【作者】 Ruchuon Wanna；

【导师】 徐志宏；

【作者基本信息】 浙江大学 ， 农业昆虫与害虫防治， 2010， 博士

【摘要】 鳞翅目尤其是夜蛾科,包括了大量的农作物毁灭性害虫。其中棉铃虫对棉花和多种蔬菜等经济作物造成严重危害,在许多国家均属于重要害虫。由于棉铃虫对多种主要化学杀虫剂产生了抗药性,一度成为中国棉花生产的主要威胁。在中国,棉铃虫有几种天敌寄生蜂,其中之一是中红侧沟茧蜂,生产实践上我们需要多种综合措施来改变目前单一使用化学农药来控制棉铃虫的情况。近年的研究趋向于采用生物杀虫剂,尤其是Bt来控制害虫。这种杀虫剂对天敌更友好。由于在中国近年来广泛种植转基因Bt棉,棉铃虫的危害已得到成功控制。虽然最近的实验室研究表明棉铃虫有可能产生对Bt毒素的抗性,这些发现更体现了棉铃虫综合治理的重要性,特别是其中的利用天敌来防治害虫将发挥更重要的作用。在世界各地的多种农业生态系统中,多种天敌共同发挥作用控制棉铃虫。最近的研究工作表明更多的选择性杀虫剂可用于天敌协同作用。复合毒素杀虫剂,BtA阿维苏云菌,由Bt与阿维菌素(由阿佛曼链霉菌发酵产生)复配而成,用于强化对靶标害虫的控制作用。BtA比Bt更广谱杀虫,见效更快速,但目前还没有BtA对棉铃虫和其天敌寄生蜂影响效果的报道。本研究的目的是评价BtA的大量应用对寄生蜂的影响。而这些寄生蜂对害虫的控制发挥了重要作用,因此,研究BtA对棉铃虫和其天敌中红侧沟茧蜂生物学的影响十分重要。在第一个试验中对BtA和其它7种常用杀虫剂(阿维菌素、苏云金杆菌、氯氰菊酯、辛硫磷,定虫隆,氰戊菊脂,和丁硫克百威)杀棉铃虫的效果进行了室内和室外的评估和比较,这些杀虫剂的毒力测定,采用叶片浸渍法,在室内进行生测,24小时后进行观察。结果表明。与辛硫磷、BtA、氰戊菊脂、丁硫克百威、氯氰菊酯、定虫隆、苏云金杆菌相比,阿维菌素对棉铃虫3龄幼虫毒性最强(LC50=0.7364 mg/ml)。饲养于经药剂处理的青菜叶表的3龄幼虫死亡率,在24、48、72小时明显不同,处理幼虫24-72小时后。阿维菌素和辛硫磷残效达到40-70%,而且在辛硫磷室外处理中有发现有药害。BtA,氰戊菊脂、丁硫克百威、氯氰菊酯的处理,随着处理时间的推移,幼虫死亡率上升,定虫隆和Bt在处理后48、72小时开始产生杀虫效果。BtA与其它杀虫剂相比对棉铃虫幼虫杀虫效果没有明显不同,且BtA对青菜无药害。适时使用BtA可以防治棉铃虫危害。第二个试验是用于室内测定BtA对中红侧沟茧蜂及其寄主棉铃虫发育的影响。棉铃虫幼虫体重增长被延缓,但幼虫发育历期增加,蛹重增加(如食料中包括BtA)由于寄主幼虫发育历期增加。寄主幼虫被中红侧沟茧蜂寄生的敏感期相应增加,寄主幼虫饲料中BtA含量为0.5、1、2、4μg/g,如初羽化的寄生蜂成虫饲以BtA浓度为200μg/ml的蜂蜜水时与饲以蜂蜜水的初羽化成虫相比,寄生蜂雌虫和雄虫寿命均明显减少,饲食蜂蜜水和BtA蜂蜜水的成蜂寿命与饲食BTA蒸馏水或蒸馏水或无饲料的成蜂相比,平均寿命明显延长。设有BtA浓度为50、100、200μg／ml，饲食蜂蜜水的雌虫的子代在生物学特性上与对照没有差异,这些生物学特性包括卵-幼虫历期,茧重、雌雄虫茧期,成虫鲜重和成虫寿命。如雌蜂寄生用BtA饲料的寄主幼虫,其雌雄蜂的茧期与对照(无BtA)相比明显延长。最后一个实验中室内采用点滴法残留生测,测定BtA与其它7种杀虫剂相比,其对中红侧沟茧蜂的蛹和成虫的触杀毒性,点滴法测定的结果表明,各处理之间有明显不同。氰戊菊脂对中红侧沟茧蜂的毒力最强(蛹死亡率达73.17%)明显高于其它杀虫剂对蜂蛹的死亡率。而BtA、阿维菌素和辛硫磷对蜂蛹的毒力较弱。而且之间没有显著差异,在残留毒性测定方面,中红侧沟茧蜂雌成虫死亡率有显著差异。辛硫磷和丁硫克百威毒力最强,成蜂死亡率100%。显著高于其它几种杀虫剂,BtA对雌成虫的死亡率为10%,毒性最低。Bt和定虫隆对中红侧沟茧蜂的成虫没有残留毒性的影响。其死亡率与对照相比无显著差异。在两种生测中Bt和定虫隆均未表现出对雌成虫的触杀毒性,并且与对照相比没有显著差异。所以结果表明(1) BtA LC50= 0.7364 mg/ml,叶面生测与其它杀虫剂(阿维菌素、苏云金杆菌、氯氰菊酯,辛硫磷,定虫隆,氰戊菊脂,和丁硫克百威)相比,对棉铃虫毒性中等,(2)在72小时田间试验中BtA与上述其它7种杀虫剂相比没有明显差异,与Bt与对照相比,幼虫死亡率有增加：(3)如果棉铃虫幼虫取食BtA,则BtA对棉铃虫幼虫和中红侧沟茧蜂有影响。取食含0.5-4.0μg/g BtA 6天的棉铃虫体重明显下降。取食含0.5-4.0μg/g BtA的棉铃虫龄期明显增加。如果棉铃虫取令1.0,2.0, and 4.0μg/gBtA,则蛹重明显增加。使用BtA后敏感虫期明显增加。(4)BtA增加了棉铃虫被寄生的敏感虫期长度。使中红侧沟茧蜂有更多的虫期可以寄生。试验表明幼虫取食0.5-4.0μg/g BtA则敏感虫期增加。(5)BtA影响中红侧沟茧蜂成虫寿命。当中红侧沟茧蜂取食BtA 200μg/ml,雌雄虫寿命明显增加。(6)如果成虫取食50-200μg/ml BtA,则BtA对其子代卵幼虫期,蛹重,雄蛹,蛹,成虫鲜重,雄虫和雌虫寿命均无影响,(7)如果寄主幼虫取食BtA 0.5-4.0μg/g和4.0μg/g, BtA对中红侧沟茧蜂有影响,幼虫期和蛹重明显减少。如果寄主幼虫取食4.0μg/g BtA,雌雄虫蛹期明显延长。如果寄主取食2.0-4.0μg/g BtA成虫鲜重明显减少。(8)与化学杀虫剂相比(阿维菌素,氯氰菊酯,辛硫磷,丁硫克百威),BtA对中红侧沟茧蜂的蛹成虫杀虫效果较差。与氯氰菊酯,辛硫磷,丁硫克百威相比。BtA的触杀毒性明显低了13.82%,而且,与阿维菌素,氯氰菊酯,辛硫磷和丁硫克百威相比。BtA对中红侧沟茧蜂成虫触杀毒性较低,少于10%,(9)BtA对于中红侧沟茧蜂比阿维菌素和其它杀虫剂更友好,(10)BtA对靶标生物效果更好,而对非靶标生物更有效,因此建议在生物防治对策中考虑应用。更多还原

【Abstract】 The order Lepidoptera, and more specifically the family Noctuidae, comprise a large number of destructive crop pests. One of these pests is the bollworm Helicoverpa armigera (Hiibner) (Lepidoptera:Noctuidae) which causes damage on cotton and various vegetables, a serious pest of economically important crops in many countries. H. armigera has become a major threat to cotton production in China due to its capacity to develop resistance over time to each of the major synthetic insecticides used in its management. In China, several parasitoid species attack H. armigera in the field; one of these is the braconid wasp Microplitis mediator (Haliday) (Hymenoptera:Braconidae). A revised management strategy is needed to control this pest that incorporates more tactics than insecticide alone provides. Current research is directed toward using biological pesticides, especially Bacillus thuringiensis Berliner or Bt, which are compatible with natural enemies. These findings have highlighted the importance of integrated pest management (IPM) strategies for H. armigera, in which natural enemies could play an important role. A broad complex of natural enemies acts against H. armigera in various agro-ecosystems worldwide. Recent work indicates that more selective insecticides can be developed to combine with natural enemies that are not disrupted by such chemicals. A new multiple-toxin, mixed biocide BtA, Bt toxin mixed with abamectin, produced by fermentation of Streptomyces avermitilis, was formulated, in order to enhance controlling efficiency against more target pests. BtA has overcome the disadvantages of Bt by possessing toxicity against a broader range of pests and a relatively rapid killing speed. However, there are no reports regarding the effects of BtA on H. armigera and its parasitoids M. mediator. The overall objective of this thesis was to evaluate the potential of BtA against H. armigera and the effects on its parasitoid M. mediator. In first experiment, laboratory and field evaluations were conducted to evaluate the efficacy of BtA in comparison to the seven commercial insecticides (Abamectin, Bt, (3-Cypermethrin, Phoxim, Chlorfluazuron, Fenvalerate, and Carbosulfan), against Helicoverpa armigera. Toxicity of these compounds to H. armigera by leaf dip bioassays within 24 h in the laboratory showed that Abamectin was the most toxic (LC50= 0.0062 mg/ml) to the third instar larvae of H. armigera compare to Phoxim, BtA, Fenvalerate, Carbosulfan,β-Cypermethrin, Chlorfluazuron, and Bt, respectively. The mortality of the third instar larvae exposed to Chinese cabbage Brassica rapa var. pekinensis treated with various commercial insecticides were significantly different at 24,48, and 72 h. Abamectin and Phoxim residual efficacy against the third instar larvae at 24 to 72 h after treatment, resulted in larval mortalities from 40 to 70%. BtA, Fenvalerate, Carbosulfan, andβ-Cypermethrin showed increased larval mortalities of H. armigera as time after application increased. Chlorfluazuron and Bt primarily affected H. armigera larvae at 48 and 72 h after treatment, respectively. BtA was not significantly different from the other commercial insecticides against H. armigera larvae. Properly timed treatments of BtA may be used to prevent damage by H. armigera.Second experiment was conducted for determination on the effects of BtA on the development of parasitoid Microplitis mediator (Haliday) (Hymenoptera:Braconidae) and its the bollworm host, Helicoverpa armigera (Hubner) (Lepidoptera:Noctuidae), were evaluated in the laboratory. Weight gain in larvae of H. armigera was initially delayed, but larval developmental period increased and pupal weight increased when they were fed on a diet containing BtA. Due to increased longevity of the host larvae, the susceptible period to parasitization of H. armigera by M. mediator increased when the host larvae were reared on the diets containing BtA at concentrations of 0.5,1,2, and 4μg/g. Longevity of female and male parasitoids significantly decreased when newly emerged wasps were fed on a honey solution containing 200μg/ml BtA in comparison with those fed only on a honey solution. Mean longevity was significantly prolonged when parasitoids were fed on honey solution and BtA-honey solution in comparison with those fed on BtA-distilled water solutions, or distilled water, or nothing. There were no significant differences compared with the control in any biological characteristics for the offspring of female parasitoids fed on the honey solutions containing BtA at concentrations of 50,100, and 200μg/ml; characteristics measured include the egg-larval period, pupal weight, male and female pupal periods, adult fresh weight, and adult longevity. When the female parasitoids parasitized host larvae that had been fed on the diets containing BtA, their male and female pupal periods were significantly prolonged compared to the control (without BtA).Final experiment was conducted for the effects of BtA to the seven commercial insecticides (Abamectin, Bt,β-Cypermethrin, Phoxim, Chlorfluazuron, Fenvalerate, and Carbosulfan) on the pupae and adult stages of M. mediator were conducted to contact toxicity of residual effects in the laboratory by direct-dip and residual bioassays, respectively. Results of direct-dip bioassay showed Fenvalerate was the highest toxicity (pupae mortality values of 73.17%) to M. mediator pupae and significantly higher than pupae mortalities of the other commercial insecticides. BtA, Abamectin, and Phoxim were low contact toxicity to M. mediator pupae and not significantly different. For residual bioassay, Phoxim and Carbosulfan were extremely the highest toxicity (adult mortalities values of 100%) to female of M. mediator adult and significantly higher than adult mortality of the other commercial insecticides. BtA showed the lowest toxicity with mortality value less than 10%. Bt and Chlorfluazuron were no residual effects on M. mediator pupae, with mortalities were not significantly different compare with the control.Therefore, these results suggest that (1) BtA had moderate toxicity of lethal effect (LC50 = 0.7364 mg/ml) on the third instar of H. armigera larvae compare with the other commercial insecticides (Abamectin, Bt,β-Cypermethrin, Phoxim, Fenvalerate, Carbosulfan, and Chlorfluazuron) at 24 h by leaf residue bioassay in the laboratory. (2) BtA was not different efficacy in the field from the other commercial insecticides (Abamectin, Bt,β-Cypermethrin, Phoxim, Fenvalerate, Carbosulfan, and Chlorfluazuron) against H. armigera larvae at 72 h after treatment. BtA showed increased larval mortality of H. armigera as time after application increased. Trend was for increased larvae mortality of H. armigera in residual activity of BtA compared to Bt alone and the control. (3) BtA had affect on the host larvae H. armigera of parasitoid M. mediator when the host larvae fed on the diets containing BtA. Larval weight of H. armigera after feeding on the diet containing 0.5-4.0μg/g BtA for six days was significantly lower compared to the control. Larval period was significantly prolonged at all concentrations of 0.25-4.0μg/g BtA diets. Pupal weight was significantly increased from the control when H. armigera larvae fed on the diets containing 1.0,2.0, and 4.0μg/g BtA. (4) BtA had extended the susceptible larval period of the host larvae H. armigera for parasitization by parasitoid M. mediator and period more opportunity for M. mediator parasitization to occur. The susceptible period increased when the host larvae were reared on the diets containing BtA at concentrations of 0.5-4.0μg/g. (5) BtA had affected on the adult longevity of M. mediator. Female and male longevities were significantly decreased when they fed on a honey solution containing 200μg/ml BtA comparison with a honey solution. (6) BtA was no effect in any biological characteristics (egg-larval period, pupal weight, male pupal period, female pupal period, adult fresh weight, male and female longevity) for the offspring of female parasitoid M. mediator when their mother fed on the honey solutions containing 50-200μg/ml BtA. (7) BtA had affected on the development of the parasitoid M. mediator in the host larvae H. armigera fed on the diets containing BtA. The egg-larval period and pupal weight were significantly decreased when the host larvae fed on the diets containing 0.5-4.0μg/g and 4.0μg/g, respectively. Male and female pupal periods were prolonged when the host larvae fed on a diets containing 4.0μ.g/g. Adult fresh weight was significantly decreased when the host fed on the diets containing 2.0-4.0μg/g. (8) BtA was low effect of contact toxicity to the pupae and adult stages of M. mediator comparison with the other commercial insecticides (Abamecin,β-Cypermethrin, Phoxim, and Carbosulfan) in the laboratory. BtA was significantly lower contact toxicity (mortality value of 13.82%) to M. mediator pupae at the time till emerging thanβ-Cypermethrin, Phoxim, and Carbosulfan within 24 h by direct-dip bioassay. And then, BtA showed the lowest contact toxicity to adult of female M. mediator compare with Abamectin,β-Cypermethrin, Phoxim, and Carbosulfan with mortality value less than 10% within 24 h by residual bioassay. (9) BtA is more conservation of parasitoid M. mediator than Abamectin and the other commercial insecticides used at the same rate in the laboratory. (10) BtA should be included in the developing biological control strategies in crop fields. Because BtA to maximize the positive effects on the target pests and to minimize the negative impact on natural enemies and other non-target organisms.更多还原