Suh Eunho, Koh Sang-Hyun, Lee Joon-Ho, Shin Key-Il, Cho Kijong
Division of Environmental Science and Ecological Engineering, Korea University, Anamdong, Sungbuk-ku, 136-701, Seoul, Korea.
Exp Appl Acarol. 2006;38(2-3):151-65. doi: 10.1007/s10493-006-0009-z.
This study aimed to monitor the present and future developments of the resistance of Tetranychus urticae Koch to fenpyroximate and pyridaben, using the relationship of the LC(50) and slope of the concentration-mortality line in a probit model, for the provision of reliable resistance management tactics. Tetranychus urticae populations were collected from 16 commercial greenhouses, where various crops were cultivated, as well as from 10 apple orchards throughout Korea. The resistance to fenpyroximate and pyridaben of each population was estimated by calculating the median lethal concentration (LC(50)), resistance ratio (RR) and slope of the concentration-mortality regression. Most of the greenhouse populations exhibited moderate levels of resistance, whereas the apple orchard populations showed only low levels, indicating that T. urticae populations in greenhouses were more strongly selected than those in apple orchards. Four population groups were established based on either the habitats (greenhouse and apple orchard) or acaricides (fenpyroximate and pyridaben). To test the hypothesis, "the slope is greatest at low and high levels of resistance," the slopes were regressed as a function of the LC(50), and fitted to a polynomial regression. The polynomial regression model explained this relationship well for the four population groups (p < 0.05), indicating that the development of resistance toward fenpyroximate or pyridaben was consistent with the gradient. A laboratory selection study agreed with the results from both acaricide field populations. These results suggest that the gradient was a good indicator of the susceptibility of T. urticae to genetic variations, which was related to the LC(50). The application of these findings is also discussed in relation to the resistance management of T. urticae.
本研究旨在利用概率模型中半数致死浓度（LC(50)）与浓度-死亡率曲线斜率的关系，监测二斑叶螨（Tetranychus urticae Koch）对唑螨酯和哒螨灵抗性的当前及未来发展情况，以提供可靠的抗性治理策略。从韩国各地16个种植各种作物的商业温室以及10个苹果园中采集二斑叶螨种群。通过计算半数致死浓度（LC(50)）、抗性倍数（RR）和浓度-死亡率回归曲线的斜率，估算每个种群对唑螨酯和哒螨灵的抗性。大多数温室种群表现出中等抗性水平，而苹果园种群仅表现出低抗性水平，这表明温室中二斑叶螨种群比苹果园中的种群受到更强的选择压力。根据栖息地（温室和苹果园）或杀螨剂（唑螨酯和哒螨灵）建立了四个种群组。为了验证“在低抗性和高抗性水平下斜率最大”这一假设，将斜率作为LC(50)的函数进行回归，并拟合为多项式回归。多项式回归模型很好地解释了这四个种群组的这种关系（p < 0.05），表明对唑螨酯或哒螨灵的抗性发展与梯度一致。一项实验室选择研究与杀螨剂田间种群的结果一致。这些结果表明，该梯度是二斑叶螨对与LC(50)相关的遗传变异敏感性的良好指标。还讨论了这些研究结果在二斑叶螨抗性治理方面的应用。
