Toxicity and resistance of the cotton leaf hopper, Amrasca devastans (Distant) to neonicotinoid insecticides in Punjab, Pakistan

Cotton leaf hopper, Amrasca devastans (Distant) is a key pest of cotton (Gossypium hirsutum L.), vegetables, and many other crops in several Asian countries including Pakistan. Insecticides are most often used as the sole management tactic for this pest. Resistance to neonicotinoids have been studied in several insect pests, but there is a lack of information on A. devastans. Therefore, the aim of this study was to monitor the resistance in this pest to neonicotinoids. Six populations of A. devastans collected from Bahawalpur, Multan, Muzaffargarh, Rajanpur, Sahiwal and Vehari were evaluated for resistance to selected neonicotinoid insecticides by the leaf dip method. Resistance ratios (RRs) were in the range of 2.3-29.3 fold for acetamiprid, 4.8-95.0 fold for imidacloprid, and 19.1-1197.9 fold for thiamethoxam in different populations of A. devastans compared to the reference Multan population. Insecticide resistance monitoring plans and integrated resistance management approaches including the judicious use of insecticides with correct application rate and methods, rotation of insecticides with different modes of action and bio-control tools should be implemented to prevent field control failures, particularly in areas where A. devastans has developed resistance to the tested neonicotinoids.