Toxicity of insecticides against mealybug, Phenacoccus solenopsis on transgenic cotton in Punjab

The comparative toxicity of different insecticides was determined against mealybug, Phennacoccus solenopsis (Tinsley) collected from cotton grown in different districts of Punjab. The LC₅₀ values for chlorpyriphos, buprofezin, profenofos, sulfoxaflor after 24 hours were 0.463, 0.122, 0.024, 0.008 against mealybug populations collected from Ludhiana; 0.879, 0.175, 0.024 and 0.012, respectively from Mansa; 0.532 (chlorpyriphos) and 0.024 (profenofos) from Bathinda; 2.373 (chlorpyriphos) and 0.038 (profenophos) against mealybug population from Muktsar, respectively. Based on relative toxicity and toxicity index, sulfoxaflor > profenofos > buprofezin >chlorpyriphos for Ludhiana and Mansa districts were arranged. However, for Bathinda and Muktsar district they were arranged as profenofos> chlorpyriphos> buprofezin, sulfoxaflor. After 48 hours, the LC₅₀ values were 0.140, 0.107, 0.010 and 0.007 against mealybug populations collected from Ludhiana; 0.035, 0.046, 0.010 and 0.008 for Mansa; 0.377 (chlorpyriphos) and 0.010 (profenofos) for Bathinda and 0.322 (chlorpyriphos) and 0.014 (profenofos) against mealybug population from Muktsar, respectively. Based on the LC₅₀ values, insecticides were arranged in descending order as sulfoxaflor > profenofos > buprofezin > chlorpyriphos for Ludhiana and Mansa district. However, for Bathinda and Muktsar district, the most toxic insecticide was profenofos followed by chlorpyriphos. After 72 hours bioassay LC₅₀ values were 0.034, 0.024 and 0.009, respectively for chlorpyriphos buprofezin and profenofos against mealybug populations collected from Mansa; 0.204 (chlorpyriphos) and 0.000 (profenofos) of Bathinda and 0.247 (chlorpyriphos) and 0.011 (profenofos) against mealybug population of Muktsar, respectively. Based on the LC₅₀ values and toxicity index, sulfoxaflor was found to be most toxic in Ludhiana and Mansa districts after 24 and 48 hours. However, profenofos was found to be most toxic in Bathinda and Muktsar districts upto 48 hours, whereas sulfoxaflor was found to be most toxic insecticide after 144 hours.