寄生蜂翅型分化的环境可塑性机制研究

Wing dimorphism is commonly observed in insects as a strategy to face trade-offs between flight capability and fecundity, and it may confer an important adaptive value to populations. At present, researches on the wing polymorphism are often conducted in phytophagous insects, only very few study cases have been reported in parasitoids. Several bethylid wasps, which have been widely used for controlling the wood boring insect pests in China, exist wing dimorphism. But most of the females are wingless, so their dispersal and host searching abilities are very limited, which is disadvantageous to use in practice. In this proposed project, the effects of parasitoid density during immature stage, temperature, photoperiod, host quality, exogenous hormone, and their combinations on the mechanisms for wing differentiation of female bethylid wasp will be determined using the Sclerodermus pupariae as the model research object. Then the individual fitness of different wing morph females will be evaluated for explaining the influence of genetic, environment and their combined effects on the development of parasitoid wing. And the extrinsic conditions for phenotypic plasticity in response to environmental cues will be analyzed. The evolutional process in insect population during exploration of new habitats and increase of fecundity can be clarified. Thus we can culture high proportional winged female parasitoids via artificial manipulation. These studies can provide theoretical supports for improvement of biological control efficiency using natural enemy, but also have prospective application value in practice.

翅二型现象在昆虫中广泛存在，被认为是昆虫在飞行扩散和繁殖能力之间权衡的一种策略，对种群具有重要的适应意义。目前在植食性昆虫中研究较多，有关寄生蜂的翅型分化鲜见报道。我国广泛用于防治林木蛀干害虫的几种肿腿蜂均存在翅二型现象，但雌性主要为无翅型，不利于种群的扩散和搜索寄主，从而影响了生物防治效果。本申请项目拟以白蜡吉丁肿腿蜂为研究对象，通过测量寄生蜂自身密度、温度、光周期、寄主质量、外源激素刺激等因素及其交互作用对雌性肿腿蜂翅型分化的影响机制，评价不同翅型雌性个体的适合度差异，明确遗传因素、环境因素及其相互作用对寄生蜂翅型分化的影响。分析遗传基因的环境可塑性条件，探讨基因型的不同表达与环境诱导的关系，阐明寄生蜂在开发新栖境和提高繁殖率之间的种群进化过程。通过人为干预，培养出高比例的有翅型雌蜂，不仅为提高天敌的生物防治效率提供理论基础，在生产实践上也将具有重要意义。

昆虫翅型分化是昆虫平衡生殖和扩散能力的一种策略，有翅型寄生蜂的扩散和寄主搜索能力显著高于无翅型。我国广泛应用于蛀干害虫防治的肿腿蜂都存在翅二型现象，但雌蜂绝大多数为无翅型，制约了寄生蜂种群的扩散，影响了控害效果。本研究以白蜡吉丁肿腿蜂为研究对象，优化了寄生蜂的人工饲养方法，调查了该蜂翅型比例随季节变化的规律，并通过实验室连续继代培养，测量了寄生蜂自身密度、温度、光周期、寄主、外源激素等对其后代翅型分化的影响，比较了不同翅型雌性个体的适合度差异。结果表明：该蜂野外种群越冬后的第一代子代雌性有翅率最高，随后逐代显著下降，直至全部后代为无翅型。在室内人工饲养寄生蜂时，当培养条件为高温（30℃）、短日照（8 L:16 D）、弱光强条件下有利于产生有翅型子代。温度、母代产卵量、成蜂密度、长时间冷藏均对子代有翅型有显著影响，呈正相关关系。而发育历期与温度呈负相关关系，但在长时间冷藏后显著增加。子代雌性有翅比例与其母代产卵量呈显著负相关关系，但随培养世代数的增加而降低。寄主种类对子代翅型分化没有影响，但对其他参数均有一定影响。对不同翅型寄生蜂适合度进行对比发现有翅型雌蜂的后代有翅率显著低于无翅型雌蜂的后代，其繁殖力和寄生能力也较无翅型弱，寄生蜂翅型对个体大小、发育历期、寿命均无显著影响。这些研究结果明确了寄生蜂翅型分化的有利条件，证实了寄生蜂在翅型分化和自身繁殖力之间存在权衡机制，为人工培育有翅型寄生蜂，提高寄生蜂寄主搜索能力和扩散能力，有效控制林木蛀干害虫提供了理论基础。