Measures of parasitism often differ between hosts. This variation is thought due in part to age or sex differences in exposure to parasites and/or susceptibility to parasitism. We assessed how often age or sex biases in parasitism were found using a large, multi‐year (2006–2017) dataset of 12 parasite species of Icelandic rock ptarmigan (Lagopus muta). We found host traits (i.e. age and/or sex) accounted for significant variation in abundance of 11 of the 12 parasite species. We often found increased abundance among juvenile hosts, although significant adult biases were observed for three parasite species. Additionally, higher levels of parasitism by many species were observed for female hosts, contrary to frequent male biases in parasitism reported for other vertebrates. Abundance of six parasite species was best explained by interactions between host age and sex; some degree of decrease in abundance with host age was present for both male and female hosts for four of those parasite species. We consider various host and parasite traits that could account for observed singular and repeated patterns of age and/or sex biases in parasitism (e.g. age‐ and sex‐related grouping behaviours, age‐specific mortality in relation to parasitism, acquisition of greater immunity with age). This work provides a foundation for future studies investigating age‐related differences in acquired immunity and age‐specific parasite‐mediated mortality for males and females, as well as studies on interactions between co‐infecting parasite species.

中文翻译：

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寄主的性别和年龄通常可以解释岩雷鸟的寄生虫变化：对确定接触和易感性决定因素的意义

寄主之间的寄生虫措施通常有所不同。人们认为这种变化部分是由于年龄或性别与寄生虫接触和/或对寄生虫的敏感性不同。我们使用12个冰岛雷鸟雷鸟（Lagopus muta）寄生虫的大型多年期（2006-2017）数据集，评估了发现寄生虫的年龄或性别偏见的频率。）。我们发现宿主特征（即年龄和/或性别）占12种寄生虫物种11种的丰度的显着差异。我们经常发现少年寄主中的丰度增加，尽管在三种寄生虫物种上观察到明显的成年偏差。另外，女性寄主中观察到许多物种的寄生虫水平较高，这与其他脊椎动物报道的男性寄生虫偏见频繁相反。寄主年龄与性别之间的相互作用最好地解释了六种寄生虫的丰度。对于这些寄生虫物种中的四种，雄性和雌性宿主的丰度都随着宿主年龄的增加而有所降低。我们考虑了各种寄主和寄生虫特征，这些特征可以解释观察到的寄生虫中年龄和/或性别偏见的单一和重复模式（例如，与年龄和性别相关的分组行为，与寄生虫有关的特定年龄死亡率，随着年龄的增长获得更大的免疫力。这项工作为今后研究男性和女性获得性免疫力和年龄特异性寄生虫介导的死亡率的年龄相关差异以及共同感染寄生虫物种之间相互作用的研究提供了基础。