【作者】 钟景辉；

【导师】 陈家骅；

【作者基本信息】 福建农林大学 ， 农业昆虫与害虫防治， 2009， 博士

【摘要】 温度是影响昆虫生长、发育、生殖和存活等生命活动的重要生态因子。对极端温度的耐受能力是决定昆虫在区域间分布和扩散的一个重要因素。近年来,随着全球气候变化,极端异常天气时有发生。松突圆蚧Hemiberlesia pitysophila Takagi作为一类重大外来入侵生物,及其引进天敌花角蚜小蜂Coccobius azumai Tachikawa对极端温度的耐受性既关系到松突圆蚧潜在的入侵区域,也关系到花角蚜小蜂的有效与持续利用。本文通过测定松突圆蚧、花角蚜小蜂的过冷却点和极端温度(包括极端高温和极端低温两个方面)暴露处理下的存活情况,以及寄主、纬度和海拔对松突圆蚧极端温度耐受性的影响等,综合评价了二者对极端温度的耐受性;结合区域气候特征,预测二者及其寄生关系的潜在分布区域。对阐明外来害虫—外来天敌系统对土著生境的适应及其协同进化关系具有重要的理论意义,对松突圆蚧的风险评估、有效控制和花角蚜小蜂的充分利用具有重要的实践指导意义。主要研究结论如下:1松突圆蚧种群耐寒性的季节变化松突圆蚧的过冷却点波动在-22.4～-3.3℃之间,以冬季雌成虫的平均过冷却点最低,为-14.83℃,冬季1龄若虫、2龄性分化前若虫、2龄性分化后雄若虫、雌成虫及种群总体在-20～0℃下的死亡率、冷识别温度和半致死低温累积均明显低于夏季;1龄若虫、2龄性分化后雄若虫和种群总体的半致死低温累积与季节性平均气温均呈显著正相关,但所有发育阶段的过冷却点与其半致死低温累积的相关性均未达显著水平。表明松突圆蚧的耐寒性具有明显的季节适应性,冬季种群的耐寒性最强,夏季种群最弱;松突圆蚧耐寒性的季节变化并不依赖于过冷却点,而与气温的季节性变化密切相关。预测松突圆蚧能够突破现有分布的北界(26°N左右),但在26.5～29°N区域内冬季低温将对其种群的存活产生显著影响;在29～37°N区域也能越冬,但冬季低温将极大地限制种群的发展。2寄主植物对松突圆蚧耐寒性的影响寄生于黑松和马尾松的松突圆蚧雌成虫的过冷却点比寄生于湿地松和火炬松的显著较高,两类过冷却点平均值的差异在0.9～2.3℃之间。寄生于马尾松的2龄性分化后雌若虫的过冷却点比寄生于湿地松的显著较高,前者比后者高出2.08℃。寄生于马尾松的初孵若虫、1龄若虫、2龄性分化前若虫、2龄性分化后雌若虫、2龄性分化后雄若虫、雌成虫,以及种群总体,对低温暴露致死的起始敏感温度和-20℃低温暴露的死亡率,均比寄生于湿地松的相应虫态和种群总体低;寄生于马尾松的松突圆蚧种群的半致死有效伤害低温累积比寄生于湿地松的种群低;两种寄主植物松突圆蚧各虫态及种群总体在低温暴露下死亡率的变化规律均符合改进后的双变量Logistic模型。由此说明:寄主植物能够影响松突圆蚧的过冷却点和低温暴露死亡率,寄生湿地松的松突圆蚧种群耐寒性比寄生马尾松的种群弱。3不同地区松突圆蚧的耐寒性差异通过测定广东信宜、福建漳州、泉州和长乐4个不同纬度地区冬季松突圆蚧的过冷却点和低温暴露试验,结果表明不同地区松突圆蚧雌成虫的过冷却点有显著差异,福建长乐的过冷却点最低,广东信宜的过冷却点最高,两地差值达2.03℃。半致死有效低温累积、低温暴露死亡率等指标则不具明显差异。在10～-20℃温度暴露下,广东信宜松突圆蚧种群的死亡率明显高于福建泉州和福建长乐种群,但各地各虫态低温暴露下死亡率的变化规律均服从双变量Logistic曲线模型;广东信宜种群的半致死有效伤害低温累积明显大于福建泉州和长乐种群。说明松突圆蚧对低温有较强的适应性,随着该虫分布纬度的上升,其耐寒性存在逐步增强的趋势。松突圆蚧耐寒性的地理适应性对其进一步向北扩散蔓延具有重要的进化意义。4海拔对松突圆蚧极端温度耐受性的影响采用过冷却点、极端温度暴露死亡率和半致死温度等指标,评价了不同海拔(80、251、391、510和725 m)松突圆蚧的耐寒性和耐热性。结果表明:不同海拔松突圆蚧雌成虫过冷却点存在显著差异,其过冷却点的平均值波动在-15.30～-13.09℃,以海拔391 m的过冷却点最低,510 m次之,251 m最高。不同海拔松突圆蚧1龄若虫、2龄若虫和雌成虫的死亡率均随低温暴露温度下降而增大,在-25℃下均不能存活。在0～-10℃范围内,海拔对松突圆蚧1龄若虫和雌成虫低温暴露的存活率具有显著影响。从半致死低温看,海拔391 m松突圆蚧各发育阶段的耐寒性都最强,海拔80 m最弱,而海拔251、510和725 m的耐寒性因不同发育阶段而不同。不同海拔松突圆蚧的死亡率随暴露温度升高而增大,在45℃下都不能存活;1龄若虫的半致死高温以海拔510 m最高,80 m次之,391 m最低;2龄若虫以海拔510 m最高,725 m次之,80 m最低;雌成虫以海拔391 m最高,251 m次之,80 m最低。松突圆蚧对极端温度耐受性与海拔高度呈非线性关系。5松突圆蚧种群耐热性的季节变化通过比较分析不同季节、不同虫态松突圆蚧在高温暴露下的死亡率和半致死高温累积,结果表明不同发育阶段松突圆蚧的耐热性季节变化不同,但夏季2龄性分化前若虫、2龄性分化后雌若虫和种群总体相对于其他季节,具有明显较强的耐热性,而春季种群耐热性最弱,表现出较强的季节适应性。根据其致死高温45℃,预测松突圆蚧的可以入侵我国南方所有松林分布的区域和毗邻国家与地区。松突圆蚧各发育阶段的半致死高温累积与季节性月平均气温、季节极端高温和平均降水量3个气象因子变化的关系均不密切。6花角蚜小蜂耐寒性的季节变化花角蚜小蜂雌成虫在春、夏、秋、冬4个季节的平均过冷却点分别为-13.7559、-11.9700、-12.7936和-13.6000℃,冬、春季显著低于夏季;雄成虫在春、夏、秋3个季节的平均过冷却点分别为-15.3917、-13.8400和-13.2143℃,春季显著低于夏、秋季;春、夏季雌虫的平均过冷却点显著高于雄虫。-15℃暴露下,各季节雌虫均不能存活;0℃暴露下,春季的死亡率显著低于夏季,-5℃和-10℃暴露下,春季的死亡率均显著低于夏、秋季。各季节雌成虫低温累积-死亡率的关系均服从改进的Logistic模型,但不同季节的半致死低温累积(LSCIT50)有显著差异,春季平均LSCIT50显著低于夏、秋季,秋季也低于夏季,但无显著差异;雌虫的过冷却点、LSCIT50随着季节极端低温下降和极端温差的增加表现出下降的趋势;其LSCIT50也随着过冷却点的降低表现出下降趋势,在一定程度上说明过冷却点与耐寒性具有密切关系,秋季可能是该虫耐寒性由弱变强的重要过渡季节。表明花角蚜小蜂成虫的耐寒性具有明显的季节适应性,降低过冷却点是增强其耐寒性的重要策略,这可能与其在秋季受到较低极端低温和较高极端温差的适应性锻炼有关。各季节花角蚜小蜂雌成虫在0℃暴露下的死亡率均较低,春季在-5℃下的死亡率也较低,在-10℃下的死亡率接近90%。花角蚜小蜂雌成虫的耐寒能力明显弱于松突圆蚧雌成虫(详见第2节),在不考虑海拔高度、气候类型和大气环流等对气温变化的影响及花角蚜小蜂其他虫态的耐寒性情况条件下,预测花角蚜小蜂的潜在利用区域在28°N以南,而在27～28°N之间,花角蚜小蜂的利用将受到海拔和气候异常年份等的限制;随着松突圆蚧进一步北移,花角蚜小蜂—松突圆蚧这一寄生系统的稳定性将被打破,花角蚜小蜂不能继续跟随控制松突圆蚧。7花角蚜小蜂耐热性的季节变化通过比较分析花角蚜小蜂雌成虫春、夏、秋季耐热性变化和夏季种群雌、雄成虫耐热性的差异。结果表明:随着暴露温度升高,花角蚜小蜂各季节的死亡率均逐渐增大,秋季、春季、夏季种群分别在39.5、40和41℃时死亡率均达到100%。暴露温度为39～40.5℃时,不同季节之间种群死亡率具有显著差异,表现为夏季种群的死亡率显著较低。比较对花角蚜小蜂雌成虫造成热伤害的高温累积下限(LLSEHIT)和半致死高温累积(LSHIT50)大小,不同季节雌成虫的耐热性呈现明显的季节变化,其耐热性大小序列为夏季>秋季>春季,但秋季种群死亡对高温累积增加最为敏感,夏季次之,春季最弱。花角蚜小蜂雌成虫半致死高温累积LSHIT50与月平均气温、季节极端高温的季节变化关系十分密切,随着平均气温、季节极端高温的升高,LSHIT50表现出明显的升高趋势。而半致死有效高温累积LSEHIT50与季节性气象因子无明显相关性。表明花角蚜小蜂雌成虫的耐热性具有明显的季节适应性,夏季的耐热性强于秋季和春季。41℃是花角蚜小蜂雌、雄成虫存活的极限温度。在39～40.5℃高温暴露时,雄成虫对高温更敏感,死亡率显著高于雌成虫。在不考虑亚致死高温对花角蚜小蜂的伤害和林间海拔、气候类型、植被、生境等重要的温度因子影响的情况下,在潜在的松突圆蚧极限高温41～45℃入侵区(详见第6节),花角蚜小蜂—松突圆蚧寄生系统在理论上将无法构建,必须寻找新的控制手段。更多还原

【Abstract】 Temperature is an important factor influencing insect physiological characteristics such as growth, development, reproduction and survival. Capacity of tolerance against temperature stress combined with other factors determine the potential distribution and spreading. The introduction of Coccobius azumai Tachikawa to control the typical exotic invasive species Hemiberlesia pitysophila Takagi is an economical, sustainable, effective and common-used measure. This paper makes a comprehensive evaluation on the tolerance capacity of H. pitysophila and C. azumai against extreme temperature, which was embodied by the supercooling point, discriminating temperature (DT), semi-lethal sum of temperature (LST50) and mortality. The effects of host, latitude and altitude on tolerance of H. pitysophila were also evaluated. In addition, we predicted the potential distribution areas of H. pitysophila, C. azumai and their parasitism relationship by combining with regional climate characteristics, which theoretically had an important value for revealing adaptability of the exotic species to local niches and effectively control of H. pitysophila using C. azumai as a biocontrol agent. The main results were as follows:1 Seasonal variation in cold tolerance of the population of H. pitysophilaThe parameters of supercooling point (SCP), mortality exposed to designated low temperature (ME), discriminating temperature (DT) and semi-lethal sum of chill injurious temperature(LSCIT50) of H. pitysophila collected from different seasons were measured and compared in Quanzhou, Fujian Province, China from 2007 to 2008. The individual SCPs of this pest fluctuating from -22.4℃to -3.3℃were measured. Among all the developmental stages of the pest in each season, the winter female adults had the lowest mean SCP (-14.83℃), which was significantly lower than those of the summer female adults, the winter newly hatched nymphae and 1st instar nymphae. However, the mean SCPs of other developmental stages between winter and summer all showed no markedly differences. Experiments exposed to low temperature indicated that the parameters of ME, DT and LSCIT50 of the 1st instar nymphae, 2nd instar nymphae before sex differentiation, 2nd instar male nymphae after sex differentiation, female adults and entire population were all obviously lower in winter than in summer. A linear correlative analysis showed that there were significant positive correlations between the mean air temperature and the LSCIT50s of the 1st instar nymphae, 2nd instar male nymphae after sex differentiation and the entire population, but no significant correlations between SCPs and LSCIT50s at each developmental stage. These results suggest that there is a clearly seasonal adaptability independent of SCP and nearly correlative with air temperature in cold tolerance of H. pitysophila. The cold tolerance of this pest population seems to peak in winter and touch bottom in summer. The SCP isn’t a reliable indicator for the cold tolerance of H. pitysophila.2 Effects of different host plants on the cold tolerance of H. pitysophilaThe supercooling point (SCP) and mortality of H. pitysophila exposed to a designated and regulated low temperature were measured, which feeded on the four different plants, Pinus massoniana, P. elliottii, P. taeda and P. thunbergii. Significant effects of plant on SCP of female adult were observed that the mean SCPs were 0.9～2.3℃higher on P. massoniana and P. thunbergii than on the other two plants. The mean SCP of the 2nd instar female nymphae after sex differentiation was 2.08℃higher on P. massoniana than on P. elliottii. However, a separate experiment showed no remarkable difference between the SCPs of the 2nd instar male nymphae after sex differentiation on the two plants. Another separate experiment of exposure to low temperature indicated that relations between low temperature and mortality of all the insect developing stages and the population on the two plants were all in accordance with a revised double-variable Logistic model. Nevertheless, the incipient sensitively low lethal temperature and mortality exposed at -20℃condition of these developing stages and the population were all lower on P. massoniana than on P. elliottii. The semi-lethal sum effective of chill injurious temperature (LSECIT50) of the population was lower on P. massoniana than on P. elliottii. These results suggest that the SCP and mortality of H. pitysophila exposed to low temperature can be significantly affected by host plants.3 Cold tolerance of H. pitysophila in different regionsThe supercooling points (Scps) and mortality of H. pitysophila exposed to designated low temperature were measured in different regions in China, including Xinyi, Guandong Province, Zhangzhou, Quanzhou and Changle, Fujian Province in the winter of 2007. The results showed that Scps of the female adults had significant differences among the four regions that the lowest mean Scps appeared in Changle, while the highest in Xinyi, whose difference reached 2.03℃. As exposed to low temperature of 10 to -20℃, the mortality of H. pitysophila was remarkably higher in Xinyi than in Changle and Quanzhou. However, the relationship between exposed low temperature and mortality of the population in Xinyi, Quanzhou and Chanle were all in accordance with double variable Logistic model, so were the five insect developing stages such as the 1st instar nymphae, 2nd instar nymphae before sex differentiation, 2nd instar females, 2nd male nymphae after sex differentiation and female adults. The semi-lethal sum effective of chill injurious temperature (LSECIT50) was also higher in Xinyi than in Quanzhou and Changle. This paper indicates that H. pitysophila can adapt to low temperature, and the cold tolerance might become stronger with the latitude rising.4 Extreme temperature tolerance of H. pitysophila at different altitudesCold tolerance and heat tolerance of at altitudes of 80, 251, 391, 510 and 725 m were measured and compared by the indices of supercooling point (Scp), mortality and semi-lethal temperature (LT50). The results showed that there were remarkable differences among Scps of female adults at different altitudes that the lowest Scp appeared at the altitude of 391 m, while the highest at 251 m. It was an increasing trend in mortality as the exposed low temperature declining, and no survivals existed at -25℃. When exposed to the low temperature of 0～-10℃, mortalities of H. pitysophila were significantly affected by altitudes.. Its lowest LT50 of low temperature appeared at the altitude of 391 m. It was an increasing trend in mortality as the exposed high temperature rising, and no survivals existed at 45℃. The altitude also significantly affected the pest’s mortality exposed at high temperature conditions, and its highest LT50 of high temperature appeared at the altitude of 391～510 m.. This study suggests that the extreme temperature tolerance of this pest had no linear relationship with altitudes.5 Seasonal variation in heat tolerance of H. pitysophilaBy means of the heat exposure methods, the mortality and semi-lethal sum of high injurious temperature (LSHIT50) of H. pitysophila among different seasons and developmental stages were analyzed and compared, and its the heat tolerance and seasonal adaptability were also synthetically evaluated. The results showed that the 2nd instar nymph before sex differentiation, the 2nd instar female nymph after sex differentiation and the entire population had significantly higher heat tolerance in summer than in other seasons, and appeared to a clearly seasonal adaptability characteristics. The lethal high temperature might be fluctuated around 45℃, thus it had the potential to spread southward and to make more bad damages. However, this seasonal adaptability to heat had no remarkable relationship with the three climate factors of mean air temperature, extreme high temperature and rainfall.6 Seasonal variation in cold tolerance of C. azumaiThe parameters of supercooling point (SCP), mortality exposed to designated low temperature and semi-lethal sum of chill injurious temperature (LSCIT50) of the chalcid adults collected from different seasons were measured and compared in Quanzhou, Fujian Province, China during 2007 to 2008. Mean SCP values of female adults from spring, summer, autumn and winter were -13.7559,-11.9700,-12.7936 and -13.6000℃, respectively, and spring and winter female adults had all a significantly lower value than summer female adults. Mean SCP values of male adults from spring, summer and autumn were -15.3917,-13.8400 and -13.2143℃, respectively, and the value was significantly lower from spring than from summer and autumn. Additionally, mean SCP values of female adults were all markedly lower than those of male adults in spring and summer, while was equivalent in autumn. Experiment of exposure to low temperature suggested that none of female adults from any seasons survived at -15℃. However, mortality of female adults was clearly lower in spring than in summer at 0℃, and than in summer and autumn at -5℃and -10℃. The relationships between sum of exposed to low temperature and mortality of female adults from each season were all highly fitted to revised Logistic model. Significant differences were observed between LSCIT50s of female adults estimated by this model from different seasons. Mean LSCIT50 of spring female adults was significantly lower than those of summer and autumn female adults. Its SCP and LSCIT50 seemed to decease with decrease in seasonal extreme low air temperature and increase in seasonal extreme difference in air temperature, and its LSCIT50 also seemed to decease with SCP decreasing. These results suggested that there is an obvious adaptability to seasonal variation of air temperature in cold tolerance of C. azumai adults; in the wild, autumn may be an important duration for increasing its cold tolerance by acclimation of seasonal low extreme air temperature and high extreme difference in air temperature.7 Seasonal variation in heat tolerance of C. azumaiThe heat tolerance of C. azumai was analyzed and compared in different seasons through exposure to high temperature method. The results showed that there was an increasing trend of mortality in the parasitoid of female adults from each season with the rising of exposed temperature. However, significant death differences were observed among different seasons when the parasitoids exposed to 39～40.5℃, and the mortality of summer female adults seemed to be the lowest. The results for the indices of the lower limited sum of effective heat injurious temperature (LLSEHIT) and the semi-lethal sum of heat injurious temperature (LSHIT50) showed that the sequence of heat tolerance in female adults in various seasons was summer >autumn>spring, and a clearly seasonal adaptability to heat was proved. The monthly mean air temperature and seasonal extreme high temperature might be the main causes of this adaptability. A separate experiment showed that the extreme high temperature was 41℃either in female or male adults. Whereas, mortality in male adults displayed higher mortality than that in female adults when exposed to 39～40.5℃, which indicated that the female adults had higher heat tolerance than male adults.更多还原