类社会性寄生蜂自组织聚集的行为机制研究

Aggregation is widespread in insects and can appear in response to environmental heterogeneities or by attraction between individuals in a homogeneous environment. Currently, studies on insect aggregation have almost focused on the phytophagous and eusocial insects. Much less attention has been paid to the parasitic wasps, especially for some quasisocial counterparts. The quasisocial parasitic wasp, Sclerodermus pupariae, can aggregate as different sizes of groups in a homogeneous environment. According to their aggregation could be formed without any exogenous stimulations, we, therefore, regard it as a type of self-organized aggregation. Nonetheless, we are completely in the dark about the forming conditions, processes, and ecological significances of this typical behavior. Here, we propose to explore the formation and evolution of the self-organized aggregation of this quasisocial parasitoid. Firstly, we plan to investigate the influence of parasitoid sex, density, and age on the dynamic procedures of the aggregation base on the behavioral recording. Once the conditions and processes of the formation of aggregation are confirmed, we then analyze the chemical components in the groups of parasitoid successful aggregate vs. refused aggregate, and aggregate forming vs. aggregate dispelling by gas chromatography-mass spectrometer. At the third step, we plan to use two-choice trap test to confirm whether the chemicals derive from the parasitoids are related to their self-organization. Finally, we investigate the behavioral variations of Orco knock down parasitoids for reconfirming whether the self-organized aggregation of this quasisocial parasitoid is mediated by its olfactory pathway. The findings of this project would be helpful to provide valid evidences for clarifying the behavioral mechanisms of self-organized aggregation in this bethylid wasp, and could also promote us to further understanding the adaptive evolutions and ecological benefits of the self-organized aggregation in quasisocial insects.

聚集是昆虫最常见的行为之一，其形成可因环境异质性引起，也可在均质环境中由个体间的吸引而产生。昆虫聚集相关研究多为植食性和真社会性昆虫，对寄生蜂关注很少，特别是对一些具有类社会性的寄生蜂鲜有研究。白蜡吉丁肿腿蜂是一种类社会性寄生蜂，申请者发现其在均质环境中可形成大小不一的聚集态，具有自组织性；但对此聚集的形成条件、过程和意义并不了解。本项目拟以白蜡吉丁肿腿蜂为研究对象，从性别、密度和日龄变量入手，通过行为记录来确定肿腿蜂自组织聚集的形成条件和动态过程。同时分析肿腿蜂在可形成与不可形成聚集条件下和聚集动态过程中所释放的化学信息且结合行为生测，以此来明确信息素是否参与了聚集调控。最后，测定敲降嗅觉通路必备元件–气味受体共表达受体Orco后，肿腿蜂聚集行为是否改变来确认嗅觉是否为聚集调控的主要途径。该研究对阐明肿腿蜂自组织聚集的行为机制和了解类社会性昆虫自组织聚集的适应性进化和生态功能有重要意义。

聚集是昆虫最常见的行为之一，其形成可因环境异质性引起，也可在均质环境中由个体间的吸引而产生。肿腿蜂是一种类社会性寄生蜂，其在均质环境中可形成大小不一的聚集态，具有自组织性；但对此聚集的形成条件、过程和意义并不了解。本项目基于肿腿蜂自组织聚集形成的过程无外源信息参与，完全由虫体自身所介导这一核心。设计了从性别、密度和日龄变量，解析了在不同条件下，肿腿蜂自组织聚集的形成条件和动态。测定了肿腿蜂虫体所携带的化学物质对其聚集行为的作用，明确了聚集信息素的主要来源。最后测定了肿腿蜂嗅觉对聚集行为的调控，并解析了肿腿蜂化学感受器结构和化学感受相关基因的特征。本项目取得的主要结论如下：.（1）肿腿蜂的自组织聚集行为与性别密切相关。当仅有雄蜂时，不会形成聚集态。当群体内存在雌蜂时，聚集态才会形成，即雌蜂是聚集形成的必要条件。.（2）肿腿蜂的自组织聚集行为与群体密度密切相关，密度越大越利于聚集的形成，聚集态持续的时间也越长。当聚集形成后，聚集体会主动地消散；但人为引入寄主信息并不会促进其聚集态的消散。.（3）肿腿蜂产生聚集行为的信息物质来源于雌蜂体表所携带的化学物质，这些物质主要是一些烷烃，即雌蜂表皮碳氢化合物。肿腿蜂的嗅觉是聚集行为主要的调控途径。肿腿蜂气味受体特异性扩张的进化分枝，可能是识别这些重要化学物质的主要分子基础；而雌雄蜂触角感受器的种类的性二型特征，则可能是介导雌雄蜂聚集行为差异的关键原因。.以上结果丰富了我们对类社会性寄生蜂自组织聚集行为过程的了解，为研究肿腿蜂聚集行为的分子和神经基础奠定了基础。

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