When a prey is perceived and attacked, it may adopt direct anti-predator strategies, such as fleeing and tonic immobility (TI). During this latter, individuals remain in a motionless posture, which may reduce chances of being preyed, but retain close distance to the predator. Alternatively, fleeing increases distance from the threat, while enhancing chances of predation by visually guided predators. Thus, there is a trade-off between these two opposite direct anti-predator strategies. Here, we characterize the balance between these two behaviors in Zabrotes subfasciatus, a beetle that when stimulated displays binary responses: TI or running away. We investigated which factors determine TI frequency, probability, and duration. We examined the roles of period of the day (3 AM, 9 AM, 3 PM, and 9 PM), environmental temperature, sex, body size, and consecutive stimuli (three successive). None of these factors influenced TI duration. However, TI exhibition was higher at 3 PM, with no effects regarding sex or stimulus. As temperature raises, TI probability increases. This is paradoxical because ectothermic animals are expected to present increased locomotive activity under higher temperatures due to metabolic dependence. As far as we know, this is the first report of temperature positive relating to TI, especially in an ectothermic animal. At hotter periods of the day, while visually guided ectothermic animals are more active, Z. subfasciatus TI frequency is higher. As TI success is based on the lack of movement, which triggers killing behaviors of visually guided predators, this association may increase chances of survival against ectothermic predators.

中文翻译：

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放热动物的逃避行为与强直性行为之间的权衡

当猎物被感知并受到攻击时，它可能会采取直接的反捕食者策略，例如逃跑和补品固定（TI）。在后者的过程中，个体保持静止状态，这可以减少被捕食的机会，但与捕食者保持近距离。或者，逃跑增加了与威胁的距离，同时增加了视觉引导的掠食者的掠食机会。因此，在这两种相反的直接反捕食者策略之间需要权衡。在这里，我们描述了Zabrotes subfasciatus中这两种行为之间的平衡，被刺激时显示二进制响应的甲虫：TI或逃跑。我们调查了哪些因素决定了TI的频率，概率和持续时间。我们检查了一天中的时段（凌晨3点，9 AM，3 PM和9 PM），环境温度，性别，体重和连续刺激（三个连续）的作用。这些因素均不影响TI持续时间。但是，TI展览在下午3点更高，对性或刺激没有影响。随着温度升高，TI概率增加。这是自相矛盾的，因为预计在较高的温度下由于代谢依赖性，放热动物会表现出增加的机车活动。据我们所知，这是与TI相关的温度正温度的第一个报告，尤其是在放热动物中。在一天中较热的时段，筋膜下梭状芽胞杆菌TI频率较高。由于TI的成功是基于缺乏运动而引发的，这种运动会触发视觉引导的捕食者的杀戮行为，因此这种关联可能会增加抵抗外吸捕食者的生存机会。