四种杀菌剂对玉米螟赤眼蜂酚氧化酶活性的影响

为明确杀菌剂对玉米螟赤眼蜂Trichogramma ostriniae Pang et Chen毒性大小及其成蜂体内酚氧化酶（phenoloxidase, PO）活性影响, 本实验通过测定三唑酮（triadimefon）、 肟菌脂（trifloxystrobin）、 咪鲜胺（prochloraz）、 申嗪霉素（phenazino-1-carboxylic acid）4种杀菌剂对玉米螟赤眼蜂的急性毒性, 并分别测定活体和离体条件下各杀菌剂处理后酚氧化酶的比活性。结果表明, 各药剂对赤眼蜂的急性毒性大小为： 三唑酮＞咪鲜胺＞肟菌酯＞申嗪霉素, 其LC₅₀值分别为3.27, 6.46, 4.06和 9.72 mg/L, 其安全系数依次为0.07, 0.10, 0.20和1.47, 其中申嗪霉素为中等风险性, 其余3种药剂为高风险性, 且杀菌剂明显激活了PO的活性。活体条件下亚致死剂量处理得到的PO比活力高于离体处理, 且三唑酮处理组具有明显的剂量效应。本实验为研究杀菌剂对赤眼蜂的毒性及对PO的影响作了初步的探索, 为进一步研究赤眼蜂对杀菌剂的抗性及免疫能力奠定基础。

Effects of four fungicides on phenoloxidase activity in Trichogramma ostriniae (Hymenoptera: Trichogrammatidae)

 In this study, the acute toxicity of four fungicides, i.e., triadimefon, trifloxystrobin, prochloraz and phenazino-1-carboxylic acid, to newly emerged adults of Trichogramma ostriniae and their effects on PO activity in these wasps were determined. The results showed that triadimefon had the highest toxicity to this wasp with the LC₅₀ value of 3.27 mg/L, followed by prochloraz, trifloxystrobin and phenazino-1-carboxylic acid with the LC₅₀ values of 6.46, 4.06 and 9.72 mg/L, respectively, and their safety factors are 0.07, 0.10, 0.20 and 1.47, respectively. Phenazino-1-carboxylic acid is so evaluated as with moderate risk, while others are as with high risk to this wasp. PO activities were measured in adults that were previously treated with the four fungicides (in vivo test) and in the crude extracts that were obtained from the untreated adults and treated in vitro with the fungicides (in vitro test), respectively. At sublethal concentrations, these fungicides induced remarkably higher PO activities in vivo than in vitro, showing the obvious dosage effect. At the tested concentrations, triadimefon displayed a much more evident dosage-effect on PO activity than the other three fungicides. The results provide a basis for further exploring PO-based immune mechanisms in parasitoid wasps exposed to fungicides.