Status of Insecticide Resistance in Lipaphis erysimi (Kalt.) on Rapeseed-mustard

The results of laboratory studies carried out during 2019–20 and 2020–21 to investigate the development of resistance towards recommended insecticides in mustard aphid, Lipaphis erysimi (Kalt.) are reported. Among different populations, Shri Muktsar Sahib population was the least susceptible with LC₅₀ values ranging from 0.0011–0.0591 per cent whereas Ludhiana population was the most susceptible with LC₅₀ values ranging from 0.0005–0.0238 per cent to all the insecticides tested. Among different insecticides, thiamethoxam with LC₅₀ values ranging from 0.0005 to 0.0011 per cent showed maximum toxicity while dimethoate was found to be the least effective insecticide with LC₅₀ values ranging from 0.0238 to 0.0591 per cent. Medium to high levels of resistance (16.2 – 74.2x) were observed towards dimethoate 30 EC, chlorpyriphos 20 EC and oxydemeton methyl 25 EC, whereas level of resistance towards thiamethoxam 25 WG was found to be very low (2.5 – 5.5x) in Punjab.