摘 要 ：为进一步评价雷公藤中主要杀虫活性成分生物碱的杀虫活性及其应用前景,采用室内生测法研究了雷公藤总生物碱对粘虫Mythimna separate (Walker)取食、存活及生长发育等的影响。结果表明,雷公藤总生物碱对粘虫幼虫具较强的拒食活性,3、4、5龄幼虫24、48h的拒食中浓度(AFC50)分别为37.92、50.23、119.53mg·L-1和42.39、60.47、122.91mg·L-1;具有一定的胃毒活性,对粘虫3龄幼虫4、5天的LC50值分别为157.18mg·L-1和129.92mg·L-1;对粘虫幼虫的生长发育有明显抑制作用,表现在体重、体重增加量和相对生长率均显著降低,60mg·L-1处理组幼虫第2天体重、体重增加量、相对生长率比对照分别下降26.13%、42.74%和22.26%,幼虫龄期延长,存活率、化蛹率和成虫羽化率均明显下降,成虫产卵量减少;此外,还具有一定的杀卵作用,卵孵化率和初孵幼虫存活率明显降低。
Abstract:Total alkaloid from Tripterygium wilfordii Hook was bioassayed with Mythimna separate (Walker) for its insecticidal activities. The antifeedant effect of the total alkaloid on third to fifth instar larvae of M.separate increased with the treatment concentrations. The AFC50 values (24h and 48h) of the alkaloid against third, fourth and fifth instars larvae were 37.92, 50.23, 119.53mg·L-1 and 42.39, 60.47,122.91mg·L-1, respectively. The alkaloid were toxic to third instar larvae with oral application and the LC50 value (4d and 5d) against third instar larvae were 157.18 and 129.92mg·L-1, respectively. The alkaloid also imposed great influence on the growth of M.separate larvae. The treated larvae showed big reduction on body weight, weight gain and relative growth rate comparing with the control. In the second day of treatment with the dose of 60mg·L-1 alkaloid, the body weight, weight gain and relative growth rate reduced 26.13%, 42.74% and 22.26%, respectively. The alkaloid could prolong the instar stage, reduce the survival rate and pupation rate of M.separate larvae. The emergence rate, fecundity and longevity of adults were lower than that of the control. The hatching rate of eggs and the survival rate of larvae were also reduced.