Predation threat modifies Pieris rapae performance and response to host plant quality
Predation threat modifies Pieris rapae performance and response to host plant quality
复制标题
捕食威胁改变菜青虫的性能和对寄主植物质量的反应
作者：
M. Lund;D. Brainard;T. Coudron;Z. Szendrei
捕食者通过消耗性和非消耗性影响猎物种群，例如猎物对捕食威胁的行为和生理变化。此外，各种自上而下的(如捕食者特征)和自下而上的因素(如植物营养)可能会影响非消耗性影响，但对这些因素如何相互作用了解甚少。研究了不同植物氮水平对菜青虫寄主植物选择、叶片消耗和生长的影响，以及代表不同威胁程度的两种捕食者--聚甲虫(Hippodamia Convergen)和斑纹夜蛾(Podisus Maculiventris)对寄主植物的选择和生长的影响。我们发现，当受到两种不同的捕食者物种威胁时，菜粉蝶成虫和幼虫在自下而上和自上而下的因素上做出了类似的选择。成虫和幼虫在受到聚合型棉铃虫的威胁时选择高N植物，但在受到P.maculiventris的威胁时，植物N不影响寄主植物的选择。此外，当受到聚合型赤眼蜂的威胁时，幼虫会消耗更多的叶组织并变得更大，但在P.maculiventris的威胁下，叶片组织的消耗和幼虫的生长没有改变，这表明如果幼虫能够迅速超过易被捕食的生活期，它们的行为可能会改变。这些结果表明，自上而下的捕食者身份等因素可能决定了菜青虫在利用反捕食者行为时如何调节它们对寄主植物质量等自下而上因素的反应。
Predators impact prey populations through both consumptive and non-consumptive effects, such as behavioral and physiological changes by prey in response to a predation threat. Additionally, various top-down (e.g. predator characteristics) and bottom-up factors (e.g. plant nutrients) may impact non-consumptive effects, yet little is understood about how these interact. We studied how host-plant choice, leaf consumption, and growth of an herbivore, Pieris rapae, were impacted by different levels of plant nitrogen (N) and two predator species representing varying degrees of threat, Hippodamia convergens (predator of early-instars) and Podisus maculiventris (predator of all-instars). We found that P. rapae adults and larvae made similar choices about bottom-up and top-down factors when threatened by two different predator species. Adults and larvae preferred high N plants when threatened by H. convergens, but plant N did not influence their host plant choice when threatened by P. maculiventris. Additionally, larvae consumed more leaf tissue and grew larger when threatened by H. convergens, but leaf tissue consumption and larval growth did not change under threat by P. maculiventris, suggesting that larvae may change their behavior if they are able to quickly outgrow life stages vulnerable to predation. These results indicate that top-down factors such as predator identity may determine how P. rapae modulate their responses to bottom-up factors such as host plant quality when utilizing anti-predator behaviors.