J Econ Entomol. 2014 Apr;107(2):860-6. doi: 10.1603/ec13526.
Insecticides can have lethal or sublethal effects upon targeted pest species, and sublethal effects may even favor pest outbreaks if insecticide-induced hormesis occurs. Hormesis is a biphasic dose-response of a given chemical compound that is stimulatory at low doses and toxic at high doses. The former response may result from the disruption of animal homeostasis leading to trade-off shifts between basic ecophysiological processes. A growing interest in the use of biorational insecticides, such as azadirachtin to control stored-product pests, raises concerns about potential sublethal effects. In this study, we explored the hypothesis that azadirachtin can negatively impact the reproductive capacity of the Mexican bean weevil, Zabrotes subfasciatus (Boheman) (Chrysomelidae: Bruchinae), a key pest of stored beans. In addition, we investigated whether adults of this species could compensate for any sublethal effect that might have affected any of their reproductive parameters by adjusting the allocation of its reproductive efforts. The results showed that females of Z. subfasciatus increased fecundity daily to compensate for azadirachtin-induced decreased longevity. In addition, a stage-structured matrix study revealed that populations of Z. subfasciatus engendered from females exposed to azadirachtin exhibited a higher rate of population increase (r) and a higher net reproductive rate (R(o)). Finally, a projection matrix analysis showed notably higher densities along the generations for azadirachtin-exposed Z. subfasciatus populations. Thus, our study provides empirical evidence for the capacity of Z. subfasciatus to adapt to sublethal effects caused by biorational insecticides; consequently, this study highlights the importance of understanding this phenomenon when devising pest management strategies.
杀虫剂对目标害虫物种可能具有致死或亚致死作用，如果昆虫诱导的兴奋作用发生，亚致死作用甚至可能有利于害虫爆发。兴奋作用是一种给定化合物的双相剂量反应，在低剂量下具有刺激性，在高剂量下具有毒性。前者的反应可能是由于动物体内平衡的破坏，导致基本生理过程之间的权衡转变。人们越来越关注使用生物合理性杀虫剂，如印楝素来控制储存产品害虫，这引起了对潜在亚致死作用的关注。在这项研究中，我们探讨了这样一个假设，即印楝素可能会对墨西哥豆象 Zabrotes subfasciatus（Boheman）（鞘翅目：豆象科）的生殖能力产生负面影响，这是储存豆类的关键害虫。此外，我们还研究了该物种的成虫是否能够通过调整其生殖努力的分配来补偿任何可能影响其生殖参数的亚致死作用。结果表明，Z. subfasciatus 的雌性每天增加生育能力以补偿印楝素诱导的寿命缩短。此外，阶段结构矩阵研究表明，暴露于印楝素的雌性产生的 Z. subfasciatus 种群具有更高的种群增长率（r）和更高的净生殖率（R(o)）。最后，投影矩阵分析表明，暴露于印楝素的 Z. subfasciatus 种群的世代密度明显更高。因此，我们的研究为 Z. subfasciatus 适应生物合理性杀虫剂引起的亚致死作用的能力提供了经验证据；因此，当制定害虫管理策略时，本研究强调了理解这一现象的重要性。
