论文部分内容阅读
为了明确苏云金杆菌Bacillus thuringiensis(Bt)和高效氯氰菊酯的协同作用,采用Bt预处理及直接混用2种方式施药,室内饲毒法测定了2种药剂对美国白蛾Hyphantria cunea(Drury)2龄幼虫的活性,同时研究了高效氯氰菊酯对Bt生长曲线的影响。结果表明:试虫先用每mL含1×106个孢子的Bt S19菌悬液预处理,1 d后再用系列浓度的高效氯氰菊酯处理,其48 h的LC50值为0.76 mg/L,而未经预处理,仅用高效氯氰菊酯处理48 h的LC50值为1.28 mg/L;2种处理在高效氯氰菊酯质量浓度为2.25 mg/L时对试虫的半致死时间(LT50值)分别为9.2 h和34.7 h,两者间增效作用明显。对于直接混用,采用1×106个/mL的Bt S19与6 mg/L的高效氯氰菊酯混剂处理,增效作用明显,72 h的共毒系数为122.5,此后再增加高效氯氰菊酯的浓度则表现出轻微的拮抗作用。高效氯氰菊酯处理可使Bt生长对数期延迟,且浓度越高影响越大,说明高效氯氰菊酯可影响Bt芽孢萌发,使菌体增殖延迟。研究表明,先用Bt预处理后再使用高效氯氰菊酯对美国白蛾的作用效果优于二者直接混用。
In order to clarify the synergistic effect of Bacillus thuringiensis (Bt) and beta-cypermethrin, Bt pretreatment and direct mixed application were used in two ways to determine the effects of two agents on the 2nd instar larvae of Hyphantria cunea (Drury) The effect of beta-cypermethrin on the growth curve of Bt was also studied. The results showed that the test insects were pretreated with 1 × 106 spores of Bt S19 suspension per mL for 1 d and then treated with beta-cypermethrin at a concentration of 0.76 mg / L at 48 h After pretreatment, the LC50 value was only 1.28 mg / L for 48 h treatment with alpha-cypermethrin alone. The LC50 of the two treatments at the concentration of beta-cypermethrin of 2.25 mg / L were 9.2 h and 34.7 h, the synergy between the two obvious. For direct mixing, the combination of 1 × 106 cells / mL Bt S19 with 6 mg / L beta-cypermethrin showed obvious synergistic effect, with a co-toxicity coefficient of 122.5 at 72 h and then an increase of beta-cypermethrin concentration Slight antagonism. Beta-cypermethrin treatment can delay the logarithmic phase of Bt growth, and the higher the concentration the greater the impact, indicating that beta-cypermethrin can affect the germination of Bt spores, so that cell proliferation delay. Studies have shown that the first use of Bt pretreatment and then the use of beta-cypermethrin on the white moth effect is better than the two direct mixing.