Resistance Risk And Sublethal Effect Of Chlorantraniliprole In Diamondback Moth,Plutella Xylostella (Lepidoptera: Plutellidae)

The diamondback moth, Plutella xylostella （L.）（Lepidoptera: Plutellidae）, is one of the mostdestructive insect of cruciferous plants which is worldwide distribution. Chlorantraniliprole is areduced-risk insecticide with brand new mechanism of action which has significant effect in lepidopterainsect. It selectively binds to ryanodine receptors in insect muscles resulting in an uncontrolled release ofcalcium from internal stores. In this paper, we research resistance risk and sublethal effect ofchlorantraniliprole in diamondback moth.1．Resistance selection and cross resistance to chlorantraniliprole in Plutella xylostellaThe resistance population with16.81-fold resistant ratio （17.11-fold resistant ratio to initialpopulation） has been treated23times by chlorantraniliprole in the laboratory, preliminary to mediumresistance level. The resistance population and susceptible population of diamondback moth were usedfor evaluating cross-resistance to12common insecticdes which were generally used in diamondbackmoth prevention and cure with leaf-dipping method in the laboratory. The result showed that theresistance population has medium cross-resistance to cyantraniliprole, and a little cross-resistance toflubendiamide, abamactin and emamectin benzoate. There were no cross-resistance to beta-cypermethrin,chlorfluazuron, diafenthiuron, indoxacarb, dursban, fipronil, chlorfenapyr and spinosad in the resistancepopulation. The result suggested that it could be hepful to delay chlorantraniliprole resistancedevelopment in diamondback moth control when applied in alternation with no cross-resistance or a littlecross-resistance insecticides in the field.2. Realized heritability of resistance to chlorantraniliprole in Plutella xylostellaIn order to evaluate the resistance risk of diamondback moth （R） to chlorantraniliprole, Realizedheritability （h²） of different stages was evaluated based on the method of Tabashnik’s. The result showedthat the realized heritability for the entire stage was0.1260, as well as0.09610（F₀-F₈） for the first stageand0.1321(F₉-F₂₅) for the later stage. Assuming that the slope was2.0that similar to the actual valueand h²was0.1260, it required9.02-19.94generations of resistance population for its resistance increase10-fold, under the situation of mortality between50%and90%. This suggested that there wassubconsciously resistance risk of diamondback moth to chlorantraniliprole.3．Biochemical mechanisms of resistance to chlotraniliprole in Plutella xylostellaThree synergists of piperonyl butoxide, phosphate defoliant and diethyl maleate have significantsynergism to chlorantraniliprole with the ratio of2.032,3.932,2.422in the resistance population, but nosynergism in the susceptible population. Activities of three kinds of detoxification enzymes were allincreased in resistance population compared with homologous susceptible population, as well as theactivity of esterase increased most. The result showed that the activity of mixed function oxidase,esterase and glutathione-s-transferase should contribute to the chlorantraniliprole resistance indiamondback moth.4．Sublethal effect of chlorantraliprole to Plutella xylostellaTo provide guidance to the appliment of chlorantraniliprole, sublethal effects of chlorantraniliprole on diamondback moth were evaluated by treating2ndand3rdlarvae. LC₂₅and LC₄₀doses of theinsecticide were determined by leaf dipping bioassay method. Based on the bioassay method, mortality,feeding amount, pupa time, pupal weight and adult emergence of the insect were researched. Comparedwith control group, the growth and development of the treatment group larvae were significantlyrestrained, the larval stage were remarkably prolonged, feeding amount, pupal weight and pupation ratewere also reduced, as well as the increase of mortality. The result demonstrated that sublethal dose ofchlorantraniliprole had a negative effect on the population development of diamondback moth and itprovided significance toward the establishment of IPM program.