Efficacy Evaluation of Commercial Insecticides for the Management of Tomato Leaf Miner (Tuta absoluta) in Tomato in Bharatpur, Chitwan

Abstract

Tomato leaf miner (Tuta absoluta) is one of the most destructive pests affecting tomato crop. In Nepal, it is currently one of the major pests spreading all over the country after its first appearance in May 2016 in Kathmandu valley. A field experiment was conducted to evaluate the efficacy of commercial insecticides against tomato leaf miner in Bharatpur, Chitwan, Nepal. This experiment was laid out in a randomized complete block design with six treatments and four replications. The different treatments included: i) Azadirachtin 1500 ppm (dose: 5 ml/liter), ii) Emamectin benzoate 1.5% + Indoxacarb 7.5% SC (dose: 0.625 ml/liter), iii) Spinetoram 11.7% w/w SC (dose: 0.5 ml/liter), iv) Bifenthrin 10% + Dinotefuran 20% SC (dose: 4ml/liter), v) Emamectin benzoate 5.7% WDG (dose: 0.3125 gm/liter) and vi) control (water spray). Treatments were applied 3 times at 10 days intervals and data were recorded at 3 Days After Spray (DAS), 6 DAS, and 9 DAS. The lowest percentage of leaf and fruit damage was recorded on spinetoram followed by emamectin benzoate + indoxacarb and emamectin benzoate. Similarly, the highest percentage of population reduction over control in leaves was observed in spinetoram (64.50%) followed by emamectin benzoate + indoxacarb (63.59%) and emamectin benzoate (59.43%) and the highest percentage of population reduction over control in fruits was observed in spinetoram (86.83%) followed by emamectin benzoate (83.53%) and emamectin benzoate + indoxacarb (80.24%). Maximum yield (44.71mtha^-1) was obtained in spinetoram treated plots whereas minimum was in control (38.03mtha^-1). The highest Benefit/Cost ratio was obtained in spinetoram (1.72) followed by emamectin benzoate (1.63) and emamectin benzoate + indoxacarb (1.60). Thus, spinetoram was found to be a superior insecticide for the management of Tuta absoluta followed by emamectin benzoate + indoxacarb and emamectin benzoate under field conditions in Bharatpur, Chitwan.