杀虫剂对不同蔬菜上小菜蛾毒力及种群动态的影响

通过毒力测定和田间调查,测定了甘蓝、小白菜上的小菜蛾幼虫对敌敌畏、高效氯氰菊酯、阿维菌素的药剂敏感性,以及阿维菌素作用下的不同蔬菜品种上的小菜蛾幼虫的种群动态。结果表明,不同年份、不同蔬菜品种上的小菜蛾对不同杀虫剂的药剂敏感性存在差异。2003年敌敌畏对甘蓝上小菜蛾LC50与2004年的之间没有差异,但2005年的LC50明显高于2003年,但在各调查的年份,小白菜上的小菜蛾对敌敌畏的药剂敏感性没有差异,从蔬菜品种来看,只有在2005年,敌敌畏对甘蓝上小菜蛾的LC50大于小白菜;在各个调查年份,高效氯氰菊酯对甘蓝上小菜蛾的药剂敏感性没有差异,只有2005年高效氯氰菊酯对小白菜上小菜蛾的LC50明显高于2003年,高效氯氰菊酯对甘蓝上小菜蛾的LC50与小白菜上的没有差异;2003年阿维菌素对甘蓝和小白菜上的小菜蛾LC50与2004年之间没有差异,但2005年的LC50明显高于2003年;在调查的各个年份,阿维菌素对甘蓝上小菜蛾的LC50与小白菜上的没有差异。施用阿维菌素对小菜蛾田间种群有明显抑制作用。施用1次阿维菌素的菜田中,虫量回升缓慢,最高值虫量仅约为对照菜田最高峰时的一半;施用阿维菌素2次的菜田中,虫量相对较低,仅在第2次药前有一个小高峰;在甘蓝和小白菜菜田中,小菜蛾幼虫种群数量动态基本一致,但甘蓝菜田的小菜蛾数量明显高于小白菜菜田。

Toxicity of insecticides to larvae of Plutella xylostella collected from different cruciferous vegetable types and influence of abameetin on their population dynamic

Based on the bioassay and field investigation, toxicity of dichlovos, beta-cypermethrin and abameetin to larvae of Plutella xylostella collected from different cruciferous vegetable types were tested, and the influence of abameetin on their population dynamic were also carried out. It shows different insecticides exhibited different toxicity to P. xylostella larvae collected from different hosts. Compared with 2003,dichlovos didn''t show significant discrimination to P. xylostella larvae collected from B. oleracea in 2004,while showed a significant higher toxicity in 2005 than in 2003. Only in 2005, P. xylostella from B. oleracea showed more susceptible to dichlovos than from B. chinensis. Beta-cypermethrin showed no significant difference in susceptibility to P. xylostella larvae collected from B. oleracea among three years, but showed higher toxicity to larvae from B. chinensis in 2005 than those in 2003. Abameetin caused significantly higher LC50 to larvae form B. oleracea in 2003 than those in 2005 while there was no difference between 2003 and 2004. In three years investigated, abameetin didn''t lead to the LC50 difference between larvae from two hosts. Population dynamic in two host fields were similar with lower larvae amount in B. chinensis. Fields treated with abameetin for 1 time could attribute to about half lower peak of P. xylostella larvae than control field. There were no significant peak in the fields treated with with abameetin for 2 time.