Effectiveness of different chemical pesticides in controlling Tomato Leaf Miner (Tuta absoluta Meyrick, 1917) in Kathmandu, Nepal

Abstract

Tomato farming in Kathmandu faces many pest problems, including leaf miners, fruit borers, and whiteflies. The most problematic is the tomato leaf miner (Tuta absoluta), which damage vegetative and reproductive stages, leading to up to 100% crop loss. The experiment was conducted on the tomato variety Kabita during March-June 2024 in a farmer's field in Chandragiri Municipality-1, Kathmandu, under open-field conditions. This research studied the effects of different chemical pesticides on infestation percentage in leaves and fruits, tunnels per infested leaf and fruit, and larvae per infested leaf. Seven treatments were evaluated: chlorantraniliprole 18.5% SC @3 ml/l, azadirachtin 3000 ppm @4 ml/l, control, emamectin benzoate 1.5% + indoxacarb 7.5% SC @0.625 ml/l, chlorfenapyr 10.5% + spinosad 2.5% SC @0.1 ml/l, spinetoram 11.7% SC @0.8 ml/l, and chlorfenapyr 10% + tolfenpyrad 10% SC @1 ml/l, with three replications laid out in a Randomized Complete Block Design (RCBD) with 4.32 m² per plot. The experiment showed significant pesticide effects on larval mortality and damage reduction. The lowest infestation in leaves (11.26%) and fruits (0.94%), with the fewest tunnels per infested leaf (0.41) and fruit (0.22), was in chlorfenapyr + tolfenpyrad, followed by spinetoram. The lowest larval population per infested leaf was in spinetoram (0.31), followed by chlorfenapyr + tolfenpyrad. The lowest yield loss (2.70%) was in chlorfenapyr + tolfenpyrad, followed by spinetoram. Thus, chlorfenapyr + tolfenpyrad, followed by spinetoram, were the most effective pesticides for managing Tuta absoluta under Chandragiri field conditions.