Ixodes pacificus

像所有爬行动物一样，蜥蜴是ectotherms(external regulation of body temperature). Their behaviour is key to how they regulate their body temperature, such as basking in the sun or moving into shade. They have an optimum temperature range, however sometimes they choose sub-optimum temperatures for a variety of reasons, one of which may be due to parasitic infections.

Hosts may alter temperature seeking behaviours, e.g. by choosing higher/lower temperatures despite the negative impact on their physiology, if they are experiencing negative effects from being infected by a parasite. This is a balance between fever which fights infection and hypothermia which protects vital organs during “metabolic trauma” (e.g. from infestations). Both have associated costs.

tick是蜥蜴的常见外寄生虫。尽管没有关于tick负担对蜥蜴的影响的研究，但当前的证据表明，tick侵犯可能会对蜥蜴的健身水平产生负面影响，包括移动性，速度，距离，耐力，在繁殖季节的展示和交配机会。

在最近的一篇文章中Megía-Palma等（2019）the authors looked at the impact of tick infestation on lizard body mass and temperature-seeking behaviour and how this behaviour may be disrupted by coinfections with coccidian parasites.

研究蜥蜴，壁虱和球虫

这项研究的作者收集了77个成人西方栅栏蜥蜴Sceloporus occidentalisin Santa Cruz county (42 in April, 35 in June). This lizard species is parasitised by the Western black-legged tickIxodes pacificus(known to cause hemolysis in the lizard’s blood) andcoccidian内寄生虫。作者假设蜥蜴会显示出行为反应，以限制tick侵犯的症状，以预测：

• Lizards with high tick load will choose lower temperatures/hypothermia to limit cost of tick infestation and reduce blood loss
• Lizards will lose weight proportionally to tick load

Each lizard was housed individually in terraria mimicking natural conditions. Data on sex, size (snout to vent length SVL), weight and body condition as a Scaled Mass index (SMi) were recorded at the start of the study and repeated after 11 days. Experimental thermal gradients ranging from 25-48 °C were set up and used to track the thermal behaviour of the lizards. Body temperature was recorded every minute during the 120 minute trial. Preferred temperature was calculated as thearithmetic mean of measured body temperatures。还记录了最高和最低体温。通过计算第1天和第11天的壁虱数量（tick负载）记录的蜥蜴的寄生感染。血液的慢性感染（Lankesterella occidentalis）和肠道（Acroeimeria sceloporis）使用一种描述的方法诊断Megía-Palma et al. (2018)at the beginning of the trial.

蜥蜴的首选温度受捕获月份的影响以及总滴答负荷和共同感染状态的相互作用。在没有球虫感染的蜥蜴和仅患有腹膜球虫的蜥蜴的蜥蜴中，tick负载和首选温度（和最高体温）是负相关的。当蜥蜴感染肠道球虫（无论是单独还是与血液球虫）感染时，这种关联就会失去。蜥蜴在11天后失去了体重，体重变化与捕获时的壁虱负荷有显着负相关，而蜥蜴的滴答性会增加更多的体重。在Terraria的11天后，总的TICK负载显着下降，但是当分类时，作者表明，只有美联储的数量减少，而不是非喂养tick的数量。

Lizards, infections and climate

tick侵染与蜥蜴的追求（“行为体温过低”）行为有关，较高的tick负载与较低的首选温度和较低的最高体温有关。tick侵犯与体重损失有关，这与tick负载成正比。蜥蜴的体重与战斗和交配成功for males and offspring condition in females. Thus body mass loss due to tick infestations could be a direct fitness cost.

这项研究中记录的“行为体温过低”可能是S. occidentalis滴答虫病的季节性变化的蜥蜴。蜥蜴可以通过“行为体温过低”来减少其代谢活性，以减少外周血循环，从而通过限制tick虫的血液摄入（因此在这项研究中的fick虫中减少）来控制tick虫的侵袭。

研究结果还表明肠occidian寄生虫A. sceloporis破坏了tick虫的蜥蜴的这种冷淡的行为。为什么？作者呼吁进行更多的研究，以了解为什么可能是这种情况：是否有更高的成本与肠道球虫寄生虫相关，需要不同的行为反应（例如，更多的觅食，温暖的温度更温暖？），或者是否有机制引起的机制A. sceloporis寄生虫for it’s own benefit (host-manipulation).

蜥蜴和其他阶级需要微栖息地和一系列可供选择的温度，不仅可以进行热管调节，还可以使它们使用温度来控制寄生虫侵袭和感染的影响。蜥蜴需要能够获得较冷的温度，以减少tick虫的影响。欧克特动物使用“行为热”，选择更高的温度来控制感染感染感染感染感染，并选择冷温度来控制感染侵扰。气候变化构成了对热的巨大风险，在这种情况下，消除了他们控制和减少寄生虫感染和感染对健康的负面影响的能力。