Host plant, host plant chemistry and the polyembryonic parasitoid Copidosoma sosares : indirect effects in a tritrophic interaction
Host plant, host plant chemistry and the polyembryonic parasitoid Copidosoma sosares : indirect effects in a tritrophic interaction
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DOI：
10.1111/j.0030-1299.2004.12323.x
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发表时间：
2004-02
期刊：
影响因子：
3.4
通讯作者：
P. Ode;M. Berenbaum;A. Zangerl;I. Hardy
中科院分区：
文献类型：
--
作者：
P. Ode;M. Berenbaum;A. Zangerl;I. Hardy
寄主植物身份和寄主植物化学通常被证明会影响天敌对寄主的发现和接受，但相对较少的关注寄主植物和寄主植物化学对其他天敌适应度相关性的三营养效应，例如存活率、窝大小、体型和性别比。此类研究对于了解植物对天敌的选择性影响以及天敌对植物性状相互选择性影响的潜力至关重要。我们研究了由三种伞形植物（Pastinaca sativa、Heracleum sphondylium 和 H. mantegazzianum）、防风网虫（Depressaria Pastinacella）和多胚寄生蜂 Copidosoma sosares 组成的三营养系统中寄主植物和寄主植物化学的影响。所有这些植物都会产生呋喃香豆素，这是防风草网虫的已知抗性因子。呋喃香豆素浓度与给定植物上的网虫的存在和数量均不相关。两种呋喃香豆素的浓度与 C. sosares 的适应度呈负相关：异罂粟碱与特定网虫被寄生的可能性相关，黄毒素与巢内存活率（全雄性和混合性别巢）和窝数相关。幼蜂性别比和个体黄蜂的体型与呋喃香豆素化学无关。由于呋喃香豆素化学特性在水稻中存在加性遗传变异，因此这些特性会受到网虫通过草食性的选择。第三营养级对呋喃香豆素性状的选择性影响可能包括选择减少那些影响寄生蜂存活但不影响食草动物对寄主植物选择的化学物质的产量。具有不同侵染历史的苜蓿种群中呋喃香豆素的生产模式表明情况可能就是如此。在荷兰，C. sosares 的网虫寄生率很高，与美国中西部的 P. sativa 种群相比，植物产生的所有线性呋喃香豆素水平较低，并且相应地较少异罂粟内素，而美国中西部的 P. sativa 种群实际上不存在网虫的天敌。
Host plant identity and host plant chemistry have often been shown to influence host finding and acceptance by natural enemies but comparatively less attention has been paid to the tritrophic effects of host plant and host plant chemistry on other natural enemy fitness correlates, such as survivorship, clutch size, body size, and sex ratio. Such studies are central to understanding both the selective impact of plants on natural enemies as well as the potential for reciprocal selective impact of natural enemies on plant traits. We examined the effects of host plant and host plant chemistry in a tritrophic system consisting of three apiaceous plants (Pastinaca sativa, Heracleum sphondylium and H. mantegazzianum), the parsnip webworm (Depressaria pastinacella) and the polyembryonic parasitic wasp Copidosoma sosares. All of these plants produce furanocoumarins, known resistance factors for parsnip webworms. Furanocoumarin concentrations were correlated neither with the presence nor the number of webworms on a given plant. Concentrations of two furanocoumarins were negatively associated with C. sosares fitness correlates: isopimpinellin with the likelihood that a given webworm would be parasitized and xanthotoxin with both within-brood survivorship (of all-male and mixed-sex broods) and clutch size. Brood sex ratio and body sizes of individual wasps were not correlated with furanocoumarin chemistry. Because additive genetic variation exists in P. sativa for furanocoumarin chemical traits, these are subject to selection by webworms through herbivory. Third trophic level selective impacts on furanocoumarin traits may include selection for reduced production of those chemicals that affect parasitoid survivorship yet do not influence host plant choice by the herbivore. That such might be the case is suggested by patterns of furanocoumarin production in populations of P. sativa with different histories of infestation; in the Netherlands, where parasitism rates of webworms by C. sosares are high, plants produce lower levels of all linear furanocoumarins and proportionately less isopimpinellin than do midwestern U.S. populations of P. sativa, where natural enemies of the webworm are effectively absent.