We describe two classes of models used for fungicide and antibiotic resistance dynamics. One class assumes that the density of the pathogen (or severity of the disease caused by the pathogen) has no feedback effects on the rate at which new infections arise. The second class does not make this assumption. A quantitative relationship between these two classes is derived. We then discuss the two sets of assumptions made in the literature about initial conditions: either both the fungicide-sensitive strain and the -resistant strain are initially at low density, or the sensitive strain is resident at nonlow density and the resistant strain is initially at low density. We show that models of fungicide resistance dynamics with and without density-dependent feedback give contrasting predictions on the effects of pathogen life-cycle parameters and the effects of the fungicide (dose, frequency, use of mixtures, spatial usage restrictions) on the evolution, invasion, and spread of fungicide resistance. We further show that the evaluation of a resistance management strategy requires a very precise definition of what constitutes a good strategy.

中文翻译：

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杀菌剂抗性动力学模型。

我们描述了两类用于杀菌剂和抗生素抗性动态的模型。一类假设病原体的密度（或病原体引起的疾病的严重程度）对新感染的发生率没有反馈影响。第二类不做这个假设。导出了这两个类之间的定量关系。然后我们讨论了文献中关于初始条件的两组假设：杀菌剂敏感菌株和抗性菌株最初都处于低密度，或者敏感菌株位于非低密度而抗性菌株最初处于低密度。我们表明，有和没有密度依赖反馈的杀真菌剂抗性动力学模型对病原体生命周期参数的影响和杀真菌剂（剂量、频率、混合物的使用、空间使用限制）对进化的影响给出了对比预测，杀真菌剂抗性的入侵和传播。我们进一步表明，对抗性管理策略的评估需要非常精确地定义什么是好的策略。