Occurrence of insecticide resistance in field populations of Spodoptera litura (Lepidoptera: Noctuidae) in Pakistan

Field populations of Spodoptera litura from Pakistan were evaluated for their resistance to conventional insecticidal chemistries viz. organochlorine (endosulfan), organophosphates (chlorpyrifos, phoxim, quinalphos, profenofos), carbamates (methomyl, thiodicarb) and pyrethroids (bifenthrin, cyfluthrin) during 1997–2005 using a leaf-dip bioassay method. Generally, resistance levels were very low to low to endosulfan, chlorpyrifos, phoxim, quinalphos, profenofos, bifenthrin and thiodicarb, and moderate to high to methomyl and cyfluthrin. Correlation analysis indicated that insecticides belonging to the same class such as organophosphate, carbamate or pyrethroid exhibited a positive cross-resistance in S. litura. Positive correlation was also found between endosulfan and carbamates. Except methomyl and bifenthrin, which were negatively correlated, there was no cross-resistance between organophosphate or carbamate or pyrethroid insecticides in the resistant populations of S. litura. Integrated pest management tactics aimed at reducing pesticidal applications, rotating chemistries of diverse modes of action and conserving natural enemies are recommended.