Interaction of hexaflumuron and flubendiamide mixture against the larvae of diamondback moth Plutella xylostella

Diamondback moth has a high potential for insecticide resistance. Usage of insecticides with different modes of action as a mixture is one of the strategies of insecticide resistance management. It can reduce the resistance development rate. In this study, hexaflumuron and flubendiamide were tested as alone and their mixture against the third instar larva of diamondback moth. Three concentrations of each insecticide were used in the mixture. The LC50’s values of hexaflumuron and flubendiamide were calculated as 1.48 and 10.27 mg L-1 against the third larvae, respectively. Bioassay of both insecticide mixtures showed that the mixture at the low concentrations had a synergistic effect, whereas it was cumulative effect at the highest concentration mixture. Binary combination of flubendiamide at the lower concentration with hexaflumuron can increase larval mortality. It reduces latent effectiveness of hexaflumuron and causes to decrease crop loss after treatment. Therefore, the use of mixed insecticides in IPM of diamondback moth is possible only with expert advice in the limited concentrations of them.