Effect of Nitrogen Fertilization on Aphids, Their Natural Enemies and on Wheat

This study evaluates the effects of varied nitrogen (N) fertilization (0, 75, 150 and 225 kg ha^-1) and varieties (HD 3086 and PBW 660) on aphids and their natural enemies in wheat crop. The experiment was conducted during 2017–18 and 2018–19. The observations revealed a two-fold increase in aphid incidence as the N fertilization increased from 0 to 225 kg ha^-1. Aphid/ tiller was maximum in irrigated variety HD 3086 (12.76-15.20) at 225 kg ha^-1, which declined with decrease in N-levels. In rainfed grown PBW 660 at 225 kg ha^-1 N, the aphid incidence (13.23 aphids/ tiller) was similar to the irrigated HD 3086 at 150 kg ha^-1 (12.73 aphids/ tiller). Similar trend was observed with successive N levels, with the level until 150 kg ha^-1 resulting in significant increase in number of ears m^-2, number of grains/ earhead and 1000-grain weight. N-levels beyond 150 kg ha^-1 harboured relatively more number of aphids/ tiller, revealing that 150 kg ha^-1 of N is the optimum fertilizer dose to balance the aphid infestation.