Bio-efficacy of synthetic insecticides against onion thrips, Thrips tabaci Lindeman (Thysanoptera: Thripidae)

Abstract

The experiment was conducted under field condition at Haveli Farm, University of Horticultural sciences, Bagalkot to evaluate the efficacy of synthetic insecticides against onion thrips during kharif season (2017 - 18). The experiment plot area was replicated thrice and eight treatments with randomised block design. The results revealed that thiamethoxam 25 WG @ 25 g a.i./ha recorded significantly lowest population of thrips after first, second and third spray during the experimental period by recording 4.90 thrips per plant which was at par with imidacloprid 17.8 SL @ 22.25 g a.i./ha with 5.19 thrips per plant indicating the superiority of both the treatments against onion thrips. The next best treatments were, cyazypyr10.26 OD @ 76.95 g a.i./ha, diafenthiuron 50 WP @ 250 g a.i./ha and tolfenpyrad 15 EC @ 150 g a.i./ha with 6.89, 7.29 and 7.56 thrips per plant, respectively. Whereas, lamda cyhalothrin 5 EC @ 12.5 g a.i./ha and chlorfenapyr 10 SC @ 12.5 g a.i./ ha found to be least effective in reducing thrips population with 8.67 and 8.46 thrips/plant. The data on bulb yield indicated that highest bulb yield was registered in thiamethoxam 25 WG @ 25 g a.i./ha and imidacloprid 17.8 SL @ 22.25 g a.i./ha treated plots with 25.39 and 24.67 t per hectare, respectively. Whereas, minimum bulb yield was noticed with lambda cyhalothrin 5 EC @ 12.50 g a.i./ha treated plots (17.94 t/ha).