Synthesis of Alumina Powders and their Insecticidal Effect Against Acanthoscelides Obtectus Say

Abstract

Alumina powders were synthesized by citrate/nitrate autocombustion method with different citrate/nitrate molar ratios (0.5, 0.8 and 1.2). XRD analysis of the powders calcined at 1200 °C for 1 h showed only the presence of α–Al2O3 phase. Particle size of the powders determined by SEM analysis varied from nano- and submicron size of several µm. The powders were mixed with grains of bean to examine their insecticide effect against bean weevil (Acanthoscelides obtectus Say, 1831). Mortality of insects after seven days of exposure was the highest for the powder synthesized at 1.2 molar ratio, which contained the highest portion of submicron particles. This suggested that lager amount of citric acid could prevent higher degree of particles agglomeration. Mortality cause of insects is assumed to be related to the degree of powder coverage of the insects’ exoskeleton. The same powder also provided the best efficiency in suppressing the emerge of F1 generation and seed protection even at lower concentrations.