Plant Extracts for the Control of Sitophilus zeamais (Motschulsky, 1895) (Coleoptera: Curculionidae)

Brazil is one of the largest grain producers in the world, but its productive potential is threatened by the presence of stored product pests that compromise quality and quantity. The use of synthetic insecticides and selective pressure make many of these pests increasingly resistant to control. Concern for health and the environment requires the development of less toxic and persistent products for the management of these undesirable organisms. The insecticide activity of aqueous extracts of 15 vegetal species was evaluated to control grain beetles, Sitophilus zeamais Motschulsky in maize stored. The adult insects came from the laboratory at Biological Institute of Sao Paulo. They were fed with sterilized grains of maize and kept in a room at 25 +/- 2 degrees C and 70 +/-% of relative humidity. The plants for the aqueous extracts were crushed in distilled water and the vegetal mass was filtered next. The liquid resulting from the filtering process was stored in plastic containers and frozen for later use. Two tests were conducted: impregnation of filter paper and treatment of grains. Ten insects were evaluated in each batch. Only the aqueous extract of Dahlia pinnata Cavanilles was satisfactory in controlling S. zeamais showing an efficiency of 10.00% in the contact test and an efficiency of 56% in the treated corn kernels.