Young giant water bug nymphs prefer larger prey: changes in foraging behavior with nymphal growth in Kirkaldyia deyrolli

Raptorial characteristics may evolve in predators because of their importance in obtaining food. The giant water bug, Kirkaldyia deyrolli, possesses a claw on the terminal segment of the raptorial foreleg that is crucial for capturing prey. Claw curvature has been previously shown to change during growth in this species, but the adaptive significance of this change has not yet been explored. Predation experiments have demonstrated that young nymphs with highly curved claws caught proportionally larger prey than older nymphs with less-curved claws. Catching behaviours for a certain prey size differed significantly between young and older nymphs. The observation that nymphal growth affects prey-catching behaviour in the giant water bug supports the hypothesis that predators can change catching behaviours based on changes in raptorial characteristics in order to maximize prey resources acquired at each developmental stage.

掠捕特征（raptorial characteristics）可能会在掠食者体内演化，因其在获取食物的过程中发挥着至关重要的作用。巨型水蝽（giant water bug, Kirkaldyia deyrolli）的捕捉足（raptorial foreleg）末端体节生有一枚爪，该爪对于其捕获猎物而言不可或缺。此前已有研究表明，该物种在生长发育过程中，其爪的弯曲度会发生变化，但这类变化的适应性意义尚未得到探究。捕食实验结果证实，爪弯曲度较高的低龄若虫，相较于爪弯曲度较低的高龄若虫，能够捕获到体型相对更大的猎物。针对特定体型猎物的捕获行为，在低龄与高龄若虫之间存在显著差异。巨型水蝽的若虫生长发育会影响其猎物捕获行为，这一观测结果支持了如下假说：掠食者可根据其掠捕特征的变化调整捕获行为，从而最大化其在每个发育阶段所获取的猎物资源。