齐螨素(Avermectin)对菜蛾的防效及对菜田害虫—天敌群落结构的影响

Studies on effectiveness of avermectin to Plutella xylostella and its effects to farmland community structure of pests and their natural enemies:

通过多次的田间药效试验和室内毒力测定 ,明确齐螨素在浙南菜区推广 5年来 ,菜蛾对其尚未产生明显抗药性 ,其毒力回归式Y =4 .994 9+0 .892 0X ,LC50 =1.0 132mg/L ,田间防效可达 90 %以上 ,仍具有很高的推广价值 ;本研究同时表明 ,齐螨素对菜田蜘蛛毒性较强 ,对菜蛾绒茧蜂的毒性较小 ;由于菜田防治区主要害虫和天敌的数量受到有效的抑制 ,群落多样性指数 (D、H’和Bril louin)与对照相比 ,处于低值水平 ,菜田害虫—天敌群落结构和稳定性遭受较大破坏 。

Through repeated field trials of pesticide and indoor toxicity evaluation.we found out since spreading of Avermectin in the south Zhejiang vegetable areas five years ago, Piutella Xylostella has not become resistant to the pesticide.The toxicity regression formula is Y =4.9949+0.8920 X ,LC 50 is 1.0132 mg/L,the field revention effect is more than 90 percent.Therefore Avermectin still has very high spreading values.This research found out the toxicity of Avermectin to farmland spiders is strong,and has little toxicity to braconid wasp.Because the main pests and natural enemies have been effectively controlled in quantities,the diversity index of community (D,H',Brillouin,etc.)were lower than those of the conrol.The farmland community structure and of pests and their natural enemies its stability have been strongly destroyed,which shows the application of Avermectin quiet disturbed vegetable field ecosystem.