Aggregation in Aphis Varians: An Effective Strategy for Reducing Predation Risk
Aggregation in Aphis Varians: An Effective Strategy for Reducing Predation Risk
复制标题
变异蚜虫的聚集：降低捕食风险的有效策略
DOI：
10.2307/1941369
复制
发表时间：
1989
期刊：
影响因子：
4.8
通讯作者：
P. Kareiva
中科院分区：
文献类型：
--
作者：
P. Turchin;P. Kareiva
有人认为，通过聚集在一起，即使是毫无防御能力的猎物也可能减少被捕食者吃掉的机会。然而，聚集的优势，猎物可能会被否定的捕食者的猎物集群的强烈聚集反应。我们研究了平衡的力量，确定集群的优势或劣势的猎物在一个特定的情况下：蚜虫的变化（同翅目：蚜虫科）和它的捕食者Hippodamia convergens（鞘翅目：瓢虫科）之间的相互作用。蚜虫的运动是聚集性的，即，蚜虫倾向于呆在同类的集群中。此外，通过量化不同大小的蚜虫群体的人均人口增长率，我们发现单个蚜虫通过聚集在一起而受益。然而，捕食者排除实验表明，集群是有益的蚜虫只有在捕食者的存在。为了从机理上理解蚜虫聚集降低个体捕食风险的原因，我们研究了捕食者对蚜虫密度的行为反应。捕食者表现出强烈的聚集反应：大的蚜虫殖民地被更多的捕食者比小殖民地。此外，瓢虫的取食率随着群体大小的增加而增加。然而，捕食者从群体中捕获的猎物总数却赶不上蚜虫群体规模的增加，因此捕食个体猎物的风险被猎物数量“稀释”。
It has been suggested that by clumping together, even defenseless prey may reduce their chances of being consumed by a predator. However, the advantage of clumping to prey may be negated by a strong aggregative response of predators to prey clusters. We studied the balance of forces that determine the advantage or disadvantage of clumping to prey in one particular case: the interaction between the aphid Aphis varians (Homoptera: Aphididae) and its predator Hippodamia convergens (Coleoptera:Coccinellidae). Aphid movement was congregative, i.e., aphids tended to stay within clumps of conspecifics. Furthermore, by quantifying the per capita population growth rates for aphid colonies of differing sizes, we found that individual aphids benefited by being clumped together. However, a predator—exclusion experiment indicated that clumping was beneficial to aphids only in the presence of predators. To gain a mechanistic understanding of why aphid congregation reduced predation risk to individuals, we examined the behavioral response of predators to aphid density. Predators exhibited a strong aggregating response: large colonies of aphids were attacked by more predators than were small colonies. In addition, ladybird feeding rate increased with increasing colony size. The total number of prey taken from colonies by predators, however, could not keep pace with the increase in aphid colony size, and thus the risk of predation to individual prey was "diluted" by prey numbers.