Host associated variations in neonicotinoid susceptibility in Bemisia tabaci and correlation with CYTP450

Neonicotinoid susceptibility in five populations of Bemisia tabaci (Gennadius) from two major cotton growing regions of India was evaluated. These included-North region: Sriganganagar (Rajasthan), Ludhiana (Punjab) and New Delhi and Central region: Khandwa (Madhya Pradesh) and Amravati (Maharashtra). To establish a correlation between neonicotinoid susceptibility and populations, LC₅₀ (imidacloprid, thiamethoxam and acetamiprid), and activity of cytochrome P450 were explored. Bioassay revealed that population from Amravati recorded the maximum lethal concentration with least susceptibility to neonicotinoids with LC₅₀ values ranging from 1317.21 to 1448.22 mg/l, whereas New Delhi population was the most susceptible (LC₅₀ values ranging from 328.18 to 552.51 mg/l). This was also evident from level of cytochrome P450 levels. The difference in cytochrome P450 monooxygenase activity was observed to be non-significant. New Delhi population was taken as a unity to compare increase in cytochrome P450 activity with increase being in the range of 1.90 to 2.39 for cotton, 2.12 to 3.11 for brinjal and 1.87 to 3.08 for tomato as a hosts.