Toxicity of some Botanical Insecticides against Larvae of fall Army Worm Spodoptera frugiperda (J E Smith)

Abstract

The fall army worm Spodoptera frugiperda (J E Smith) (Lepidoptera: Noctuidae) is a major invasive maize pest whose reliance on synthetic insecticides has driven resistance. The contact toxicity and lethal time (LT50) of three plant-derived materials viz., oil palm empty fruit bunch (OPEFB) liquid smoke, neem oil (Azadirachta indica), and citronella oil (Cymbopogon nardus)- were compared in a preliminary screening against third-instar larvae during 2025. Larvae were exposed by a leaf-dip method to 20, 40 and 60 ml l-1 of each material, plus an untreated control, in a completely randomized design. Mortality at 24, 48, and 72 hr was observed to increase with concentration and exposure time. These differed significantly among treatments. At 60 ml l-1 1, all three materials caused complete mortality by 48 hr; citronella oil was most active, causing 89% mortality at 20 ml l-1 within 24 hr, followed by neem oil and OPEFB liquid smoke. Although based on a limited design, the results indicate that these botanicals merit development as ecofriendly components of IPM.