Monitoring of phosphine resistance in Indian populations of Tribolium Castaneum (Herbst) from stored wheat

Despite heavy dependence on phosphine (PH3) for fumigating stored products, the resistance status of Tribolium castaneum in India has not undergone a thorough investigation. Hence in the present study, for monitoring the resistance in T. castaneum to phosphine, populations were collected from stored wheat in FCI godowns of five states viz., Uttar Pradesh (Jhansi, Pratapgarh and Hapur), Punjab (Ludhiana, Sangrur and Patiala), Haryana (Sirsa, Narwana and Gohana), Madhya Pradesh (Malanpur, Sanwer and Indore) and Rajasthan (Jaipur, Bikaner and Ajmer) and compared with the susceptible strain collected from TNAU, Coimbatore. The populations were bioassayed for estimation of median lethal dose values to know the relative susceptibility, and significant variations in the susceptibility levels to phosphine were observed. The populations from Ajmer, Indore, Jaipur, Hapur, Jhansi, Ludhiana, Narwana, Malanpur and Sirsa recorded higher degree of tolerance, while those from Sangrur, Pratapgarh, Sanwer, Patiala and Bikaner region showed moderate level of tolerance, and the onses from Gohana showed low level of tolerance. The highest median dose value was observed in the population from Ajmer (1.901 mg/l), while lowest value was in the population from Gohana (0.358 mg/l).