This paper reports on an evaluation of the insecticidal activity of extracts prepared from leaves of Tapirira guianensis Aubl. (Anacardiaceae), Attalea phalerata (Mart. ex Spreng.) Burret (Arecaceae), Eugenia uniflora L. (Myrtaceae), and Gomphrena elegans Mart. (Amaranthaceae) and from stems of Myracrodruon urundeuva Allemão (Anacardiaceae). Four extracts and 18 fractions with a range of polarities were tested. Ten-gram batches of wheat grains were each nebulized with 1 mL of a separate extract at 10% w/v. After solvent evaporation at 38 ºC, the grains were placed into flasks along with 20 unsexed 10- to 20-day old adult individuals of Sitophilus zeamais. The assessment was carried out on the fifth and tenth day by counting and discarding the dead insects. Leaf extracts of G. elegans showed an insecticidal effect ranging from 27% to 60% by the fifth day, whereas the effect of the remaining extracts tested (if active at all) did not exceed 20% in the same period. By the tenth day, the most active extracts were those of A. phalerata (hexanic, 36.5%) and all those of G. elegans (5280.5%), whereas the effect of the other extracts did not exceed 30%.
secondary metabolites; insecticidal plant; maize weevil; Sitophilus zeamais
