Mobile parasitoids may restrict the spatial spread of an insect outbreak
Mobile parasitoids may restrict the spatial spread of an insect outbreak
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移动寄生蜂可能会限制昆虫爆发的空间传播
DOI：
10.2307/5965
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发表时间：
1997
影响因子：
4.8
通讯作者：
S. Harrison
中科院分区：
文献类型：
--
作者：
P. A. Brodmann;C. Wilcox;S. Harrison
1.西部草丛蛾Orgyia vetusta，一个食叶者与不会飞的成年女性，形成局部爆发较大面积的栖息地。这些暴发可能持续数年（> 10年），几乎没有传播的趋势。2.根据反应扩散模型，种群密度的空间格局可能是由一个移动的捕食者和一个不太移动的猎物之间的相互作用引起的。这是因为捕食者在猎物种群的边缘“溢出”，创造了捕食者与猎物比例升高的区域。3.为了验证这种“捕食者扩散”的假设，我们把它们的卵和幼虫沿着一个500米的样带远离边缘的草丛蛾爆发。通过合适但人烟稀少的栖息地我们测量了攻击率的黄蜂卵寄生蜂和四种寄蝇幼虫到蛹寄生蜂对这些实验未成熟的蛾。4.正如预测的那样，在疫情爆发的周围地区，寄生率升高。对于一些寄生蜂物种，寄生率和距离爆发之间的关系是线性的，对于其他人来说，它是抛物线。5.这些结果与包括捕食者扩散假说在内的几种解释是一致的。无论是何种机制，结果表明，寄生限制了空间分布，因此在这个系统中的主机昆虫的全球丰富度。
1. The western tussock moth Orgyia vetusta, a defoliator with flightless adult females, forms localized outbreaks within larger areas of its habitat. These outbreaks may persist for several (> 10) years with little tendency to spread. 2. According to reaction-diffusion models, spatial patterns in population density may arise from the interaction between a mobile predator and a less-mobile prey. This occurs because predators 'spill over' around the edges of prey populations, creating zones in which ratios of predators to prey are elevated. 3. To test this 'predator diffusion' hypothesis for tussock moths, we placed their eggs and larvae along a 500-m transect leading away from the edge of a tussock moth outbreak. through suitable but sparsely occupied habitat. We measured attack rates by a wasp egg parasitoid and four species of tachinid fly larval-to-pupal parasitoids on these experimental immature moths. 4. As predicted rates of parasitism were elevated in the zone surrounding the outbreak. For some parasitoid species, the relationship between parasitism and distance from the outbreak was linear; for others it was parabolic. 5. These results are compatible with several explanations, including the predator diffusion hypothesis. Whatever the mechanism, the results suggest that parasitism restricts the spatial distribution and therefore the global abundance of the host insect in this system.