The Resistant Risk Assessement Of Diamondback Moth(Plutellaxylostella(L.)) To Chlorantraniliprole And It’s Mixtrue

Diamondback moth,Plutella xylostella(L.),is a major pest of crucifer vegetables.In the long-term use of chemical insecticides against P.xylostella,the issue of insecticide resistance stands out.As a novel insecticide with special action mechanism,chlorantraniliprole makes efficient effect on Lepidoptera pest such as diamondback moth and ensures the safety for human and animals.This paper detects the resistance levels of P.xylostella field population from different regions in Guangxi to three insecticides,assesses the resistance risk of P.xylostella to chlorantraniliprole and it’s mixtrue and preliminarily studies on the cross-resistance and metabolic resistance mechanisms of P.xylostella to chlorantraniliprole.The study provides the theoretical basis for the utilization of this insecticide in the production,prolong lifetime and develop preventing resistance management.The main results were as follows:1.The establishment of experiment population of diamondback moth.The susceptible strains was acquired from Hunan Agricultural University,which the diamondback moth had been reared ten years and it hard never used chemical insecticide.The field population was acquired from Anji,Nanning City、Wuming country、Bingyang country、Lipu country、Liujiang country and Tiandong country.The experiment populations of diamondback moth were established with its leaf of sprouts.The laboratory rearing population of diamondback moth was for bioassay and selection.2.The susceptible toxicity baselines of P.xylostella to chlorantraniliprole,flubendiamid and metaflumizone were determined by the leaf dipping method(IRAC Method No.7)to measure the susceptibility of chlorantraniliprole,flubendiamide and metaflumizone against the larva of six field populations of P.xylostella(L.)in Guangxi province,were evaluated to determine the resistance levels.The results indicated that the resistance levels to the three pesticides of these aera P.xylostella(L)are not up to 5 fold compared with the susceptible strain,except Tiandong Population.In Tiandong country the field population was achieved with resistance ratio 7.6 compared with the susceptible strain.3.The resistant levels of the Anji population of P.xylostella to chlorantraniliprole were monitored from 2010 to 2011.The results showed that the population was still sensitive to chlorantraniliprole,but the resistance ration increased 3.57-4.24 folds.4.The susceptible population of P.xylostella was selected for resistance to chlorantraniliprole,and the resistance realized heritability and resistance risk of P.xylostella were evaluated in the laboratory.After the selection of chlorantraniliprole in the fourteenth time during fifteenth generation,we obtained the data demonstrated that the resistance of P.xylostella against chlorantraniliprole are 13.9 folds.With the method of Tabashnik introducted,the realized heritability(h2)of resistance to the insecticide in diamondback moth was estimated to be 0.124.It was predicted that the strain would require to spend 9.1,13.1,16.9,20.8 generations to take a 5,10,20,40 fold increased to chlorantraniliprole under selective pressure of the sample experiment conditions.5.The susceptible population of P.xylostella were selected for resistance to the mixed of chlorantraniliprole· thiamethoxam,and comparative analysis on the resistance realized heritability between chlorantraniliprole and it’ s mixtrue and resistance risk of P.xylostella were evaluated in the laboratory.After the selection of chlorantraniliprole· thiamethoxam in the fourteenth time during fifteenth generation,we obtained the data demonstrated that the resistance of P.xylostella against chlorantraniliprole· thiamethoxam mixture are 10.6 folds.With the method of Tabashnik introducted,the realized heritability(h)of resistance to the insecticide in diamondback moth was estimated to be 0.117.It was predicted that the strain would require to spend 10.8,15.4,20.4,24.7 generations to take a 5,10,20,40 fold increased to chlorantraniliprol’s mixtrue under selective pressure of the sample experiment conditions.The results showed that mixed agent can dealy the insecticide resistant of diamondback moth to chlorantraniliprole.6.The resistant strain which resistance ratio was 13.9 fold to chlorantraniliprole caused cross-resistance to insecticide.The results show that cross-resistance to beta-cypermethrin,hexaflumuron,chlorpyrifos,emamectin benzoate,bisultap,avermectins was 3.36,2.30,1.96,1.21,1.12,1.09-fold,respectively.7.The activities of detoxication enzymes in susceptible strain and two resistant strain of diamondback moth were detected.The results of biochemical determine showed that:(1)The specific activity of MFOs in chlorantraniliprole resistant strain was significantly higher than that of the susceptible strain,with 2.3 fold of activity ratio.The specific activities of CarE,GSTs were not significantly difference between susceptible strain and chlorantraniliprole resistant strain.(2)The specific activities of MFOs and CarE in chlorantraniliprole·thiamethoxam resistant strain were significantly higher than that of the susceptible strain,with 1.8 fold and 2.09 fold of activity ratio.The specific activity of GSTs was not significantly difference between susceptible strain and chlorantraniliprole· thiamethoxam resistant strain.(3)Comparative on the activities of detoxication enzymes between chlorantraniliprole·thiamethoxam resistant strain and chlorantraniliprole resistant strain,the specific activity of MFOs in chlorantraniliprole· thiamethoxam resistant strain was 0.118 OD.min-1.mg-1 protein,significantly lower than chlorantraniliprole resistant strain’s 0.145 OD.min-1.mg-1 protein.But the specific activity of CarE in chlorantraniliprole· thiamethoxam resistant strain was significantly higher than chlorantraniliprole resistant strain was 3.465 OD.min-1.mg-1 protein,1.650 OD.min-1.mg-1 protein,respectively.And the specific activities of GSTs against all strains were not significant.The activity of detoxication enzymes show that the MFOs play an important role in resistance of P.xylostella to chlorantraniliprole,but the CarE and GSTs were not related significantly.