Insecticidal Activity of Ricinus communis Leaf Extracts Against Bactrocera zonata and Bactrocera cucurbitae: Identification of Potential Bioactive Compounds

The melon fruit fly, Bactrocera zonata, and the pumpkin fruit fly, Bactrocera cucurbitae (Diptera: Tephritidae), are important agricultural pests that cause significant losses in a wide range of fruit and vegetable crops. Increasing concerns over pesticide resistance and environmental contamination have driven interest in plant-derived insecticide alternatives. This study investigated the insecticidal activity of Ricinus communis L. leaf extracts against both species. The crude leaf extract was fractionated using solvents of increasing polarity (n-hexane, methanol, and ethyl acetate). The resulting fractions were assessed for insecticidal activity, and the most active fraction was further purified using column chromatography. Chemical constituents were identified using gas chromatography–mass spectrometry (GC-MS) and Fourier transform infrared spectroscopy (FTIR). Bioassay results indicated that the methanol, n-hexane, and ethyl acetate fractions exhibited the highest insecticidal activity against both B. zonata and B. cucurbitae. GC-MS analysis revealed several bioactive constituents in the active fractions, including neophytadiene, fatty acid derivatives, and 11,14,17-eicosatrienoic acid, which was tentatively identified as a candidate constituent associated with the most active fractions. These findings suggest that R. communis leaf extracts contain bioactive constituents with insecticidal properties against tephritid fruit flies and may contribute to the development of plant-based pest management strategies. However, further work is required to isolate pure compounds and confirm their individual toxicological roles under field conditions.