Bioefficacy and cost effectiveness of different insecticides against aphids infesting wheat.
The efficacy and cost-effectiveness of phosphamidon (250 g a.i./ha), monocrotophos (180 g a.i./ha), chlorpyrifos (100 g a.i./ha), oxydemeton-methyl (125 g a.i/ha), dimethoate (187 g a.i./ha), quinalphos (125 g a.i./ha), imidacloprid (125 g a.i./ha), fenvalerate (75 g a.i./ha), cypermethrin (50 g a.i./ha) and deltamethrin (15 g a.i./ha) against aphids (Rhopalosiphum padi and Macrosiphum miscanthi) on wheat (cv. HD 2329) was investigated during 1997-98 and 1998-99 in New Delhi, India. In 1997-98, lower aphid infestation rates, compared with the control, were observed 7 and 15 days after the application of all insecticides evaluated. Seven days after insecticide application, the lowest number of aphids (1.60 per tiller) was observed in plants treated with fenvalerate. In the 1998-99 season, the highest mean reduction in aphid population after 1, 2, 7 and 15 days of application was recorded for monocrotophos. The grain yield (37.67 q/ha), net profit (RS. 9168/ha) and cost benefit ratio (1 : 17.92) were also highest with this treatment.