Asymmetric larval interactions between introduced and indigenous ladybirds in North America
Asymmetric larval interactions between introduced and indigenous ladybirds in North America
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DOI：
10.1007/s00442-004-1680-6
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发表时间：
2004-12-01
期刊：
影响因子：
2.7
通讯作者：
Takizawa, T
中科院分区：
文献类型：
--
作者：
Yasuda, H;Evans, EW;Takizawa, T
了解导致引进物种成功的机制将有助于预测未来的入侵和管理入侵系统。我们研究了最近引进到北美的两种掠食性瓢虫，七星瓢虫（CS）和绿瓢虫（HA），以及两种本土瓢虫，横纹瓢虫（CT）和会聚瓢虫（HC）之间的相互作用。通过对不同蚜虫可得性条件下的幼龄和老龄幼虫进行配对，研究了不同蚜虫种群间捕食不对称程度、竞争效应对幼虫生长发育的影响以及攻击和逃避行为的性质。相互作用通常是不对称的，引进物种的幼虫最常作为野生动物的捕食者，而本地物种的幼虫最常作为野生动物的猎物（然而，两种球菌属的相互捕食率相似）。由于它们的攻击性特别强，而其他幼虫逃避攻击的成功率最低，因此HA的幼虫对两种本地物种的幼虫的负面影响比CS的幼虫更强。当蚜虫可用性较低时，这种负面影响表现得最为强烈，对两种本地物种中较小的HC尤其不利。总体而言，年龄较大的幼虫之间的相互作用比年幼的幼虫之间的相互作用更强烈，并且年龄较大的幼虫对年幼的幼虫的相互作用尤其强烈。我们的研究结果表明，HA比CS更可能对本土瓢虫作为一种野生捕食者构成威胁，而IGP在促进HA成功入侵北美方面的作用可能比七星瓢虫强。
Understanding the mechanisms that result in the success of introduced species will contribute to predicting future invasions and managing invaded systems. We examined interactions between larvae of two predatory ladybird species recently introduced to North America, Coccinella septempunctata (CS) and Harmonia axyridis (HA), and two indigenous ladybirds, Coccinella transversoguttata (CT) and Hippodamia convergens (HC). By pairing young and old larvae in the laboratory at low and high levels of aphid availability, we assessed the degree of asymmetry in intraguild predation (IGP), the strength of competitive effects on growth and development of larvae escaping predation, and the nature of attack and escape behavior among the species. Interactions were generally asymmetric, with larvae of introduced species acting most frequently as intraguild predators and larvae of indigenous species serving most frequently as intraguild prey ( the two Coccinella spp., however, preyed on each other at similar rates). Because they were especially aggressive and because other larvae were least successful in escaping their attacks, larvae of HA had stronger negative effects on larvae of the two indigenous species than did larvae of CS. Such negative effects, expressed most strongly when aphid availability was low, were especially adverse for the smaller of the two indigenous species, HC. In general, older larvae interacted with each other more strongly than young larvae did, and older larvae had especially strong negative effects on young larvae when interactions occurred between age classes. Our results suggest that HA more than CS may represent a threat to indigenous ladybirds as an intraguild predator, and that IGP in turn may play a stronger role for HA than for C. septempunctata in promoting the successful invasion of North America.