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RESUMEN Sitophilus zeamais (gorgojo del maíz) en cereales almacenados se controla principalmente con insecticidas sintéticos. Una alternativa son los insecticidas botánicos, especialmente los aceites esenciales. En Chile, los mejores resultados se han obtenido con los de Peumus boldus (boldo), Laurelia sempervirens (laurel) y Laureliopsisphilippiana (tepa). Se estudió en laboratorio la repelencia de estos tres extractos sobre S. zeamais a lo largo del año. Los componentes principales de P. boldus fueron 1-8-cineol (14,9 a 40%) y ascaridol (24,37%). En L. sempervirens destacaron metil-eugenol (4,6 a 39,7%) y safrol (38,5 a 64,7%), y en L. philippiana safrol (17 a 39,6%) y linalool (0,9 a 34,5%). Salvo los extractos de L. philippiana y P. boldus al 0,125 y 0,25%, todos los tratamientos causaron repelencia, con mayor nivel en concentraciones ≥ 4%. Sólo el aceite esencial de L. sempervirens presentó variación estacional, con mayor repelencia en el follaje colectado en verano. La falta de efecto estacional de los aceites esenciales de P. boldus y L. philippiana se estiman promisorias para el control de plagas de granos almacenados durante todo el año. ABSTRACT Sitophilus zeamais (maize weevil) in stored cereals is mainly controlled with the use of synthetic insecticides. Botanical insecticides, particularly essential oils, are an alternative to use of synthetic insecticides. In Chile, the best results have been obtained with the use of essential oils of Peumus boldus (boldo), Laurelia sempervirens (laurel) and Laureliopsis philippiana (tepa). A study was conducted in the laboratory to evaluate the repellency of these three extracts against S. zeamais throughout the year. The main components of each essential oil were: 1-8-cineol (from 14.9 to 40%) and ascaridol (24.37%) in P. boldus; methyl eugenol (from 4.6 to 39.7%) and safrole (from 38.5 to 64.7%) in L. sempervirens; safrol (from 17 to 39.6%) and linalool (from 0. 9 to 34.5%) in L. philippiana. Except for the extracts of L. philippiana and P. boldus at 0.125 and 0.25%, all treatments caused repellency, reaching higher levels at concentrations ≥ 4%. Only the essential oil of L. sempervirens presented seasonal variation, with greater repellency in the foliage collected in summer. Due to the absence of seasonal effects, essential oils of P. boldus and L. philippiana are considered promising for the control of pests in stored grains throughout the year. |
