EFEITO RESIDUAL DE INSETICIDAS NATURAIS NO CONTROLE DE SITOPHILUS ZEAMAIS MOTS. EM MILHO ARMAZENADO

Abstract

The residual effect of natural insecticides was evaluated on adults of Sitophilus zeamais Mots. (Coleoptera: Curculionidae) on stored corn grains. Clove (Syzygium aromaticum L.), white pepper (Piper nigrum L.), neem (Azadirachta indica A. Juss) and silica dioxide powders were tested as well as neem, eucalyptus (Eucaliptus globulus Labill and Eucaliptus citriodora Hook.), eugenol, andiroba (Carapa guianensis Aubl.), rosemary (Lippia gracillis HBK.), cedar (Cedrela fissilis Vell.) and pequi (Caryocar brasiliense Camb.) oils. Powders were tested at concentration of 1kg/t in 50g-corn-plot and the oils at dosage of 50¿L in 20g-corn-plot. The plots infestation was accomplished using 20 and 8 adults (males and females) of S. zeamais being 0 to 15 days old, respectively, in the experiments with powders and oils. Silica dioxide caused 46.7, 38.3 and 37.5% of mortality, respectively, in the initial (soon after the treatment with the powders or oils) and at 60 and 120 days of storage periods, but the mortality induced by the other powders was inexpressive. In the three studied storage periods, silica dioxide was the more efficient in reducing adults emergency. At the initial storage period, all the oils caused mortality above 79%, however, after 60 and 120 days, mortality was lower than 2.5%. The adult emergency increased as stored period increased, although at 120 days the best performance was obtained using neem, followed by andiroba, cedar, rosemary and E. globulus oils.