异硫氰酸苄酯作用下大豆胞囊线虫的运动及孵化

摘要

为研究异硫氰酸苄酯（benzyl isothiocyanate，简称BITC）对大豆胞囊线虫（soybean cyst nematode，SCN， Heterodera glycines）的影响，对BITC和3种背景溶剂（乙醇、甲醇和二甲基亚砜）处理下大豆胞囊线虫二龄幼虫（J2）的活动和卵的孵化率进行测定。结果表明，3种溶剂对S C N卵的孵化及J2的行为影响差异显著。J2对3％和5％的乙醇、甲醇以及2％、4％的二甲基亚砜（DMSO）敏感。3％、5％的乙醇处理1 h后，J2视觉评估分析（VAA）值与对照相比下降明显；3％、5％的甲醇处理1 h后，J2的活动显著被抑制，但1％的甲醇和清水对照处理没有显著差异。2％和4％的DMSO处理后线虫活性与对照相比显著降低。以1％甲醇为溶剂，0．02和0．03mmol／L BITC能迅速降低J2的活性，0．03 mmol／L BITC处理2h和0．02mmol／L处理4h，J2完全失去活动能力；0．03mmol／L BITC处理6d的卵孵化率显著降低（P＜0．05）；不同浓度BITC处理完整胞囊后48h，孵化率与对照仍无显著差异。结果表明，大豆胞囊线虫J2对不同溶剂的敏感性差异明显，以1％甲醇为溶剂，0．02和0．03mmol／L BITC可显著降低J2活动能力，自由卵和胞囊卵比J2更抗BITC。试验结果可为杀线虫药剂筛选时溶剂的选择提供重要的信息，为深入研究BITC的作用机理提供理论依据。%The effects of three solvents and different concentrations of benzyl isothiocyanate (BITC)on the be-havior of soybean cyst nematode (SCN,Heterodera glycines)second -stage juveniles (J2)and eggs were deter-mined through micro-well bioassays.The results showed that responses varied with the test materials and concen-trations.Behavioral bioassay scoring by visual assessment assay (VAA)was performed with different solvents and different dosages of BITC.The nematode was sensitive to ethanol and methanol 1 h after exposure,and the J2 VAA scores after 3% and 5% ethanol treatments significantly decreased comparing with the control.Both 3% and 5%methanol treatments significantly inhibited J2 movement 1 h after exposure,but no significant difference was ob-served between 1%methanol and the control (water).Both 2%and 4%dimethylsulfoxide (DSMO)significantly decreased comparing with the control.Meanwhile,0.02 and 0.03 mmol/L BITC significantly decreased J2 activity immediately;J2 lost its activity 2h after exposure to 0.03 mmol/L and 4h after exposure to 0.02 mmol/L.J2 loco-motor behavior could not be recovered with water 2h and 3h after exposure to different BITC concentrations.Moreo-ver,0.03 mmol/L BITC remarkably affected the hatching of fresh eggs,showing a significantly lower hatching rate than those of control and other treatments 6d after incubation in BITC solution (P<0.05).Hatching rate of eggs from the cysts exposed for 48 h to different BITC concentrations had no significant difference from that exposed to water control.These results suggested J2 showed obvious difference in sensitivity after exposure in different solvents,and 0.02 mmol/L and 0.03 mmol/L BITC significantly reduced J2 activity,free eggs and cyst eggs had higher resistance to BITC than those of J2.Our finding could be useful for selecting solvents of screening nematicideand toxic mechanism of BITC to J2 of Heterodera glycines.