Screening of optimum proportion and field effect of mixtures of chlorfenapyr, indoxacarb and chlorfluazuron against Plutella xylostella

Key Words：wordsPlutella xylostella, chlorfluazuron, cotoxicity coefficient, mixture of insecticides, field effec

Abstract：       To develop strategies to control the resistance of the diamondback moth (DBM) to insecticides, the effectiveness of mixtures of chlorfluazuron, chlorfenapyr and indoxacarb were evaluated. The results show that a ratio of 13.20∶1.72 chlorfluazuron to chlorfenapyr was optimal and that this blend had synergic action and a cotoxicity coefficient (CTC) of 241. The optimal ratio of chlorfluazuron and indoxacarb was 2.20∶3.60; this also had synergic action and a CTC of 142. Results of field trials indicated that dilute mixtures of chlorfluazuron and chlorfenapyr and chlorfluazuron and indoxacarb reduced DBM abundance by 84.24% and 85.08% respectively 7 days after spraying. These results were significantly greater than those achieved by the other treatments.