Essential oils from leaves of Petroselinum crispum (Mill.) Fuss (Apiaceae) and Pimenta racemosa var. racemosa (Mill.) J.W. Moore (Myrtaceae) were evaluated for their repellent properties, insecticidal and fumigant activities against Dinoderus porcellus Lesne (Coleoptera: Bostrichidae). The essential oils of these plants were obtained by Clevenger-type hydro distillation method with yield of 0.47% and 1.09% w/w for P. crispum and P. racemosa, respectively. Essential oils of both plants exhibited a low repellent activity (class I and II of repellency) against D. porcellus at all tested concentrations. The P. crispum and P. racemosa essential oils were toxic to D. porcellus in contact, ingestion and fumigant assays. The D. porcellus adults were more susceptible to contact action of P. crispum (LD50 = 1.15 µL/adult) than P. racemosa (LD50 = 414.38 µL/adult) at 72 h, whereas in ingestion assay, P. crispum essential oil was the most effective toxin (LC50 = 3.88 µL/g) at 21 days interval time. Strong feeding deterrence (68.97 %) was achieved in D. porcellus adults by using P. crispum essential oil at a concentration of 0.4 µL/g of yam chips. In the fumigation assays, P. crispum (LC50 = 7.22 µL/L air) essential oil was more toxic than P. racemosa (LC50 = 3.39×106 µL/L air) against D. porcellus adults within 7 days. These findings, suggest that P. crispum essential oil was more active against D. porcellus adults and showed its potential for development as natural antifeeding agent, and fumigant insecticide for managing D. porcellus adults in stored yam chips.
Keywords: contact toxicity, feeding deterrence, fumigant toxicity, repellent activity, storage insects