Chemical composition and repellent potential of essential oil from Croton tetradenius (Euphorbiaceae) leaves against Aedes aegypti (Diptera: Culicidae)

Essential oils are volatile compounds that contain chemical constituents with different biological activities, including repellent activity. Thus, the investigation of aromatic species with repellent potential against insect vectors, such as Aedes aegypti (Linnaeus 1762) has increased. The present study evaluated the spatial activity index, the chemical composition of the essential oil from Croton tetradenius leaves, as well as the effective repellent concentration and protection time against female Ae. aegypti mosquitoes. For the biological assays, mosquitoes with up to seven days of emergence were used, which were subjected to different essential oil concentrations in a nonionic emulsion. The chemical composition was determined by gas chromatography, coupled with mass spectrometry and flame ionization detector. The essential oil showed a higher repellent spatial activity for the concentrations of 200 and 300 mg/cm2. The estimated concentration of 14.1 and 163.4 mg/cm2 showed an effective repellency of 50 and 99%, respectively. Regarding the protection time, 84% landing inhibition, and 100% blood-feeding inhibition were observed for the concentration of 200 mg/cm2 within 240 min. Thirty-three compounds were identified in the chemical characterization, and camphor (30.25%), p-cymene (13.39%), alpha-terpinene (10.59%), and gamma-terpinene (5.32%) were the major compounds. Therefore, the essential oil from Croton tetradenius leaves proved to be a promising repellent alternative in protecting against the Aedes aegypti mosquito.