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

The pomegranate (Punica granatum 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 n-hexane was assessed by evaluating toxic (contact and ingestion), repellent, antifeedant, and nutritional effects towards Sitophilus granarius (L.) (Coleoptera, Curculionidae) adults. Contact toxicity assays revealed significant mortality induced by the acetone and n-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.