Persistence of essential oils in stored maize submitted to infestation of maize weevil

The essential oils and constituent compounds have been studied for their insecticidal activity against stored grain pests. In this research, persistence of the essential oils in stored maize subject to infestation by maize weevil, Sitophilus zeamais Mots. (Coleoptera: Curculionidae) were evaluated. Persistence of oils and eugenol were evaluated in the initial period (after impregnation) and at 30, 60, 90 and 120 days of storage. Mortalities of S. zeamais in the initial period ranged between 93.8 (Piper hispidinervum, Melaleuca leucadendron and eugenol) to 100% (Eugenia uniflora, green fruits of Schinus terebinthifolius and Piper marginatum). From the 30th day, mortalities declined, except for P. marginatum (92.2%), which reached 53.1% at 120 days of storage. According to the regression equations adjusted for the number of S. zeamais emerged throughout the storage period, there was no significance for the oils of S. terebinthifolius, P. marginatum and the control. Considering general average, the oil of P. marginatum was the most persistent, providing emergency of 0.30 insects; differing from the other oils, as eugenol and the control. The other treatments differed in relation to the control.