噻虫胺对桃蚜的毒力及其亚致死剂量对桃蚜解毒酶系活力的影响

为明确噻虫胺对桃蚜Myzus persicae (Sulzer)的毒力和桃蚜的代谢解毒机制, 本研究采用点滴法、 叶片浸渍法和叶柄内吸法分别测定了噻虫胺对桃蚜的毒力, 以及胡椒基丁醚（PBO）、 磷酸三苯酯（TPP）和顺丁烯二酸二乙酯（DEM）对噻虫胺毒力的影响; 检测了噻虫胺在亚致死剂量LC₆, LC₁₅和LC₃₀下对桃蚜体内乙酰胆碱酯酶、 羧酸酯酶和谷胱甘肽-S-转移酶活力的影响。结果表明: 噻虫胺对桃蚜点滴、 浸渍和内吸LC₅₀分别为1.891, 2.341和1.303 mg/L; 3种酶抑制剂分别与噻虫胺按1∶1混用, PBO对噻虫胺增效达2.41倍, 增效作用显著; TPP对噻虫胺增效达1.52倍, 增效作用也较明显; DEM对噻虫胺无增效作用。以噻虫胺LC₃₀浓度处理桃蚜, 处理后24 h其体内乙酰胆碱酯酶比活力受到显著抑制, 抑制率达41.2%; 以LC₁₅和LC₃₀浓度的噻虫胺处理桃蚜, 处理后24 h其体内羧酸酯酶比活力分别是对照的1.29和1.36倍, 有显著诱导激活作用; 以噻虫胺LC6, LC₁₅和LC₃₀浓度处理的桃蚜, 对其体内谷胱甘肽-S-转移酶的抑制率分别达7.9%, 11.9%和22.7%。结果说明噻虫胺对桃蚜具有较高毒力, 羧酸酯酶和多功能氧化酶可能是桃蚜体内代谢噻虫胺的主要酶系。

The toxicity and effects Of sublethal doses On detoxifying enzymes of clothianidin to Myzus persicae(Sulzer)(Hemiptera: Aphididae)

In order to clarify the toxicity of clothianidin to Myzus persicae (Sulzer) and the metabolic detoxification mechanisms in the aphid, the toxicity of clothianidin to M. persicae was detected using topical application, leaf dipping and petiole wrapping methods, the synergism of piperoayl butoxide (PBO), triphenyl phosphate (TPP) and diethylmaleate (DEM) to clothianidin was determined, and the influence of sublethal doses of clothianidin on detoxifying enzymes was determined with biochemical method at the doses of LC₆, LC₁₅ and LC₃₀. The results showed that the LC₅₀ values through guttate, impregnation and systemic toxicity were 1.891, 2.341 and 1.303 mg/L, respectively. The synergism ratios of PBO and TPP to clothianidin were 2.41 and 1.52, respectively, whereas DEM had no significant synergism to clothianidin. Under the treatment of sublethal doses of clothianidin, the specific activity of AChE was inhibited significantly at 24 h after treatment, and its inhibition rate reached 41.2% at the dose of LC₃₀; the specific activity of CarE, however, increased obviously, and the synergistic ratios at the doses of LC₁₅ and LC₃₀ at 24 h after treatment were 1.29 and 1.36, respectively; and the GST activity was also inhibited significantly with the inhibition rates of 7.9%, 11.9% and 22.7% at the doses of LC₆, LC₁₅ and LC₃₀, respectively. These results suggest that clothianidin has high toxicity to M. persicae, and GST and MFO may be the major detoxifying enzymes in metabolizing clothianidin in the aphid.