Influência do óleo essencial de citronela (cymbopogon spp) na repelência e mortalidade de sitophilus zeamais mots., 1855 (coleoptera: curculionidae) em milho armazenado

Abstract

During storage, maize (Zea mays) is subject to attack by pests such as weevil, Sitophilus zeamais, a beetle that causes profound injury to product quality. Weevil control is conventionally carried out chemically. In agroecological methods this substance becomes undesirable due to its toxicity. Studies indicate that citronella essential oil (Cymbopogon spp.) Has repellent substances, and its use may have a significant effect on the control of S. zeamais in stored corn grains. In this context, the proposal to investigate the potential use of citronella essential oil as an alternative method to corn weevil control becomes relevant in the context of undesirable insect control in stored grain systems. The experiment was based on the performance of repellency, survival, germination and vigor tests, in order to determine the ideal concentration of use of the essential oil for repellency and insecticide effect. The essential oil was applied at concentrations 0.2; 0.4; 0.6 and 0.8% on porous absorbent paper and then deposited in a system of arenas containing corn grain and weevil. The results would show a significant effect of increased weevil repellency at concentrations of 0.6 and 0.8%. In survival tests citronella had no insecticidal effect as expected, because in treatments of 0.2 and 0.4% did not cause mortality, and a low mortality was observed at concentration of 0.6 and 0.8%, not reaching lethal concentration (LD50). The application of oil had significant interference in egg laying in the treatments 0.4 and 0.6%. The most efficient concentrations for repellency (0.6 and 0.8%) were used for the germination and vigor test, and the oil was not significantly affected the germination capacity of the seeds, interfering only in the germination speed. The grains subjected to the effect of the essential oil caused repellency of the weevil by the corn, showing that this substance has some kind of repellent effect, but not insecticide. Thus we can infer that the essential oil in suitable concentrations has potential for use and further research is required for application under storage conditions.