Efficacy of selected insecticides against Diamondback moth, Plutella xylostella (Linnaeus) on cabbage

Abstract

The present study entitled “Efficacy of selected insecticides against diamondback moth [Plutella xylostella (Linnaeus)] on cabbage” was carried out during the Rabi season of 2020-21 at Vegavaram village, West Godavari district, Andhra Pradesh. The experiment was laid out in a randomized block design with three replications. Eight treatments were evaluated, comprising: (T₁) Spinosad 45% EC @ 200 ml ha⁻¹, (T₂) Fenvalerate 20% EC @ 60–75 g ha⁻¹, (T₃) Indoxacarb 14.5% SC @ 60 g ha⁻¹, (T₄) Permethrin 25% EC @ 100–150 g ha⁻¹, (T₅) Flubendiamide 480 SC @ 40 g ha⁻¹, (T₆) Emamectin benzoate 5% SG @ 135–175 ml ha⁻¹ and (T₇) Rynaxypyr 18.5% SC @ 30 g a.i. ha⁻¹ along with an untreated control (T₀), to assess their effectiveness against diamondback moth infestation. Larval populations were recorded 24 hours before treatment (pre-treatment) and at 3, 7, and 14 days after each spray to determine treatment efficacy. Among the tested insecticides, the lowest mean larval population was observed in T₇ (Rynaxypyr 18.5 SC) with 0.44 larvae per plant, followed by T₁ (Spinosad 45 EC) with 0.71 larvae per plant and T₆ (Emamectin benzoate 5 SG) with 1.11 larvae per plant, in comparison to the untreated control. Cabbage yield in the insecticide-treated plots ranged from 228 to 298 q ha⁻¹. The highest yield was obtained with T₇ (Rynaxypyr 18.5 SC) at 298 q ha⁻¹, followed by T₁ (Spinosad 45 EC) with 275 q ha⁻¹ and T₆ (Emamectin benzoate 5 SG) with 268 q ha⁻¹. The cost benefit ratio varied among treatments from 1:3.1 to 1:6.3, with the maximum economic return recorded in T₇ (Rynaxypyr 18.5 SC; 1:6.3), followed by T₁ (Spinosad 45 EC; 1:5.6) and T₆ (Emamectin benzoate 5 SG; 1:5.6).