苏云金杆菌乳剂防治二代棉铃虫保护天敌控制伏蚜的研究

在二代棉铃虫Heliothis armigera卵高峰期,一般年份用200倍,大发生年份用100倍苏云金杆菌(B.t.)乳剂喷雾防治效果达75%以上,可将虫口密度压低到经济损失允许水平以下。防治后调查生防田主要捕食性昆虫天敌比化防田高3倍左右,对伏蚜有较好的控制作用。伏蚜高峰期主要捕食性天敌与伏蚜之比,维持在1:200以上水平,可将防治伏蚜时间推迟10—15天,减少防治1—2次。

THE APPLICATION OF B.T.EMULSION AGAINST COTTON BOLLWORM AND ITS PRESERVING EFFECT FOR NATURAL ENEMIES TO SUPPRESS SUMMER COTTON APHID

0.5% in normal Years or 1% in outbreak years of B.t.emulsion(a preparation of Bacillus thuringiensis),spraying at the egg peak of second generation of cotton bollworm Heliothis armigera,got more than 75% mortality of larvae and kept its population density below the economic injury level.The number of major predators in B.t.treated field is three times more than in insecticide treated field,and maintained the ratio of predators/summer cotton aphid over 1:200 in peak aphid period. The timing and times of control in B.t.treatment were 10-15 days later and 1-2 times less,respectively,than those in insecticide treatment.