【作者】 解海翠；

【导师】 何康来； 彩万志；

【作者基本信息】 中国农业大学 ， 农业昆虫与害虫防治， 2014， 博士

【摘要】 “作物-害虫-天敌”系统对大气CO2浓度升高的适应性规律及机制是全球变暖对农业生产影响的重要研究内容。玉米是我国主要粮食作物之一,亚洲玉米螟及玉米蚜均为玉米生产上重要害虫。研究大气CO2浓度升高等因素介导的玉米、害虫和天敌的生长、发育和繁殖的适应性变化特征及其互作机制,理论上可为阐明未来气候变化情景下“玉米-害虫-天敌”系统的演变规律提供重要的科学依据,实践上对于明确未来气候变化情景下玉米害虫发生危害趋势及天敌控制作用及合理利用具有指导意义。本文通过田间及室内模拟未来大气CO2浓度升高环境下玉米、亚洲玉米螟和玉米蚜及玉米螟卵寄生蜂的生长、发育、繁殖及相互作用。取得以下主要结果。建立了适于我国东北气候条件下玉米种植的24座开顶式气室(Open-top chanber, OTC)。 OTC内CO2浓度稳定控制在试验所需范围内(上下波动不超过50μL/L),OTC内温度、相对湿度均显著高于室外环境。不同CO2浓度处理的OTC内温度、相对湿度间显著不差异。因此,本实验所建OTC群具有一定的增温、增湿效果,能够满足“玉米-害虫-天敌”系统对大气CO2浓度升高响应的试验需求。在3个大气CO2浓度处理,即当前大气(对照),550μL/L和750μL/L CO2浓度的OTC内种植玉米,并接种亚洲玉米螟初孵幼虫。结果显示,与对照相比,高CO2浓度处理玉米株高及产量增加,玉米组织内TNC:N升高,第二代幼虫单株存活率降低。高CO2浓度显著降低越冬幼虫体重及过冷却点,但对其存活率影响不显著。高CO2浓度使越冬后的亚洲玉米螟单雌产卵量降低。大气CO2浓度升高使玉米组织营养质量下降,导致亚洲玉米螟的生存适合度降低。在以下5个处理中饲养亚洲玉米螟：(1)C1(对照CO2浓度处理的CDC环境)+M1(对照CO2浓度处理的OTC内生长的玉米组织),(2) C2(550μL/LCO2浓度处理的CDC环境)+M2(550μL/L CO2浓度处理的OTC内生长的玉米组织),(3) C3(750μL/L CO2浓度处理的CDC环境)+M3(750μL/L CO2浓度处理的OTC内生长的玉米组织),(4) C1+M2(5) C1+M3。结果显示,与C1+M1处理相比,其他处理中幼虫历期均延长、取食量及排粪量增加,并且其他处理间无显著差异。因此,无论是否去掉CO2浓度对幼虫直接影响(幼虫在高CO2浓度处理的CDC环境),幼虫历期均延长,取食量及排粪量增加。与C1+M1处理相比,其他处理中幼虫体重与MRGR均降低。第二代亚洲玉米螟仅在C1+Ml C2+M2和C3+M3处理中饲养。测定指标在处理间变化趋势不变,在同处理的两世代间也无显著差异。但CO2浓度升高降低了第二代亚洲玉米螟存活率。因此,大气CO2浓度升高主要通过改变寄主营养质量而间接影响亚洲玉米螟的生长发育。在不同CO2浓度(Ambient,550μL/L口750μL/L)处理的CDC中测定了赤眼蜂单雌寄生与OTC模拟田间放蜂防治试验。结果显示,在CDC内,与对照相比,高CO2浓度下两种赤眼蜂对亚洲玉米螟卵的单雌寄生发生率、寄生卵粒数、羽化蜂数、羽化率和雌蜂率没有变化,但高CO2浓度显著缩短两种赤眼蜂的子代体长。在OTC内,进行人工接卵后释放松毛虫赤眼蜂,从而模拟田间放蜂试验的结果表明：与对照相比,高CO2浓度下幼虫对玉米为害程度及其存活率没有影响,即释放松毛虫赤眼蜂对亚洲玉米螟的防效不变。高CO2浓度使子代蜂体缩小,因此,大气CO2浓度升高可能降低赤眼蜂对亚洲玉米螟卵的适合度。在CDC内的以下4个处理中用大麦连续饲养两代玉米蚜,(1)对照温度(L/D=22/18℃)与对照CO2浓度(350-400μL/L)；(2)对照温度与高CO2浓度(750μL/L)；(3)高温(26/22℃)与对照CO2浓度；(4)高温与高CO2浓度。多因子方差分析结果显示,温度升高缩短了玉米蚜各龄历期,而高CO2浓度与连续世代分别缩短了玉米蚜4龄及若虫历期。因此,温度为影响玉米蚜发育历期的关键因子。同时,高温、高CO2浓度及连续世代均著提高了玉米蚜繁殖力。并且高温、高CO2浓度使有翅蚜比率提高,因此,蚜虫的扩散能力可能增强。在高温与高CO2浓度的处理中,蚜虫内禀增长力最高,并且连续世代使此趋势加剧。因此,高温和高CO2浓度共同作用下,可能加重玉米蚜对其寄主的为害程度。更多还原

【Abstract】 The adaptation and mechanism of "crop-pest-enemy" to elevated CO2are the main research for the effects of global warming on agricultural production. Maize is one of the main food crops in our country. Asian corn borer, Ostrina furnacalis, and the corn leaf aphid, Rhopalosiphum maidis, are key pests in maize production. The study for effects of elevated CO2on growth and development of maize, pest, enemy and their interaction could provide important scientific evidence for evolution rule of "maize-pest enemy" system under climate change in theory, understand occurrence trend of maize pests, enemy control and rational utilization under climate change in practice. This research simulates the growth and development of maize, pest, egg parasitoid wasps and their interaction under elevated CO2. The results are as following:Improved24open-top chambers (OTCs) were setted up for our trial, that adapt to the maize planting and local northeast climate in China. The CO2concentration within the OTCs was stably controled and closed to the required CO2level (fluctuating range less than50μL/L). The temperature and relative humidity in the chambers were higher than outside. The temperature and relative humidity had no difference among different chambers with each CO2level. Therefore, the chambers could keep the air warmer and wetter. The improved OTCs could meet the requirements of trials of effects of elevated CO2on "maize-pest enemy" system.Newly hatched larvae of O. furnacalis were inoculated in maize plants, and maize plants were planted in the OTCs with different CO2levels (ambient CO2,550μL/L and750μL/L). Elevated CO2increased the plant height and yield of maize plants, decreased the TNC: N in maize tissue, decreased the number of survival larvae per plant for second generation. Elevated CO2decreased the wintering larval body weight and supercooling point. Therefore, the cold hardiness of wintering larvae is enhanced under elevated CO2. While the survival rate of wintering larvae had not been influenced by elevated CO2. The number of egg per female was decreased by elevated CO2. Elevated CO2change the nutritional qulity of maize, which decrease the survival fitness of O. furnacalis.The following5treatments were designed to raise O. furnacalis:1) C1(ambient CO2in CDC)+M1(maize planted in OTC with ambient CO2),2) C2(550μL/L CO2in CDC)+M2(maize planted in OTC with550μL/L CO2),3) C3(750μL/L CO2in CDC)+M3(maize planted in OTC with750μL/L CO2),4) C1+M2,5) C1+M3. Compared with C1+M1, the larval duration was longer and its food consumption and frass were increased in other treatments, and there was no significant difference among other treatments. Therefore, with or without the direct effect of elevated CO2to O. furnacalis, the above results had not been changed. Compared with C1+M1, larval body weight and MRGR were decreased in other treatments. Second generation of O. furnacalis was rared in Cl+M1, C2+M2and C3+M3treatments, the change for above measured indexes among three treatment was similar with above, and there was no difference between two generations in the same treatment. Elevated CO2decreased the larval survival rate in the second generation. Threrefore, elevated CO2could indirectly influence the growth and development of O. furnacalis by nutritional qulity of maize.Parasitism capacity of per female trichogramma(Trichogramma dendrolimi and T. ostriniae) and T. dendrolimi population were conducted respectively in CDC and OTC with different CO2concentrations (ambient,550μL/L and750μL/L). Parasitism occurrence rate, number of parasitized eggs, number of emergence offspring per trichogramma, emergence rate and female ratio were not influenced by elevated CO2in CDC. But elevated CO2decreased the body length of offspring for two trichogramma species. To simulate the field release trial for T. dendrolimi in the OTC, egg card was inoculated in maize plant, at the same time the T. dendrolimi population was released. The damage of O. furnacalis to maize and its survival rate were not influenced by elevated CO2, which indicate that elevated CO2do not influence the effect of T. dendrolimi on the control of O. furnacalis. And the more small body of two trichogramma species under elevated CO2may reduce its fitness to eggs of O. furnacalis.The corn leaf aphid, Rhopalosiphum maidis reared on barley for two generations were examined under four treatments:1) control temperature (22/18℃=L/D) and ambient CO2(350-400μL/L),2) control temperature and elevated CO2(750μL/L),3) elevated temperature (26/22℃=L/D) and ambient CO2,4) elevated temperature and elevated CO2. Multiple variance analysis was used in this experiment. The developmental duration for each age stage was significantly reduced by elevated temperature. The elevated CO2only reduced the development time of4th instar nymph, and the succsesive generation reduced the duration of nymph. Thus, the temperature was the dominant factor to development duration of R. maidis. The fecundity of R. maidis was significantly increased under the elevated temperature, CO2and later generation. Elevated temperature and CO2increased the number of winged aphids, which may enhance the aphid migration. R. maidis had the highest rm under the elevated temperature and CO2treatment, and the effect was increased in the following generation. These results indicated that the combined effects of both elevated temperature and CO2on aphid biology may exacerbate aphid damage on barley under the climate with elevated temperature and CO2level.更多还原