The interplay between density- and trait-mediated effects in predator-prey interactions: a case study in aphid wing polymorphism
The interplay between density- and trait-mediated effects in predator-prey interactions: a case study in aphid wing polymorphism
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DOI：
10.1007/s00442-003-1185-8
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发表时间：
2003-04-01
期刊：
影响因子：
2.7
通讯作者：
Weisser, WW
中科院分区：
文献类型：
--
作者：
Kunert, G;Weisser, WW
天敌不仅影响猎物密度，而且还可以改变猎物的性状。虽然这种非致命的影响可能是非常重要的动态和结构的猎物种群，很少有人知道他们的相互作用与密度介导的影响天敌。研究了两种蚜虫-捕食者相互作用中捕食率、猎物密度与性状变异之间的关系。豌豆蚜（Acyrthosiphon pisum，Harris）已被证明产生翅传播变形的存在瓢虫或寄生性天敌的反应。这种性状的改变影响了蚜虫的扩散和殖民新栖息地的能力，因此对猎物的种群动态有影响。在两个实验中，我们研究了翅诱导豌豆蚜虫作为捕食率的函数时，食蚜蝇幼虫（Episyrphus balteatus）和草蛉幼虫（Chrysoperla carnea）被允许在豌豆蚜虫殖民地觅食。与对照处理相比，悬翅蝇和草蛉幼虫引起后代中翅型的百分比显著增加，强调在天敌存在下的翅诱导是豌豆蚜虫的一般反应。有翅后代的百分比，但是，依赖于捕食率，捕食对蚜虫翅诱导在很高和很低的捕食率的影响很小，和强烈的反应，蚜虫在中等捕食率。蚜虫翅诱导的捕食率和由此产生的猎物密度之间的相互作用的影响。我们的研究结果表明，密度介导和性状介导的影响，天敌是密切相关的，并共同决定了捕食种群动态的天敌。
Natural enemies not only influence prey density but they can also cause the modification of traits in their victims. While such non-lethal effects can be very important for the dynamic and structure of prey populations, little is known about their interaction with the density-mediated effects of natural enemies. We investigated the relationship between predation rate, prey density and trait modification in two aphid-aphid predator interactions. Pea aphids (Acyrthosiphon pisum, Harris) have been shown to produce winged dispersal morphs in response to the presence of ladybirds or parasitoid natural enemies. This trait modification influences the ability of aphids to disperse and to colonise new habitats, and hence has a bearing on the population dynamics of the prey. In two experiments we examined wing induction in pea aphids as a function of the rate of predation when hoverfly larvae (Episyrphus balteatus) and lacewing larvae (Chrysoperla carnea) were allowed to forage in pea aphid colonies. Both hoverfly and lacewing larvae caused a significant increase in the percentage of winged morphs among offspring compared to control treatments, emphasising that wing induction in the presence of natural enemies is a general response in pea aphids. The percentage of winged offspring was, however, dependent on the rate of predation, with a small effect of predation on aphid wing induction at very high and very low predation rates, and a strong response of aphids at medium predation rates. Aphid wing induction was influenced by the interplay between predation rate and the resultant prey density. Our results suggests that density-mediated and trait-mediated effects of natural enemies are closely connected to each other and jointly determine the effect of natural enemies on prey population dynamics.