Relative toxicity of fipronil and flonicamid against Bemisia tabaci (Gennadius) on cotton

The cotton whitefly Bemisia tabaci (Gennadius) has developed resistance against almost all insecticides including neonicotinoids. This study evaluates fipronil and flonicamid against B. tabaci on cotton and relative detoxification enzyme system is quantified. The populations maintained in laboratory conditions on cotton collected from Sriganganagar (Rajasthan), Ludhiana (Punjab), Khandwa (Madhya Pradesh), Amravati (Maharashtra) and Delhi are included. Of these, the New Delhi population revealed a high degree of toxicity followed by the Khandwa, Ludhiana, Sriganganagar and Amravati ones. Fipronil was more effective than flonicamid. The CYP450 monooxygenases levels were found to be maximum in Amravati population (793.70 nmol/mg of protein) followed by Sriganganagar (460.39 nmol/mg of protein), Ludhiana (456.69 nmol/mg of protein), Khandwa (380.12 nmol/mg of protein) and New Delhi ones (279.32 nmol/mg of protein). With increase in the CYP450 monooxygenases level, the degree of resistance also increased. However, enzymes like esterase and GST did not show significant changes.