Melon aphid ( Aphis gossypii) resistance to pesticides

Abstract

Eleven pesticides were applied at their recommended concentrations through a Potter Tower to melon aphid (Aphis gossypii), (Homoptera: Aphididae) from potted chrysanthemums (Chrysanthemum x morifolium) in Auckland. The aphids were either topically sprayed or placed on spray residues on chrysanthemum leaf discs embedded in agar. Mortality was assessed after 48 h. The LC50 for topical application of pirimicarb was also assessed and was over 10 times the recommended field spray concentration. The synthetic pyrethroids, lambda-cyhalothrin and tau-fluvalinate, caused low mortality. The residues of dichlorvos, demeton-s-methyl, methamidophos, acephate, methomyl, maldison and pirimiphos methyl/permethrin mixture, gave lower mortality than topical applications. Mortality was similar for maldison and methomyl in both tests. Endosulfan gave 100% mortality in both tests. Growers are recommended to implement a melon aphid resistance management strategy.