Efeito residual do óleo essencial de Baccharis trimera sobre Sitophilus zeamais em grãos de milho armazenados

Abstract

The excessive use of pesticides in agriculture has caused untold damage since the green revolution, causing damage to the environment and health. Corn, is one of the most produced cereal in the world has a fundamental role in human and animal nutrition. Among the main pests that affect the storage, Sitophilus zeamais is one of the most expressive. In this sense, the search for new alternatives to chemicals is of great relevance. This study aimed to evaluate the residual effect of Broom (Baccharis trimera) on maize weevil (S. zeamais) in maize grains stored. Plants were harvested in the city of Severiano de Almeida - RS, and stored in the UFFS Erechim-Campus laboratory, and dried at room temperature. To obtain the oil, the hydrodistillation method was used beyond Clevenger apparatus. For identification of the components of the oil, the gas chromatography method was used. The insects were breed on conditions of temperature (25 ± 2 ° C) and humidity (65 ± 10%). To evaluate the residual effect, it was applied the essential oil, previously described, at doses of 0, 20, 40, 60, 80 and 100 uL in circular pots containing 20g of corn. Soon after the treatment of the grains (time zero) and at 15, 30, 45, 60 and 90 days grains, they were kept in pots infested with 20 adult insects, and readings were made at an interval of 10 days. The oil presented a high residual effect showed greater than 85% mortality at 90 days of exposure, lower doses showed rapid degradation over time but can be an option for producers who do not store grain for long periods.