Abstract

Parasites may impair host behavior in ways that reduce host fitness, especially when access to territories or mates becomes disrupted. Western fence lizards (Sceloporus occidentalis) are a key host to western blacklegged ticks (Ixodes pacificus). Males are highly aggressive during the mating season, competing with rivals through displays of color badges, pushups, and other behaviors. We hypothesized that experimental tick infestation diminishes the performance of male western fence lizards in intrasexual contests, via either blood loss, damage to sensory structures, or both. We infested adult males with larval ticks for 7 to 10 days, staged contests between infested and quality-matched control males, and measured their behavior in enclosure arenas. Infested lizards were less aggressive and exhibited decreased hematocrit, compared to non-infested animals. We found no relationships between aggression and either body size or blue ventral badge color traits, for either infested or uninfested males. There was also no effect of tick attachment location and hemoparasite infection on host contest behavior. This is the first demonstration of the impact of I. pacificus parasitism on intraspecific interactions of western fence lizards and suggests that tick infestation has substantial impacts on lizard fitness. Because I. pacificus rely heavily on these lizards for blood meals and dispersal, these impacts could also influence the abundance of ticks and the pathogens they vector.

Significance statement

Parasitism frequently impairs host behavior. We investigated the effect of blacklegged tick parasitism on western fence lizard contest behavior using a lab-based manipulation experiment. We demonstrated that tick infestation reduced lizard aggressiveness, which may lead to territory loss and reduced mating opportunities in the wild. We found no evidence that host body size or coloration are correlated with aggression. This study adds to a growing body of evidence that tick parasitism is costly for lizards, while demonstrating the usefulness of manipulation experiments to understand host-parasite interactions.

中文翻译：

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ick虫寄生损害了西栅栏蜥蜴（Scoloporus occidentalis）的比赛行为

摘要

寄生虫可能会通过降低宿主适应性的方式损害宿主行为，尤其是在无法进入领地或伴侣的情况下。西部栅栏蜥蜴（Scoloporus occidentalis）是西部黑脚tick（Ixodes pacificus）的重要寄主）。雄性在交配季节具有极强的攻击性，通过展示彩色徽章，俯卧撑和其他行为与竞争对手竞争。我们假设实验性tick虫侵扰会导致失血，感觉结构受损或两者同时减少，从而减少雄性西部围栏蜥蜴在性竞赛中的表现。我们用幼虫s感染成年雄性，持续7至10天，在成虫和质量匹配的对照雄性之间进行比赛，并在围场内测量其行为。与未感染的动物相比，被感染的蜥蜴的攻击性较小，并且血细胞比容降低。我们发现，对于出没或未出没的雄性，侵略性与体型或蓝色腹徽颜色特征之间没有关系。tick虫附着位置和血寄生虫感染对宿主竞赛行为也没有影响。这是第一个示范影响太平洋寄生虫对西部篱笆蜥蜴的种内相互作用有寄生作用，并表明tick虫侵扰对蜥蜴的适应能力有重大影响。由于I. pacificus严重依赖这些蜥蜴的血粉和扩散，因此这些影响也可能影响s的丰度和它们传播的病原体。

重要性声明

寄生虫经常损害宿主的行为。我们使用基于实验室的操作实验调查了黑脚tick寄生对西部篱笆蜥蜴比赛行为的影响。我们证明tick虫侵扰减少了蜥蜴的侵略性，这可能导致领土损失和野外交配机会减少。我们没有发现任何证据表明宿主的体型或颜色与侵略性有关。这项研究增加了越来越多的证据表明tick寄生对蜥蜴来说是昂贵的，同时证明了操纵实验对理解宿主-寄生虫相互作用的有用性。