Modeling effects of ecological factors on evolution of polygenic pesticide resistance
Modeling effects of ecological factors on evolution of polygenic pesticide resistance
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DOI：
10.1016/j.jtbi.2018.07.034
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发表时间：
2018-11-07
影响因子：
2
通讯作者：
Tenhumberg, Brigitte
中科院分区：
文献类型：
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作者：
Haridas, C., V;Tenhumberg, Brigitte
农药的广泛使用导致世界范围内许多害虫产生抗药性，限制了其在害虫防治中的使用。有效的害虫和抗性管理实践需要了解抗性遗传学和害虫的生活史。大多数农药抗性模型都假设抗性是单基因的，由单个基因赋予。然而，抗性可能会进化为由多个基因的作用引起的多基因数量性状，特别是当农药剂量较低时。此外，害虫的适应性可能取决于密度，并且可能取决于非生物因素，例如温度。目前尚不清楚这些因素如何影响多基因抗性的进化或抗性进化时害虫种群动态。我们使用西方玉米根虫 Diabrotica virgifera virgifera 作为案例研究，并使用转基因 Cry3Bb1 毒素的密度依赖性存活率、遗传力和存活率数据以及相应的 LC50 值来模拟对 Cry3Bb1 的多基因抗性。我们发现，即使在死亡率低于 99.9% 的剂量下，LC50 也会迅速增加。然而，只有当死亡率高达99.9%时，存活率才能达到100%。对高选择压力的快速响应产生周期性幼虫密度，而较低的选择压力产生平衡密度。有趣的是，我们发现在人群中观察到的相对较低的密度可能并不能证明农药的存活率较低。因此，我们发现较大的避难所可能不一定有助于降低害虫密度，尤其是在农药死亡率较低的情况下。这种效应是由选择反应和密度依赖性之间的权衡而产生的，需要根据生存率和害虫密度的变化仔细评估抗性的进化。当选择压力较低时，较低的初始密度会导致对选择的较大响应。最后，我们表明，无论选择压力如何，发育时间较短的种群最初会更快地产生抗性。然而，当选择压力较低时，发育时间较长的种群的存活率最终会更高。由于发育时间取决于度数，温度的时空变化可能是多基因抗性进化的一个重要因素。 (C) 2018 Elsevier Ltd. 保留所有权利。
Widespread use of pesticides has resulted in the evolution of resistance in many insect pests worldwide limiting their use in pest control. Effective pest and resistance management practices require understanding of the genetics of resistance and of the life history of the pest. Most models for pesticide resistance assume that resistance is monogenic, conferred by a single gene. However, resistance could evolve as a polygenic quantitative trait resulting from the action of several genes, especially when pesticide dose is low. Further, fitness of the pest could be density-dependent and might depend upon abiotic factors such as temperature. It is not known how these factors affect the evolution of polygenic resistance or pest population dynamics when resistance evolves. We use the western corn rootworm, Diabrotica virgifera virgifera, as a case study and use data on density-dependent survival, heritability and survival rates on the transgenic Cry3Bb1 toxin and corresponding LC50 values, to model polygenic resistance to Cry3Bb1. We found that LC50 increased rapidly even at doses that produced a mortality of less than 99.9%. However, survival reached 100% only when mortality was as high as 99.9%. Fast response to high selection pressure produced cyclical larval densities while lower selection pressures produced equilibrium densities. Interestingly we found that a relatively low density observed in a population may not be evidence for a low survival to the pesticide. As a consequence we found that larger refuges might not necessarily help in reducing pest densities especially when pesticide mortality is low. This effect, arising from the tradeoff between response to selection and density dependence, calls for careful assessment of the evolution of resistance based on change in survival as well as on pest densities. When selection pressure is low a lower initial density resulted in a larger response to selection. Finally, we showed that populations with shorter developmental times developed resistance faster initially irrespective of selection pressure. However, when selection pressure is low survival eventually became higher in populations with longer developmental times. Since developmental time depends on degree days spatio-temporal variation in temperature could be an important factor in polygenic resistance evolution. (C) 2018 Elsevier Ltd. All rights reserved.