Eco-friendly management and developmental biology of Pieris brassicae (Lepidoptera: Pieridae) using different bio-pesticides

Abstract

Cabbage (Brassica oleracea var. capitata L.) is an economically and nutritionally important crop, providing income and serving as a dietary staple worldwide. Among its insect pests, the cabbage butterfly (Pieris brassicae) is one of the most destructive. A study conducted during 2023 in laboratory and experimental field of the Department of Entomology evaluated developmental biology of P. brassicae and the efficacy of various bio-pesticides and botanical extracts, Spinosad, Emamectin benzoate, Bacillus thuringiensis var. kurstaki, Beauveria bassiana, Azadirachtin, and Agni astra against its larvae and their impact on cabbage yield. The bio-efficacy trial followed a randomized complete block design (RCBD) with three replications and four sprays at 7-day intervals. The larvae fed on cabbage leaves, pupated on host plants, and emerged as adults in mid-spring. Eggs were laid in clusters on the undersides of outer leaves. The incubation period was 5.50±0.02 days, larval development took 24–25 days, and the pupal stage lasted 10.50±0.02 days. Male and female wing spans were 54.5±1.40 mm and 60.32±0.37 mm, respectively. Spinosad 45% SC was most effective, reducing larval populations by 87.16% and causing 88.02% mortality, followed by Emamectin benzoate (64.35% reduction, 26.32% mortality). Agni astra showed the lowest efficacy (36.38% reduction, 26.32% mortality). The highest yield was recorded with Spinosad (4.73 kg/plot), followed by Emamectin benzoate (4.01 kg/plot). The study concludes that bio-pesticides and plant extracts are environmentally safe and effective tools for managing P. brassicae and should be integrated into cabbage IPM programs.