Effect of edible and non edible oils as synergists in suppressing insecticide resistance in diamond back moth, Plutella xylostella (L.)

Investigations were carried out to study the effect of edible and non edible oil as synergists on resistant individuals of diamondback moth, Plutella xylostella (Linnaeus) in suppressing the insecticide resistance. Among the plant oils tested, the edible oils (palm, sunflower, simarouba, cotton seed and castor) did not show any synergistic activity with monocrotophos, quinalphos, carbosulfan and fenvalerate. The non-edible oils viz., rosemary and lemongrass oil suppressed the monocrotophos, quinalphos, carbosulfan and fenvalerate resistance significantly. Rosemary oil had shown high level of synergistic activity with a suppression of resistance (SR) of 74.07, 25.93, 66.67 and 72.41% to monocrotophos, quinalphos, carbosulfan and fenvalerate, respectively. Lemon grass oil exhibited moderate synergism with a SR of 48.15, 21.43, 29.17 and 48.15% to monocrotophos, quinalphos, carbosulfan and fenvalerate, respectively.