【作者】 魏智娟；

【导师】 尤民生；

【作者基本信息】 福建农林大学 ， 农业昆虫与害虫防治， 2008， 硕士

【摘要】 氮是植物和节肢动物生长发育过程中不可缺少的重要营养元素之一,长期大量施用氮肥是引起害虫猖獗为害的主要原因之一,但是有关氮沉积对植食性昆虫影响的研究还很少。本文研究了不同施氮量对乌龙茶幼龄茶树Camellia sinensis生长力和生理、茶树主要害虫假眼小绿叶蝉Empoasca vitis Gothe和茶蚜Toxoptera aurantii Boyer的生态适应性以及主要天敌草间钻头蛛Erigonidiumgraminicolum Sundevall捕食量的影响。结果表明:1.氮肥对茶树生长和生理的影响幼龄茶树的新梢生物量、根生物量和总生物量以及茶叶产量随施氮量的增加而下降,说明幼龄茶树对氮肥的需求量较小。新梢全氮、叶绿素、游离氨基酸、茶多酚和咖啡碱的含量随着施氮量的增加而增加。新梢叶绿素、游离氨基酸和咖啡碱的含量随着含氮量的增加而增加,而过度施氮或过高的全氮含量使新梢总糖含量下降。其原因是随着施氮量的增加,茶树含氮量提高,降低了碳氮比,大量的碳水化合物被分配用来合成含氮化合物,使茶树游离氨基酸、咖啡碱和叶绿素的含量持续增加,并使总糖含量下降。新梢生物量与其硝态氮含量和游离氨基酸总量显著负相关;根生物量与根碳氮比和新梢咖啡碱含量显著负相关;茎叶生物量和总生物量与根含氮量显著正相关,但与根硝态氮含量和新梢氨基酸含量显著负相关;这是由于过度施氮极显著提高了茶树氨基酸代谢水平,使用于茶树生长的碳代谢产物（如总糖）显著减少,进而影响茶树的生长。2.氮肥对假眼小绿叶蝉和茶蚜影响假眼小绿叶蝉成虫对寄主植物的选择与施氮量呈二次抛物线回归关系,成虫嗜好中等含氮量的寄主植物,而若虫不会区别不同含氮量的寄主植物。假眼小绿叶蝉对茶梢部位的取食存在显著差异,其主要在的3—6叶上取食。成虫产卵时不会区别不同含氮量寄主植物。茶苗施氮会延长假眼小绿叶蝉卵期,不同施氮量对假眼小绿叶蝉二龄和三龄若虫历期的影响较大,进而影响整个若虫历期。根据不同施氮量下的假眼小绿叶蝉实验种群生命表的结果发现:除了施氮量为1.50g/盆时,假眼小绿叶蝉净增殖率R₀为12.84为最低值外,其总体趋势是随施氮量的增加,先上升后下降,最高值30.35出现在2.00g/盆;随着施氮量增加,世代平均周期T值呈下降趋势,而在2.50g/盆处理时,T又有所提高;其内禀增长率r_m与周限增长率λ相差不大,分别在0.14-0.20、1.15-1.22之间。假眼小绿叶蝉幼期死亡率高,其存活曲线属于C型。施氮对连续3代茶蚜的若虫期、生殖力、存活率和体重的影响是不同的。成蚜的寿命随施氮量的提高而显著提高,从不同施氮水平下的各代茶蚜存活率曲线可以看出,三代茶蚜存活曲线均属于B型。组建不同施氮量下的茶蚜连续三个世代实验种群生殖特征生命表,结果表明:随着世代的增加,净增殖率、世代平均周期普遍增加;内禀增长力、周限增长率随着施氮量提高,呈现先上升后下降的S型的变化趋势,中等施氮和过高施氮都有较低r_m和入。两个茶蚜种群趋势指数I＞1。说明,各施氮处理茶蚜种群都会明显增加。分别将假眼小绿叶蝉和茶蚜生长、发育、存活等各特征与茶树各生理因子进行偏相关分析,结果表明:虽然施氮对茶树生理特性有显著的影响,但由寄主植物引起昆虫生物学和生态学的变化是个复杂的过程,很难以某几个指标来评估施氮对昆虫的影响。3.氮肥对草间钻头蛛捕食作用的影响在不同施氮水平下,草间钻头蛛对假眼小绿叶蝉的捕食作用与施氮量无关;草间钻头蛛对茶蚜的日平均捕食量与施氮量呈二次曲线相关,在中等含氮量的茶树上草间钻头蛛对茶蚜的捕食作用最强,茶树含氮量过高会使草间钻头蛛对茶蚜的捕食作用下降。更多还原

【Abstract】 Nitrogen is one of important and necessary nutritional elements for growth and development of tea plants and arthropods.The excessive application of nitrogen fertilizer was considered as one of key factors of rampancy of pest herbivores.But little was known about the effects of nitrogen aplication on herbivores.In this thesis, the effects of different rates of nitrogen application on growth,productivity and physiology of Oolong tea plant Camellia sinensis,ecological fitness of green leafhopper Empoasca vitis Gothe and tea aphid Toxoptera aurantii Boyer,as well as predation of Erigonidium graminicolum Sundevall werestudied.The experiment was conducted in a greenhouse with daily mean temperature of 25℃,70-80%RH and L:D=12:12,at Fujian Agriculture and Forestry University,by varying nitrogen application rates(0.00,0.50,1.00,1.50,2.00,and 2.50 g N·pot^-1).1.Productivity and physiologcal responses of tea plants to different rates of nitrogen applicationThe biomass of young shoots,biomass of roots,total biomass and yield of young tea plants decreased significantly with nitrogen application rate increasing,indicating that the young plants require lower intake and application of nitrogen.The contents of tissue nitrogen,total free amino acids,tea polyphenols,caffeine and Chlorophyll of young shoots increased significantly as the rate of nitrogen application increased.The contents of total free amino acids,caffeine and Chlorophyll of young shoots increased significantly with tissue nitrogen concentration increasing, but the content of total sugars reduced with excessive nitrogen application or high tissue nitrogen concentration of young shoots.These results might result from that more carbon resources were allocated to nitrogen metabolism with increasing nitrogen application,promoting the accumulations of free amino acids,caffeine and Chlorophyll and reducing the accumulation of carbohydrate.The biomass of young shoots was significantly,negatively correlated with the contents of nitrate nitrogen of roots and total free amino acids of young shoots.The biomass of roots was significantly,negatively correlated with the ratio of carbon to nitrogen of roots and caffeine concentration of young shoots.Shoot biomass and total biomass of tea plant were significantly,positively correlated with tissue nitrogen concentration of roots,but were negatively correlated with nitrate nitrogen concentration of roots and the content of total free amino acids of young shoots.The results suggested that the productivity reduction of tea plants with excessive nitrogen application might result from increased total free amino metabolism and decreased carbon-compounds（e.g.,total sugar）.2.Ecological fitness of green leafhopper and tea aphid against the rate of nitrogen applicationAdult leafhopper preferred moderate nitrogen fertilized host,but the nymphae were unable to distinguish different tissue N concents of young shoots.There was a significantly difference among leafhopper feeding positions,usually they feeding on 3rd to 6th leaves.Adult oviposition were also unable to distinguish different tissue N concents.Nitrogen application could prolong the egg period of leafhopper;different nitrogen application rates had strong effects on 2^nd- and 3^rd-instar nymph period of leafhopper,and then impacted the whole nymph period.Based on laboratory population life table of leafhopper against the rates of nitrogen application,we found that,except 1.50 g/pot nitrogen application,net reproduction rate（R₀）of leafhopper was the lowest;the R₀ trend increased at first and subsequently decreased as the rate nitrogen application increased.In reverse,average generation period（T）decreased and then increased.Innate capacity of increase（r_m）and finite rate of natural increase（λ） had no obvious difference between 0.14-0.20 and 1.15-1.22,respectively.Green leafhopper had high death rate in nymphae stage,its survival curves was C style.The effects of different rates of nitrogen applications on the nymph state, fecundity,surival rate and weight of each of 3 continuous generations of tea aphid were different.The life time of adult aphid enhanced with nitrogen application increased.The survival curve of tea aphid was B style,survival rates increased with nitrogen application.Based on the laboratory population life table of tea aphid against the rates of nitrogen application,we found that R₀ and T generally increased with nitrogen application increasing,r_m andλtrends also increased at first and subsequently decreased as S style curve with nitrogen application increasing;I of all 3 generation was more than 1,then the population of aphid obviously increased.Partial correlation analysis between physiological factors of tea plants and the characteristics（including growth,development and survival）of Empoasca vitis and Toxoptera aurantii indicated that nitrogen played a significant part in physiological characteristics of tea plants.But,it also showed that it was difficult to assess the effects of nitrogen to the two pests with a few physiologica indexes of tea plants. Biological and ecological changes of pests induced by host quality were a complex process.3.Spider predation against the rates of nitrogen applicationAverage predation rate of spider Erigonidium graminicolum Sundevall to green leafhopper had no relation to the rate of nitrogen application;but to tea aphid,it had a quadratic relation to the rate of nitrogen application.The most predation to tea aphids occured on tea plant with moderate nitrogen application,excessive nitrogen application decreased spider predation to tea aphids.更多还原