We examined the pupicidal, adulticidal, repellent, and oviposition-deterrent activities of essential oils (EOs) from Lippia alba, L. origanoides, Eucalyptus citriodora, Cymbopogon citratus, Cymbopogon flexuosus, Citrus sinensis, Cananga odorata, Swinglea glutinosa, and Tagetes lucida plants against Aedes aegypti under laboratory conditions. Pupicidal and adulticidal activities were assessed at exploratory concentrations of 250, 310, and 390 parts per million (ppm); and 30, 300, and 1,000 ppm, respectively. The greatest pupicidal activity was exhibited at 390 ppm with a 24-h exposure by L. origanoides, and 390 ppm with a 48-h exposure by Citrus sinensis. Lippia origanoides killed all adult mosquitoes at 300 ppm after 120 min of exposure. Only L. origanoides and E. citriodora EOs, applied at 1,000 ppm to human skin, produced the greatest repellency (100%) to host-seeking Ae. aegypti after 2 min of exposure; the repellency decreased between 12% and 10% after 15 min. Complete oviposition deterrence b...

Skin irritation has been reported to be the main adverse effect of excessive use of N,N-diethyl-m-toluamide (DEET) and ethyl 3-acetyl(butyl)amino (IR3535) commercial repellents. Therefore, there is an interest in alternatives of natural origin such as essential oils (EOs) and major compounds, which have repellent effects but have no contraindications. The main purpose of the present study was to identify the repellent effect of selected terpenes on Aedes aegypti Linnaeus, 1762 (Diptera: Culicidae) by in silico analysis based on their affinity with the odorant protein AaegOBP1. The protein-metabolite interactions in 20 terpenes were analyzed using the SwissDock tool. Terpenes presenting the highest affinity compared with commercial repellents were selected to evaluate repellent activity at concentrations 0.1, 10, and 25% against Ae. aegypti. Different periods (0–2, 2–15, 15–60 min) were evaluated with DEET as a positive control. The toxicity of terpenes was verified through Osiris and Molinspiration Cheminformatics Software, and cytotoxicity assays in Vero and HepaRG cells were performed using the MTT method. Two formulations were prepared with polyethylene glycol to evaluate skin long-lasting in vivo assay. The results showed four terpenes: geranyl acetate, nerolidol, α-bisabolol, and nerol, with affinity to AaegOBP1 comparable with DEET and IR3535. Geranyl acetate, nerolidol, and their mixtures showed no cytotoxicity and protection percentages close to 100% during the test at concentrations 10 and 25%. Long-lasting assays with geranyl acetate and nerolidol formulate showed 3 h as maximum protection time with 100% protection percentage. These metabolites and their mixtures are candidates to repellent formulations with times and protection percentages similar to DEET.

Different studies have evaluated the biocidal activity of essential oils (EO) in mosquito larvae of medical importance. However, limited research focused on analyzing the EO effect at all the stages of the life cycle of Aedes aegypti has been done. This study evaluates the biological activity of the EO Salvia officinalis against Ae. aegypti . The ovicidal activity was evaluated at 1, 5, 37 and 50 mg.L ⁻¹ concentrations in eggs from 0-12 h and eggs from 0-72 h. Larvicidal, pupicidal and adulticidal activities were assessed at exploratory concentrations (EC) and multiple concentrations. We employed an EC of 1,000 mg.L ⁻¹ for repellent activity and used an exposure time of 0-2 min and 2-15 min on the forearms of volunteers. The deterrent action was estimated at EC of 5, 50 and 200 mg.L ⁻¹ . The EO caused malformations in embryos as well as larvae alteration. The highest larvicidal activity was at 63 and 76 mg.L ⁻¹ (27 ± 13.4 and 37 ± 18.6%) with 24 h exposure. The greatest pupicidal mortality was at 310 and 390 mg.L ⁻¹ (89 ± 1.53 and 100 ± 0%) with 48 h exposure. Adulticidal mortality at 300 mg.L ⁻¹ was 57.5 ± 0% and the percentage of repellency was 42 ± 4.7%. The dissuasive action at 200 mg.L ⁻¹ was 97 ± 4.81%, with an oviposition activity rate of -0.94. S. officinalis showed a biocidal effect on embryos and mortality of pupae and adults, indicating that its potential use in control programs should be focused on these stages of development.

The current study describes the effects of sub-lethal concentrations and constituent compounds (citral and geranyl acetate) of Cymbopogon flexuosus essential oil (EO) on the development of Aedes aegypti (L.) eggs and larvae. To demonstrate the ovicidal activity of EO, we treated embryonated eggs with 6, 18, and 30 mg.L ^-1 and larvae with 3 and 6 mg.L ^-1 EO concentrations. Citral and geranyl acetate were evaluated at 18, 30, and 42 mg.L ^-1 and compared with commercial growth inhibitors (diflubenzuron and methoprene) at 3 and 6 mg.L ^-1 concentrations. For each treatment, we measured larval head diameter, siphon length, and body length. To complement the morphological analysis, we examined concentrations of moult hormone (MH) and juvenile hormone III (JH III) using high-performance liquid chromatography (HPLC) coupled to mass spectrometry. The EO decreased egg hatching at all concentrations: 6 mg.L ^-1 in 45.3%; 18 mg.L ^-1 in 23.3%, and 30 mg.L ^-1 in 34.6%. EO also altered molting among larval instars and between larvae and pupae, with an increase in the length (3 mg.L ^-1 : 6 ± 0.0 mm; 6 mg.L ^-1 : 6 ± 0.7 mm) and head width (3 mg.L ^-1 : 0.8 ± 0 mm; 6 mg.L ^-1 : 0.8 ± 0.0 mm) compared with the control group (length: 5.3 ± 0 mm; head width: 0.7 ± 0.0 mm). We did not detect chromatographic signals of MH and JH III in larvae treated with C. flexuosus EO or their major compounds. The sub-lethal concentrations C. flexuosus EO caused a similar effect to diflubenzuron, decreasing hormone concentration, extending the larval period, and death.

Characterizing the sand fly diversity is crucial for an effective design of control strategies for Leishmaniasis. We aimed to characterize the sand fly biodiversity around the Tona Reservoir (Santander, Colombia) and to compare the performance of four sampling methods. A sampling of insects was performed in 2017 in the most preserved and least preserved areas close to the Tona Reservoir, using Torre Vigia-UIS and HomeTrap-UIS, two sticky traps previously designed by our working group, CDC, and Bg-Sentinel traps. We collected 268 Phlebotominae specimens, most with CDC (47.8%) and Torre Vigia-UIS (30.2%) traps. Some specimens (47%) could not be determined because of their preservation status; these samples came mostly from the sticky traps. We found 16 sand fly morphospecies, of which 12 were determined to species level. Here, we report two new records for Santander: Pintomyia youngi (Feliciangeli and Murillo, 1987) and Lutzomyia ceferinoi (Ortíz and Álvarez, 1963). We also collected some confirmed vectors of Leishmania : Pi. youngi , Lutzomyia gomezi (Nitzulescu, 1931), and Lu. longipalpis (Lutz and Neiva, 1912). The highest diversity was collected in the most disturbed area (15 spp.), and in the rainy season (April, 12 spp.). Pintomyia youngi distribution was broad through the Tona Reservoir in all the sampled periods, and we suggest tracking it to infer leishmaniasis risk in the Tona Reservoir. Torre Vigia-UIS seems a valuable tool for vector control, but we do not recommend it for biodiversity studies.