印楝素乳油对梨小食心虫的防控效果研究

【目的】探索0.3%印楝素乳油对梨小食心虫Grapholita molesta的控制效果。【方法】根据梨小食心虫的生物习性,采用浸渍法和浸虫法对梨小食心虫1日龄、3日龄、5日龄的卵和3龄、5龄幼虫进行了杀虫活性测定,采用药膜法对梨小食心虫初孵幼虫进行毒力测定,并通过田间试验测定0.3%印楝素乳油对梨小食心虫的控制效果。【结果】0.3%印楝素乳油对梨小食心虫1日龄、3日龄和5日龄卵的致死中量分别为6.5195、4.5789、6.6268 mg/L,对初孵幼虫的致死中量为6.0495 mg/L,效果较好,而对3龄和5龄幼虫几乎没有杀伤作用。使用有效成分为2.0 mg/kg~3.0 mg/L的印楝素乳油在田间进行梨小食心虫防治试验时,药后5 d和10 d的防治效果在63.18%~76.22%之间,至药后15 d时,防效则下降到27%以下,果实受害明显,表明该药剂已失去控制作用。【结论】印楝素乳油不能作为防治梨小食心虫的专用药剂,仅可在其发生危害的初期,防治其他害虫时,作为兼治的药剂来使用。

Effectiveness of azadirachtin EC in controlling the oriental fruit moth Grapholita molesta(Busck)

Objectives] To evaluate the effectiveness of the botanical pesticide 0.3% azadirachtin (AZ) EC as a means of controlling the oriental fruit moth (Grapholita molesta). Methods] Immersion and dipping tests were used to determine the insecticidal activity of AZ EC against 1-day-old eggs, 3-day-old eggs, 5-day-old eggs, third instar larvae and fifth instar larvae, and the residual film method to assess the toxicity of this pesticide to newly hatched larvae. The degree and duration of control by spraying AZ EC was also investigated in the field. Results] LC50s of AZ EC with respect to 1-day-old eggs, 3-day-eggs, 5-day-old eggs, and newly hatched larvae, were 6.5195, 4.5789, 6.6268, 6.0495 mg/L, respectively, but the pesticide had no effect on third instar larva and fifth instar larvae. Application of AZ EC at dosages of 2.0-3.0 mg/L reduced the abundance of G. molesta in the field by 63.18%-76.22% 5-10 days after spraying, but decreased to just 27% 15 days after spraying. Conclusion] AZ EC is not an effective insecticide against G. molesta.