Toxicidade por Malation em formigas Odontomachus brunneus (Hymenoptera: Formicidae)

Abstract

The use of insecticides to regulate the insect population is a common practice in agricultural production and also for urban insect control. Among the insecticides commonly used in urban environments, we highlight malathion, used in through smoke to control insect vectors such as the Aedes aegypti mosquito. In addition to mosquitoes, other insects, such as ants found in urban environments, can be affected by the use of this insecticide, therefore, our objective was to evaluate the toxicity of malathion to the ant Odontomachus brunneus. Four concentrations of the insecticide were tested: starting from the dose recommended by the manufacturer and following serial dilutions of 10 times, being: 1000 µg/mL, 100 µg/mL, 10 µg/mL and 1 µg/mL. In addition to the concentrations, a control group was maintained with distilled water only for each test. After contact contamination of groups of ants, the mortality rate was evaluated every hour during the first six hours, and a final evaluation after 24 hours. Our results showed that the three highest concentrations (1000 µg/mL, 100 µg/mL and 10 µg/mL) caused the death of more than 98.14% of individuals after 24 hours, with 92.2% of deaths occurring in first 3 hours of observations. The weakest concentration of 1µg/mL obtained a result closer to the control group, with only 2 deaths (2.5%). Therefore, we can state that malathion is not a selective insecticide, proving to be highly toxic to non-target insects, as in the case of the ant Odontomachus brunneus, which can be directly affected by fumigation.