Potencial entomotóxico de extrato de Eragrostis plana NEES em modelo experimental de Nauphoeta Cinerea Olivier

Abstract

Among the main strategies adopted by invasive plants are the release and propagation of their secondary metabolites in the environment. The Eragrostis plana Nees (capim-annoni-2) is an invasive vegetable, originating from the African continent, introduced in Brazil in the early 1950s, which has been successfully propagated in the national territory, since it is a strong competitor due to its allelopathic potential. The objective of this work was to evaluate the entomotoxic activity of the aqueous extract of capim-annoni-2 in an experimental model of cockroaches (Nauphoeta cinerea). For this, aerial parts of E. plana were ground to obtain the crude extract, after dilution in milli-q water in 7 doses (0.5, 2.5, 5.0, 12.5, 25.0, 50, 0 100.0 μg / g animal) saline solution was used for the control treatment. To determine the receptors and pathways involved in response to the doses of hydroalcoholic extracts of capim-annoni-2 (EHCA), a treatment with the drug octopamine and its inhibitor the phentolamine was prepared. In all experiments male and adult cockroaches were used for standardization. In grooming, 30 subjects were used for each dose tested, whereas for the semi-isolated heart test 10 subjects were used per dose. For the insecticidal activity assay EHCA was used at the doses of 100, 200, 400, 600, 800 μg / g animal and saline for the control treatment, the LD50 lasted 72 hours, each dose was tested 15 animals, dose where the highest mortality rate was considered the lethal dose. All data were expressed as mean ± error (E.P.M), being analyzed by the ANOVA two-way test, followed by the Tukey or Dunnett tests, being considered significant when p <0.05. After the experiments were carried out it was found that the EHCA induced a significant effect on leg grooming at all concentrations except for the concentration of 100 μg /g animal, whereas the same did little modulate antenna grooming. Concerning the receptors and pathways involved, it was observed that the octopamine both isolated and with the extract had a significant effect on leg grooming, while the phentolamine, together with the extract had an effect on antenna grooming. Regarding the effect of the extract on the semiisolated heart, it was noted that the same doses that affected grooming affect the heart rate by lowering the heart rate. At no concentration, at the end of the treatment there was heart rate recovery. In the insecticidal activity, the concentration of 400 μg/g of animal had a higher mortality rate. This confirms that the EACA has an entomotoxic potential.