【作者】 冯晓慧；

【导师】 方继朝；

【作者基本信息】 南京农业大学 ， 农业昆虫与害虫防治， 2011， 硕士

【摘要】 大螟Sesamia inferens Walker隶属于鳞翅目Lepidoptera/、夜蛾科Noctuidae,是水稻重要害虫之一。其寄主范围很广,是典型的杂食性昆虫。近年来因各种原因,大螟在局部地区大发生,在部分地区上升为主要害虫。为此,本研究主要从三方面解析大螟种群的发育特性及防控因子。一是因近年来各地种植业结构变化,经济和饲料作物面积不断增加,大螟是多食性昆虫,不同寄主植物对其影响尚不明确,为此进行了大螟幼虫对不同寄主植物的选择性以及在不同寄主植物上饲养其生长发育特性的研究；二是针对目前生产上主治药剂对大螟防效不佳,缺乏明确的高效防治药剂,进行各种药剂的室内活性筛选及田间防效评价；三是切合绿色食品及食品安全需要,研发生物农药资源,收集田间大螟病虫体,分离病原微生物,并测定其杀虫活性。主要结果如下。1.大螟初孵幼虫对茭白(自市场购买)、小麦(扬麦8号)、玉米(晶甜3号、晶糯3号)、水稻(南京11号、武育粳3号、两优培九)共7种寄主植物有明显的选择性。Y型嗅觉仪测定表明,大螟幼虫对不同寄主植物两两组合的选择性存在显著性差异,依次优先选择甜玉米(晶甜3号)、茭白、糯玉米(晶糯3号)、杂交籼稻(两优培九)、常规籼稻(南京11号)、粳稻(武育粳3号)、小麦(扬麦8号)。分别用这7种寄主植物饲养大螟,其取食不同寄主植物的发育和繁殖也存在明显差异。利用种群生命表参数综合评价表明,茭白最适合大螟种群的发育和繁殖,其后依次为籼稻南京11号、杂交稻两优培九、粳稻武育粳3号、晶甜3号、晶糯3号、小麦。2.在室内测定不同类型药剂对大螟的卵和3龄幼虫的触杀活性以及对初孵幼虫的胃毒作用,在此基础上,对毒力较高的两种药剂进行了田间防效试验。结果表明,室内测定的13种杀虫剂中,阿维菌素、高效氯氰菊酯、甲氨基阿维菌素苯甲酸盐和康宽对大螟三种不同虫态的杀虫活性均较高；发现国内创制的环氧虫啶对大螟的卵及初孵幼虫也有较高杀虫活性,LCso分别为9.187 mg/L和10.383 mg/L。田间试验表明,5%甲维盐WG 11.25 g (a.i.)/hm2防治效果最佳,杀虫效果达95.54%,保穗效果为97.37%,20%康宽SC 30 g (a.i.)/hm2杀虫效果为89.61%,保穗效果为95.33%,均显著优于对照药剂40%毒死蜱EC 480 g (a.i.)/hm2或92.1%杀虫单1200 g (a.i.)/hm2的相应防效。3.从大螟病虫体上分离多种微生物,从形态学观察,包括12种细菌、9种真菌。其中5种细菌(B11,B12,B22,B30,B32)和1种真菌(F1),对甜菜夜蛾和斜纹夜蛾都有致病性。B11,B12,B22,B30,B32对两种夜蛾3龄幼虫的校正死亡率达58%以上；其中B30对两种夜蛾的毒力最高,感染5天幼虫校正死亡率分别为89.29%和79.41%。F1对3龄甜菜夜蛾和斜纹夜蛾的幼虫致病性很高,对甜菜夜蛾的致死中量LDso为5.0×103孢子/头,对斜纹夜蛾的LD5o为2.65×105孢子/头；饲喂含5×106孢子的人工饲料,感染的甜菜夜蛾和斜纹夜蛾幼虫6天校正死亡率分别为100%和76.50%。更多还原

【Abstract】 Sesamia inferens walker (Lepidoptera:Noctuidae) is one of the major pests to rice. It has a wide host range, so it is a typical of omnivorous insects. In recent years, for various reasons, S. inferens has significantly risen as a major pest in extensive areas where various crops including rice, special varieties of maize and vegetables are widely planted. This study is designed to aim at three aspects related to the upward population of S. inferens. First, to adapt to the market economy of our country in recent years, local cropping structure has changed greatly on a nation wide scale. Economic and forage crop planting area has been evidently increasing. In that S. inferens is one of polyphagous insects, the influence of different host plants to it has been unclear yet. So we need to study how the S. inferens larvae select different host plants and what its growing and developing characteristics are respectively after eating different host plants. Second, because effect of the currently and extensively used insecticides for control of S.inferens is not good, we need a screening in laboratory and further efficacy evaluation in field of distinct types of insecticides against the pest. Third, to meet the needs for green food and food safety, we need to exploit environment-friendly biocontrol agents by, first of all, collecting and isolating entomopathogenic resources from a disease or dead S. inferens in field, and identifying their insecticidal activity. The main results in this study are as follows.Newly hatched larvae of S. inferens to 7 kinds of host plants that are water bamboo (in market), wheat (Yangmai NO.8), corn (Jingtian NO.3, Jingnuo NO.3), rice (Nanjing NO. 11, Wuyujing NO.3, Liang-you-pei-jiu) showed significantly selectivity between a combination of two different host plants. And development and reproductivity of the S. inferens population varied significantly when it feeded on different kinds of host plants. Comprehensive evaluation using life table parameters showed that the most suitable plant for S. inferens development and reproduction is water bamboo, followed by Nanjing NO. 11, Liang-you-pei-jiu, Wuyujing NO.3, Jingtian NO.3, Jingnuo NO.3, and the wheat.Toxicity of several kinds of chemical insecticides to the eggs, first instar larvae, and third instar larvae of S. inferens was respectively determined in laboratory conditions. The results showed that the toxicity of avermectins, beta cypermethrin, emamectin benzoate (banleptm) and chlorantraniliprole to the S. inferens eggs,1 instar larvae, and 3rd instar larvae was evidently better than that of other tested insecticides. Found that the toxicity Cycloxaprid to the S. inferens eggs and 1 instar larvae was only less than the above four insecticides and LC was respectively 9.187 mg/L and 10.383 mg/L. The field test showed the similar results that efficacy of dosage 11.25 g (a.i.)/hm2 of emamectin benzoate 5% WG was 95.54% for control of S. inferens and 97.37% for control of damaged rice white heads (panicles), the best among those of the four tested insecticides in paddy, and efficacy of dosage 30 g (a.i.)/hm of chlorantraniliprole 20%SC was 89.61% for control of the borers and 95.33% for control of the rice white heads, much better than that of the control insecticide chlorpyrifos 40%EC at 480 g (a.i.)/hm2 or monosultap 92.1%T at 1200 g (a.i.)/hm. So emamectin benzoate or avermectins, and chlorantraniliprole were both kinds of insecticides more effective than the others for control of S. inferens in rice production.The microbes including 12 isolates of bacteria and 9 isolates of fungi were separated from disease-producing S. inferens worms. Of the microbes 5 isolates B11, B12, B22, B30 and B32, and one fungus F1 are evidently entomopathagenic to the 3rd instar lavae of Spodoptera exigua and Spodoptera litura in laboratory with the corrected mortality of 50% or more noctuids, And B30 virulence is the highest of the entomopathagens to the both noctuids respectively with the mortality of 92.9% against S. exigua and 79.4% against Spodoptera litura larvae just infected 5 days. The Fl pathogenicity to the 3rd instar larvae of S. exigua and S. litura was high respectively with LD of 5.0 x 10 and 2.65 x 105 spores per larva. And the corrected mortality of S. exigua and S. litura larvae feeding on diet including 5 X 106 F1 spores was respectively 100%和76.50%6 days.更多还原