POWDERY FORMULATION OF ESSENTIAL OILS FOR THE CONTROL OF RICE WEEVIL SITOPHILUS ORYZAE L. (COLEOPTERA: CURCULIONIDAE)

Abstract

In spite of the effectiveness of the essentials oils and flour of leguminous seeds against insect attacks, they are less attractive to producers that continue to use chemicals that have potential adverse effects on consumers and the ecosystems through pollution. The present research was carried out to evaluate insecticidal properties of powdery formulations of essential oils of 3 plants: leaves of Eucalyptus citriodora (Myrtaceae), dried fruits of Xylopia aethiopica (Dunal) A. Richard (Annonaceae) and the roots of Echinops giganteus var. lelyi C.D Adams (Asteraceae) with seeds of black bean on Sitophilus oryzae. The toxicity by contact-inhalation of essential oils, alone or in combination, in different concentrations is evaluated against young adults of S. oryzae with two weeks old after 24 hours. For powdery formulation, the test of contact-ingestion and inhalation is evaluated in different doses each week during 7 weeks. The research carried out reveals that X. aethiopica is the most active on S. oryzae with the lethal doses 50 and 90 respectively 37.1 and 57 ppm. In combination, E. giganteus which alone is not insecticidal, enhance significantly the insecticidal efficiency of the 2 other essential oils. The most insecticidal powdery formulation is that of E. citriodora with 100% of mortality two weeks after the application. The present work gives evidence of the insecticidal efficiency of a powdery formulation in the protection of stored cereals from weevil attacks. This method potentially has no adverse effect on consumers and on the environment at the doses used and could be developed and popularized.