【作者】 郑霞林；

【导师】 雷朝亮； 王小平；

【作者基本信息】 华中农业大学 ， 农业昆虫与害虫防治， 2012， 博士

【摘要】 甜菜夜蛾Spodoptera exigua Hiibner是一种重要的世界性农业害虫,常暴发危害,造成严重的经济损失。甜菜夜蛾是一种避冻型昆虫,无滞育特性,可通过迁飞逃避寒冷的冬季,但也观察到其在高纬度部分地区能以幼虫或蛹顺利越冬,以致于其暴发危害地区的虫源是迁飞而来还是当地的越冬种群仍无定论,所以关于甜菜夜蛾越冬相关的研究也一直是国际关注的焦点问题之一。鉴于此,本论文研究了甜菜夜蛾在我国的越冬区,以期为后续分析虫源性质和预测预报等提供重要的基础资料。主要研究结果如下：1.甜菜夜蛾的抗寒力抗寒力是评价昆虫越冬潜力的重要指标之一。为了弄清甜菜夜蛾是否具备越冬的潜力,研究了季节性和昼夜变温、光周期(Photoperiod, PP)、寄主和土壤湿度对甜菜夜蛾抗寒力的影响。研究结果表明：甜菜夜蛾卵、幼虫和蛹具有一定的抗寒力,且变温(季节性和昼夜温度变化)、寄主和土壤湿度均对其抗寒力有一定的影响。季节性的降温过程(Cold acclimation, CA)显著降低其过冷却点,同时提高了其低温下的存活率,当打破低温驯化时,其低温下的存活率迅速下降。昼夜变温(快速低温驯化Rapid cold hardening, RCH;快速高温驯化Rapid heat hardening, RHH)对各虫态低温下的存活率均有不同程度的影响。在温周期(Thermoperiod, TP)过程中,遭遇快速低温驯化或快速高温驯化时(温周期+快速低温驯化或温周期+快速高温驯化),其存活率显著增加,但恢复高温或低温(温周期+快速低温驯化+快速高温驯化或温周期+快速高温驯化+快速低温驯化)后,其存活率迅速下降；光周期对过冷却点和虫体含水量(Body water content, BWC)无显著性影响,且光周期和龄期间的交互作用对其也无显著性影响；寄主植物对幼虫及蛹抗寒力和冷冻保护剂含量均有显著性影响。寄主对3龄和5龄幼虫及蛹的过冷却点均有显著性影响,但不同虫态的主要冷冻保护剂不同,海藻糖是3龄幼虫体内的冷冻保护剂,甘油是5龄幼虫及蛹体内的冷冻保护剂。土壤湿度对蛹抗寒力没有显著性影响,而土壤湿度主要影响幼虫的化蛹进度及幼虫和蛹的死亡率。土壤湿度越大,幼虫化蛹进度越慢,幼虫和蛹的死亡率越高。基于环境因素对甜菜夜蛾抗寒力影响的结果,提出了其间歇性暴发是由于暖冬、少雨及合适的越冬寄主共同作用所致的假设。2. Climex和ArcGis软件预测甜菜夜蛾在中国的越冬区首次利用Climex和ArcGis软件预测昆虫的越冬区。基于甜菜夜蛾在全球已知越冬点的文献资料,结合中国758个气象站点的历史气象资料,利用Climex中的地点比较法,得出甜菜夜蛾在中国越冬的点状分布图。将生态气候指数(Ecological Index, EI)导入ArcGis中,通过Kriging插值法将EI值的点状图转换成面状图,得出甜菜夜蛾在中国越冬区的南界位于北回归线附近(23.5°N),北界位于长江流域(30°N)。3.甜菜夜蛾在中国越冬区的验证为验证Climex和ArcGis软件预测结果的准确性,采用笼罩实验、越冬实地调查和成虫监测的方法进行验证。以长江流域的武汉地区(软件预测的越冬北界)为代表点进行的笼罩实验,结果表明：蛹能在武汉地区越冬。同时,越冬实地调查(1-3月份)时也调查到了越冬幼虫,且田间的性诱装置也诱捕到了成虫。在全国范围内选取的14个点进行越冬实地调查,结果表明：三亚和广州地区可常年发生,属于常年发生区；龙南、永修、南昌、宜宾和武汉地区调查到了越冬幼虫和蛹,属于越冬区；句容、南京、西安、泰安、安丘、章丘和北京均未调查到越冬虫态,属于非越冬区。这些结果和软件预测结果十分吻合,认为Climex和ArcGis软件预测的甜菜夜蛾在中国越冬区的结果非常准确。更多还原

【Abstract】 The beet armyworm, Spodoptera exigua Hiibner (Lepidoptera:Noctuidae) is an important and cosmopolitan agricultural crops pest, whose populations often explode intermittently resulting in serious economic losses in many areas of the world. S. exigua is a species of freezing intolerance, has known no diapause, and escape the cold winter through migration. However, a few larvae and pupae had been observed to overwinter in high latitude regions so that the primary question that the population source of outbreak regions migrated from southern provinces, or arose from local or both haven’t still a conclusion. So, the issue is always paid attention to as one of focus of the species in the world. In this study, overwintering regions of S. exigua was studied as the basis for analyzing the population source, monitoring and forecasting of this species. Main results are summarized as following:1. Cold hardening of S. exiguaCold hardening is one of the important indicators for evaluating the potential capability of overwintering. The effects of seasonal and diel change of air temperature, photoperiod (PP), host plant and soil moisture on cold hardening were studied. The results showed that S. exigua eggs, larvae and pupae could endure the low temperature above their supercooling point (SCP) and these factors could influence their cold hardening except for PP. The process of seasonal change of air temperature (cold acclimation, CA) decreased significantly their SCPs, and incresasing their survival rate when they were exposed to extreme low temperature after CA. Interestingly, the survival rate decreased rapidly when the process of CA was discontinued. Diel change of air temperature, such as rapid cold hardening (RCH) and rapid heat hardening (RHH), could affect the survival rate of these stages to some extend. During the thermoperiod (TP), survival rate increased significantly after encountering the RCH/RHH (TP+RCH/RHH) of these stages. However, the survival rate at low temperature decreased rapidly when these unexpected temperatures (TP+RCH/RHH) return to RHH/RCH (TP+RCH+RHH or TP+RHH+RCH). Photoperiod didn’t affect the SCPs and BWC of the species, and the interaction between PP and instars could not also influence them. Host plant could influence the cold hardening of larvae and pupae and the levels of cryoprotectant. Host plant could influence the SCP of3rd and5th instar larvae, and pupae, but the cryoprotectants of these stages are different. Trehalose was the cryoprotectant of3rd instar larvae, and glycerol was the cryoprotectant of5th instar larvae and pupae. Soil moisture couldn’t influence the cold hardening of pupae, but affected the larval developmental progress before pupation and larval and pupal mortalities. Soil moisture was higher, the developmental progress of larvae before pupation was slower, and the larval and pupal mortalities were higher. We presumed that the cause of intermittence outbreak over a wide region in S. exigua could be partially attributed to a comprehensive effect of warm winter, little rain and adaptable host plant during winter based on these information mentioned above.2. Projecting overwintering regions of S. exigua in China, using Climex and ArcGis modelOur attempt is the first to explicitly predict the over-wintering range of an insect. In this study, the overwintering regions of S. exigua in China was projected by the method of Compare Locations in Climex model based on the information of overwintering sites consistent with the literature and databases and combined with the meteorological database of758stations in China. The final Ecological Index (EI) for S. exigua in China was output and integrated the output files into ArcGIS. Then, the interpolation method of Kriging within ArcGIS was used to obtain the El surfaces. The results exhibited that the southern and northern overwintering boundaries of S. exigua in China located at the Tropic of Cancer (about23.5°N) and the Yangtze River valley (about30°N).3. Steps toward model validationThree methods, including caged experiment, fieldwork during winter and monitoring the population dynamic of adult by sex pheromone in the field, were adopted toward model validation. Wuhan City located at the Yangtze River valley (the northern overwintering boundary) was chosed as representative point to conduct the caged experiment, and the results indicated that S. exigua pupae could overwinter in Wuhan regions. Furthermore, the living larvae were found from January to March in the fieldwork during winter, and the adult were also captured by sex pheromone from January to March in the region. Fourteen sites were chosed throughout China from southern to northern provinces, and the results showed that all stages of this insect were found throughout the year in Sanya and Guangzhou Cities, so these regions can be considered as perennial damage regions. Living larvae or pupae were found during winter in Longnan and Yongxiu Counties, and Nanchang, Yibin and Wuhan Cities, so these regions can be considered as overwintering regions. However, no individuals were found in Jurong and Nanjing Cities of Jiangsu Province, Xi’an City of Shanxi Province, Tai’an, Anqiu and Zhangqiu Cities of Shandong Province, and Beijing City, so these regions can be considered as non-overwintering regions. All of these data were consistent with the results projected by Climex and ArcGis model. Therefore, we considered that the overwintering regions of S. exigua were accurately projected by Climex and ArcGis model.更多还原