【作者】 吴国星；

【导师】 赵景玮；

【作者基本信息】 福建农林大学 ， 农药学， 2002， 硕士

【摘要】 小菜蛾Plutella xylostella L．属鳞翅目菜蛾科，是世界性十字花科的主要害虫，主要为害甘蓝、花椰菜和青菜等十字花科蔬菜，对蔬菜生产构成极大威胁。为了给小菜蛾的防治工作提供理论依据，本论文就小菜蛾对辛硫磷的抗性发展动态以及两种酯酶的活性动态、温度与药剂毒力的关系、药剂毒力与龄期的关系进行了研究。主要结果如下： 1．辛硫磷对小菜蛾的抗性选育结果显示：小菜蛾对辛硫磷的抗性发展迅速。F₀代的LC₅₀值为297.014mg／L，选育12代以后LC₅₀变为1343.747mg／L，抗性增长到4.524倍，差异较显著，说明已经形成抗性种群。 2．小菜蛾抗药性机理研究显示：在抗性选育过程中，小菜蛾乙酰胆碱酯酶酶活性增长迅速，其比活力由F₀的0.5312μM·mg^-1Pr·15min^-1上升为F₁₂的3.1467μM·mg^-1Pr·15min^-1，增长到5.924倍，酶活性差异非常显著；小菜蛾羧酸酯酶酶活性增长迅速，其比活力增长到12.768倍，酶活性差异非常显著。 3．2种药剂对小菜蛾各龄幼虫的毒力测定结果表明：5％锐劲特悬浮剂SC对1-4龄小菜蛾幼虫的LC₅₀分别为0.640mg／L、0.683mg／L、1.009mg／L、和1.210 mg／L；1.8％阿维菌素EC对1-4龄小菜蛾幼虫的LC₅₀分别为1.185mg／L、1.610mg／L、1.717mg／L和2.342mg／L。可以看出，5％锐劲特SC和1.8％阿维菌素EC对小菜蛾各龄幼虫的致死中浓度LC₅₀是随龄期的增加而增大，即小菜蛾各龄幼虫对1.8％阿维菌素EC和5％锐劲特SC敏感度是随龄期的增加而降低的。其中阿维菌素的LC₅₀随龄期 福建农林大学硕士论文 小菜蛾抗药性机理及治理的研究 ＊ 的增加变化比较大。 4．不同温度下4种药剂对小菜蛾3龄幼虫的毒力测定结果表明： 在17－33C范围内1．80阿维菌素EC、5O锐劲特SC、400辛硫磷EC的 杀虫效果均随温度的升高而升高，说明在这个温度范围内这3种药剂均 为正温度系数的杀虫剂10％氯氰菊酯＊C对小菜蛾的＊Q。在17℃、21 aC、25aC、29oC、33aC 5个温度下分别为 363＊69 mg／L、2I7．409 mg几。 264＊73 mg／L、186＊3＊mg／L和 176．904mg／L。可见在21aC一25℃的范 围内，氯氰菊酯对小菜蛾的LC。。随温度的升高而升高u呈负温度系 数＼ 在 17aC—ZIC和 2：SOC～33aC的范围内，氯氰菊酯却呈正温度系数。 5．阿维菌素和锐劲特配方的联合毒力测定结果表明5个配方均为增 效作用。配方1－5 的尹毒系数分别是238．84、177．32、455．90、246．93 和 221．48。更多还原

【Abstract】 Diamondback moth (Plutella xylostella L.), which belongs to Lepidoptera Plutellidae, is an important worldwide pest to cruciferous vegetables. It causes-serious damage to cruciferous vegetables such as cabbagQ(Brassica oleracea var. Capitata), cauliflower(5. oleracea var. Botrytis) and greengrocery. So vegetable production is seriously tlireatened. To provide theoretical basis for Plutella xylostella integrated control,studies on the dynamics of resistance development to phoxim, the dynamics of AchE and CarE, the relationship between temperature and pesticides toxicity, the relationship between pesticides toxicity and different diamondback moth development stages,were conducted. The results are summarized as follows:1. The rapid resistance development could be seen in the resistance selection result of phoxim to diamondback moth. The LC50 of phoxim to F0 generation was 297.014mg/L but that of phoxim to F12 generation was 1343.747mg/L,which was 4.524-fold as that of F0. Significant difference existed between the LC50 of phoxim to F0 and F12. It indicates resistant population has come into being.2. The studies on the resistance mechanism of diamondback moth showed that the AchE activity increased quickly during the selection process, which rose from 0.5312nM-mg’PrlSmin-1 (F0) to 3.1467uM-mg-1Pr l5min-1 (F12), and increased by 5.924-fold. The great difference could been seen. Difference in the activity of CarE also existed between F0 and F12. The activity of CarE rose rapidly, that of F12 was12.768-fold as that of F0.3. The toxicity tests results of 2 pesticides on different diamondback moth development stages were as follows, the LC50 values of 5% fipronil SC(suspension concentration) to 1-4 instars larvae were 0.640 mg/L, 0.683 rng/L, 1.009mg/L and 1.210mg/L respectively and those of Avermectins EC(emulsifiable concentration) to 1-4 instars larvae were 1.185mg/L, 1.610mg/L, 1.717mg/L and 2.342mg/L respectively. The LC50 of both insecticides to the larvae of diamondback moth increased with the increase of instars. In other words, the sensitivity of different instars larvae to the two insecticides decreased with the development stages. Moreover, the LC50 value of Avermectins increased faster than that of fipronil4. The toxicity test result of insecticides to 3rd instar larvae under different temperatures showed that the lethal effect of fipronil, Avermectins and phoxim enhanced with temperatures increase. This suggested that the 3 insecticides were all positive-temperature pesticides.At 17℃,2rC,25℃,29℃ and 33℃, the LC50 value of cypermethrin to 3rd instar larvae of Plutella xylostella were 363.069mg/L, 217.409mg/L, 264.673mg/L, 186.237mg/L and 176.904mg/L respectively. The LC50 values of cypermethrin increased with the increase of temperature between 21 ℃ and 25℃. This showed could explain cypermethrin was a negative-temperature pesticide within this temperature range. Otherwise, cypermethrin was positive-temperature pesticide within 17 ℃ ~21 ℃ and 25℃ ~33℃.5. Cotoxicity test of Avermectins and fipronil mixtures showed that synergism existed at the five chosen ratios.The cotoxicity coefficients were 238.84,177.32,455.90,246.93 and 221.48 respectively.更多还原