Larvicidal susceptibility of essential oils from Cinnamodendron dinisii, Callistemon viminalis and Myrcia tomentosa against Culex quinquefasciatus (Say) (Diptera: Culicidae)

Abstract

Culex quinquefasciatus Say, 1823 (Diptera: Culicidae) is a vector of pathogens and parasites, whose form of control is the use of synthetic insecticides. However, the indiscriminate use of these products has led to the emergence of resistant populations. The objective was to evaluate the susceptibility of C. quinquefasciatus larvae to essential oils (EOs) from leaves of Cinnamodendron dinisii Schwacke (CD), Callistemon viminalis (Sol. ex Gaertn.) G.Don (CV) and Myrcia tomentosa (Aubl.) DC. (MT), and the influence on biochemical parameters, in addition to the in silico potential of the most promising EO for the target acetylcholinesterase (AChE) enzyme. The steam distilled EOs were analysed by gas chromatography/mass spectrometry. The EOs lethal concentration of 50 % (LC50) was estimated using different concentrations and probit analysis. Then, the larvae were exposed for 1 h to the LC75 of the most promising EO, and the biochemical parameters were evaluated in vitro: soluble protein concentration, reduced glutathione content, hydrogen peroxide production, lipid peroxidation levels, and AChE enzyme activity. The AChE molecular docking was also performed. The main chemical constituents in CD were pinenes, sabinene and bicyclogermacrene; in CV were α-pinene and 1,8-cineole and in MT were (E)-caryophyllene and germacrene D. The lowest LC50 (1.43 mg. L−1) was estimated for CD EO, although LC75 reduced all biochemical parameters and inhibited AChE activity. The docking results for the major (bicyclogermacrene) and minor compounds (aromadendrene, α-copaene, drymenol, σ- and β-elemene) present in CD EO have high affinity with AChE. In conclusion the effects indicate the promising potential of the CD EO for the development of larvicide against the C. quinquefasciatus.