of P. xylostella during 72 h and 4th instar larvae of P. rapae during 48 h were 64.11% and 75.18%, respectively. The AFC50 was 1.1392 mg·mL-1 against M. separata during 48 h and the LC50 was 0.3606 mg·mL-1 against T. cinnabarinus during 4 h. The bioassay results also showed the extraction fractions of B. albiflora, especially the petroleum ether extracts and ethyl acetate one, cound inhibit the growth and development of insects, leading to abnormal pupation and eclosion finally.