Current perspectives and difficulties in the design of acaricides and repellents from plant-derived compounds for tick control.

Ticks and tick-borne diseases have gained increasing attention in recent years due to their impact on public health and significant losses in livestock production. The use of synthetic compounds for tick control is becoming problematic, mainly due to the resistance to commercially available products as well as their toxicity. Therefore, new alternative control methods are required. For this purpose, plant-derived extracts may be considered as effective repellents and/or acaricides. The present literature review focuses on studies evaluating the acaricidal and repellent activity of plant-derived extracts and plant secondary metabolites. We also noted recent advances in protein-ligand-docking simulation to examine the possible toxic effect of natural chemical compounds on ticks. In conclusion, plant-derived repellents/acaricides can be effective against ticks, especially in rural areas and livestock farms.

Differentiation of action mechanisms between natural and synthetic repellents through neuronal electroantennogram and proteomic in Aedes aegypti (Diptera: Culicidae).

Natural-based compounds with repellent activity arise nowadays with the possibility to replace commercial synthetic repellents wholly or partially, such as N,N-Diethyl-m-toluamide (DEET). It is due to DEET's demonstrated toxicity and cutaneous irritation for human beings. Besides, research recommends avoiding using it with kids and pregnant women. The search for a repellent product implies early stages of detailed research that resolve the modes of action against the target insect. Therefore the objective of the current study was to analyze neuronal electrophysiological signals and olfactory system protein expression when the Aedes aegypti mosquito with exposition to natural-based repellents. Adult females of Ae. aegypti of Rockefeller strain were exposed to specific concentrations of repellent compounds like geranyl acetate, α-bisabolol, nerolidol, and DEET. The neuronal effect was measured by electroantennography technique, and the effect of exposure to either DEET or a mixture of natural molecules on protein expression was determined with 2D-PAGE followed by MALDI-TOF-mass spectrometry (MS). This approach revealed that DEET affected proteins related to synapses and ATP production, whereas natural-based repellents increased transport, signaling, and detoxification proteins. The proteomic and electrophysiology experiments demonstrated that repellent exposure disrupts ionic channel activity and modifies neuronal synapse and energy production processes.

Effect of altitude on wing metric variation of Aedes aegypti (Diptera: Culicidae) in a region of the Colombian Central Andes.

In mosquitoes of medical importance, wing shape and size can vary with altitude, an aspect that can influence dispersion and, consequently, their vector capacity. Using geometric morphometry analysis, Aedes aegypti wing size and shape variation of males and females was studied in four altitudes in the second-smallest department in Colombia: 1,200 m (Tebaida), 1,400 m (Armenia), 1,500 m (Calarcá), and 1,700 m (Filandia). Wing shape in males (P < 0.001) and females (P < 0.001) was significantly different through the altitudinal gradient; in turn, wing size in males followed the altitudinal gradient males (R2 = 0.04946, P = 0.0002), females (R2 = 0.0011, P = 0.46). Wing allometry for males (P < 0.001) and females (P < 0.001) was significant. Likewise, the shape and size of the wings of males (P < 0.001) and females (P < 0.001) had significant fluctuating asymmetry. It is concluded that, in a small scale with an altitudinal variation of 500 meters, it is detected that the size and shape of the wings varied in A. aegypti, main vector the agents that cause dengue, chikungunya, and Zika. The fluctuating asymmetry is present in the individuals studied and could be associated with environmental effects caused by vector control campaigns present in some sampling locations.

Design of a Repellent Against Aedes aegypti (Diptera: Culicidae) Using in silico Simulations With AaegOBP1 Protein.

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.

Dinámica de oviposición de Aedes (Stegomyia) aegypti (Diptera: Culicidae), estado gonadotrófico y coexistencia con otros culícidos en el área Metropolitana de Bucaramanga, Colombia / Oviposition dynamics of Aedes (Stegomyia) aegypti (Diptera: Culicidae), gonadotrophic state and coexistence with other culicidae in the metropolitan area of Bucaramanga

Resumen Introducción: Las zonas urbanas tropicales favorecen la presencia de Aedes aegypti en el continente americano. Otros culícidos pueden compartir la misma área de distribución con este mosquito, lo cual justifica que se deban monitorear. Objetivo: Conocer la dinámica de oviposición de A. aegypti, evaluar su estado gonadotrófico y determinar taxonómicamente la presencia de otros culícidos en el área metropolitana de Bucaramanga. Metodología: Para este propósito fueron instaladas trampas de oviposición (N=960) cebadas con infusión de heno (10%) durante un año en cuatro localidades (Norte, Girón, Piedecuesta y Floridablanca). Las ovitrampas permanecieron instaladas durante cinco días en intradomicilio y peridomicilio, paralelamente se colectaron larvas en plantas como bromelias y depósitos de agua en cada lugar de colecta. En el mes de mayo de 2014 fueron capturadas con un aspirador eléctrico y trampas StegTrap hembras de A. aegypti y Cx. quinquefasciatus a las cuales se les estimó su estado gonadotrófico. Datos ambientales como precipitación y temperatura fueron correlacionados con índices de oviposición. Resultados: Se obtuvieron 25.254 huevos de A. aegypti (Girón 39,1%, Bucaramanga 36,8% Floridablanca 15,2% y Piedecuesta 8,9%) en general los índices de oviposición fueron mayores en peridomicilio con correlaciones positivas (> 0. 5) entre los índices NOP, NH e IPO en peridomicilio y IPO y IDH en intradomicilio con la precipitación y la humedad. En cuanto al estado gonotrófico se determinó que las hembras de A. aegypti presentaron hasta dos ciclos gonadotróficos en las áreas examinadas. En las colectas activas en peridomicilio se encontró, Culex spissipes, Culex quinquefasciatus, Limatus durhamii, Toxorhynchites spp y Wyeomyia davisi. Conclusión: A. aegypti fue presente en todas localidades y se reportan otros culícidos potenciales vectores en el área metropolitana.

Abstract Introduction: Tropical urban areas favor the presence of Aedes aegypti in the American continent. Other mosquitoes can share the same geographic distribution with this mosquito, which justifies that they must be monitored. Objective: It is to know the dynamics of oviposition of A. aegypti, evaluate its gonadotrophic state and determine taxonomically the presence of other culicidae in the metropolitan area of Bucaramanga. Methodology: Oviposition traps (N = 960) were baited with hay infusion (10%) for one year in four locations (Norte, Girón, Piedecuesta and Floridablanca). The ovitraps were kept for five days indoors and outdoors, while larvae were collected in plants such as bromeliads and water reservoirs from each collecting site. In the month of May 2014, were captured with an electric aspirator and traps to catch females of A. aegypti and Culex quinquefasciatus to which were estimated their gonadotrophic state. Environmental data such as precipitation and temperature were correlated with the collected eggs and their oviposition indices. Results: 25,254 eggs of A. aegypti were obtained (39.1% Girón, 36.8% Bucaramanga, 15.2% Floridablanca and 8.9% Piedecuesta). In general, oviposition rates were higher outdoors. As for the gonotrophic state, it was detected that females of A. aegypti can have for over two gonadotrophs cycles. In the active catch outdoors were found Culex spp., Culex quinquefasciatus, Limatus durhamii, Toxorhynchites spp and Wyeomyia davisi. Conclusion: A. aegypti was present in all localities and other mosquitoes are reported in the metropolitan area.

New records of mosquito species (Diptera: Culicidae) for Santa Catarina and Paraná (Brazil) / Novos registros de espécies de mosquitos (Diptera: Culicidae) em Santa Catarina e Paraná (Brasil)

We provide eight new mosquito species records for Santa Catarina (Limatus flavisetosus Oliveira Castro 1935, Mansonia flaveola (Coquillett 1906), Ma. titillans (Walker 1848), Psorophora forceps Cerqueira 1939, Sabethes xyphydes Harbach 1994, Toxorhynchites bambusicolus (Lutz & Neiva 1913), Tx. theobaldi (Dyar & Knab 1906) and Wyeomyia lassalli Bonne-Wepster & Bonne 1921) and three for Paraná (Ochlerotatus argyrothorax Bonne-Wepster & Bonne 1920, Uranotaenia pallidoventer Theobald 1903 and Wyeomyia pilicauda Root 1928). Additionally, we list all species in these eight genera recorded previously in the two states. The known distribution and possible epidemiological implications of the new species records are discussed.

Relatamos o primeiro encontro de oito espécies de mosquitos para Santa Catarina (Limatus flavisetosus Oliveira Castro 1935, Mansonia flaveola (Coquillett 1906), Ma. titillans (Walker 1848), Psorophora fórceps Cerqueira 1939, Sabethes xyphydes Harbach 1994, Toxorhynchites bambusicolus (Lutz & Neiva 1913), Tx. theobaldi (Dyar & Knab 1906) e Wyeomyia lassalli Bonne-Wepster & Bonne 1921) e três para o Paraná (Ochlerotatus argyrothorax Bonne-Wepster & Bonne 1920, Uranotaenia pallidoventer Theobald 1903 e Wyeomyia pilicauda Root 1928). Adicionalmente, apresentamos lista de todas as espécies destes oito gêneros com registro nos dois estados. A distribuição conhecida das espécies e sua possível importância epidemiológica são discutidas.