Repellency, Fumigant and Contact Toxicities of Litsea cubeba (Lour.) Persoon Against Sitophilus zeamais Motschulsky and Tribolium castaneum (Herbst)

Abstract

Litsea cubeba is found in many parts of Thailand and has medicinal properties. Mature fruit of L. cubeba was collected from Doi Ang-khang, in the Fang District of Chiang Mai Province, Thailand in June 2007 and the essential oil was extracted by a water-distillation method. The insecticidal properties of L. cubeba were evaluated under laboratory conditions. The results showed that the essential oil of L. cubeba strongly repelled Sitophilus zeamais and Tribolium castaneum even at low concentrations, but its repellency was more marked toward T. castaneum. Of interest was the fact that the repellency against T. castaneum was fairly consistent over the 5 h period of the experiment. Moreover, it showed both contact and fumigant toxicities against the tested species. Probit analysis showed that S. zeamais was more susceptible than T. castaneum in both the fumigant and contact bioassays. Hence, the essential oil of L. cubeba might be used as an alternative for grain protection against stored-grain insects. Further
studies are needed prior to its commercial use.