Óleo essencial de Piper baccans (MIQ.) C.DC: uma alternativa natural no controle do Aedes aegypti (Linnaeus, 1762) (Diptera: Culicidae)

Abstract

Synthetic insecticides have been the main way to control insect vectors. However, indiscriminate use has triggered the development of resistance. In addition, synthetic insecticides are highly toxic products for the environment. On the other hand, essential oils (EOs) extracted from plants such as the genus Piper are important larvicides with neurotoxic and cytotoxic action against insect vectors such as A. aegypti. Thus, the aim of the study was to investigate the chemical profile of the EO from Piper baccans and to evaluate its biological activity and mechanism of action against A. aegypti, as well as to evaluate its toxicity against non-target aquatic animals. The chemical profile of the EO extracted from P. baccans leaves analyzed by chromatographic methods (GC-MS) was evaluated against A. aegypti larvae, while the mechanisms of action were based on enzymatic (AChE) and cytological analyses. The toxicity of EO was investigated against predators of culicide larvae Diplonychus indicus and Anisops bouvieri. GC-MS analyses of the EO revealed the majority presence of δ-cadinene (11.64%), elemol (10.12%), (-)-10-epi-γ-eudesmol (9.39%), isocaryophelene (6.73%), γ-muurolene (7.49%), caryophyllene oxide (7.09%) and epi-γ-eudesmol (5.5%). The EO showed significant larvicidal activity (LC50 of 10.68 µg/mL and CL90 of 22.11 µg/mL), caused by the neurotoxic action after inhibition of the AChE enzyme (IC50 of 38.37 µg/mL), as well as by genotoxic action promoted by micronucleus malformation and chromosomal destructio with apoptotic and necrotic cells, metaphase chromosome loss, metaphase chromosome groups and binucleated cells. EO at 31.25 µg/mL was not toxic against D. indicus and A. bouvier. However, showed high toxicity at 62.50 µg/mL, killing 100% of these animals. The results demonstrate that the EO extracted from leaves from P. baccans is a significant natural larvicide against A. aegypti larvae, with a neurotoxic and cytological mode of action. However, its use should be evaluated at concentrations below 31.25 µg/mL.