尼氏真绥螨是多种作物上的常见种，捕食害螨和其它小型节肢动物，可有效控制叶螨种群数量，同时该螨是桔园捕食螨的优势种，是害螨的生物防治作用物。然而针对植绥螨系统进化及地理分布的研究却很少。 本项目拟以植绥螨科中广泛分布且具有生物防治作用的尼氏真绥螨为研究对象，以mtDNA和核基因等为遗传标记，着重从分子水平，并结合形态特征性状来研究尼氏真绥螨系统发生过程和演化途径，同时结合地理历史事件，特别是更新世以来的历史事件，探明其遗传结构和种群扩散模式，阐明种群地理分布格局和进化机制的成因，为尼氏真绥螨的起源进化和分类地位提供合理的解释，也为进一步保护利用尼氏真绥螨提供理论依据。

Euseius nicholsi is one of the common phytoseiid mite in citrus,prey on pest mites and some other small arthropods, is considered to be biological control agents against harmful mites. The few phylogeography of phytoseiid mites is investigated, and especially phylogeography of E.nicholsi has never been reported. In this project, E.nicholsi,which widely distributes in Phytoseiidae and can be used for biological control, is obtained as the research object,completing on mtDNA and nuclear genes sequences,and the morphological taxonomic traits data are analyzed in E.nicholsi, and we mainly aim to rebuild its phylogeny and evolutionary track,and explain its genetic structure and population expansion model based on phylogenetic methods and geographic historical affairs. Secondly,in this project the geographical distribution patterns and evolution mechanism in populations are also discussed to explain the evolutionary origin and taxononic status of E.nicholsi. The result of this research also provide the theory foundation for the further protection and utilization of E.nicholsi.