Seasonal Incidence of Insect Pests and Natural Enemies in Foxtail Amaranthus and Spinach and Efficacy of Dimethoate Against Insect Pests Infesting Leafy Vegetables

Abstract

An investigation was made to study the efficacy of dimethoate against sucking and defoliator pest-infesting foxtail amaranths and spinach. The efficacy of dimethoate was evaluated at two doses, one at the recommented does of 200 g active ingredient (a.i.) ha-1 and other at double the recommended dose of 400 g a.i. ha-1 along with control and the other at double the recommended dose of 400 g a.i ha-1 along with control. The incidence of leaf webber (Hymenia recurvalis), ear-head bug (Cletus pugnator), Thrips (Thrips tabaci) and leaf miner (Liriomyza trifoli) were observed in foxtail amaranth. In spinach, leaf-eating caterpillars (Spodoptera litura), cutworm (Agrotis ipsilon) and Thrips (Thrips tabaci) were recorded. In spinach at the third leaf stage, nearly 9.20% leaf defoliation, 10.34% leaf damage and a mean thrips population of 3.48/five plants with a mean predator population of 0.32/ five plants were recorded. In the efficacy study, dimethoate was efficient in reducing the infestation of the leaf webber population with pre-mean count of 4.4± 0.87 in control and 1.2± 0.03 in X dose and 0.0± 0.0 in 2X dose after a day after treatment (DAT) in foxtail amaranths. In an efficacy study of dimethoate on thrips in spinach and foxtail amaranth, a complete reduction of thrips population was observed on 3 DAT at X dose and 2X dose with mean thrips population on control was 17.1± 2.12 in spinach and 8.5± 1.24 in foxtail amaranth 3 DAT. These findings indicate that dimethoate application has promising potential as a practical approach for managing insect pests in foxtail amaranth and spinach crops.