神经敏感性的降低是棉铃虫对拟除虫菊酯抗药性的重要机制

用扫描电子显微镜和光学显微镜的染色观察，研究了棉铃虫Helicoverpa armigeraHubner 3龄幼虫腹部神经一肌肉的分布，表明其腹纵肌细胞适合于作电生理细胞内记录。用电生理细胞内微电极记录法研究了棉铃虫三个品系：对照品系、功夫菊酯抗性品系(Cy-R，抗性指数13.4)和氰戊菊酯抗性品系(Fn-R，抗性指数37.9)的3龄幼虫神经一肌肉材料对相应杀虫剂的神经敏感性。结果表明：用10^-6mol/L的功夫菊酯处理Cy-R，在30min内有40%的个体对药剂无反应，另外60%的个体产生反应所需的时间是对照品系的3.5倍。用10^-6mol/L的氰戊菊酯处理Fn-R，在30min内有47%的个体对药剂无反应，另外53%的个体产生反应所需的时间是对照品系的4.2倍。这些结果说明神经敏感性降低是棉铃虫对拟除虫菊酯抗药性的重要机制。

DECREASED NERVE SENSITIVITY IS AN IMPORTANT PYRETHROID RESISTANCE MECHANISM OF COTTON BOLLWORM

The morphology of the 3rd instar larval cotton bollworm (Helicoverpa armigera Hubner) ventral nerve and muscle was studied by scanning electron and light microscopes. The results of observation showed that all of the ventral longitudinal muscle cells are suitable for the electrophysiological intracellular recording. The nerve sensitivity to the corresponding pesticides of 3rd instar larval neuromuscular synapses of three strains of the cotton bollworm including the control, the cyhalothrin resistant (Cy- R, resistance ratio: 13.4) and the fenvalerate resistant (Fn-R, resistance ratio: 37.9)strains was studied by using the electrophysiological intracellular microelectrode recording technique.The results showed that when Cy-R was treated by 10-6mol/L cyhalothrin. 60% individuals had the repetitive discharge within 30min; however, the reaction time was 3.5 times as much as that of the control. And the other 40%individuals had no reaction. When Fn-R was treated by 10-6mol /L fenvalerate,53% individuals had the repetitive burst discharge within 30min, however, the reaction time was 4.2 times as much as that of the control' And the other 47% individuals had no reaction. It implies that the decreased nerve sensitivity is an important pyrethroid resistance mechanism of cotton bollworm.