The objective of the present study was to test the insecticidal activity of vegetable powders on Sitophilus zeamais. Powders of Anadenanthera colubrina (leaves); Annona muricata (seed); Azadirachta inidica (leaves and flowers); Caesalpinia pyramidalis (leaves); Chenopodium ambrosioides (leaves and flowers); Cymbopogon sp. (leaves); Cymbopogon citratus (leaves); Momordica charantia (leaves and fruits); Piper nigrum (seed); and Ricinus communis (leaves) were evaluated. In addition, we evaluated the insecticidal potential of leaves and flowers of C. ambrosioides at different dosages. In the evaluation of repellency a preference index was established, and the t test was used to compare the means of plant species. The means of plants that were classified as repellent were also compared. To assess mortality, we proceeded with the analysis of variance and comparison of means by Tukey test and also the t test for comparing the means of the C. ambrosioides and P. nigrum treatments. The emergence data were analyzed by Tukey test. To evaluate the data on mortality caused by C. ambrosioides, the CL50 was determined using Probit analysis. The emergence data were verified by regression analysis. Plants that caused repellency were Cymbopogon sp., C. citratus and C. ambrosioides. The plant that most affected the survival of the pest was C. ambrosioides, which caused total mortality of insect infestations and no adult emergence. Adults of S. zeamais are most susceptible to the concentration of 0.125 g of C. ambrosioides powder.
Natural insecticides; toxicity; maize weevil