Valorization of mandarin orange (Citrus reticulata) peel waste as a bioactive insecticidal agent against the pulse beetle (Callosobruchus chinensis L.)

Mandarin orange ( Citrus reticulata ) is a commercially important horticultural crop valued globally for its nutritional and medicinal properties. However, its outer peel, rich in bioactive compounds, is often discarded as waste. In the present study, fresh orange peels collected from the local market in Mysuru were washed, shade-dried, powdered, and stored at room temperature for further analysis. The insecticidal potential of peel extracts was evaluated against the pulse beetle ( Callosobruchus chinensis ), a major pest of stored pulses. Four solvent fractions and their combinations were tested for anti-ovipositional activity. Among them, the acetone: methanol combination fraction completely inhibited oviposition at a dosage of 150 μL/100 g of pulses, with a clear dose-dependent reduction observed. Gas chromatography–mass spectrometry (GC–MS) analysis of the crude extract and individual fractions revealed the presence of key phytochemicals, including Eucalyptol (16.2%), β-Pinene (11.2%), 2-Naphthalenemethanol (10.3%), o-Cymene (5.0%), and D-Limonene (4.18%). Importantly, treatments did not affect seed viability. These findings demonstrate that orange peel waste from the horticultural industry can serve as an effective, eco-friendly prophylactic agent for the management of C. chinensis in small- and large-scale pulse storage systems, offering both pest control and waste valorization benefits.