Pyrethroids synergize new chemical insecticides in field populations of plutella xylostella (Lepidoptera: Plutellidae)

Diamondback moth,an important insect pest,causes major economic losses to cruciferous vegetables. two field strains were tested for single as well as their mixtures at respective lc50 values for synergistic interaction with laboratory standard leaf-dip bioassays method. there existed no variation in response of p. xylostella to tested x-cyhalothrin,profenofos,emamectin benzoate and lufenuron for both field strains. x-cyhalothrin when mixed with emamectin benzoate and lufenuron proved synergistic for taxila strain but other combinations were antagonistic. same insecticide mixtures when tested on rawalpindi strain showed synergistic effect for all the tested combinations. variation is response might be due to possible different insecticide use. importance of insecticide mixtures with relevance to resistance field problems has been discussed. copyright 2013 zoological society of pakistan.