Convergent adaptation of ootheca formation as a reproductive strategy in Polyneoptera
Erxia Du, Shuai Wang, Yun-Xia Luan, Caisheng Zhou, Zhaoxin Li, Na Li, Shutang Zhou, Tingting Zhang, Wentao Ma, Yingying Cui, Dongwei Yuan, Chonghua Ren, Jianzhen Zhang, Siegfried Roth, Sheng Li
2月22日，国际著名期刊《分子生物学与进化》在线发表了华南师范大学生命科学学院、昆虫科学与技术研究所李胜教授团队最新研究成果——复新翅亚部卵鞘趋同进化的适应性生殖策略。
热带和亚热带地区包括草地贪夜蛾和小菜蛾等重大害虫在内的绝大多数昆虫均产单个卵而不产包裹多个卵的卵鞘，而复新翅亚部的蟑螂、螳螂和蝗虫等少数昆虫产生卵鞘以包裹多个卵。卵鞘产生的环境驱动因素、选择压力、分子机制和生物学意义是什么？卵鞘在进化上隐藏着哪些奥秘，具体进化规律是什么？这些重要的科学问题常年来一直困扰着昆虫学家和进化生物学家。
研究人员采用多组学技术、功能验证和化石证据揭示了复新翅亚部两个产卵鞘的主要类群——网翅总目（蟑螂+螳螂）和蝗虫卵鞘的蛋白和化学成分、形成机制、生理功能以及趋同演化机理。
李胜对《中国科学报》表示，该研究取得了两个相辅相成的原创性和突破性成果：一是从分子层面上阐释了美洲大蠊雌性粘液腺产生多种卵鞘蛋白和小分子化合物，在产卵过程中包裹~16粒卵，经黑化和硬化后形成致密有弹性的卵鞘，以减少卵的水分丢失而保护胚胎发育，从而适应高温高湿的恶劣环境，进一步诠释了“蟑螂为小强”的分子奥秘；二是从发育-进化生物学（evo-devo）角度揭示了在白垩纪晚期-侏罗纪早期，网翅总目和蝗虫为了适应高温高湿环境而独立形成卵鞘而发生趋同演化，揭示了复新翅亚部中卵鞘趋同进化的这一重要适应性生殖策略，深入认识了现生蟑螂、螳螂和蝗虫适应热带和亚热带的分子机制和进化规律。
该研究还为害虫生物防治提供了特异性的分子靶标，有利于研发安全绿色的蟑螂等重大害虫的防控方法和策略，具有非常重要的社会、生态、经济和科学意义。
来源：中国科学报 朱汉斌
Abstract
Insects have evolved numerous adaptations and colonized diverse terrestrial environments. Several polyneopterans, including dictyopterans (cockroaches and mantids) and locusts, have developed oothecae, but little is known about the molecular mechanism, physiological function, and evolutionary significance of ootheca formation. Here, we demonstrate that the cockroach asymmetric colleterial glands produce vitellogenins, proline-rich protein, and glycine-rich protein as major ootheca structural proteins (OSPs) that undergo sclerotization and melanization for ootheca formation through the cooperative protocatechuic acid pathway and dopachrome and dopaminechrome subpathway. Functionally, OSP sclerotization and melanization prevent eggs from losing water at warm and dry conditions, and thus effectively maintain embryo viability. Dictyopterans and locusts convergently evolved vitellogenins, apolipoprotein D, and laminins as OSPs, while within Dictyoptera, cockroaches and mantids independently developed glycine-rich protein and fibroins as OSPs. Highlighting the ecological-evolutionary importance, convergent ootheca formation represents a successful reproductive strategy in Polyneoptera that promoted the radiation and establishment of cockroaches, mantids, and locusts.
