László Z, Tóthmérész B
Hungarian Department of Biology and Ecology, Babeş-Bolyai University, Str. Clinicilor Nr. 5-7, 400006 Cluj-Napoca, Romania.
Bull Entomol Res. 2013 Jun;103(3):326-35. doi: 10.1017/S0007485312000764. Epub 2012 Dec 7.
We tested the enemy hypothesis for gall morphology on a model system comprising two Diplolepis rose gall wasp species and their associated parasitoids. The enemy hypothesis predicts both that gall traits will influence parasitoid attack rates within species, and that galls with contrasting morphologies will support different parasitoid communities. This hypothesis is supported by studies at both intraspecific and broader taxonomic levels (i.e. between genera), but patterns remain to be explored in closely related species. Our aims were to explore the relationships between aspects of gall morphology (number of larval chambers, overall gall size and thickness of the gall wall) in each of Diplolepis mayri and D. rosae, and to explore correlations between these traits and both the presence/absence (=incidence) and attack rates imposed by parasitoids. We found in both galls that chamber number is positively correlated with gall size. In galls of D. mayri, parasitoid incidence was negatively correlated with thickness of the wall of the larval chamber, but there was no significant correlation between parasitoid attack rates and overall gall size. In D. rosae galls, parasitoid incidence was positively correlated with chamber wall thickness, but parasitoid attack rates were negatively correlated with gall size, suggesting that selection may favour the induction of galls containing more larval chambers. These results confirm that gall extended phenotypes can significantly influence enemy attack rates, consistent with the 'enemy hypothesis'. Further, differences in gall morphology between the two Diplolepis species may underlie differences in their associated parasitoid communities--further research is required to test this hypothesis.
我们在一个由两种蔷薇双距瘿蜂及其相关寄生蜂组成的模型系统上，对瘿形态的“天敌假说”进行了测试。“天敌假说”预测，瘿的特征既会影响物种内寄生蜂的攻击率，形态迥异的瘿会支持不同的寄生蜂群落。这一假说在种内和更广泛的分类水平（即属间）的研究中均得到了支持，但在近缘物种中的模式仍有待探索。我们的目的是探究马里蔷薇双距瘿蜂和蔷薇蔷薇双距瘿蜂各自的瘿形态特征（幼虫室数量、瘿的总体大小和瘿壁厚度）之间的关系，并探究这些特征与寄生蜂的存在/缺失（=发生率）和攻击率之间的相关性。我们发现，在两种瘿中，室数量与瘿大小呈正相关。在马里蔷薇双距瘿蜂的瘿中，寄生蜂的发生率与幼虫室壁的厚度呈负相关，但寄生蜂的攻击率与瘿的总体大小之间没有显著相关性。在蔷薇蔷薇双距瘿蜂的瘿中，寄生蜂的发生率与室壁厚度呈正相关，但寄生蜂的攻击率与瘿大小呈负相关，这表明选择可能有利于诱导产生包含更多幼虫室的瘿。这些结果证实，瘿的扩展表型可显著影响天敌的攻击率，这与“天敌假说”一致。此外，两种蔷薇双距瘿蜂的瘿形态差异可能是其相关寄生蜂群落差异的基础——需要进一步研究来验证这一假说。
