GUPTA, DIVENDERSINGH, GAGANDEEP2016-11-172016-11-172013http://krishikosh.egranth.ac.in/handle/1/86117ABSTRACT The studies on bioefficacy of neonicotinoids, biopesticides/plant products and their combinations carried out against peach leaf curl aphid, Brachycaudus helichrysi infesting nectarine and peach crops revealed foliar application of neonicotinoids, imidacloprid and thiamethoxam (both @0.008%) at pink bud stage followed by oxy-demeton methyl (0.025%) at fruit set stage, most effective (8.89-10.00% infestation) and superior over the recommended insecticide, oxydemeton methyl (15 and 20 % infestation in nectarine and peach) treatment. The biopesticides did not prove effective in managing the aphid. The pruning treatment was found superior over biopesticide treatments and even comparable to oxy-demeton methyl (0.025%) treatment. Toxicity studies conducted in the laboratory revealed oxy- demeton methyl (0.025%) extremely toxic to Coccinella septempunctata causing cent per cent mortality of the beetles. Imidacloprid (0.008%) and thiamethoxam (0.008%) were found moderately toxic (15-25% mortality) whereas, the plant products (pongamia and neem oil both @1%) were the safest (<2.5% mortality). In the field also, in the treatments where oxy-demeton methyl (0.025%) was used as second spray at fruit set proved harmful to the coccinellids whereas there was not much effect on syrphid flies population. The avoidable loss was appreciable (63-65%) in the treatments where imidacloprid/thiamethoxam was used as first spray followed by oxy-demeton methyl (0.025%). The treatments where imidacloprid (0.008%) spray was followed by oxy-demeton methyl (0.025%) showed highest benefit cost ratio in nectarine (51.21) and peach (41.72). None of the treatments showed any symptoms of phytotoxicity/ fruit injury indicating thereby their safety to both nectarine and peach.enThesis