Insecticidal and Repellent Activity of Different Pomegranate Peel Extracts Against Granary Weevil Adults

The pomegranate (<i>Punica granatum</i> L.) fruit peel is an agro-industrial by-product rich in bioactive compounds. In this study, the bioactivity of pomegranate peels (cv. Ako) extracted with acetone, diethyl ether, and <i>n</i>-hexane was assessed by evaluating toxic (contact and ingestion), repellent, antifeedant, and nutritional effects towards <i>Sitophilus granarius</i> (L.) (Coleoptera, Curculionidae) adults. Contact toxicity assays revealed significant mortality induced by the acetone and <i>n</i>-hexane extracts, with 24-h LD₅₀ values of 76.93 and 81.14 μg/adult, respectively. In ingestion bioassays, at the highest dose tested (750 μg/disk), the acetone pomegranate peel extract showed a strong feeding deterrence (FDI: 80%), and significantly reduced food consumption (RCR) and relative growth rate (RGR). In filter paper repellency assays, the acetone extract induced positive contact repellency, with PR values ranging from 80% to 30%. GC-MS analysis identified sitosterol, 9,12-octadecadienoic acid, and α-tocopherol as the major constituents of the acetone extract. These results highlight the potential of pomegranate peel as a sustainable source of bioactive compounds for stored-product insect pest management.