除虫菊酯对云杉卷叶蛾的毒力测定

云杉卷叶蛾（Choristoneura fumiferana（Clemens））是北美地区严重的森林食叶害虫之一。本试验室采用浸叶法测定植物源杀虫剂除虫菊酯对云杉卷叶蛾4龄幼虫的致死剂量,分析幼虫死亡率与致死时间致死浓度之间的相互关系。结果表明,在浓度为12.5、25、50、100和200 μg·L-1时,幼虫LT50（50%害虫死亡的时间）分别为94.78、45.54、20.36、14.39和11.37h,在120 h累积死亡率依次达到50%、67%、93%、100%和100%。4龄幼虫的LC50（50%害虫死亡的浓度）为16.1μg·L-1。因此,除虫菊酯对云杉卷叶蛾幼虫的致死率随着浓度增加而增加,而致死时间随着浓度增加而降低。本实验为除虫菊酯为效防治云杉卷叶蛾提供参考依据。

Lethal effects of pyrethrins on spruce budworm (Choristoneura fumiferana)

Spruce budworm (Choristoneura fumiferana (Clemens)) is one of the most serious forest insect pests in North America. Laboratory bioassays were performed to determine the lethal doses and lethal time of pyrethrins (a botanical insecticide) on 4th instar larvae of spruce budworm using larval dip assay. Results show that the LT50 values (time of 50% larval mortality) for spruce budworm at the pyrethrins concentrations of 12.5, 25, 50, 100, and 200 tg. L-1 were 94.78, 45.54, 20.36, 14.39and 11.37 h, respectively. The percentage of cumulative mortality at the mately 50%, 67%, 93%, 100% and 100% within 120 h, respectively. The LC50 value (concentration of 50% larval mortality) for the 4th instar larin a concentration-dependent manner, and lethal time decreased with increasing pyrethin concentrations. These findings suggest that pyrethrins have a potential in controlling spruce budworm populations.