Vol. 11, Special Issue 12 (2022)

The bioassay was carried out to know the insecticide resistance against acephate, monocrotophos and carbosulfan in the brown planthopper of different populations of Karnataka during kharif 2020-2021 using the seedling dip method. Results showed that higher levels of average resistance were recorded against acephate in populations of Cauvery command area (Mandya and Shivalli with LC50 of 199.5 and 197.6 mg/L, respectively), followed by TBP and UKP (Lingasugur) populations. Hilly and Coastal populations were highly susceptible to acephate. Significantly higher mean lethal concentrations against monocrotophos were recorded in populations representing the TBP area with 135.2 and 121.8 mg/L in Gangavathi and Sulekal, respectively, followed by UKP and TW populations. TBP, UKP and TW populations were more tolerant to carbosulfan compared to other field populations. Significantly lower resistance was noticed in Coastal and Hilly populations, as farmers in these areas were growing paddy for their daily use rather than commercial purpose, so farmers in these regions were rarely used insecticide.