苏云金芽孢杆菌防治柑桔害虫的后效作用

1985年在广西隆安县从未施过Bt菌剂的柑桔园中喷洒Bt菌剂(Bt5a5b).1986年对该园的土壤和柑桔叶片取样分析,结果表明,施菌区土壤及叶片的Bt(H5a5b)检出率均高于不施菌剂的对照区。1987年检测果园的鳞翅目害虫,施菌区活虫的Bt检出率为51.4％,其中Bt(H5a5b) 占60.2％,死虫的Bt检出率为81.3％,其中Bt(H5a5b)占67.1％。对照区活虫Bt检出率为20.5％,其中Bt(H5a5b)占34.3％,死虫的Bt检出率为35.7％,其中Bt(H5a5b)占10％。说明施用菌剂两年后,果园中仍残留一定量的Bt,对害虫有致死的作用。

A FIELD STUDY OK THE PERSISTING EFFECT OF BACILLUS THURINGXENSIS IN CITRUS GROVES

In 1985, a B. thuringiensis preparation, Bt H5a5b, was applied in a citrus orchard of Longan County, Guangxi Province which had no previous application of Bt pathogens, to control lepidopterous pests. Samples of the soil and citrus leaves from the orchard in 1986 indicated that the amount of detected Bt was significantly greater than that from a control orchard where Bt was not applied in the previous year. In 1987, two years after the application, various lepidopterous larvae were sampled from the treatment and the control orchards. The percent detected Bt from living and dead larvae from the treatment orchard was 51.4% and 81.3%; respectively. Among them, Bt H5a5b accounted for 60.2% and 67.1%,respectively. In the control orchard, the detected Bt was 20.5%, and 35.7%,from the living and dead larvae, respectively; Bt H5a5b accounted for 34.3% and 10%, respectively. The results demonstrated that Bt could persist for two years in the citrus orchards with remained toxicity -to lepidopterous pests.