Insecticidal and repellency activity of essential oil of Eucalyptus sp. against Sitophilus zeamais Motschulsky (Coleoptera, Curculionidae)

Background: The objective of this work was to evaluate the insecticidal and repellent effect of essential oils of Eucalyptus dunnii, E. saligna, E. benthamii, E. globulus and E. viminalis in the control of Sitophilus zeamais in maize grains.Results: The essential oils chemical composition showed that the E. benthamii presents the cis-ocimene (56.88%) as major compound. Results permitted us to verify that the evaluated species presented different insecticidal action under Sitophilus zeamais. About 100% of mortality was achieved with doses of 65, 100 and 400 μL for E. dunnii, E. saligna and E. benthamii, respectively. After regression analysis the LD50 values were calculated and E. dunnii was shown to be the most efficient (25.03 μL), followed by E. saligna (37.93 μL) and E. benthamii (121.09 μL). Using the previously calculated LD50 values, the repellency activity was calculated, allowing us to conclude that all species presented significant values in terms of this important parameter.Conclusion: The essential oil of Eucalyptus sp. presented insecticidal and repellency against Sitophilus zeamais Motschulsky (Coleoptera, Curculionidae). Although from an economic point of view synthetic chemicals are still more frequently used as repellents, natural products (essential oils) have the potential to provide efficient and safer repellents for humans and the environment. © 2010 Society of Chemical Industry.