Efficacy of plant-based formulations containing Chrysanthemum cinerariifolium, Cinnamomum zeylanicum, Urtica dioica, Quassia amara and Brassica napus extracts against Spodoptera littoralis (Boisduval, 1833) (Lepidoptera: Noctuidae)

Spodoptera littoralis (Boisduval) is one of the most destructive polyphagous pests affecting numerous crops worldwide. The intensive use of synthetic insecticides for its control has led to increasing concerns regarding resistance development, environmental contamination, and adverse effects on non-target organisms. Consequently, environmentally friendly alternatives such as plant based formulations have gained considerable attention. This study evaluated the insecticidal activity of five plant-based formulations, namely canola oil (Brassica napus L.), Urtica dioica L., Quassia amara L., cinnamon (Cinnamomum zeylanicum) and chrysanthemum (Chrysanthemum cinerariifolium (Trevir.)Vis.), against second-instar larvae of S. littoralis under laboratory conditions. Mortality was assessed at different concentrations after 24, 48, and 72 h of exposure. Lethal concentration values (LC₅₀) were estimated using probit analysis. Significant effects of concentration and exposure period on larval mortality were observed for all tested formulations (P < 0.05). Mortality generally increased with increasing concentration and exposure time. Among the plant based formulations, U. dioica produced the highest larval mortality (96.67%) after 72 h at the highest tested concentration, followed by Q. amara (90.00%), canola oil (83.33%), C. cinerariifolium (76.67%), and cinnamon (66.67%). Spinosad, used as the reference insecticide, caused 100% mortality. Probit analysis confirmed marked differences in intrinsic toxicity among the tested plant based formulations, with LC₅₀ values ranging from 0.159 to 172 mg mL⁻¹. The findings demonstrate that plant-based formulations possess considerable potential for the control of S. littoralis. In particular, U. dioica showed insecticidal activity comparable to that of spinosad and emerged as the most promising botanical alternative. These results support the potential integration of plant-based formulations into sustainable pest management strategies aimed at reducing dependence on conventional synthetic insecticides.