Nonhost diversity and density reduce the strength of parasitoid-host interactions.
Nonhost diversity and density reduce the strength of parasitoid-host interactions.
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DOI：
10.1002/ece3.2191
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发表时间：
2016-06
影响因子：
2.6
通讯作者：
Sanders D
中科院分区：
文献类型：
--
作者：
Kehoe R;Frago E;Barten C;Jecker F;van Veen F;Sanders D
众所周知，非猎物或非宿主的存在会增加消费者寻找其资源所需的努力，从而降低消费者-资源相互作用的强度。这些干扰效应可以对消费者资源动态产生稳定作用，但也被用来解释寄生蜂的灭绝。为了了解非寄主对寄生蜂的影响，我们利用实验寄主-寄生蜂群落来控制非寄主蚜虫的密度和多样性，并测试了这如何影响两种寄生蜂的寄生效率。为了进一步研究寄生蜂对非寄主的行为反应，我们测试了寄生蜂时间分配的变化与它们寻找寄主的策略的关系。非寄主的存在降低了两种寄生蜂的攻击成功率(攻击率)。大蜂受非寄主多样性增加的影响较大，其侵染率从无非寄主时的0.39降至非寄主多样性较高时的0.05，而蚕茧蜂对非寄主多样性的反应较弱，但对非寄主密度的增加有较明显的影响。我们的实验进一步表明，非寄主多样性的增加导致大斑潜蝇的寄主搜索和攻击活动水平下降，但在大斑潜蝇中没有下降；大斑潜蝇在非寄主存在一段时间后，通过增加休息时间来改变其行为。这项研究表明，环境中的非宿主密度和多样性是消费者-资源相互作用强度的关键决定因素。它们对消费者效率的影响很大程度上取决于寄主/猎物的寻找策略，这一点从两种寄生蜂物种的不同反应中可见一斑。我们讨论了寄主和非寄主物种之间的这些由特征介导的间接相互作用对于群落的稳定是重要的，它们的稳定或不稳定取决于非寄主密度或多样性的水平。
The presence of nonprey or nonhosts is known to reduce the strength of consumer– resource interactions by increasing the consumer's effort needed to find its resource. These interference effects can have a stabilizing effect on consumer–resource dynamics, but have also been invoked to explain parasitoid extinctions. To understand how nonhosts affect parasitoids, we manipulated the density and diversity of nonhost aphids using experimental host–parasitoid communities and tested how this affects parasitation efficiency of two aphid parasitoid species. To further study the behavioral response of parasitoids to nonhosts, we tested for changes in parasitoid time allocation in relation to their host‐finding strategies. The proportion of successful attacks (attack rate) in both parasitoid species was reduced by the presence of nonhosts. The parasitoid Aphidius megourae was strongly affected by increasing nonhost diversity with the attack rate dropping from 0.39 without nonhosts to 0.05 with high diversity of nonhosts, while Lysiphlebus fabarum responded less strongly, but in a more pronounced way to an increase in nonhost density. Our experiments further showed that increasing nonhost diversity caused host searching and attacking activity levels to fall in A. megourae, but not in L. fabarum, and that A. megourae changed its behavior after a period of time in the presence of nonhosts by increasing its time spent resting. This study shows that nonhost density and diversity in the environment are crucial determinants for the strength of consumer–resource interactions. Their impact upon a consumer's efficiency strongly depends on its host/prey finding strategy as demonstrated by the different responses for the two parasitoid species. We discuss that these trait‐mediated indirect interactions between host and nonhost species are important for community stability, acting either stabilizing or destabilizing depending on the level of nonhost density or diversity present.