Smagghe G, Carton B, Decombel L, Tirry L
Laboratory of Agrozoology, Department of Crop Protection, Faculty of Agricultural and Applied Biological Sciences, Ghent University, Ghent, Belgium.
Arch Insect Biochem Physiol. 2001 Mar;46(3):127-39. doi: 10.1002/arch.1023.
Treatment of last-instar larvae of multi-resistant cotton leafworm Spodoptera littoralis with four dibenzoylhydrazines, methoxyfenozide (RH-2485), tebufenozide (RH-5992), halofenozide (RH-0345), and RH-5849, resulted in premature molting leading to death. Methoxyfenozide was the most toxic followed by tebufenozide, halofenozide, and RH-5849. To explain differences in toxicity, especially between multi-resistant and laboratory strains, absorption in the body tissues and oxidative metabolism were tested with 14C-labeled ecdysone agonist and a Lineweaver-Burk assay, respectively. Then to address different compound potencies in multi-resistant strains, the potency of the four ecdysone agonists was measured based on their ability to mimic the natural insect molting hormone, 20-hydroxyecdysone (20E) by inducing evagination in isolated imaginal wing discs. Using monoclonal antibody 9B9, the presence of ecdysteroid receptors in imaginal discs in vitro was confirmed. In parallel, Scatchard plot analysis with whole imaginal wing discs cultured with different concentrations of 3H-labeled ponasterone A indicated no significant difference in affinity and in number of target sites for binding between multi-resistant and susceptible laboratory strains. The four compounds tested caused the effect as agonists of 20E in vitro, and typically the order of their toxicities (LC50s) corresponded with that for evagination-induction with whole imaginal discs.
用四种二苯甲酰肼类化合物，即甲氧虫酰肼（RH - 2485）、虫酰肼（RH - 5992）、氯虫酰肼（RH - 0345）和RH - 5849处理多抗性棉铃虫末龄幼虫，导致其提前蜕皮并死亡。甲氧虫酰肼毒性最强，其次是虫酰肼、氯虫酰肼和RH - 5849。为了解毒性差异，特别是多抗性品系和实验室品系之间的差异，分别用14C标记的蜕皮激素激动剂和线性回归分析检测了其在虫体组织中的吸收和氧化代谢。然后，为了研究多抗性品系中不同化合物的效力，基于四种蜕皮激素激动剂通过诱导离体成虫翅芽外翻来模拟天然昆虫蜕皮激素20 - 羟基蜕皮酮（20E）的能力，测定了它们的效力。使用单克隆抗体9B9，证实了体外成虫翅芽中蜕皮甾体受体的存在。同时，用不同浓度的3H标记的波那甾酮A培养全成虫翅芽进行Scatchard作图分析，结果表明多抗性品系和敏感实验室品系之间在结合亲和力和靶位点数量上没有显著差异。所测试的四种化合物在体外作为20E的激动剂发挥作用，通常它们的毒性顺序（LC50）与全成虫翅芽外翻诱导的顺序一致。
