Development of insecticide resistance in field populations of Brevicoryne brassicae (Hemiptera: Aphididae) in Pakistan.

Cabbage aphid Brevicoryne brassicae (L.) (Hemiptera: Aphididae) is a serious pest of crucifers in Pakistan. After incidences of poor control by recommended insecticides, the current study was undertaken to find out the status of insecticide resistance in Pakistani B. brassicae. Apterous adult aphids were bioassayed from 2006 to 2010 for their response to 12 insecticides using an adult immersion method. No or very low levels of resistance was found to endosulfan; and the organophosphates: chlorpyrifos and profenofos. Resistance to methomyl; emamectin benzoate; the pyrethroids: cypermethrin, lambdacyhalothrin, bifenthrin and deltamethrin; and the neonicotinoids: imidacloprid, acetamiprid, and thiamethoxam; increased progressively in concurrence with their regular use on vegetables. B. brassicae resistance to these insecticides remained very low to low in 2007 and 2008, but then it increased to moderate to high levels in 2009 (except cypermethrin and bifenthrin) and 2010. Under heavy infestations of this aphid, the application of insecticides having no, very low and low resistance is recommended in rotation.