宁夏枸杞两种瘿蚊致瘿差异及其机制研究

Wolfberry red gall midge (WRGM) is the most serious pest of Lycium barbarum because of their causing of flower bud galls, known as “Cancer of the wolfberry”. Wolfberry white gall midge (WWGM) is a newly founded flower gall midge, the feeding site of these two midges were the same, while the caused gall structure were significant difference. Plant galls represent a unique and complex interspecific interaction and mutual adaptation between the plant and the gall-inducing insect. However, the different gall midges stimulate on the same site but formed different galls is very rarely. We deduced that the slight discrepancy stimulation of WRGM and WWGM was amplified by their host plant during the gall formation, and thus caused the different galls. In this project, the WRGM, WWGM and wolfberry are used as research materials, focus on the development progress of these two galls, through morphology, nutrition, physiology, molecular biology researches to reveal the formation progress, distinction and mechanism of these two different galls. Our research also contribute to reveal the coevolution relationship among plant and gall insects, and explore the association between gall midge and wolfberry, and finally provide a theoretical basis for integrated pest management and resistance breeding of L. barbarum.

枸杞红瘿蚊直接为害枸杞花蕾形成虫瘿，因防治难度大而号称“枸杞癌症”，枸杞白瘿蚊是申请人新发现的另一种花蕾致瘿害虫，两种瘿蚊取食部位一致但虫瘿结构有显著差异。虫瘿是植物与昆虫协同进化的高级产物，具有高度专一性，不同瘿蚊为害同一部位但虫瘿结构不同的现象非常罕见，推测枸杞红瘿蚊、枸杞白瘿蚊致瘿刺激的微小差异在成瘿过程中不断被植物放大，而形成不同虫瘿结构。本课题以枸杞红瘿蚊、枸杞白瘿蚊和宁夏枸杞为研究对象，围绕两种瘿蚊虫瘿的生长发育及其变化过程，从形态学、生理学、分子生物学等方面开展研究，深入剖析两种瘿蚊致瘿过程、致瘿差异及其致瘿机制，为更好的了解植物与致瘿昆虫的协同进化关系，揭示两种瘿蚊与宁夏枸杞之间互作关系，为科学防治及枸杞抗瘿蚊育种提供理论基础。

枸杞红瘿蚊Gephyraulus lycantha Jiao & Kolesik是宁夏枸杞上重要的成灾害虫，一直以来被公认为是形成枸杞花蕾虫瘿的唯一害虫，本研究发现并证实了枸杞白瘿蚊Contarinia sp.是继枸杞红瘿蚊后为害宁夏枸杞花蕾的另一种瘿蚊科害虫，两种瘿蚊均以幼虫为害枸杞幼嫩花蕾并致其成瘿，对枸杞生产影响严重。枸杞白瘿蚊和枸杞红瘿蚊在幼虫、蛹和成虫形态上均有明显差异，可通过这些差异特征对两种瘿蚊进行有效区分；同时，两种瘿蚊所致虫瘿外观形态及解剖结构上也差异显著，枸杞红瘿蚊所致虫瘿主要表现为子房膨大，而枸白瘿蚊所致虫瘿主要表现为花冠膨大，在田间也可通过该特征对虫瘿进行区分，该结果对两种瘿蚊的鉴定、预测预报及科学防控均有重要意义。枸杞白瘿蚊和枸杞红瘿蚊主要通过影响枸杞花蕾不同部位的植物激素浓度而形成结构不同的虫瘿，枸杞红瘿蚊通过诱导子房部位细胞分裂素浓度升高而使得子房细胞数量增多引起子房膨大成瘿，枸杞白瘿蚊主要通过诱导花冠生长素浓度升高而使得花冠细胞体积增大引起花冠膨大成瘿，但子房部位过高浓度的生长素反而抑制了白瘿蚊虫瘿子房的生长。虫瘿是植物和昆虫协同进化的高级产物，两种瘿蚊为害同种植物同一部位而虫瘿结构差异显著的情况少见，是研究植物与昆虫互作关系的理想材料。本研究揭示了植物激素种类及浓度的差异是导致枸杞红瘿蚊和枸杞白瘿蚊所致虫瘿部位细胞数量及大小差异的主要因素，从而引起虫瘿外观形态的差异，可为揭示致瘿昆虫的致瘿机制及其与植物间协同进化关系提供支撑。