Host attachment is a necessary behavior in the evolution of parasitism. It is hypothesized that populations pass through a stage of facultative parasitism before the evolution of obligate parasitism. Previous research has revealed the impact of extrinsic factors on the expression of parasitic tendencies, but to our knowledge, the role of individual behavioral variation driving parasitic tendencies remains to be tested. Here, we used repeated behavioral assays to quantify attachment propensity and activity level of individual Macrocheles muscaedomesticae , facultatively parasitic mites of flies, from two different populations. Mites from both populations exhibited repeatability in attachment propensity and mites from one population exhibited repeatability in activity level. We did not find a relationship between an individual’s activity level and attachment propensity. Our data suggest that facultative parasitism may not simply describe a phenotypically plastic strategy that responds to environmental cues, but perhaps that individual differences in parasitic tendencies may appear like facultative parasitism at the population or species level.

中文翻译：

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寄生人格：兼性寄生螨的行为存在一致的个体差异

寄主依附是寄生进化过程中的必要行为。假设种群在专性寄生进化之前经历了兼性寄生阶段。先前的研究揭示了外在因素对寄生倾向表达的影响，但据我们所知，个体行为变异驱动寄生倾向的作用仍有待检验。在这里，我们使用重复的行为分析来量化来自两个不同种群的个体 Macrocheles muscaedomesticae（苍蝇的兼性寄生螨）的附着倾向和活动水平。来自两个种群的螨在附着倾向上表现出可重复性，而来自一个种群的螨在活动水平上表现出可重复性。我们没有发现个人的活动水平和依恋倾向之间的关系。我们的数据表明，兼性寄生可能不仅仅描述了一种对环境线索做出反应的表型可塑性策略，而且寄生倾向的个体差异可能在种群或物种水平上看起来像兼性寄生。