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在室内分别测定了吡虫啉、吡虫啉 +增效剂、氰戊菊酯、硫丹、乐果和灭多威 6种杀虫剂对桃蚜MyzuspersicaeSul zer、七星瓢虫CoccinellaseptempunctataLinnaeus和龟纹瓢虫Propyleajaponica (Thunbery)的毒力 ;比较了药剂在桃蚜和两种瓢虫之间的选择毒力比值 (STR) ,以及药剂之间选择性差异 ;研究了桃蚜对不同药剂相对适合度。结果表明 :吡虫啉 +增效剂 (SV1 )和吡虫啉对桃蚜的毒力均很高 ,LC50 分别是 0 .462 8mg L和 0 .95 3 5mg L。吡虫啉在七星瓢虫和桃蚜之间、龟纹瓢虫和桃蚜之间的STR值分别是 3 7.6和 1 3 .0 ,吡虫啉 +增效剂的STR分别是 9.84和 7.75 ,硫丹的SR分别是 5 4.0和 7.2 8,都表现出显著的毒力选择性。而氰戊菊酯、乐果和灭多威的STR值均很小 (0 .0 2～ 0 .2 1 ) ,不仅对桃蚜毒力低 ,而且对两种瓢虫也不安全。用吡虫啉和吡虫啉 +SV1的LC50 浓度处理桃蚜 ,其存活个体的产仔率和单雌产仔量明显减少 ,与其它药剂处理相比 ,显著降低了桃蚜的相对适合度。六种杀虫剂处理的桃蚜种群 ,其相对适合度大小排列为 :乐果EC(0 .92 ) >氰戊菊酯EC(0 .67) >灭多威EC(0 .66) >硫丹EC(0 .5 1 ) >吡虫啉WP(0 .40 ) >吡虫啉+增效剂 (SV1 )EC(0 .1 8)。由此证明 ,吡虫啉不仅对桃蚜毒力高 ,对天敌瓢虫杀伤力小 ,
The effects of imidacloprid, imidacloprid + synergist, fenvalerate, endosulfan, dimethoate and methomyl against Myzus persicae Suzer, Coccinella septempunctata Linnaeus and Propylea japonica (Thunbery ). The selective virulence ratio (STR) of pesticides between Myzus persicae and two kinds of ladybugs was compared, and the selectivity difference between them was also studied. The relative fitness of Myzus persicae to different agents was studied. The results showed that the virulences of imidacloprid + synergist (SV1) and imidacloprid were all high to Myzus persicae with LC50 of 0.4662 8 mg L and 0.9535 mg L. respectively. Imidacloprid between the ladybird and Myzus persicae, the STR value between Propylaea japonica and Myzus persicae were 3 7.6 and 13.0 respectively, STR for imidacloprid + synergist were 9.84 and 7.75, respectively, for SR Respectively 5 4.0 and 7.2 8, showed significant virulence selectivity. However, the values of fenvalerate, dimethoate and methomyl were both small (0. 02 ~ 0. 21), which were not only virulent to Myzus persicae, but also insecure to both species of ladybug. The myzus persicae treated with imidacloprid and imidacloprid + SV1 at a concentration of 50 mg / kg significantly reduced the relative litter size of peach aphids compared with other pesticides. The relative suitability of the six insecticide-treated Myzus persicae populations was ranked as: dimethoate EC (0.92)> fenvalerate EC (0.67)> methomyl EC (0.66)> sulfur Dan EC (0.51)> Imidacloprid WP (0.40)> Imidacloprid + Synergist (SV1) EC (0.18). It proves that imidacloprid is not only high virulent to Myzus persicae, but also has a small lethality against the natural enemies Ladybug,