海氏桨角蚜小蜂与烟粉虱对逆境胁迫响应的适应性与机制

The highly developmental synchronization between parasitoid and host is a particularly key factor in determining effectiveness for biological control. Climate change such as elevated carbon dioxide (CO2) concentration and temperature can affect host and parasitoid synchronization. Hosts and parasitoids may have different adaptability and speed of response under different environmental stresses. These might lead to an asynchrony between host and parasitoid in space and time, decreasing the efficiency for biocontrol. The interactive effects of elevated temperature and CO2 level on organism may differ from their independent effects. The whitefly, Bemisia tabaci (Hemiptera: Aleyrodidae), is a destructively invasive insect pest of agriculture and horticulture worldwide, and causes severe damages through feeding and honeydew production, with resultant sooty mold and disease transmission. Eretmocerus hayati (Hymenoptera: Aphelinidae) is a well-known parasitoid ovipositing externally under the whitefly nymphal host, and has been found to play a prominent role worldwide in controlling this serious pest. We research interactions across three trophic levels, Euphorbia pulcherrima, B. tabaci and Er. hayati as affected by elevated CO2 concentrations, temperature or both factors in combination. The specific contents for this research are as follows: (1) change secondary (phenolics compound, condense tannins, alkaloid) and nutritional compounds (water concentration, protein, starch, soluble sugars, C and N contents) of host plant; (2) effect on successive five generations of B. tabaci in an attempt to determine whether different generations and stages of the insect's life cycle respond in a similar way; (3) change digestive enzyme (amylase, pepsin, lipase), oxidative stress (AChE, CarE, SOD, GSH, POD) and nutrition metabolism (sorbitol, glycerin, glycogen and lipid) of B. tabaci; (4) change host-handling strategies (trade-off) successive five generations of Er. hayati; (5) affect the onset of development, longevity, sex, fecundity, parasitism, host feeding, size of progeny produced of successive five generations of Er. hayati; (6) change digestive enzyme (amylase, pepsin, lipase), oxidative stress (AChE, CarE, SOD, GSH, POD) and nutrition metabolism (sorbitol, glycerin, glycogen and lipid) of Er. hayati. Our goal is to elucidate the adaptability and mechanism of Er. hayati and B. tabaci response to environmental stresses, predict the future influence of elevated CO2 and temperature on Er. hayati and B. tabaci population dynamics, and propose new management strategy.

寄生蜂与寄主昆虫发育同步性是决定生物防治成效的关键因素。在不同的逆境条件下，寄生蜂与寄主昆虫由于对逆境胁迫的适应能力与响应速度不一致，可能导致出现不同步性。本项目围绕高温和CO2浓度升高对"寄生蜂与寄主昆虫对胁迫响应的差异与适应性"的科学问题，以重大入侵害虫烟粉虱及其优势寄生蜂海氏桨角蚜小蜂为研究对象，采用繁殖生物学、比较生物学、昆虫行为学、分析化学等学科的实验技术与方法，研究高温和高CO2浓度长期胁迫下一品红次生代谢物质和营养组分的变化，烟粉虱连续多代如何从生物、生态学和生理代谢应对环境胁迫而保持种群生存与繁衍，进而研究海氏桨角蚜小蜂连续多代的寄主处理策略（生存和生殖权衡）以及寄生蜂与寄主昆虫的种间协同关系，阐明烟粉虱及其寄生蜂对高温和高CO2浓度胁迫的响应和适应性机制，为预测未来温度和CO2浓度升高下害虫及其天敌种群生存与繁衍的趋势，提出全球气候变化背景下害虫防治的新策略和新方法。

全球变暖和CO2浓度升高可能改变寄主昆虫和寄生蜂的种间关系，进而影响生防效果。本项目从三营养级互作关系的角度，主要研究不同环境因子（温度、CO2浓度等）长期胁迫下寄主植物生理代谢的变化、烟粉虱如何应对植物的变化，进而研究寄生蜂如何响应烟粉虱的变化。重要结果表明：（1）CO2和温度对植物不同生长时间的生理代谢产生不同影响，并有不同程度的交互作用，生理代谢随生长时间表现出动态性。CO2升高提高了叶片干物质含量、C/N比、可溶性糖、淀粉和非结构性碳水化合物和总酚含量，降低了叶片N含量和游离氨基酸总量。高温下CO2升高促进了温度对干物质的积累作用，但对总酚含量无明显影响；CO2和温度对不同生长时间叶片游离氨基酸含量的变化有不同影响。（2）CO2、温度和代数对烟粉虱1-4龄若虫发育期有不同影响，温度升高降低了各代发育历期，常温下CO2升高延长了各代总的发育历期，降低了若虫期的存活率。CO2和温度对粉虱各代的抗氧化能力有不同影响，且交互作用显著。不同处理下粉虱第三代总氨基酸含量低于其他代，温度、CO2和代数均能引起不同游离氨基酸含量的变化。粉虱内共生菌含量受温度、CO2和代数影响显著，随代数增加，Rickettsia含量明显下降，Hamiltonella含量上升。（3）海氏桨角蚜小蜂喜欢寄生和取食低龄若虫，高温下CO2升高寄生蜂寄生和取食若虫数量明显增加，但对粉虱龄期的偏好性没有变化。CO2升高提高了寄生蜂第二和第三代的发育时间，温度升高降低了寄生蜂各代的发育时间。温度和CO2、温度和代数对寄生蜂寿命有交互作用。温度升高降低了寄生蜂的寿命。温度和CO2对寄生蜂繁殖力有显著影响,但各因子间对寄生蜂繁殖力没有明显的交互作用。不同条件下，寄生蜂各代间的平均繁殖力没有显著差异，但个体间产卵数量差异较大。本项目研究为阐明害虫及其寄生蜂在不同因子联合作用下的响应和适应性机制以及为未来气候条件变化背景下害虫防治新策略和新方法的制定提供了重要证据。