ESSENTIAL OIL OF Eucalyptus globulus Labill AND Eucalyptus nitens H. Deane & Maiden (MYRTACEAE) FOR THE CONTROL OF Sitophilus zeamais Motschulsky

Abstract

Synthetic pesticides are the most widely used method to control insect pests. However, today we have insecticide resistance reports and mammal intoxications. The essential oil of Eucalyptus species has shown promising results in the control of several insect pests. The objective of this research was to assess the chemical composition, toxicity and repellent effect under laboratory conditions of essential oil of Eucalyptus globulus and Eucalyptus nitens against adults of Sitophilus zeamais. The phytochemical analysis indicates that the major constituents of both essential oils are 1.8-cineol (eucalyptol) (55.49% in E. globulus and 59.85% in E. nitens) and ?-pinene (18.18% in E. globulus and 18.36% in E. nitens). The oils of both species showed no significant contact toxicity although they affected the F1 emergence of S. zeamais, which was reduced in more than 50% with E. globulus in concentrations of 4 and 8% without affecting seed germination. Fumigant toxicity values of mortality higher than 70% were obtained with E. nitens in treatments of 20, 25, 30 and 35 ?L and in E. globulus with 35 ?L. All treatments were repellents to S. zeamais. We conclude that essential oils of E. globulus and E. nitens have significant insecticidal fumigant properties against S. zeamais.