Studies of insecticide resistance in Myzus persicae (Sulz.) (Hem., Aphididae)

Ten insecticides were assayed for toxicity against an unselected and a resistant strain of Myzus persicae (Sulz.). Of the six topically applied insecticides parathion was the most effective, followed by diazoxon, diazinon, aldrin, dichlorvos and p, p′DDT in that order, while the resistance levels were, in descending order, parathion, dichlorvos, diazinon, diazoxon, p, p′DDT and aldrin. Of the four systemic insecticides, pirimicarb was most toxic, followed by dimethoate, phorate and demeton in that order, while resistance ratios were in descending order dimethoate, phorate, demeton and pirimicarb. The organophosphorus resistance spectrum for M. persicae indicated that more than one resistance mechanism is involved, and that resistance acts against diethoxy and dimethoxy compounds.