The expansion of available resources leads organisms to adapt to novel niches and create new biological interactions. Galerucella grisescens (Coleoptera: Chrysomelidae) is usually associated with Polygonaceae in Japan but a population feeding on an invasive plant species Myriophyllum aquaticum (Haloragaceae) was found in Chiba Prefecture, Honshu. To infer the process of host range expansion and possible rapid adaptations of G. grisescens to M. aquaticum, we studied larval host plant suitability and female oviposition site preference by G. grisescens in different strains. In laboratory rearing experiments, adult body weight and egg mass size of G. grisescens were smaller on M. aquaticum than on the native host Persicaria lapathifolia (Polygonaceae), suggesting that Polygonaceae are more suitable hosts for G. grisescens than M. aquaticum. On M. aquaticum, the larval survival rate was significantly higher in the Chiba strain collected from M. aquaticum than in the Saga strain originating from Polygonaceae. This raises the possibility that the Chiba strain rapidly adapted to M. aquaticum and improved survival rate on the plant. Oviposition site preference of G. grisescens females was slightly different between individuals reared on Polygonaceae and M. aquaticum. These results suggest that G. grisescens represents early stages of ecological adaptation to the introduced plant and it is a possible biological control agent against M. aquaticum.

中文翻译：

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Poly科相关叶甲虫向入侵水生植物Myriophyllum aquaticum（Haloragaceae）的寄主范围扩展

可用资源的扩展导致生物适应新的生态位并创造新的生物相互作用。在日本，禾本科Galerucella grisescens（Coleoptera：Chrysomelidae）通常与Poly科有关，但是在本州千叶县发现了以入侵植物物种Myriophyllum aquaticum（Haloragaceae）为食的种群。为了推断宿主范围的扩展以及格氏假单胞菌对水生格氏菌的快速适应性，我们研究了格氏假丝酵母在不同菌株中的幼虫宿主植物适应性和雌性产卵位点偏好。在实验室饲养的实验中，成年体重和卵块大小G. grisescens均较小M.缕比在天然宿主酸模叶蓼（蓼），这表明蓼更合适的宿主为G. grisescens比M.缕。在水生分枝杆菌上，从水生分枝杆菌收集的千叶菌株的幼虫存活率显着高于起源于Poly科的佐贺菌株。这增加了千叶菌株迅速适应水产莫拉氏菌并提高了植物存活率的可能性。在Poly科和水生分枝杆菌上繁殖的禾本科雌性的产卵位点偏好略有不同。这些结果表明格氏草（G. grisescens）代表了对引进植物的生态适应的早期阶段，它是一种可能的防治水生格氏菌的生物制剂。