Study of detoxification enzymes in Bemisia tabaci (Hemiptera: Aleyrodidae) populations collected from four districts of Punjab, Pakistan

Bemisia tabaci is a perilous pest of cotton and other crops due to its wide host range. It is responsible for the large scale economic devastation owing to the transmission of various lethal diseases. In Pakistan, B. tabaci is threatening the agricultural stability and food security by damaging the crops through direct and indirect means. Globally, the most prevalent practice to control B. tabaci is application of insecticides. Unfortunately, the persistent and erroneous use of insecticides is responsible for control failure and resistance in whitefly. Activation of detoxifying enzymes in Bemisia tabaci population with evolving resistance has been vastly studied. Resistance in whitefly against insecticides leads to the adverse results for growers. This experiment conducted to study the activities of detoxifying enzymes CarE and GST and kinetic parameters Km and Vmax in B. tabaci. Biochemical assay revealed that carboxylesterase activity recorded significantly high (2.15-fold) in Multan population and Bahawalpur (2.09-fold) as compared to other districts Jhang and Toba Tek Singh and susceptible strain. Detoxifying enzyme glutathione s-transferase activity (GST) recorded high in Bahawalpur population (3.83-fold) as compared to Multan, Jhang and Toba Tek Singh and susceptible strain. The activities of CarE and GST recorded significantly lower in Jhang and Toba Tek Singh populations as compared to other districts. Kinetic parameter (Km) value for CarE was significantly high 4.71 mmol L- 1 of Multan and Bahawalpur 4.07 mmol L- 1 as compared to Toba Tek Singh 2.99 mmol L- 1 and Jhang 2.46 mmol L- 1 populations. The values of Km for GST were noted higher in Bahawlpur 5.72 mmol L- 1 and Multan 5.24 mmol L- 1 populations as compared to other districts. Vmax values for CarE was recorded significantly higher 14.42 mu mol min- 1 for Multan population as compared to other districts and susceptible strain. Vmax values for GST activity were recorded higher in Toba Tek Singh 11.37 mu mol min- 1 as compared to other Vmax values of remaining districts and susceptible strain. The systematic study of enzymes to evaluate the pivotal role of detoxifying enzyme involved in detoxification process of insecticides and results will be used to make rational choices about insecticides selection to prevent resistance in B. tabaci in future.