Abstract
Tabebuia avellanedae is an important timber source belonging to the family of Bignoniaceae. The latter is known for its richness in terms of variety of bioactive chemical constituents, and it has been used in folk medicine for treatment of various diseases. The aim of this work was to investigate the chemical composition, oviposition deterrent and larvicidal activities of the wood extracts of T. avellanedae from the Cerrado of Brazil. Extracts of acetone, ethyl acetate and ethanol from T. avellanedae were obtained using various extraction methods. Quantitative analysis of phytochemical screening confirmed the presence of phenols and tannins in the wood extracts, however, anthraquinones, coumarins and alkaloids were absent. The toxicity of T. avellanedae extracts against 3rd instar larvae of Aedes aegypti using maceration and Soxhlet extraction methods was analyzed. The acetone and ethyl acetate extracts obtained by Soxhlet extraction were more toxic against 3rd instar A. aegypti larvae, with CL50of 100.1 and 151.0 μg/mL, respectively. The mortality values (LT50 and LT95) were 38.66 and 66.74 min for ethyl acetate extract, respectively, and 53.47 and 119.96 min for acetone extract, respectively. In all cases, the assay showed that all extracts presented mortality of 100% to 3rd instar larvae after 12 h. The oviposition assay showed that gravid A. aegypti females laid their eggs preferentially in the control ovitraps. The ethanol extract at 333.3 μg/mL strongly deterred oviposition by 89.89% while the ethyl acetate and acetone extracts presented 89.04 and 68.10% deterrence, respectively. The bioactive compounds in T. avellanedae make it a potential source for the control of A. aegypti vectors, without promoting deforestation of trees. Key words: Mosquitoes, larvae, toxicity, Ipê-roxo, Aedes aegypti, phytochemical, phenolic compounds.  
Highlights
Phytochemical screening of T. avellanedae wood residue extracts revealed the presence of tannins and phenols (Table 1)
The effect of acetone, ethyl acetate and ethanol extracts of T. avellanedae on the oviposition response of female A. aegypti was carried out according to previously described methodology (Aguiar et al, 2015)
The quantification of total phenols in the extracts obtained from the wood residue of T. avellanedae showed that phenolic compounds were present in significant quantities
Summary
Zika and chikungunya viruses deserve special attention because these viruses are currently causing negative impacts on public health and economic damage around the world (Mayer et al, 2017). Many insecticides may be used to control mosquitoes, many of them are not selective and can harm beneficial insects, increase the resistance of these insects and produce environmental contamination (Moreira et al, 2016). For the past several decades, the problem of vector resistance to insecticides has developed in many vector-borne disease endemic areas throughout the world. Botanical insecticides are less likely to bio-accumulate, as they are biodegradable (Bosire et al, 2014)
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