长颚斗蟋飞行行为多型成虫飞行与繁殖的生理权衡及其调控机理

In view of the importance of dispersal polymorphism in evolutionary developmental biology and agricultural science research, the evolutionary significance and physiological control mechanism of this phenomenon have become hotspots in basic biology research. Dispersal polymorphism includes three types: flight behavior polymorphism, flight muscle polymorphism, and wing polymorphism. There are a great number of reports on wing polymorphism of insects, but very few studies on flight bebavior polymorphism, especially the flight behavior polymorphism in wing polymorphic insects. The cricket species Velarifictorus aspersus Walker displays distinct wing dimorphism - individuals are either micropterous with much degenerate wings or macropterous with fully developed wings. Our preliminary experiments showed that macropterous adults also exhibited different flight behavior, and the fighting strategy varied between macropterous and micropterous males when competing for different resources. In this project, we plan to investigate the morphological and physiological characteristics of mobile and sedentary macropterous V. aspersus so as to elucidate the evolutionary significance of flight behavior polymorphism. To explore the underlying mechanism of juvenile hormone (JH) control of flight and reproduction, diurnal variation of haemolymph JH titer in mobile and sedentary macropterous females and micropterous females will be analyzed by using a liquid chromatography-mass spectrometry method, and effect of exogenous JH on the synthesis of flight fuels and reproductive development in mobile and sedentary macropterous females will be examined. In order to identify the key genes involved in flight and reproductive development, we will perform de novo transcriptome assembly and gene expression analysis using short-read sequencing technology combined with a tag-based digital gene expression system to compare gene expression profiles from flight muscles, fat body, and ovary in the mobile and sedentary macropterous females and micropterous females at different stage of adulthood. This research will provide new insights for understanding the evolution of dispersal polymorphism and maintaining mechanism of intraspecific polymorphism, and it will also be instructive for management of pests presenting dispersal dimorphism.

鉴于昆虫扩散多型在进化发育生物学和农业科学研究中的重要性，昆虫扩散多型的适应意义和调控机理一直是基础生物学研究的热点。昆虫扩散多型包括三种类型：飞行行为多型、飞行肌多型和翅多型。其中，飞行行为多型，尤其是翅多型昆虫的飞行行为多型现象的研究极少。本项目拟以长颚斗蟋为对象，建立扩散型和居留型遗传系，研究扩散型和居留型成虫的形态和生理学差异，探讨其飞行行为多型的适应意义；通过液质联用法检测不同扩散型雌成虫体内的保幼激素滴度变化规律，结合外源激素处理对其飞行和繁殖的影响研究，阐明保幼激素对其雌成虫飞行和繁殖的调控机理；通过转录组测序技术，对羽化后不同阶段的扩散型、居留型及短翅型雌成虫飞行肌、卵巢和脂肪体中的基因表达谱进行比较分析，筛选其调控飞行和繁殖的关键基因。研究结果将为解释昆虫扩散行为的进化及种内多型性维持机制提供新依据，为防治具扩散多型现象的农林害虫提供新的思路。

飞行能力多型现象在许多昆虫种类中均有报道，是一些农林害虫爆发成灾的重要原因之一。本项目以长颚斗蟋为研究材料，对其飞行行为多型的适应意义，飞行和繁殖的保幼激素调控机制及其表达差异基因进行了研究。研究结果显示，不同扩散型成虫在营养物质的分配上存在显著差异，且扩散型比居留型长翅成虫需飞行更长时间以开启繁殖发育，说明了飞行行为多型长颚斗蟋存在飞行和繁殖间的生理权衡关系。具飞行能力的长翅型雌虫血淋巴内的保幼激素滴度存在昼夜节律，而不具飞行能力的短翅型雌虫血淋巴内的保幼激素滴度较为恒定；外源激素处理证实保幼激素下降会抑制长翅雌虫飞行，且长翅雌虫在开启快速繁殖发育的过程中保幼激素滴度升高且保持稳定，说明短时间高滴度的保幼激素调控飞行，而长时间高滴度的保幼激素诱导繁殖。通过转录组测序分析，发现长、短翅型雌成虫共3611个基因表达存在显著差异，其中，短翅雌虫表达上调基因1397个，下调基因2214个；扩散型和居留型长翅雌成虫间存在873个差异表达基因，其中上调基因数量为492条，下调基因数量为381条，差异表达基因主要富集在代谢通路，为进一步明确飞行和繁殖的关键调控基因奠定了基础。项目研究结果为揭示飞行行为多型现象的适应意义及其调控机理提供了新的证据，对具飞行能力多型现象的农林害虫防治亦有一定的指导意义。