普通大蓟马繁殖行为调控机制

Bean flower thrips, Megalurothrips usitatus (Bagnall), is a major insect pest of Vigna unguiculata in Hainan. The management of the bean flower thrips relies primarily on the use of insecticides, which indiscriminate use leads to serious pesticide residue problem. According to the results of our previous research, we propose that manipulating sex ratio is an alternative way to control the bean flower thrips. The variation, adjustment, and manipulation of the sex ratio of the bean flower thrips will be studied with methods and technologies in reproduction biology, behavioral ecology, nutritional ecology, population ecology of insects. The temporal and spatial patterns of the natural population of the bean flower thrips on cowpea will be observed. Manipulative experiments will be done to assess the ability of females during and after mating to adjust their offspring sex ratios in response to accompanying adults varying in numbers, sex ratio, and proportion of mated females. The behavioral responses of the females to the odors released by accompanying adults will be assayed. The effects of temperature, fertilizers and their application rates, and pesticides in different sublethal doses on the sex ratio of the bean flower thrips will be evaluated to find out the tactics which results in an extremely male biased sex ratio. Finally the field control experiments will be conducted to confirm that the tactics for producing an extremely male biased sex ratio is effective and economically feasible for the control of the bean flower thrips. The anticipated results of this study will broad the knowledge of thrips reproduction biology, and provide technological supports for the safe and sustainable management of vegetable legumes with reduced synthetic fertilizer and pesticide applications.

普通大蓟马是海南豇豆生产的重大害虫，频繁使用/滥用农药使得豇豆农药残留严重超标，本研究基于前期工作基础，提出基于性比控制的防治新思路，采用昆虫繁殖生物学、行为生态学、营养生态学及种群生态学的技术和方法，重点研究：（1）普通大蓟马自然种群性比的时空动态，揭示其性比变化规律和成虫群聚特点；（2）亲代成虫的数量、性比和雌虫交配率对子代性比的影响，以及雌虫对其他成虫气味的行为反应，阐明该虫在交配期间和交配后的性比自调节机制；（3）不同温度、不同肥料及其施用水平、不同农药及其亚致死浓度对普通大蓟马子代性比的影响，确定能使性比高度偏雄的对策；（4）该对策在田间防治试验中的应用效果，明确其有效性和经济性。预期研究结果将丰富蓟马繁殖生物学知识，证实性比控制策略对普通大蓟马是切实可行的，为豇豆等豆类蔬菜的减肥和减药管理和安全生产提供技术支持。

普通大蓟马是海南豇豆上的重要害虫，作为一种单倍-二倍体生物，该虫采用两性生殖和产雄孤雌生殖方式来繁衍后代。本研究对该虫的繁殖和性别分配进行了研究。结果表明，豇豆田普通大蓟马种群性比随植株年龄而变。配对期间温度过低或过高均能压低雌虫的获精能力。低温和高温分别导致已交配雌虫的子代性比偏雌和偏雄。多种杀虫剂亚致死浓度对该虫的性别分配没有影响。但豇豆偏施氮肥能促使蓟马性比下降，这跟豇豆叶游离酪氨酸和苯丙氨酸含量的上升有关。寄主植物的气味对已交配普通大蓟马雌虫的子代性比有干扰作用。此外，普通大蓟马在交配期间能依靠嗅觉判别周边雌虫的交配状况，通过调控雌虫获精能力，实现对子代性比的自调节。以上研究结果将有助于普通大蓟马偏雄对策的研究，为该虫绿色防控新技术的研发奠定基础。目前，已顺利完成了该项目的所有关键研究内容。