Effect of synergist to breakdown the neonicotinoid resistance in cotton aphid, Aphis gossypii (Glover)

Abstract

Cotton aphid, Aphis gossypii is an important sucking pest on cotton and other crops. This insect has developed resistance against insecticides, and neonicotinoids have been widely used for its control for a longer period. A. gossypii has shown resistance against imidacloprid and other neonicotinoids. Synergists along with insecticides are useful to break the insecticide resistance in insects. Laboratory and field evaluation was conducted to determine the efficiency of synthetic synergists and plant products as a synergist along with neonicotinoids against A. gossypii in cotton at the Agricultural College and Research Institute, Madurai, Tamil Nadu. From laboratory evaluation of synergists, piperonyl butoxide (PBO) and rosemary oil (RO) were the best synergist for acetamiprid, imidacloprid and thiamethoxam with synergism ratio of PBO ranged from 1.27-1.47, 1.16-5.5 and 1.54-4.66 and RO ranged from 0.90-1.04, 1.02-1.12 and 1.02-1.17, respectively. Thiamethoxam + PBO was the most effective treatment with the highest population reduction of aphids (88.22% and 100%), followed by imidacloprid + PBO with 87.17 and 99.74 per cent reduction and acetamiprid + PBO with 86.13 and 97.11 per cent reduction after first and second sprays, respectively over untreated check. Among the plant products tested, thiamethoxam + RO was found most effective after second spray in reducing aphid population with 95.39 % followed by imidacloprid + rosemary oil (91.60%) and acetamiprid + RO (89.45%). Neonicotinoid resistance, if reported, shall be managed using synthetic PBO and or the plant based RO in the field.