Bogdziewicz Michał, Bonal Raul, Espelta Josep M, Kalemba Ewa M, Steele Michael A, Zwolak Rafał
Department of Systematic Zoology, Faculty of Biology, Adam Mickiewicz University, Poznań, Poland.
CREAF, Cerdanyola del Valles, Catalonia, Spain.
Integr Zool. 2018 May;13(3):228-237. doi: 10.1111/1749-4877.12285.
Species introduced to habitats outside their native range often escape control by their natural enemies. Besides competing with native species, an alien species might also affect the native herbivores by introducing a new source of different quality food. Here, we describe the case of northern red oak (Quercus rubra) invasion in Europe. We collected data on insect (moth Cydia spp. and weevil Curculio spp.) seed predation of northern red oak in its native (USA, North America) and invasive (Poland, Europe) range, as well as for sessile oaks (Quercus petrea) in Europe. We also evaluated the quality of acorns as hosts for weevil larvae by collecting infested acorns and measuring weevil developmental success, and quantifying acorn traits such as seed mass, tannins, lipids and protein concentration. We used DNA barcoding to identify insects to the species level. The predation by moths was similar and very low in both species and in both ranges. However, red oaks escape pre-dispersal seed predation by weevils in Europe. Weevil infestation rates of northern red oak acorns in their invasive range were 10 times lower than that of sessile oaks, and also 10 times lower than that of red oaks in North America. Furthermore, even when weevils oviposited into northern red oaks, the larvae failed to develop, suggesting that the exotic host created a trap for the insect. This phenomenon might gradually decrease the local abundance of the seed predator, and further aid the invasion.
引入到其原生范围以外栖息地的物种往往会摆脱其天敌的控制。除了与本地物种竞争外，外来物种还可能通过引入一种质量不同的新食物来源来影响本地食草动物。在此，我们描述了北美红栎（Quercus rubra）在欧洲入侵的案例。我们收集了北美红栎在其原生范围（美国，北美洲）和入侵范围（波兰，欧洲）以及欧洲无梗花栎（Quercus petrea）上昆虫（蛾类小卷蛾属和象鼻虫属）种子捕食的数据。我们还通过收集被侵染的橡子、测量象鼻虫的发育成功率以及量化橡子的特征，如种子质量、单宁、脂质和蛋白质浓度，来评估橡子作为象鼻虫幼虫宿主的质量。我们使用DNA条形码技术将昆虫鉴定到物种水平。蛾类的捕食在两个物种和两个范围内都相似且非常低。然而，北美红栎在欧洲逃脱了象鼻虫在种子传播前的捕食。北美红栎在其入侵范围内的橡子被象鼻虫侵染的比率比无梗花栎低10倍，也比北美红栎在北美洲的比率低10倍。此外，即使象鼻虫在北美红栎上产卵，幼虫也无法发育，这表明外来宿主为昆虫设下了陷阱。这种现象可能会逐渐降低种子捕食者的局部丰度，并进一步助力入侵。
