【作者】 崔旭红；

【导师】 万方浩；

【作者基本信息】 中国农业科学院 ， 生物安全， 2007， 博士

【摘要】 B型烟粉虱Bemisia tabaci(Gennadius)B-biotype和温室粉虱Trialeurodes vaporariorum Westwood都是我国重要的外来入侵害虫。两者虽为近缘种，但在生境适应过程中两者的种群优势关系产生了地域和季节性分化：在适宜寄主资源充分的生境中，种群间优势关系不以入侵生境的时间先后决定；温室粉虱主要在北方危害，而B型烟粉虱无论在北方还是在南方，均大发生，在有些地区或寄主上有B型烟粉虱逐步取代温室粉虱的趋势；在两种粉虱种群混合发生的北方，夏季高温季节以B型烟粉虱种群为主，春秋两季气候趋凉时温室粉虱种群上升为优势种群。结合两者在我国的地理分布和种群动态差异，我们推测两者对温度，特别是极端温度的适应性差异是导致两种粉虱种群动态存在差异的一个重要原因。因此我们研究了两种粉虱对热胁迫的适应性以及hsp70在B型烟粉虱抵抗高温中的作用，以期能够解释这种现象。主要结果如下：1．B型烟粉虱和温室粉虱卵、伪蛹和成虫的存活率均随着温度升高和暴露时间的延长呈现出下降的趋势。在相同的处理条件下，B型烟粉虱3个虫态的存活率均要高于温室粉虱。在37-41℃范围内高温对B型烟粉虱成虫的存活率没有显著影响；当温度上升到43℃和45℃时，成虫的存活率要低于卵和伪蛹。经过高温暴露后，温室粉虱卵的存活率要高于其它2个虫态。2．B型烟粉虱和温室粉虱都是雌虫的耐热性高于雄虫。在相同的处理条件下，B型烟粉虱雌虫的耐热性要高于温室粉虱；雄虫中也观察到相似的现象。3．非致死高温驯化可以显著的提高B型烟粉虱成虫对极端高温的抵抗力，在37℃驯化30min，B型烟粉虱成虫在45℃下的存活率由44.0％上升到63.9％；但高温驯化对温室粉虱成虫的耐热性没有显著提高。4．短时高温暴露对B型烟粉虱和温室粉虱成虫的产卵前期没有显著影响，两种粉虱都是在2天左右开始产卵。短时高温暴露对B型烟粉虱成虫的产卵量没有显著影响；温室粉虱的产卵量随着暴露温度的升高迅速下降，在43℃下暴露1h后仅有极少量的卵产出。两种粉虱成虫经过高温暴露后，产下的卵的孵化率和后代总的存活率均有所下降，温室粉虱成虫在43℃下暴露1h后产下的卵不能孵化；而B型烟粉虱成虫经过43℃和45℃高温暴露后，仍有一部分个体能够完成世代发育。高温暴露对温室粉虱后代性比没有显著影响；B型烟粉虱成虫经过43℃和45℃高温暴露后，其后代中雄虫比例显著增加。5．分别克隆了具有分子伴侣功能的B型烟粉虱和温室粉虱的热激蛋白基因hsp70 cDNA片段，比对结果表明，hsp70具有较高的保守性。6．成功构建了B型烟粉虱hsp70表达实时荧光定量检测体系，并检测了温度变化对B型烟粉虱hsp70表达的影响。结果表明，较缓和的高温对B型烟粉虱hsp70表达具有诱导作用，极端高温会抑制hsp70表达。在37-41℃范围内，hsp70的表达量随着温度的升高而升高，在41℃时达到最高峰；当温度升高到43℃和45℃，B型烟粉虱hsp70的表达量迅速降低。B型烟粉虱温室种群体内的hsp70表达量与温室内的温度有关：上午到中午随着气温的升高，B型烟粉虱体内hsp70表达量随之上升；傍晚气温降低时，hsp70表达量也随之下降。本研究揭示了两种粉虱对高温的适应性差异是导致两者在我国种群发生上存在季节性差异的一个重要原因；hsp70在B型烟粉虱抵抗高温过程中可能具有重要作用，这对揭示B型烟粉虱及其它入侵害虫的种群形成与扩张机制具有重要的科学价值，对B型烟粉虱的可持续控制具有重要的理论和实践意义。更多还原

【Abstract】 Bemisia tabaci (Gennadius) B-biotype and Trialeurodes vaporariorum Westwood are both important invasive alien pests in China. These two sympatric whiteflies species diverged in regional population predominance in the process of habitat adaptation: population predominance is not decided by time order of their first invasion under condition that suitable host plants are available in their habitat; B. tabaci B-Biotype is tending to displace T. vaporariorum in many regions or on many host plants; T. vaporariorum causes extensive damage in the northern China, while B. tabaci B-Biotype explosive outbreak almost throughout the country from the south to north areas; population of B. tabaci B-Biotype is generally predominant in hot summer while T. vaporariorum toward the cool autumn or spring. So we hypothesize the adaptability of tolerance to thermal stress may be one of the important reasons that leads to two whitefly species interspecific differentiation in seasonal dynamics and distributions. The association between interspecific differentiation in thermal adaptation and the interspecific displacement was revealed in the level of biology and molecular biology. The main results of this study are as follows.1. The survivals of three developmental stages of two whitefly species decreased with the increase of temperature and the prolonging of heating period. Further, the survival rates of eggs, red-eyed nymphs and adults of B. tabaci B-biotype were higher than those of T. vaporariorum. There were significant differences when heat tolerance between these two whitefly species was compared. The survival rates of B. tabaci B-biotype adults were not significantly affected by the temperature varied from 37 to 41℃, however, the adult had the weakest tolerant ability to extremely high temperature, 43 and 45℃. In the case of T. vaporariorum, the egg had the highest heat tolerance among the three tested stages.2. In both whitefly species, the decreased survival due to the brief exposure of high temperature represented significant difference between female and male adults and females appeared higher survival than that of males. In addition, B-Biotype B. tabaci female adults had higher survival than that of T. vaporariorum at the same conditions. The similar phenomenon was also observed in male adults of two whitefly species.3. Acclimation at non- lethal high temperature significantly influenced heat tolerance of B. tabaci B-biotype, which can enhance its survival as high as 63.9% at 45℃. However, heat tolerance of T. vaporariorum adults were not significantly enhanced after acclimation at 37℃.4. Shorter period of exposure to high temperature had no influence on pre-oviposition period of two whitefly species and female adults began to lay eggs around 2 days. The female fecundities were not significantly different when B. tabaci biotype B adults were exposed to all temperatures. In contrast, the fecundities of T. vaporariorum declined with the increase of temperature, and only a few eggs were oviposited at 43℃. Survivals or hatch rates of the F1 nymphs of both whitefly species declined as the increase of temperature, and no T. vaporariorum nymphs were hatched at 43℃. Similarly, percentages of F1 offspring developed to adults for both whitefly species also declined as the increase of temperature. Sex ratios of the F1 offspring were not significantly affected for T. vaporariorum but were slightly affected for B. tabaci biotype B at the heat shock temperatures, 43 and 45℃.5. Heat shock protein 70 (hsp70) gene functioned as molecular chaperones was cloned, with a result of 3 partial cDNA sequences for B. tabaci biotype B and 2 partial cDNA sequences for T. vaporariorum. This showed that hsp70 gene family is evolutionarily conservative.6. The plasmid with hsp70 cDNA of B. tabaci B-biotype adults was used as a template. Based on GenBank, one TaqMan-MGB probe and the corresponding primers were designed to construct a series of standards for real-time fluorescence quantitative Real-time-PCR to detect the expression of hsp70 gene of adults B. tabaci B-biotype. High temperature can induce the expression of hsp70 gene in B. tabaci B-biotype adults. Within the range of 37 to 41℃, the expression level of hsp70 gene of B-Biotype B. tabaci adults rised with the increase of temperature. However, when temperature increased to 43℃and 45℃, the hsp70 gene expression level decreased sharply. The hsp70 gene expression level of B. tabaci B-biotype adults were changed in response to the diurnal temperature change. When air temperature increased from 34℃to 41℃, the hsp70 gene expression level increased dramatically. And the hsp70 gene expression level decreased when air temperature decreased to 33℃at nightfall.Our research indicated that the differences of thermal stress tolerance between B. tabaci B-biotype and T. vaporariorum was one of the main reasons that lead to the interspecific differentiation of geographic variation in distribution and seasonal dynamics. The molecular mechanism of B. tabaci B-biotype adaptation to thermal stress was revealed. The significance of heat tolerance was elucidated in insect evolutionary adaptation and distribution. The results also have theoretical and practical significance in explaining the population expanding mechanisms of biological invasion and prediction of population dynamics.更多还原