【作者】 李姣；

【导师】 肖铁光； 戈峰；

【作者基本信息】 湖南农业大学 ， 农业昆虫与害虫防治， 2008， 硕士

【摘要】 天敌不仅直接捕食或寄生害虫,而且还能改变害虫的生长发育与繁殖,间接地影响害虫的适合度。目前对此研究较少。本论文以棉田重要害虫棉蚜Aphis gossypiiGlover及其捕食性天敌龟纹瓢虫Propylaea japonica Thunberg和寄生性天敌蚜茧蜂Lysiphlebia japonica Ashmead为对象,研究了笼罩瓢虫和笼罩蚜虫胁迫作用方式、胁迫作用时间的长短对棉蚜生长发育、繁殖和适合度的影响,分析了多世代的蚜茧蜂的寄生干扰对棉蚜生长发育、繁殖和适合度的作用,探讨了CO₂浓度升高下蚜茧蜂寄生干扰对多世代棉蚜适合度的影响。主要研究结果如下:一、龟纹瓢虫胁迫作用方式、胁迫作用时间的长短对棉蚜生长发育、繁殖和适合度的影响以棉田重要害虫棉蚜及其捕食性天敌龟纹瓢虫为研究系统,研究了笼罩瓢虫和笼罩蚜虫胁迫作用方式、胁迫作用时间的长短对棉蚜生长发育、繁殖和适合度的影响。结果表明:短时间（4h）直接放入瓢虫的胁迫方式对棉蚜的生长发育、繁殖和适合度无显著影响,但间接将瓢虫笼罩起来或将蚜虫笼罩起来对棉蚜生长发育、繁殖和内禀增长率有显著影响。这种作用依不同的作用阶段和作用时间长短而不同。经过笼罩瓢虫胁迫作用较长时间（8h、12h和24h）后,棉蚜的发育历期、平均每世代的历期显著缩短,内禀增长率极显著增加,即适合度增加;但如果将蚜虫笼罩起来,其结果则与之相反,主要以胁迫作用时间较短（4h）的胁迫处理作用显著,表现出发育历期、平均每世代的历期显著缩短,内禀增长率极显著增加的趋势;而时间较长（8h、12h和24h）的胁迫处理无显著变化。不但瓢虫胁迫不同时间的处理对棉蚜生长发育有显著影响,而且瓢虫胁迫棉蚜的不同发育阶段处理对棉蚜生长发育也有显著影响,母代产仔期的胁迫处理能够使其发育历期显著缩短,母代受到胁迫作用的效应比若蚜受到胁迫更明显;笼罩瓢虫的胁迫作用比笼罩蚜虫的胁迫作用更明显;受胁迫作用后,低龄幼虫的反应更为敏感。我们的结果清楚地表明,龟纹瓢虫的干扰胁迫作用,可以间接的增加棉蚜的适合度,促进棉蚜种群的增长,使棉蚜种群自我维持、调节到相应的水平。二、蚜茧蜂持续胁迫对多世代棉蚜生长发育、繁殖和适合度的影响以棉田重要害虫棉蚜及其蚜茧蜂为研究系统,研究了蚜茧蜂胁迫作用对不同龄期、不同世代和连续多代棉蚜生长发育、繁殖和适合度的影响。结果表明:蚜茧蜂对不同龄期棉蚜的寄生干扰作用不同;随着对棉蚜干扰龄期的推后,棉蚜的产仔量越来越少、成蚜的寿命越短。无论受到寄生蜂直接胁迫作用还是间接胁迫作用后,第1代棉蚜产仔量和净生殖率之间没有显著差异,但连续直接放寄生蜂的干扰显著增加了第二代棉蚜产仔量和净生殖率,而间接放寄生蜂明显地增加了第二代、第三代棉蚜产仔量和净生殖率。但由于直接放寄生蜂、间接放寄生蜂对第二代、第三代棉蚜平均每世代时间没有显著影响,只有寄生蜂的间接作用显著缩短了第一代棉蚜平均每世代时间,因此,综合作用的结果表明,直接放寄生蜂对各个世代棉蚜内禀增长率均没有显著的影响,而间接地放寄生蜂的干扰作用明显地增加了第二代、第三代棉蚜内禀增长率。我们的结果充分提示:寄生蜂间接干扰作用比直接干扰作用更大;寄生蜂间接干扰作用对棉蚜的生长发育和繁殖都有影响,明显地影响了后代的内禀增长率和种群动态。三、CO₂浓度升高下蚜茧蜂对多世代棉蚜适合度的影响以棉蚜茧蜂与棉蚜系统为研究对象,通过开顶式动态CO₂气室（OTC）,研究大气CO₂浓度升高到750ppm下笼罩蚜茧蜂和笼罩蚜虫胁迫作用对不同龄期、不同世代和连续多代棉蚜生长发育、繁殖和适合度的影响。结果表明:在高大气CO₂浓度条件下,蚜茧蜂对不同龄期棉蚜的寄生干扰作用后,使棉蚜的产仔量越来越少、成蚜寿命缩短;而且低龄（1龄和2龄）棉蚜受蚜茧蜂干扰作用更大。CO₂浓度、世代之间、寄生胁迫方式对棉蚜产仔量、净繁殖率R₀、平均每世代时间T和内禀增长率r_m存在着极显著的影响;CO₂浓度和寄生胁迫方式之间、CO₂浓度和棉蚜发生世代之间的交互作用对棉蚜产仔量、净繁殖率R₀和内禀增长率r_m也存在着极显著的影响。在高大气CO₂浓度条件下,直接放寄生蜂后使第一代、第三代棉蚜内禀增长率显著下降,间接放寄生蜂后除导致第二代棉蚜内禀增长率增加外,其它各个世代棉蚜没有发生显著的变化。结果提示:在高大气CO₂浓度条件下,寄生蜂直接干扰棉蚜作用比间接干扰棉蚜作用更大;而且,高大气CO₂浓度将通过影响寄生蜂的间接干扰作用,从而影响棉蚜的生长发育、繁殖、适合度和种群动态,使棉蚜种群有下降的趋势。更多还原

【Abstract】 Natural enemies not only directly influence prey density by predation and parasite but they can also indirectly cause the modification of fitness in their victims by modifying the development and fecundity of their victims. However, little is known about the indirect effect of natural enemies on their preys so far. We examined the response of the development, fecundity and fitness in A. gossypii exposed to P. japonica and L. japonica in two sets of experiments. The results were as follows:1) The indirect effect of stress from P. japonica on the development, fecundity and fitness of A. gossypii.Studies about the effects of stress from P. japonica with different action modes, time and stages on the development, fecundity and fitness of A. gossypii were conducted in laboratory. The results indicated that the intrinsic rate of increase and fitness of A. gossypii enhanced with the action time of stress from P. japonica caged prolonging. The longer the action time was, the shorter the development and mean generation time of A. gossypii was. While the absolutely different results were observed in the experiment of A. gossypii caged in the presence of stress from P. japonica with different action time, only 4-hours action time of stress have a significant influence on the development and mean generation time of A. gossypii caged.Different action stages of stress also played an important role in A. gossypii. The growth rate of A. gossypii obviously more accelerated when their maternal generation was exposed in predation risk of P. japonica than the offspring. Furthermore, the responses of the fresh ones were more susceptive to this stress than the old ones. Consequently, our results clearly demonstrated that the stress of P. japonica could indirectly increase fitness of A. gossypii and their population density, which leads to auto-regulation of A. gossypii population so that they can successfully survive.2) The impacts of stress from L. japonica on the development, fecundity and fitness of the three successive generational A. gossypiiThe second experiment was studied to evaluate adaptation of the development, fecundity and fitness on the three successive generational A. gossypii in response to exposure of L. japonica and caged L. japonica. Compare to the first-three-instars larvae, the 4-instar larvae stressed by L. japonica had the least fecundity and the shortest longevity. There was no significant difference in total and net reproduction of the 1st generational A. gossypii whatever they were threatened by L. japonica or caged L. japonica. However, the successive direct stress evidently produced more offsprings in the second generation of A. gossypii, whereas the indirect stress remarkably produced more numbers of nymphae in the second generation and third generation of A. gossypii. Both direct stress and indirect stress of L japonica didn’t influent significantly the mean generation time of the 2nd and 3rd generational A. gossypii, but only their mean generation time of the 1st generational A. gossypii encountered indirect stress was shortened. Therefore, it has been suggested that direct stress from L. japonica have no obvious effects on the intrinsic rate of increase in the three successive A. gossypii, and the indirect stress implicitly promoted the fitness of successive generational A. gossypii. Here, we emphasized on the indirect effect to population dynamics of successive generational A. gossypii.3) The impacts of stress from L. japonica on the development, fecundity and fitness of the three successive generational A. gossypii in elevated CO₂.Furthermore, the effects of elevated CO₂ （375μl / L VS 750μl / L） on the system of cotton - A. gossypii - L. japonica were studied used OTCs. The experiment would be desirable to show that a stronger effect of L. japonica-stress was seen in the first-two-instars A. gossypii in elevated CO₂, which would cause a lower fecundity and longevity. In addition, a notable trade-off interaction among CO₂ levels, generation and L. japonica-stress determined the reproduction, mean generation time and intrinsic rate of increase in cotton aphids. Here, our results suggested that the L. japonica-stress did a more forceful function to the three successive aphids that the caged L. japonica-stress in elevated CO₂, further, induced a lower aphid-population.更多还原