短期高温预处理与氟虫腈对小菜蛾3龄幼虫的联合作用

Interaction between short-term heat pretreatment and fipronil on diamondback moth [Plutella xylostella (Linnaeus)]

研究了短期高温预处理与氟虫腈对小菜蛾[Plutella xylostella(Linnaeus)]3龄幼虫的联合作用。结果表明,短期高温对氟虫腈毒力的影响随高温水平及持续时间不同而不同。30℃预处理2h或4h对试虫有一定保护作用,能够降低其后的氟虫腈毒力,但8h对试虫保护作用较弱且不稳定;35℃预处理2h或4h,对试虫保护作用较强,能够降低氟虫腈毒力,但持续时间为8h,则会提高氟虫腈的毒力;40℃预处理2h,对试虫保护作用较弱且不稳定,持续4h便只表现为不利作用。协同毒力指数可应用于Hormesis效应评价。

The interaction between short-term heat pretreatment and fipronil on 3rd instar larvae of diamondback moth [Plutella xylostella （Linnaeus）] was investigated. The results indicate that the effect of interaction between short-term heat pretreatment and fipronil on the insects varies with temperature and duration of heat-pretreatment. Heat pretreatment at 30 ℃ for 2 or 4 h can somehow protect insects from fipronil. However, the level of protection is low and unstable as the 30 ℃ pretreatment lasts for 8 h. At 35 ℃, the protection effect is observable in pretreated insects for 2 or 4 h, though 8 h pretreatment improves fipronil toxicity. At 40 ℃, only weak and unstable protection effects are noticeable at 2 h pretreatment duration. Harmful effects develop when the pretreatment is extended to 4 h. Cooperative virulence index （c.f.） may be adopted in Hormesis assessment.