长期利用赤眼蜂大面积防治玉米螟的效果评价

在辽宁省西丰县、岫岩县,通过17年来长期连续坚持利用松毛虫赤眼蜂大面积防治第1代玉米螟试验结果表明,发现自大面积放蜂治螟以来,玉米螟一代卵期赤眼峰的自然寄生率逐年提高,至今已达(?)O％左右;1、2代玉米螟幼虫和蛹的各种寄生性天敌的自然寄生率也逐年显著提高,由此使一代玉米螟的为害也逐年显著减轻,自80年代以来玉米被害率稳定于10％左右。测定玉米种籽和土壤样品表明:六六六、DDT和1605农药的残留量有所缓解,使天敌种群数量逐步回升,进而加强了这些天敌、对1,2两代玉米螟的自然控制作用,解决了玉米蝶的危害,促使农业生态系统向良性循环发展,达到在较长时期内玉米螟种群数最相对稳定在较低的动态平衡水平上。

The Effect of Long--Term Releasing of Trichogramma on Controlling Ostrinia in Large Area

Using Trichogramma dendrolimi to control the first generation of ostrinia furnacalis has carried out for about seventeen years in Xifeng and Xiuyan Counties,Liaoning Province. The experimental result has shown that the natural parasitizing rate of Trichogramma in the first egg stage of Ostrinia furnace is increased year by year and reaches about 70%, since Trichogramma has been released in large area. The natural parasit - izing rate of various parasitic natural enemise in the larva and pupa stages of the first and second generations of Ostrinia furnacalis also increased year by year obviously,hence decreased the damage rate of corn wtich has been stabilized at about 10% since 1980. Analysis of the samples of soil and corn seed showed that the residue amounts of pesticides 666,DDT,and 1605 are remitted and the population amounts of natural enemies rise aga- in, which will strengthen the natural control to Ostrinia furnacalis Thus, the agricultural ecological system can develop normally along good cycles and these effects make the population amount of Ostrinia farnacalis be maintainied in a low dynamic equilibrium level in a longer period.