入侵种二斑叶螨对本地种朱砂叶螨竞争性扩张的毒理学机制

The invasive two-spotted spider mite (TSM), Tetranychus urticae Koch, whose first record in China was 1983, and native carmine spider mite (CSM), Tetranychus cinnabarinus are the two most important phytophagous mites, both can feed with more than 1100 plant species. The fact that the competitive expansion of TSM against CSM in China was confirmed through summarizing the documented references and current research practice, however, the underlying mechanism is unclear. The reason for explaining the competitive expansion of TSM against CSM and related mechanism will be elucidated in this proposal, from which the comparative toxicology method will be adopted. The differences of toxicity effect of commonly used acaricides would be compared between TSM and CSM with bioassay; the mite species complex (individuals from TSM : CSM =1:1) will be created artificially and the spray of acaricides will be carried out according with the farming practice for understanding the effect of acaricides-stress on the structure changes of the mixed mite population; the difference of enzymatic properties would be analyzed between TSM and CSM by detecting the enzyme activities and its dynamic change with the acaricide-exposure; the differential gene expression in pre- and post-acaricide exposure would be compared with RNA-Seq deep sequencing and digital gene expression (DGE) testing; the single nucleotide polymorphisms (SNPs) of target genes will be detected and compared between two mite species via whole genome resequencing and the relationship between different SNPs and different acaricide-susceptibility will be analyzed. Combining above-mentioned research results, the biochemical and molecular mechanism for TSM possessing advantages of competitive expansion against CSM will be clarified from the aspect of pesticide toxicology.

入侵种二斑叶螨于1983年在国内首次发现,它和本地种朱砂叶螨都是重要的植食性害螨，都能为害1100多种植物。文献资料总结和现有科研实践都表明，二斑叶螨相对朱砂叶螨存在竞争性扩张现象，但相关机制并不清楚。本项目拟采用比较毒理学方法，研究并阐明二斑叶螨在中国竞争性扩张的原因及其机制。测定并明确常用杀螨剂对两种叶螨的毒力效应差异；建立叶螨混合种群（数量比1:1）、模拟生产实际喷施杀螨剂，明确药剂胁迫对叶螨混合种群结构变化的影响；检测解毒酶活性及其在药剂胁迫后的动态变化，分析两种叶螨的酶学性质差异；药剂胁迫前后进行数字基因表达谱测序，解析两种叶螨基因表达及其响应药剂胁迫的动态变化差异；分别对两种叶螨进行基因组重测序，比较药剂作用靶标基因的序列多态性（SNPs），分析SNPs差异与耐药性或抗药性差异的相关关系。最终从药剂毒理学的独特视角，阐明二斑叶螨相对朱砂叶螨获得竞争扩张优势的生化及分子机制。

二斑叶螨和朱砂叶螨同属 于蛛形纲、叶螨科、叶螨属，都是重要的农业害螨，但二者的分类地位长期存在争议。我们提出一个科学假设，即二斑叶螨更强的药剂胁迫适 应能力是其持续扩张并逐渐成为叶螨优势种群的重要原因。因此，本项目以二斑叶螨和朱砂叶螨为比较研究对象，以验证上述科学设想为研究目的，拟从毒理学的独特视角研究并阐明二斑叶螨在中国持续扩张的机制。获得的主要研究成果如 下： .1.通过文献检索间接重现二斑叶螨扩张趋势，结果表明入侵中国后，二斑叶螨相对于朱砂叶螨存在明显的竞争性扩张现象。 .2.杂交试验结果表明野外红色叶螨与室内朱砂叶螨，野外绿色叶螨与室内二斑叶螨能正常繁殖后代，而体色不同的两种叶螨间存在生殖隔离。 .3.在低温16℃，二斑叶螨相对朱砂叶螨生长发育较快且相对适合度较大(Rf为1.44)，存在适合度优势；在 26℃，两种叶螨发育历期和相对适合度无明显差异；33℃时，相对于朱砂叶螨，二斑叶螨的相对适合度为 0.55，表明二斑叶螨在高温下存在适合度劣势。 4.选用丁氟螨酯和甲氰菊酯对朱砂叶螨和二斑叶螨进行室内抗性筛选，25代后，朱砂叶螨和二斑叶螨对丁氟螨酯的抗性倍数分别发展到了13.52和29.35倍，对甲氰菊酯的抗性倍数分别发展到了28.04 和 39.57倍。.5.使用丁氟螨酯筛选 20 代后，朱砂叶螨的 P450s和 GSTs 活性分别显著升高 1.72 和 2.21 倍；二斑叶螨的 P450s、GSTs 和 CarEs 升高幅度分别为 1.92、5.40 和 2.15 倍。抗性种群解毒酶活性测定结果表明，相对于朱砂叶螨，二斑叶螨中的解毒酶对药剂选择的反应更积极。.6.从表达谱测序、比较可以看出，二斑叶螨相对朱砂叶螨耐药性/抗药性更强的分子基础是二斑叶螨本身拥有更多上调表达的基因，更为重要的是，遭受药剂胁迫时二斑叶螨参与响应的基因也显著多于朱砂叶螨。