Effects Of Pesticides On Activity Of Detoxifying Enzymes In Bradysia Odriphaga Yang ET Zhang

Carboxylesterase,Function oxidase andGlutathione-S-transferase is an important enzyme system for the detoxification of insecticides to pyrethroids,organophosphorus and carbamate insecticides.Bradysia odoriphaga Yang et Zhang is an important vegetable pest.The insect is hazard to the underground part of the bulb in liliaceae vegetable.Using chemical pesticide root control,which exacerbate environmental pollution and cause pesticide residues exceeded in the production.In order to further understand the link between the three detoxification enzymes and the insect resistance this paper provides a new idea for the research of the prevention and control of the diseases of the Bradysia odoriphaga.The main results of this study are as follows:1.Indoor toxicity measurement and determination of the sublethal dosesThe toxicity measurement were tested after the 3rd instar larvae of Bradysia odoriphagawere treated with sublethal doses of three different pesticides by the leaf dipping method bioassay.The results showed that the Bradysia odoriphaga of R-strains and S-strains LC50 respectively are 7.941 mg/L and 8.709 mg/L,278.256mg/L and 53.803 mg/L,137.276 mg/L and 62.333 mg/L which was treated with Chlorpyrifos,Lambda-cyhalotrin and Carbaryl.When Bradysia odoriphaga were treated with Chlorpyrifos Lambda-cyhalothrin and Carbaryl after 48 hours,the sensitivity increase 3.2,5.2 and 2.2 fold,resecetively.Just as well the Bradysia odoriphaga of R-strains and S-strains LC30 LC20 respectively are 14.313mg/L,9.550mg/L and 4.823 mg/L?3.374 mg/L;164.458 mg/L,119.646 mg/L and 33.186 mg/L,24.775 mg/L;106.781 mg/L,91.727 mg/L and 52.484 mg/L,47.299 mg/L by SPSS.2.The determination of detoxifying enzyme activityTo investigate the effects of Chlorpyrifos,Lambda-cyhalothrin and Carbaryl at sublethal concentrations on the active enzymes of Bradysia odoriphaga,the activities of three enzymes,carboxylesterase,function oxidase,glutathione S-tranferase were tested after the 3rd instar larvae of Bradysia odoriphagawere treated with sublethal doses of three different pesticides(LC50,LC30 and LC20)by the leaf dipping method bioassay.The ratio(R / S)of R-strains and S-strains at 12 h,24 h,36 h and 48 h was basically greater than one,and it was found that the activity of detoxification enzyme in the R-strains was higher than that in the S-strains after treated with three pesticides.The activities of detoxification enzymes were inhibited and induced by different sublethal doses and LC50 treatments.However,CarEs and MFOs were induced in R-strains and were inhibited in S-strains.In the GSTs enzyme activity,chlorpyrifos treatment is induced and the other two agents after treatment showed inhibitory effect.Tn summary,the specific activities of detoxifying enzyme in two strains of Bradysia odoriphaga obviously correlated with treated concentrations and times.