ABSTRACT
The maize weevil, S. zeamais is considered one of de most important pests of stored grains. In order to obtain an alternative method for its control, the insecticide activity of powders from fruits and from the whole plant (with fruits) of C. ambrosioides was evaluated in laboratory. The insects were obtained from a population reared on wheat grains. The insecticide effect of the powders was evaluated on the immature and adult phases, using plastic boxes containing wheat, and 20 adults of S. zeamais to oviposit. After 3 days, the insects were removed, and 0.25 g of the C. ambrosoides powders were added 15 and 21 days after the infestation of. The evaluations were made in the period of 25 to 60 days after of the initial infestation. To evaluate the residual effect, plastic boxes containing wheat plus 0.25 g of the of C. ambrosioides powders, alone and mixed with the grains were used, 20 adults of S. zeamais were released in different periods: when setting the experiment (0 day), and after 5, 10 and 20 days. The evaluations were done 5 days after the infestation. It was observed that the powders from fruits and from the whole plant (with fruits), applied 15 days after initial infestation, presented insecticide effect on S. zeamais immatures. On the other hand, powders from fruits presented insecticide residual effect against S. zeamais adults for a period up to 5 days.
KEY WORDS
Insecta; maize weevil; insecticide plants