截形叶螨对高温和哒螨灵药剂交互胁迫的应对机制

In recent years，as rapid development of hybrid corn breeding, Hexi area of Gansu Province has become the largest production bases of hybrid corn seed in China. However, Tetranychus truncatus Ehara has become one of important pests in this area due to undertaking contiguous cultivation in large regional scale, seriously affecting yield and quality of hybrid corn seed. According to previous researches, T. truncatus Ehara had been out of controlled because of its resistance to pyridaben. The biological fitness of pyridaben-resistant strain(Py-R) was significantly higher than the susceptible strain(SS) at high temperature. Therefore, in order to illuminate response mechanism in T. truncatus Ehara suffering the interaction stress of high temperature and pyridaen, the research will be done as fellows: (1) The SS population, the Py-R population and the heat-resistance population (HR) are be used to study drug- resistance, high temperature adaptability and cross-endurance, by using bioassay and life table method at a set of diurnal temperature range experiments simulating natural environment. It is will be induced by ecologically relevant the interrelation of resistance to pyridaben and high temperature of three populations. (2) The free radical and protective enzyme activities of three strains (SS, Py-R, HR) will be compared. (3) The possible roles and the expression models of the responsive genes played in T. truncatus after interactive stimulated by pyridaben and high temperature will be ascertained. This study has important biological significance for deeply understanding the biological response to environmental stress, and also provie a new path with fitness that could make resistance management.

针对甘肃省河西地区制种玉米上的截形叶螨易产生抗药性，难以控制的实际需求，围绕截形叶螨抗哒螨灵种群在高温下存在适合度优势现象这一科学问题，重点研究（1）昼夜温差环境下，截形叶螨敏感、抗哒螨灵和耐高温3个品系间的交互适应性及种群发生规律，从生态学角度明确截形叶螨生态适合度与抗药性及高温适应性之间的内在联系；（2）比较截形叶螨3个品系被高温和哒螨灵药剂交互胁迫后体内自由基和保护酶活性差异，从生理生化角度揭示截形叶螨对逆境胁迫时体内保护酶的应激变化规律；（3）发掘出参与高温和药剂生物代谢或合成的关键基因，并对相关基因进行表达量和功能分析，从分子水平探明截形叶螨抵抗药剂和高温交互胁迫的关键基因的应激表达模式。预期结果将阐明截形叶螨对高温和哒螨灵药剂交互胁迫的应对机制，解释截形叶螨抗哒螨灵种群在高温下存在适合度优势现象问题，为利用适合度制订截形叶螨抗药性综合治理方案提供科学依据。

针对甘肃省河西地区制种玉米上的截形叶螨易产生抗药性，难以控制的实际需求，围绕截形叶螨抗哒螨灵品系在高温下存在适合度优势现象这一科学问题，从生态、生理生化和分子角度重点研究了（1）自然环境昼夜温差条件下截形叶螨敏感、抗哒螨灵和耐高温3个品系对高温和哒螨灵的交互适应性及种群的动态变化规律；（2）高温发生频率和持续时间对截形叶螨不同发育阶段的影响；（3）截形叶螨不同品系在哒螨灵和高温胁迫下体内自由基含量、保护酶、糖类物质和游离氨基酸代谢变化规律；（4）高温胁迫下截形叶螨的转录组分析及关键基因的功能研究。.试验结果表明：（1）截形叶螨对高温和哒螨灵具有一定的交互适应性，温差对截形叶螨各品系的生长发育和生殖均有直接的影响，敏感品系和抗性品系整个世代发育历期和均高于高温品系，抗性和高温品系的单雌日产卵量显著高于敏感品系，而抗性和高温品系之间无显著性差异，敏感品系存在生殖不利；（2）敏感品系的卵期和未成熟期均受高温天频率的影响，而成虫期受高温天频率影响较小。抗性品系的卵期受高温频率影响较小，主要发生在未成熟期和成虫期；（3）抗性品系对逆境胁迫的生理耐受性强于敏感品系。对药剂和高温胁迫的应激反应最强的保护酶为超氧化物歧化酶SOD，糖类物质含量变化最大的为海藻糖，二者在体内活性氧代谢和能源物质代谢中起着重要作用；（4）截形叶螨雌成螨抗性和敏感品系差异基因主要富集在代谢途径和溶酶体等通路；两品系的TtSOD、TtPOD3、TtPOD4、TtGSTs2、TtCYP 3A2和 TtCYP 4V2等6个抗氧化酶基因的表达量均被高温胁迫诱导表达，且在不同螨态存在差异，RNAi结果证明TtPOD4、TtCYP 3A2和TtCYP 4V2基因在截形叶螨抵抗药剂和高温胁迫时起重要作用。以上实验结果为预测气候变暖背景下农业昆虫种群的发生和将来应用基因调控技术防治截形叶螨提供了一定的理论基础。