Susceptibility of Different Populations of Nilaparvata lugens from Major Rice Growing Areas of Karnataka, India to Different Groups of Insecticides

Susceptibility to insecticides was investigated by collecting field populations of brown planthopper from different locations of southern Karnataka, India (Gangavati, Kathalagere, Kollegala, Soraba and Mandya). All the field populations differed in their susceptibility to insecticides. In general, Soraba and Mandya populations were more susceptible to insecticides compared to Gangavati and Kathalagere populations. The resistance ratios varied greatly among the populations viz., chlorpyriphos (1.13- to 16.82-fold), imidacloprid (0.53- to 13.50-fold), acephate (1.34- to 5.32-fold), fipronil (1.13- to 4.06-fold), thiamethoxam (1.01- to 2.19-fold), clothianidin (1.92- to 4.86-fold), dinotefuran (0.82- to 2.22fold), buprofezin (1.06-to 5.43-fold) and carbofuran (0.41- to 2.17-fold). The populations from Gangavati, Kathalagere and Kollegala exhibited higher resistance to some of the old insecticides and low resistance to new molecules.