【作者】 曹广春；

【导师】 韩召军；

【作者基本信息】 南京农业大学 ， 农业昆虫与害虫防治， 2003， 硕士

【摘要】 小菜蛾Plutella xylostella（L.）是十字花科蔬菜的重要害虫，是对农药产生抗药性最严重的害虫之一。其繁殖力强，世代周期短，发育不整齐，世代重迭严重，且可以长距离迁移。这些特点均有利于小菜蛾抗药性的发展。目前在不同地区，已有对菊酯类、氨基甲酸酯类、有机磷类、酰基脲类昆虫生长调节剂、杀蚕毒素类、微生物杀虫剂和已经停用的的滴滴涕等农药产生不同水平抗性的报道。 米满（tebufenozide）是美国罗门哈斯公司开发的一类新型的杀虫剂，它只对鳞翅目有活性，它的作用方式是和甾酮类脱皮激素一样与脱皮激素受体（ECR）结合在分子水平上通过基因调控来激发脱皮过程，它同甾酮类脱皮激素不同的地方在于，它在昆虫体内不能很快的降解从而导致在甾酮类脱皮激素不存在的情况下才可以表达的下游基因不能表达，进而导致了脱皮过程的不能顺利完成，使昆虫因为不能完成脱皮而死亡。 本文以小菜蛾敏感品系为材料进行了对米满抗性品系的选育，发现小菜蛾对米满在筛选7代后产生了15.7倍的抗性，且呈现先缓慢后迅速上升的特点。通过对敏感和抗性品系的生物测定发现对米满产生10.113倍抗性的小菜蛾品系对辛硫磷、乙酰甲胺磷、氟铃脲和卡死克的耐药力显著的上升，其LD₅₀分别增加产生2.051、2.302、1.765和2.963倍，对阿维菌素更是产生了13倍的交互抗性。而对溴氰菊酯、氯氰菊酯和敌百虫的耐药力并没有产生明显的变化。 以上述对米满敏感和产生抗性的小菜蛾为研究对象，测定敏感和抗性品系雌雄幼虫代谢酶之间的差异，发现抗性小菜蛾的酯酶代谢速率增强而亲和力降低，其中对雌虫的影响最为明显，其Vm值增加了1.69倍而Km值降低了43.55倍。谷胱甘肽转移酶的活力也明显增强，以DCNB为底物时活力增强最为明显。其中雌性的活力增强了1.25倍，而雄性的增强了1.57倍。微粒体多功能氧化酶O-脱甲基活性也有明显的提高，雌性和雄性都提高了1.3倍以上，增效剂PBO的增效实验也证明了这一点。这说明小菜蛾对米满产生抗性的早期阶段，解毒代谢酶活力的提高是其重要机制。 通过构建小菜蛾对米满抗性品系（R-T）和敏感品系（S₀）的实验种群的生命表，比较了一系列生长发育和繁殖特征，并用净增殖率（R₀）来确定两个品系的相对适合度。结果表明，R-T品系与敏感品系相比具有一定程度上的繁殖不利性，包括产卵量的下降、孵化率的降低，以及性比的变化。没有观察到幼虫在发育上的不利性。R-T品系相对于敏感品系具有0.61的相对适合度。这说明小菜蛾产生抗性使生物适合度明显下降。 以上研究结果表明，虽然米满是一种作用机制特殊的新型杀虫剂，但大田推广应中文摘要用后，小菜蛾仍具有产生抗性的风险。因此应该注意合理用药和抗性治理。抗性机理研究发现，小菜蛾对米满的早期抗性主要通过解毒代谢能力的增强。因此可以考虑在制剂中加入增效剂，来提高对抗性个体的毒杀效果。另外，研究发现抗性小菜蛾的生物适合度有明显下降，因此也可以利用药剂的轮换进行抗性治理，但应避免使用有交互抗性的阿维菌素等药剂。更多还原

【Abstract】 The diamondback moth, Plutella xylostella(L.), is one of the most destructive pests of cruciferae vegetable and has been reported to produce severious resistance to various convenient insecticides, including organophosphate and pyrethroid insecticides, Bacillus thuringiensis (Bt), acylurea insect growth regulators, abamectin, and DDT, etc.Now tebufenozide has been introduced for control of this pest. Tebufenozide is developed by Rohm and Hass Co. It binds to the ecdysone receptor in insect body, like the steroidal molting hormone, but initiates a premature incomplete molt and results in death of the larva. Tebufenozide appears to be lepidoperan-specific and has been used as an environmentally friendly insecticide. In order to make better use of this insecticide and keep it from developing resistance quickly in diamondback moth, resistance selection has been carried out in laboratory to evaluate the risk, and cross-resistance and resistance mechanisms tested for setting up an effective resistance management strategy.The resistance selection revealed that the resistance to tebufenozide increased slowly at first and then speeded up, and reached 15.7 times at the 7th generation. At the same time, the selection with tebufenozide also resulted in the increase of the LD50 of phoxim, acephate, hexafiumuron, flufenoxuron by 2.051 2.302 1.765 and 2.963 times, respectively. The selected resistant strain even showed 13 time cross-resistance to abamectin. But no changes was found with the LD50 of deltamethrin, cypermethrin and trichlorfon during the selection.The detoxicating metabolism enzymes were compared between the susceptible and the resistant strain of diamondback moth. It was found that the activity of all the enzymes tested was higher in the resistant strain than in the susceptible strain. Some difference was also found between sexes. Comparing with the susceptible larvae, the activity of esterase was 1.69 times higher in the resistant females and 1.19 times higher in the males. The affinity of the esterase in resistant larvae decreased obviously, Km increase by 43.55 and 1.93 times, respectively. The activity of glutathione-s-transferases was 1.25 higher in the female and 1.57 times in the males. However, the mixed function oxidases showed no sex difference. The resistant larvae of both sexes had 1.3 times higher activity. Finally, it wasconcluded that the activity increase of the detoxicating enzymes should contribute to the resistance of diamondback moth to tebufenozide.The effects of tebufenozide resistance on fitness of diamondback moth were evaluated in terms of developmental and reproductive characteristics. Life tables of tebufenozide-resistant and susceptible strain were constructed and the relative fitness was determined by comparison of the net reproductive rate (R0). The results indicated that the resistant strain possessed reproductive disadvantages including decreased percentage of female copulation, lower egg production of female and decreased percentage of egg hatching when compared with the susceptible strain. However, no developmental defect was observed. The resistant strain was calculated to have a fitness value of 0.61 relative to the susceptible strain.In this investigate, it was found that tebufenozide have risk of developing resistance in this pest, though it has a special mode of action. We should pay attention on the rational use of insecticides and management of resistance. Because the resistance at developing stage depends on the enhancement of the activity of the detoxicating metabolism enzymes, as the results showed, we should consider of adding synergists to the insecticide formulations to increase the effect of tebufenozide on the resistant diamondback moth and delay the resistance development. Otherwise, the decreasing of the fitness of resistant strain indicate that limited use of this insecticide and alternate use it with some other insecticides without cross-resistance can be also a effective method for the resistance management.更多还原