Relative Toxicity of Different Insecticides to Bemisia tabaci (Gennadius) on Cotton in Punjab

The study reports the toxicity of different insecticides to identify the effective molecules against Bemisia tabaci. Commercial formulations of triazophos 40 EC, diafenthiuron 50 WP, pyriproxyfen 10 EC, ethion 50 EC, spiromesifen 240 SC and cyazypyr 10 OD were evaluated at twenty times lower concentration than the recommended field rates in g a.i. ha⁻¹. Based on LC₅₀ values obtained in 2012 the order of toxicity against white fly populations of Ludhiana was: ethion > diafenthiuron > cyazypyr > triazophos > spiromesifen > pyriproxyfen and Muktsar: ethion = diafenthiuron > spiromesifen > cyazypyr > triazophos > pyriproxyfen. However, against Fazilka population, the toxicity trend was different with order of: cyazypyr > diafenthiuron > spiromesifen > ethion > triazophos > pyriproxyfen and for Mansa population ethion> diafenthiuron > spiromesifen > cyazypyr > triazophos > pyriproxyfen. Based on the LC₉₀ values, the order of toxicity against Ludhiana population was diafenthiuron> cyazypyr > ethion > triazophos > spiromesifen > pyriproxyfen, and Muktsar population diafenthiuron > spiromesifen > cyazypyr > triazophos > ethion=pyriproxyfen. Against Fazilka population, the toxicity trend was: spiromesifen > diafenthiuron > cyazypyr > ethion > triazophos > pyriproxyfen and Mansa population, spiromesifen=diafenthiuron > ethion > cyazypyr > triazophos > pyriproxyfen. Similarly, in 2011 based on LC₅₀ values, the order of toxicity against Ludhiana population was diafenthiuron > cyazypyr > triazophos > spiromesifen > pyriproxyfen > ethion and Muktsar population, diafenthiuron > triazophos > ethion > spiromesifen > cyazypyr > pyriproxyfen. In Fazilka population, the toxicity trend was: cyazypyr > ethion > diafenthiuron, triazophos > spiromesifen > pyriproxyfen and Mansa population, spiromesifen > pyriproxyfen, triazophos, cyazypyr > diafenthiuron> ethion. Similarly, based on the LC₉₀ values the order of toxicity against Ludhiana population was: diafenthiuron> spiromesifen > pyriproxyfen > cyazypyr > triazophos >ethion and Muktsar, diafenthiuron > cyazypyr > ethion > triazophos > spiromesifen > pyriproxyfen. In Fazilka population the order of toxicity was: spiromesifen>diafenthiuron > cyazypyr > triazophos > ethion > pyriproxyfen and Mansa population, cyazypyr > spiromesifen > diafenthiuron > triazophos > pyriproxyfen > ethion.