截形叶螨发育速率与温度关系模拟及对哒螨灵的抗性风险评估

为明确温度对截形叶螨抗哒螨灵种群(Py-R)和敏感种群(SS)风险发育速率的影响和评估截形叶螨对哒螨灵药剂的抗性风险,本试验在16℃、20℃、24℃、28℃、32℃和36℃6个温度梯度下,用王-兰-丁模型拟合了两个种群的世代发育速率与温度的关系曲线,并采用了数量遗传学中的域性状分析法,估算了截形叶螨对哒螨灵的现实遗传力并预测了不同选择压力下截形叶螨对哒螨灵的抗性风险。研究结果表明,根据拟合的王-兰-丁模型推导,截形叶螨敏感种群SS世代发育的最低、最高临界温度分别为10.05℃和39.24℃,抗性种群Py-R发育最低、最高临界温度分别为13.45℃和41.89℃;抗性种群各螨态的最高临界温度值均显著大于敏感种群,表明截形叶螨抗哒螨灵种群对高温的忍耐程度和适应能力大于敏感种群。估算出的截形叶螨对哒螨灵的抗性现实遗传力(h~2)为0.11,且抗性筛选前期和中期的h~2值为0.12和0.18,大于筛选后期h2值(0.08),在筛选末期,h~2值又回升到0.14。在室内选择条件(h~2=0.11)下,选择压力即杀死率为50%~90%时,预计抗性增长10倍,仅需10~23代;而在田间选择压力(h2=0.05)下,同样条件下,抗性增长也只需21~46代。因此,截形叶螨对哒螨灵存在一定的抗性风险,可与其他不具交互抗性的杀虫剂之间进行轮用,并降低选择压来延缓抗药性的产生。

Simulation of developmental rate and temperature trend, and assessement of resistance risk to pyridaben of Tetranychus truncatus Ehara

In recent years, Tetranychus truncatus Ehara has become one of the main pests in Hexi area of Gansu Province, for which pyridaben was widely used due to its special physiological mechanism and broad-spectrum efficiency. However, T. truncatus has developed resistance to the sole application of pyridaben for a long perod of time. The aim of this paper was to verify the effect of temperature on risk development rate of resistant and susceptible populations of Tetranychus truncatus Ehara. Then based on the results of resistance selection, the study evaluated the resistance risk of T. truncatus to pyridaben. To do this, the relationship between development rate and temperature was analyzed using the Wang-Lan-Ding model at six temperatures (16℃, 20℃, 24℃, 28℃, 32℃and 36℃). The realized heritability (h2) of T. truncatus was estimated and the resistance risk of T. truncates to pyridaben under different resistance selection pressure predicted on the basis of resistance breeding and selection in the laboratory. Then threshold trait analysis was done in quantitative genetics to provide a theoretical support for the application of pyridaben and comprehensive control of T. truncatus. The results showed that based on the fitted Wang-Lan-Ding models, the minimum and maximum boundary temperatures of susceptible populations were 10.05 ℃ and 39.24 ℃, whereas that of the resistant populations were 13.45 ℃ and 41.89 ℃, respectively. The fitted models also showed that the maximum boundary temperature of resistant populations was significantly greater than that of susceptible populations. This implied that resistant populations had much stronger suitability to extreme temperatures than susceptible populations. The realized heritability (h2) of T. truncatus resistance to pyridaben was 0.11, and h2 for the first period and mid-term selection experiment (0.12 and 0.18, respectively) was higher than that for the later period (0.08), but h2 (0.14) sharply increased at terminal stage. Under laboratory conditions with h2= 0.11, developing a 10-fold increase of resistance to pyridaben required 10-23 generations under selection pressure (mortality) of 50%-90%. Under field conditions (h2= 0.05), it required 21-46 generations to develop the same resistance level.The results suggested that T. truncatus had resistance risk to pyridaben. However, when pyridaben was applied under rotation with other insecticides without cross-resistance and reduced selection pressure, the resistance development rate of T. truncatus delayed.