Monitoring insecticide resistance to leaffolder, Cnaphalocrocis medinalis (Guenee) (Lepidoptera: Pyralidae) in rice growing regions of Tamil Nadu

Abstract

Leaffolder, Cnaphalocrocis medinalis (Guenee) is a prominent and important insect pests of rice and more insecticides are being used for the management in the farmers’ holdings. In the present study, level of insecticide resistance in rice leaffolder was assessed by collecting leaffolder from different rice growing tracts of Tamil Nadu and using the data on discriminating dose (DD) fixed on susceptible population. The results revealed that the per cent resistance varied from 53.34 to 80.00, 51.8 to 63.34, 10.66 to 26.67 and 43.34 to 61.34 respectively for insecticides chlorpyriphos, cartap hydrochloride, chlorantraniliprole and profenophos. The order of frequency of resistance to different insecticides were chlorpyriphos > cartap hydrochloride > profenophos > chlorantraniliprole. Irrespective of the insecticides tested, high resistance was noticed in Bhavanisagar population. The order of resistance levels to chlorpyriphos, cartap hydrochloride, chlorantraniliprole and profenophos in the four major rice growing locations in Tamil Nadu were Bhavanisagar > Aduthurai > Coimbatore >Trichy.