Larvicide and repellent activity of Hypenia irregularis (Benth.) Harley in the alternative control of mosquito Aedes aegypti

Abstract

Dengue is an emerging epidemic disease and among those transmitted by the Aedes aegypti mosquito, it is the one with the highest number of cases and cases with death. With the wide dissemination of the beneficial effects of medicinal plants and the use in agriculture as a pesticide, studies on the prospection of plants with toxic activity have been increasing, highlighting extracts and essential oils. The objective of this study was to evaluate the effects of Hypenia irregularis essential oil extracted by hydrodistillation, in a Clevenger-type device modified against 3rd instar larvae and adult mosquitoes of Aedes aegypti. The chemical composition of the oil was determined using the Gas Chromatography/mass spectrometer (GC/MS) technique. The major compounds were: 2, 5-dimethoxy-ρ-cymene, thymol, o-cymene, phenol-3- (1, 1-dimethylethyl)-4-methoxy and humulene with 27.0, 21.36, 15.56, 8.89 and 5.01%, respectively. For all the tests, were applied concentrations ranging from 0.007 to 0.13 μl.ml-1, for the larvicidal test was denoted LC50 0.037 μl.ml-1 and CL95 0,122 μl.ml-1, for the time response required to achieve 95% mortality (TL95) was 27.412 min. In the oviposition bioassay it was observed that the higher the concentration of essential oil used (0.2 μl ml-1), the lower the number of eggs deposited, the less eggs being deposited as compared to the untreated tests. In addition, the action of H. irregularis oil showed better results than the commercial insect repellent composed of N, N-diethyl-m-toluamide (15%) in 135 min of exposure to mosquitoes.