柳杉毛虫两种蛹寄生蜂的共寄生格局及其资源共享策略

Dendrolimus houi (Lajonquiere) is currently one of the most dangerous and large-size caterpillars in the forests of Cryptomeria fortunei (Hooibrenk) in south of China, causing a mass of dead forest stands by overrun of these pests, and synthetic application of multiple dominant beneficial insects are thought to be sustainable and effective to suppress these caterpillar populations, but some conventional theories said multiple species of beneficial insects should be synthesized cautiously in the fields because two and more species of natural enemies with niche overlaps can not coexist within limited space at the same trophic level. However, based on our previous investigations, Kriechbaumerella dendrolimi (Sheng et Zhong) and Theronia depressa (Gupta) are the most dominant and promising species for future application with synthetic parasitism of eighteen percent in the forests, especially both species laying their eggs within same pupa of host, sharing host pupa nutrition simultaneously during their larval stages, and emerging mostly two days ahead of moth's emergence, and form a typical and universal coexistence system. Consequently, we assumed that there might be co-adaptation or inferior competition between these two species parasitoids, making coexistence system within host pupa to kill large-size caterpillars efficiently. To prove this assumption for better synthetic effect of multiple parasitoid use in the future, some conventional methods of biology will be performed to analyze sharing patterns of time, space of parasitoids within host pupa, containing observing their ovipositing behavior and preference of female adults, and individually larval development of phenology difference as well. Specific compound isotope analysis method will also be applied to trace allocation trends and assimilation strategy of host nutrition to next trophic level. Finally, wasp-associated factors and activity of antioxidant enzymes responding to interactions between parasitoids and host will be focused and studied to explore their physiological adaption mechanism. All these upcoming findings will be very helpful to form new strategy on how to maximize synthetic effect, by using multiple parasitoid species to suppress large-size pests in the fields, and further explore the specific interaction of multiple species within the multiparasitism system.

柳杉毛虫是中国南方严重危害柳杉等树种的大型食叶害虫之一，综合应用多种自然优势天敌控制该虫，被认为是当前持续有效的控制手段之一；但传统竞争理论认为：生态位重叠的物种无法共存，天敌昆虫的联合应用应该谨慎。我们前期研究发现：松毛虫凸腿小蜂和平背囊爪姬蜂是柳杉毛虫的自然优势天敌，同期寄生于蛹期，幼期共享寄主营养并同期正常羽化，二者生态位重叠却能形成普遍的共寄生体系，据此推测其种间关系可能趋于相互适应或弱性竞争。拟以该共寄生体系为对象，研究其成蜂产卵的行为选择性和幼虫发育物候适应性，解析二者对时间、空间资源的分享格局；并利用现代特定化合物同位素标记法追踪寄主营养随幼虫发育的动态分配，解析营养资源分配格局；最后，研究两种寄生蜂及其寄主互作时寄生因子及酶学应激特征，解析其生理学适应机制。预期结果将为今后联合利用多物种优势天敌控制林间大型害虫提供新策略，并进一步阐明多种天敌共存时的种间关系理论。

松毛虫凸腿小蜂与平背囊爪姬蜂是柳杉毛虫蛹期的优势寄生蜂，能与多种寄生蜂共存于林间，具有重要控害前景。研究明确了二者的生物学特性和个体发育特征，观测了松毛虫凸腿小蜂产卵选择性并解析其在林间不同寄主上的循回机制；探析了温、光等因子对寄生特性与室内繁蜂的影响，构建了松毛虫凸腿小蜂的人工繁育和林间应用技术；进一步调查并筛选多种柳杉毛虫的优势天敌资源，并获得翠凤蝶卵跳小蜂、绿点益蝽及高致病球孢白僵菌BbJL-01菌株等优势天敌，构建翠凤蝶卵跳小蜂的人工饲养体系及林间配套应用技术，为柳杉毛虫-天敌互作及生物防治研究开辟新的思路。.测定了柳杉毛虫对不同寄主的产卵与取食偏好，揭示其与寄主植物内含物、抗氧化酶及消化酶活性的关联性；明确了幼虫在转换寄主条件下会改变生长发育进程，产生不同的差异代谢物并诱导相关基因的上、下调表达，跟脂肪酸生物合成、甘油磷脂类代谢、羧酸及其衍生物代谢途径相关；不同浓度外源MeJA可使柳杉叶中的可溶性蛋白、可溶性糖含量降低，单宁、黄酮和总酚含量增加，降低了4-5龄幼虫的取食量、相对生长率、消化率、转化率和利用率；显著影响体内抗逆相关基因表达，产生甘油磷脂类、羧酸及其衍生物、糖脂类和脂肪酰基等差异代谢物，并受到硫辛酸代谢、mTOR信号通路、产热代谢、脂肪酸生物合成等调控。组装拼接了柳杉毛虫全基因组数据663.13Mb，发现柳杉毛虫与马尾松毛虫在古近纪拥有共同祖先，并有86个基因家族出现扩张，挖掘了柳杉毛虫特有基因家族62个，主要涉及抗坏血酸和盐酸盐的代谢、DNA 复制、赖氨酸降解和磷酸肌醇代谢；鉴定了102个P450基因，62 个COEs基因，25个GST基因。柳杉经虫伤诱导后产生了10412差异表达基因；茉莉酸生物合成、脱落酸反应、防御反应、蛋白激酶活性等生物进程和蛋白酶等相关基因在柳杉应激反应过程中起重要调控作用，涉及苯丙烷途径、类黄酮生物合成、氨基糖和核苷酸糖代谢、植物病原菌互作路径以及赤霉素、乙烯、茉莉酸及水杨酸等植物激素信号转导途径调控。

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