Eisenbach Jamin
Department of Biology, Eastern Michigan University, 48197, Ypsilanti, MI, USA.
Oecologia. 1996 Jan;105(2):258-265. doi: 10.1007/BF00328555.
Plant-herbivore and herbivore-parasitoid wasp interactions were examined in three hybrid zones of the cattails Typha latifolia and T. angustifolia in south-eastern Michigan over a 2-year period. Patterns of resource use by two lepidopteran species of seed-eating herbivores were studied and herbivore densities sustained by the hybrid cattail T. x glauca and its parental species were determined. Densities of the commoner seed-eating lepidopteran, Lymnaecia phragmitella, were found to be highest in seed heads of both parental species and lowest in hybrid seed heads in zones of hybridization, thus supporting the hybrid resistance hypothesis of Fritz et al. (1994). Densities of the second herbivore, Dicymolomia julianalis, on the hybrid were lower than on the parental T. latifolia, but did not differ from the mean of the combined herbivore densities of the two parental species. D. julianalis in cattails appears to fit the additive hypothesis (Fritz et al. 1994). Parasitism of L. phragmitella by four species of parasitoid wasp, Itoplectis conquisitor (Ichneumonidae), Scambus hispae (Ichneumonidae), Macrocentrus delicatus (Braconidae), and Temelucha gracilipes (Ichneumonidae), was studied to determine if rates of parasitization by these natural enemics on the different cattails were similar to the patterns of plant exploitation exhibited by their hosts. Parasitism rates of L. phragmitella were significantly higher in larvae reared on hybrid cattails. This study reveals two different patterns of hybrid utilization by two very similar herbivores. Opposite patterns of plant utilization were found for the parasitoids compared with their host (L. phragmitella) in cattail hybrid zones.
在两年时间里，对密歇根州东南部香蒲属的宽叶香蒲和狭叶香蒲的三个杂交区域内的植物 - 食草动物以及食草动物 - 寄生蜂之间的相互作用进行了研究。研究了两种以种子为食的鳞翅目食草动物的资源利用模式，并确定了杂交香蒲（T. x glauca）及其亲本物种所维持的食草动物密度。在杂交区域，发现较常见的以种子为食的鳞翅目昆虫芦苇夜蛾（Lymnaecia phragmitella）在两个亲本物种的种子头中密度最高，而在杂交种子头中密度最低，这支持了弗里茨等人（1994年）的杂交抗性假说。第二种食草动物朱利安双斑螟（Dicymolomia julianalis）在杂交种上的密度低于亲本宽叶香蒲，但与两个亲本物种食草动物密度的平均值没有差异。朱利安双斑螟在香蒲中的情况似乎符合相加假说（弗里茨等人，1994年）。研究了四种寄生蜂，即征服伊托普列克茧蜂（Itoplectis conquisitor，姬蜂科）、西班牙斯坎布斯茧蜂（Scambus hispae，姬蜂科）、精致大角啮小蜂（Macrocentrus delicatus，茧蜂科）和细柄细腹茧蜂（Temelucha gracilipes，姬蜂科）对芦苇夜蛾的寄生情况，以确定这些天敌在不同香蒲上的寄生率是否与其寄主所表现出的植物利用模式相似。在杂交香蒲上饲养的幼虫中，芦苇夜蛾的寄生率显著更高。这项研究揭示了两种非常相似的食草动物对杂交种利用的两种不同模式。在香蒲杂交区域，与它们的寄主（芦苇夜蛾）相比，寄生蜂的植物利用模式相反。
