【作者】 宋树人；

【导师】 张泽华；

【作者基本信息】 中国农业科学院 ， 农业昆虫与害虫防治， 2008， 硕士

【摘要】 目前,国内蝗虫绿僵菌疾病流行病学上的研究还较少。本研究在内蒙古锡林郭勒盟多伦县进行了蝗虫绿僵菌疾病流行学试验,对蝗虫绿僵菌疾病的扩散、传播作了初步探讨。试验地域共发现蝗虫18种,分属网翅蝗亚科、斑翅蝗亚科、斑腿蝗亚科、槌角蝗亚科、剑角蝗亚科、癞蝗亚科、蚱科共7个亚科。对不同植被类型中蝗虫群落多样性特征进行了分析,结果表明:毛足棒角蝗为早发优势种;白纹雏蝗为中期优势种;小翅雏蝗为晚发优势种。沙漠化草场蝗虫群落的Shannon-Wiener指数小于草甸草原向典型草原过渡类型草场和典型草原草场;沙漠化导致蝗虫群落多样性指数降低,沙化草场上大体型癞蝗科和斑翅蝗科所属种的数量较其在非退化草场上高。采用模型N_t=α×t^B×e^-c·t对试验当年当地蝗虫的发生动态进行了拟合,结果显示:主要蝗虫种群数量都表现出季节性单峰波动;盛发期各不相同,致使混合种群高虫口密度持续时间长。根据各蝗虫种的盛发期前后次序,确定最佳防治时期应该选在6月20号以前。采用罩笼饲养试验对个体间疾病的传播进行了模拟,结果显示:野外条件下病虫可以将疾病传播给健虫,在病、健虫混合比例分别为10:50、20:40、30:30、40:20时,同种蝗虫间疾病传播几率可达24.6%、31.0%、39.0%和52.0%;早期发生种对后期种的传播几率可达15.6%、23.5%、32.7%和40.0%;感染率及传播几率随病虫比例增大而提高,种间习性差异可能导致早发种对晚发种间传播率的降低。对圆形施药区外不同距离、方向处绿僵菌疾病田间扩散情况进行了调查,结果显示:疾病可以扩散到施药区外400 m,药后40 d疾病感染率八个方向均值可达8.95%。药区外疾病感染率随时间的推移逐渐上升;不同方向疾病感染水平不同,西北、西南方向较高,西、北、南、东北次之,东、东南方向水平最低,这可能和蝗虫的移动趋向、风向有关。施药区外短距离内疾病的扩散在对虫口有控制作用,施药区外随时间的推移校正虫口减退率逐渐上升,处理后42 d距离施药区200 m处校正虫口减退率8个方向均值可达44.05%。校正虫口减退率高低水平在不同方向上也各不相同,与疾病感染率高低方向基本一致。在施药方式上进行了条带间隔处理试验,结果表明:蝗虫移动扩散的习性可以有效地将病原传播到未施药区域;平行距离120 m的2施药条带间区域,药后49d校正虫口减退率达88.92%,防效良好,间隔施药的方式值得在现实防治中进行尝试。采用2种模型和多个空间分布型指标,对药后药区内残存蝗虫和僵虫的空间分布型进行了研究。结果显示:施药后随蝗虫种群密度的减小,处理区残虫的分布型不同时间上呈现聚集-随机交错变动,僵虫的空间分布型为聚集分布;采用Taylor幂法则、改进的Iwao模型分析表明,整个调查时段处理区残虫、僵虫的空间分布均为聚集分布。药后蝗虫点片状死亡,部分地片相对密度较高,残虫分布型趋向聚集;自然消除作用使僵虫密度很低,低密度下取样产生大量空样本,僵虫的分布型产生聚集假象。蝗虫染病死亡前的迁飞移动、取食交配等行为是病原扩散传播的主要方式之一。染病未死蝗虫携病原运动可以促使疾病的空间扩散,僵虫是疾病后期潜在的传播源,理论上,后期流行中病原种群的分布型将于僵虫一致。更多还原

【Abstract】 Epidemiology of Metarrhizium anisopliae was made in the Duolun Caimu Mountain Reservation Area in Inner Mongolian.There are 18 grasshopper species belonging to 7 subfamilies including Arcypteridae,Oedipodidae,Catantopidae,Gomphoceridae,Acrididae,Pamphagidae and Tetrigidae were recorded in the experiment area.The characteristics of grasshopper population diversity in different habitat environment was analyzed and the result showed that the predominant species was Dasyhippusbarbipes(F.-W.)in the early occurrence period,Chorthippus albonemus Cheng et Tu in the middle and Chrothgppus fOIlax(zuboysky)in the late.The Shannon-Wiener index of degraded grassland was less than that of typical steppe and transitional type between meadow steppe type and typical steppe,In addition,desertification of grassland results in the decrease of grasshoppers diversity index and the amount of Oedipodidae and Pamphagidae with bigger appetite and bigger somatotype in degraded grassland was higher than that in others habitat environment.Mathematical models of population dynamic showed the amount of main populations were fluctuating in single peak,and different full incidence period of species resulted in the longest duration of high population density,Thus,the optimum control period should be before June 22 in current year.Results of cage experiment showed that affected grasshopper could spread disease of Metarrhizium anisopliae to health.When the proportion of affected and health grasshopper was 10:50,20:40, 30:30 and 40:20,the transmission rate between individuals within same species was 24.6%,31.0%, 39.0%and 52.0%respectively,while the transmission rate from species occurring early in the season to those occurring late was 15.6%,23.5%,32.7%and 40.0%respectively,and this maybe resulted from interspecific difference.Disease of Metarrhizium anisopliae can spread 400 meters far away from spraying area,and the average of infection rates from 8 directions around treatment area was 8.95%at 40 days after spraying, and the infection rate increased with time delaying.The level of infection rates from different directions was different,and it was the highest in northwest and southwest,east,north,south and northeast took second place,southeast and west were the lowest.The migratory tendency of grasshopper and wind direction may affect the spread of disease.Decrease of grasshopper population has been obtained with the spread of disease from spray area.At 200 metres distance to the treatment area,the average of corrected mortality from 8 directions was 44.05%at 42 days after spraying.The corrected mortality of different directions were different from each other,the level of corrected mortality keep consistent with infection rate in directions.Metarrhizium anisopliae oil was sprayed on band pattern,and the results showed that moving and feeding behavior of grasshopper could spread disease,an effective control was obtained in non-spraying insecticide area between sprayed bands.The spatial distribution of residual grasshoppers and cadavers after Metarhizium flavoviride oil spraying were analyzed by some indexes comprehensively in different sample interval and verified with Taylor’s Power Law and improved Iwao’s regression method during whole investigation period.The results showed that the spatial pattern of residual grasshoppers had the characteristics of regular aggregation and random distribution with the decrease of population density,and the cadavers were in aggregated pattern of distribution in different sample interval.The analysis of improved iwao’s patchiness and Taylor’s law showed that the spatial pattern of residual grasshoppers was aggregated within the whole investigation period which the cause was different reduced degree of densities in some plots after sprayed.Cadavers appeared to a false appearance of aggregative distribution with lower density and lesser sampling numbers.更多还原