从加州新小绥螨两性发育形态学及生殖生态学差异解析其性别调控机制

Predatory mites in Phytoseiidae are important biological control agents. They play significant roles in IPMs of small piercing sucking pests, including spider mites, thrips, and whiteflies, etc. Their special pseudoarrhenotoky mode of reproduction, and stable offspring sex allocation have attracted wide interests and attentions. They must mate to reproduce, and all offspring develop from fertilized eggs. Females are diploid while males are haploid. For most species, proportion of female offspring often has relative stable values near ca. 67%. However, the theory that all individuals develop from fertilized eggs are actually debated. There are also many blanks in sex allocation mechanisms of Phytoseiidae. In this project, we choose Neoseiulus californicus as the research object, which is a worldwide commercialized natural enemy product but was recently discovered in China. The fine structures of its reproductive system, and spermatogenesis and oogenesis will be observed with scanning electron microscope and transmission electron microscope. Impact of important environment factors (such as prey.species, prey abundance and temperatures) on its reproduction will be investigated. Results in cytobiology, developmental morphology, and reproductive ecology will be integrated and will support each other in explaining reproduction and sex allocation in Neoseiulus californicus. This project will provide structural support for appealing mechanisms of Phytoseiidae reproduction.

植绥螨科捕食螨是重要的生物防治物，对多种作物上的小型吸汁性有害生物如叶螨、蓟马和粉虱等的防控发挥着巨大的作用。其特殊的“假产雄孤雌生殖”方式及后代稳定性比调控机制受到普遍的关注和兴趣。交配是生殖的必要条件，所有的个体均由受精卵发育而来，而雌螨是二倍体，雄螨为单倍体。后代雌性比稳定在67%左右。然而，上述基于所有个体均由受精卵发育而来的这一生殖理论也颇受质疑,其性比调控机理也仍有很多不明之处。本项目以世界商品化生产并于近年在国内首次发现的加州新小绥螨为研究对象，利用扫描与透视电镜，结合细胞生物学、发育形态学、生殖生态学的相关研究，对加州新小绥螨雌雄生殖系统构造、精卵发生、猎物种类与数量及温度等重要环境因素对产卵及精卵发育的影响等进行较为深入而系统的研究，其结果将相互验证，互为解释，并为解析加州新小绥螨的生殖现象与性比调控提供依据，同时也为最终揭示植绥螨科捕食螨的生殖机理提供支撑。

植绥螨科捕食螨是重要的生物防治物，对多种作物上的小型吸汁性有害生物如叶螨、蓟马和粉虱等的防控发挥着巨大的作用。其特殊的“假产雄孤雌生殖”方式及后代稳定性比调控机制受到普遍的关注和兴趣。通常认为交配是生殖的必要条件，所有的个体均由受精卵发育而来，但雄性后代发育为单倍体。后代雌性比稳定在67%左右。然而，上述基于所有个体均由受精卵发育而来的这一生殖理论也颇受质疑,其性比调控机理也仍有很多不明之处。本项目以近年在国内首次发现的加州新小绥螨为研究对象，结合细胞生物学、发育形态学、生殖生态学开展了系统研究。应用利用扫描与透射电镜观察其雌雄生殖系统构造和精卵发生，并分析了猎物种类与数量等重要环境因素对产卵及胚胎发育的影响。研究结果：1.捕食螨雄螨的内部生殖结构由射精管、贮精囊、输精管和精巢四部分组成。雌螨的导精孔位于足Ⅲ和足Ⅳ之间靠近腹板处，交配时两个导精趾其中一个通过导精孔进入雌螨体内的受精囊。交配开始后外精包产生，外精包在导精趾的协助下与螯肢基部的小孔相连，其内的精子通过与外精包相连接的螯肢上的导精趾进入雌螨体内。2.评价不同猎物（二斑叶螨和西花蓟马）对加州新小绥螨生殖的影响。发现雌成螨交配后的猎物对生殖的影响最大，交配后取食西花蓟马的加州新小绥螨总产卵量与取食叶螨的个体接近，但日均产卵量低，产卵前期和产卵期长，所产的卵体积变小。3.饥饿对加州新小绥螨生殖的影响。初羽化雄螨禁食36h后，仍然能够完成单次交配，但雌雄交配时长变长，第一粒受精囊的填充时间延长35%；对雄螨进行不同程度长期饥饿，当饥饿程度较高时，雄螨寿命下降37%，其存活阶段仍可与雌螨多次交配，但生命后期生殖能力显著下降，甚至产生仅交配不产卵等现象。此项研究为解析加州新小绥螨的生殖现象与性比调控提供依据，同时也为最终揭示植绥螨科捕食螨的生殖机理提供支撑。

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