Friedericia chica, a medicinal plant from the Amazon region, is repellent against Aedes aegypti: in vivo and molecular docking evidence.

Fridericia chica is widely distributed in Brazil, where it is commonly known as crajiru or pariri in several regions. Despite its popular use for treating inflammations and as an insect repellent, there has been limited assessment of its chemical and biological properties, including its bioinsecticide activities. In this study, we conducted phytochemical analyses and investigated the larvicidal and repellent effects of F. chica against the mosquito Aedes aegypti. The F. chica (HEFc) hydroalcoholic extract was partitioned using column chromatography, and subfractions were analyzed using chromatographic and spectroscopic analyses (ESI-IT-MSn and NMR). In addition, HEFc was evaluated for its larvicidal and repellent activities. Phytochemical analyses revealed the presence of 17 constituents, including 2,4-dihydroxybenzoic and p-coumaric acids, along with umbelliferone, acetovanilone, myricetin-3-O-glucuronide, and cis-isorhapontigenin, which are reported for the first time in this species. Although no larvicidal effect was observed at the doses tested, the HEFc exhibited promising repellent effects against A. aegypti, which aligns with its ethnopharmacological potential. In addition, molecular docking studies demonstrated that the compounds of HEFc interacted efficiently with insect odorant binding proteins (OBPs), providing repellent effects. Consistent with the chemical profile and in silico studies, preparations of F. chica have considerable repellent potential.

Chemical control of medically important arthropods in Panama: A systematic literature review of historical efforts.

Vector-borne diseases are a major source of morbidity in Panama. Herein, we describe historical usage patterns of synthetic insecticides to control arthropod disease vectors in this country. We examine the influence of interventions by vector control programs on the emergence of insecticide resistance. Chemical control has traditionally focused on two mosquito species: Anopheles albimanus, a major regional malaria vector, and Aedes aegypti, a historical vector of yellow fever, and current vector of dengue, chikungunya, and Zika. Countrywide populations of An. albimanus depict hyperirritability to organochlorine insecticides administered by indoor residual spraying, although they appear susceptible to these insecticides in bioassays settings, as well as to organophosphate and carbamate insecticides in field tests. Populations of Ae. aegypti show resistance to pyrethroids, particularly in areas near Panama City, but the spread of resistance remains unknown in Ae. aegypti and Aedes albopictus. A One Health approach is needed in Panama to pinpoint the insecticide resistance mechanisms including the frequency of knockdown mutations and behavioral plasticity in populations of Anopheles and Aedes mosquitoes. This information is necessary to guide the sustainable implementation of chemical control strategies and the use of modern vector control technologies such as genetically modified mosquitoes, and endosymbiont Wolbachia-based biological control.

Encapsulation of carvacrol and thymol with yeast cell wall and its repellent activity against Amblyomma sculptum and Rhipicephalus sanguineus (Sensu Lato).

The main way to avoid contact with ticks and consequently tick-borne disease is the use of synthetic repellents. The search of new repellent compounds to increase the possibilities of use in strategies controls are necessary. The present study evaluated the repellent activity of two natural terpenes carvacrol and thymol in each one two different formulation (encapsulated and nonencapsulated with yeast cell wall) against the ticks Amblyomma sculptum and Rhipicephalus sanguineus sensu lato nymphs. Nymphs of A. sculptum and R. sanguineus s.l. of a single generation were used. The vertical filter paper repellency assay were performed with different concentration of both terpenes encapsulated and nonencapsulated in yeast cell wall. The repellent concentration 50% (RC50) were calculated to each compound formulation. Both carvacrol and thymol (encapsulated and nonencapsulated), had a repellent activity against A. sculptum and R. sanguineus s.l nymphs. Amblyomma sculptum was more sensitive to nonencapsulated carvacrol (RC50 values: 0.0032 to 0.0082 mg/cm2 after 1 and 15 min) (P < 0.05), while R. sanguineus s.l. was more sensitive to encapsulated carvacrol (RC50 values: 0.00008 to 0.0035 mg/cm2 after 1 and 15 min) (P < 0.05). Among tick species, R. sanguineus s.l. was more sensitive for most compounds than A. sculptum (P < 0.05). Although with distinct repellent activities, carvacrol and thymol encapsulated can be a promising alternative to synthetic repellents against A. sculptum and R. sanguineus s.l.

Two Lactones Non-toxic to Humans Are Effective Repellents for the German Cockroach.

Lactones are cyclic esters of hydroxy carboxylic acids, present in several fruits and animals consumed by humans. There is evidence that some lactones modify insect behavior. The aim of the present study was to evaluate the repellent effect of four lactones (γ- and δ-nonalactone, and γ- and δ-dodecalactone) in first instar nymphs of the German cockroach, Blattella germanica (Linnaeus). To assess repellency, a nymph was placed on a circle of filter paper, half of which had been treated with lactone dissolved in acetone and the other half with acetone alone. The behavior of the nymph was recorded and the time the nymph spent in each half of the paper was quantified using Ethovision XT 10.1 software. Values of Distribution Coefficient (DC) were calculated: DC = (Tt - TA) / Tt, where Tt is the experimental time and TA is the time the nymph spent in the area treated with the repellent agent. DC can vary between 0 and 1. Values significantly higher than 0.5 indicate repellency. N,N-diethyl-meta-toluamide (DEET) was used as a positive control. DEET, δ- and γ-nonalactone caused repellency as from 77.9 µg/cm2, whereas γ- and δ-dodecalactone had a repellent effect starting at 779.0 µg/cm2. The values of DC for these concentrations were 0.89 (DEET), 0.86 (γ-nonalactone), 0.87 (δ-nonalactone), 0.83 (γ-dodecalactone), and 0.72 (δ-dodecalactone). To our knowledge, this is the first report of repellency produced by lactones in the German cockroach. This work allowed to identify two lactones that have a repellent effect similar to DEET.

A multiparametric and orthogonal approach indicates low toxicity for zein nanoparticles in a repellent formulation.

The incidence of viruses such as Zika, Dengue, and Chikungunya affects human health worldwide, and insect repellents are recommended for individual protection. Formulations incorporating nanotechnology should be carefully assessed for toxicity, particularly regarding the security levels established for human health and the environment. This study evaluates the cytotoxicity of a repellent formulation containing zein nanoparticles (NP) loading geraniol (Ger) and icaridin (Ica) in three cell lines: NIH/3T3, HaCaT, and SIRC. To address formulation hazards, IC50 values were determined by MTT and Calcein-AM assays. In both NIH/3T3 and HaCaT, the IC50 values for NP + Ger + Ica formulation were around 0.2%. For risk assessment, cell viability was also determined after a single exposure and repeated exposure to the formulation. No evidence of cytotoxicity was observed for NP + Ger + Ica formulation-treated cells. The risk assessment for eye damage revealed cytotoxicity in SIRC cells when exposed to a 5% concentration, which may be attributed to ocular geraniol toxicity, because zein nanoparticles alone did not exhibit any signs of toxicity. Cell internalization indicated low uptake in NIH/3T3 and HaCaT cells. Phenotypic profiling resulted in similar phenotypes for untreated cells and cells exposed to NP + Ger + Ica formulation. The toxicological profile outlined by the multiparametric and orthogonal approach suggests that the NP + Ger + Ica formulation poses no significant risk to the topical application under the tested conditions. Adopting an orthogonal approach brings robustness to our findings.

Use of insect repellent as personal protection among women of childbearing age in an arbovirus endemic area in Northeastern Brazil / Uso de repelente como medida de proteção pessoal por mulheres em idade fértil residentes em áreas endêmicas para arboviroses no Nordeste do Brasil

ABSTRACT Objective: To analyze the factors associated with the individual use of insect repellent by women of childbearing age living in area endemic for arboviruses in Fortaleza, Brazil. Methods: This is a cohort study carried out between 2018 and 2019 with women aged between 15 and 39 years in Fortaleza, state of Ceará, Brazil. A total of 1,173 women users of one of the four selected primary health care units participated in the study. The outcome was divided into: continued use, discontinued use, and nonuse of insect repellent. Crude and adjusted multinominal logistic regression analysis was carried out guided by a hierarchical model, with presentation of the respective odds ratio (OR) and 95% confidence intervals (95%CI). The independent variables include: socioeconomic and demographic data, environmental and sanitary characteristics, knowledge of the insect repellent, and behavioral and pregnancy-related aspects. Results: Only 28% of the participants reported using insect repellent during the two waves of the cohort. Women with higher education (OR=2.55; 95%CI 1.44-4.51); who are employed (OR=1.51; 95%CI 1.12-2.03); who received guidance from healthcare professionals (OR=1.74; 95%CI 1.28-2.36) and the media (OR=1.43; 95%CI 1.01-2.02); who intensified precautions against mosquitoes during the epidemic (OR=3.64; 95%CI 2.29-5.78); and who were pregnant between 2016 and 2019 (OR=2.80; 95%CI 1.83-4.30) had increased odds for continued use of insect repellent. Conclusion: The use of insect repellent among women of childbearing age was associated with a higher level of education, employment, guidance on insect repellent provided by healthcare professionals and the media, behavioral changes to protect against mosquitoes during the Zika virus epidemic, and pregnancy when occurring as of the beginning of the epidemic period.

RESUMO Objetivo: Analisar os fatores associados ao uso de repelente individual por mulheres em idade fértil residentes em área endêmicas para arboviroses em Fortaleza, Brasil. Métodos: Coorte realizada entre 2018 e 2019, com mulheres entre 15 e 39 anos, moradoras em Fortaleza, Ceará, Brasil. Participaram 1.173 mulheres, usuárias de quatro unidades primárias de saúde do município. O desfecho foi categorizado em: uso continuado, uso descontinuado e não uso de repelente. Realizada análise de regressão logística multinominal norteada por modelo hierárquico, com apresentação dos respectivos odds ratio (OR) e intervalos de confiança de 95% (IC95%). As variáveis independentes incluem: dados socioeconômicos e demográficos, características ambientais e sanitárias, conhecimento sobre o repelente e aspectos comportamentais e relacionados à gravidez. Resultados: Somente 28% das participantes referiram o uso de repelente durante as duas ondas da coorte. Mulheres com escolaridade superior (OR=2,55; IC95% 1,44-4,51); com emprego (OR=1,51; IC95% 1,12-2,03); que receberam orientações por profissionais da saúde (OR=1,74; IC95% 1,28-2,36) e pela mídia (OR=1,43; IC95% 1,01-2,02); que intensificaram os cuidados contra o mosquito na epidemia (OR=3,64; IC95% 2,29-5,78); estavam grávidas entre 2016 e 2019 (OR=2,80; IC95% 1,83-4,30) tiveram as chances aumentadas para uso continuado de repelente. Conclusões: O uso de repelente entre mulheres em idade fértil mostrou-se associado a um maior nível de escolaridade, ao emprego, às orientações sobre repelente fornecidas por profissionais de saúde e pela mídia, às mudanças comportamentais de cuidado contra o mosquito durante a epidemia da Zika e à gravidez quando ocorrida a partir do início do período epidêmico.

Experimental protocol to repel opossums (Didelphis marsupialis) through an artisanal odor repellent device / Protocolo experimental para ahuyentar zarigüeyas (Didelphis marsupialis) mediante un dispositivo artesanal de olor repelente / Protocolo experimental para repelir gambás (Didelphis marsupialis) por meio de um dispositivo artesanal de odor repelente

Abstract Background: The human-opossum (Didelphis marsupialis) conflict has increased during the last decades mainly due to natural habitat loss, and mediated by generalist and opportunistic habits of opossums. A potential solution to reduce this conflict is to discourage the presence of opossums in human settlements without affecting the welfare of either part. Objective: To develop an artisanal odor device and test three chemical substances (citronella, ammonia, and creolin) for their separate effectiveness to drive away opossums. Methods: We first attracted local opossums using fruits or canned sardines as bait in an urban natural park (n=2 sites) and a peri-urban forest reserve (n=4 sites), both located in the Municipality of Envigado, Province of Antioquia, Colombia. Then we installed odor devices containing one of the three chemicals on each site and let them there during two weeks. The test was repeated with each of the chemicals in all sites. The number of opossum visits per night was recorded daily using camera-traps with bait and bait+chemical. Results: We found that ammonia and creolin were associated to fewer opossum visits per night. Citronella did not reduce the presence of opossums. In addition, the number of opossums/per night was higher in the urban park compared with the forest reserve. Conclusion: We suggest to further test the repellent effect of ammonia and creolin on real human-opossum conflict scenarios; however, caution is warranted given their irritant, flammable, and corrosive properties.

Resumen Antecedentes: El conflicto entre humanos y zarigüeyas (Didelphis marsupialis) se ha acrecentado en las últimas décadas debido, principalmente, a la pérdida de hábitats naturales y mediado por los hábitos generalistas y oportunistas de las zarigüeyas. Una posible alternativa de solución a este conflicto es desalentar la presencia de zarigüeyas en áreas habitadas por humanos, sin afectar el bienestar de ninguna de las dos partes. Objetivo: Desarrollar un dispositivo artesanal de olor y probarlo con tres sustancias químicas de manera separada (citronela, amoniaco, y creolina) probando su efectividad para ahuyentar a las zarigüeyas. Métodos: Inicialmente cebamos con frutas o sardinas enlatadas para atraer las zarigüeyas locales en un parque natural urbano (n=2 sitios) y una reserva forestal peri-urbana (n=4 sitios), ambas en el Municipio de Envigado, Departamento de Antioquia, Colombia. Posteriormente, instalamos el dispositivo con uno de los tres químicos en cada sitio durante dos semanas. El test se repitió con los tres químicos en todos los sitios. El número de zarigüeyas/noche se registró diariamente usando cámaras-trampa con cebo, y con cebo+químico. Resultados: El amoníaco y la creolina se asociaron con un menor número de visitas de zarigüeya/noche. Por otro lado, cuando se adicionó citronela, el número de visitas no disminuyó. Adicionalmente, el número de zarigüeyas/noche registradas en el parque urbano fue mayor con respecto a la reserva forestal peri-urbana. Conclusión: El amoniaco y la creolina tienen efecto ahuyentador de zarigüeyas. Sugerimos evaluar su efecto en ambientes de conflicto real humanos-zarigüeyas, tomando precauciones durante su manipulación dadas sus propiedades irritantes, corrosivas e inflamables.

Resumo Antecedentes: O conflito humano-gambá (Didelphis marsupialis) tem aumentado durante as últimas décadas devido principalmente à perda do habitat natural e tem sido mediado pelos hábitos generalistas e oportunistas do gambá. uma solução potencial para reduzir esse conflito é desencorajar a presença de gambás em assentamentos humanos sem afetar o bem-estar de ambas as partes. Objetivo: Desenvolver um dispositivo artesanal de odor com três diferentes produtos químicos: citronela, amônia e creolina, e testamos sua eficácia para afastar gambás. Métodos: Inicialmente atraímos gambás locais usando frutas ou sardinhas em lata como isca em duas áreas, um parque natural urbano (n=2 locais) e uma reserva florestal periurbana (n=4 locais), ambos em Envigado, Antioquia, Colômbia. Posteriormente, instalamos o dispositivo de odor usando um dos três produtos químicos em cada local durante duas semanas. O ciclo foi repetido com todos os três produtos químicos em todos os locais. O número de gambás/noite foi registrado diariamente usando câmera-armadilhas com isca e isca+produto químico. Resultados: Verificamos que a amônia e a creolina estiveram associadas ao menor número de gambás/noite, mesmo quando os locais ainda estavam iscados, e que a citronela não diminuiu a presença de gambás/noite quando adicionada aos locais iscados. Além disso, o número de gambás/noite foi maior no parque urbano em relação à reserva florestal. Conclusão: Sugerimos avaliar o efeito repelente da amônia e da creolina em cenários reais de conflito entre humanos e gambás; no entanto, deve-se ter cuidado devido às suas propriedades irritantes, inflamáveis e corrosivas.

Increased Repellent Effect of DEET on Aedes aegypti (Diptera: Culicidae) Field Population.

Insecticides and repellents are routinely used in Brazil because of the high rates of arbovirus transmission and the nuisance caused by mosquitoes. However, few studies have assessed the effectiveness of repellents against mosquito populations that have been under exposure to xenobiotics, mainly insecticides and repellents. This study investigated the sensitivity of a field population of Aedes aegypti (Linnaeus, 1762) from a dengue-endemic area under high insecticide pressure to N,N-diethylmethylbenzamide (DEET), the active ingredient in common repellent products. The field (Laranjeiras, Sergipe, Brazil) and laboratory (Rockefeller) populations were characterized for the presence of the Val1016Ile kdr mutation, associated with pyrethroid resistance, and locomotor activity. Repellency bioassays were performed to assess the response of the mosquitoes to human odor by exposing them to 10% DEET applied to the skin in ethanol. Samples from the field population showed higher frequency of the kdr mutation, 21.9% homozygous and 21.9% heterozygous, greater locomotor activity and greater sensitivity to DEET than the laboratory population. These results suggest increased sensitivity to DEET in field populations and a possible interaction between insecticide exposure and sensitivity to DEET.

Host-Guest Inclusion Complexes of Natural Products and Nanosystems: Applications in the Development of Repellents.

Repellents are compounds that prevent direct contact between the hosts and the arthropods that are vectors of diseases. Several studies have described the repellent activities of natural compounds obtained from essential oils. In addition, these chemical constituents have been pointed out as alternatives to conventional synthetic repellents due to their interesting residual protection and low toxicity to the environment. However, these compounds have been reported with short shelf life, in part, due to their volatile nature. Nanoencapsulation provides protection, stability, conservation, and controlled release for several compounds. Here, we review the most commonly used polymeric/lipid nanosystems applied in the encapsulation of small organic molecules obtained from essential oils that possess repellent activity, and we also explore the theoretical aspects related to the intermolecular interactions, thermal stability, and controlled release of the nanoencapsulated bioactive compounds.

Assessment of host-guest molecular encapsulation of eugenol using ß-cyclodextrin.

Eugenol is a natural compound with well-known repellent activity. However, its pharmaceutical and cosmetic applications are limited, since this compound is highly volatile and thermolabile. Nanoencapsulation provides protection, stability, conservation, and controlled release for several compounds. Here, eugenol was included in ß-cyclodextrin, and the complex was characterized through X-ray diffraction analysis (XRD) and Fourier-transform infrared spectroscopy (FTIR). Additionally, we used molecular dynamics simulations to explore the eugenol-ß-cyclodextrin complex stability with temperature increases. Our computational result demonstrates details of the molecular interactions and conformational changes of the eugenol-ß-cyclodextrin complex and explains its stability between temperatures 27°C and 48°C, allowing its use in formulations that are subjected to varied temperatures.

Evaluating Volatile Plant Compounds of Psidium galapageium (Myrtales: Myrtaceae) as Repellents Against Invasive Parasitic Diptera in the Galapagos Islands.

Plant-based repellents represent a safe, economic, and viable alternative to managing invasive insects that threaten native fauna. Observations of self-medication in animals can provide important cues to the medicinal properties of plants. A recent study in the Galapagos Islands found that Darwin's finches apply the leaves of Psidium galapageium (Hooker 1847) to their feathers, extracts of which were repellent to mosquitoes and the parasitic fly Philornis downsi (Dodge & Aitkens 1968; Diptera: Muscidae). Introduced mosquitoes are suspected vectors of avian pathogens in the Galapagos Islands, whereas the larvae of P. downsi are blood-feeders, causing significant declines of the endemic avifauna. In this study, we investigated the volatile compounds found in P. galapageium, testing each against a model organism, the mosquito Anopheles arabiensis (Patton 1905; Diptera: Culicidae), with the aim of singling out the most effective compound for repelling dipterans. Examinations of an ethanolic extract of P. galapageium, its essential oil and each of their respective fractions, revealed a mixture of monoterpenes and sesquiterpenes, the latter consisting mainly of guaiol, trans-nerolidol, and ß-eudesmol. Of these, trans-nerolidol was identified as the most effective repellent to mosquitoes. This was subsequently tested at four different concentrations against P. downsi, but we did not find a repellence response. A tendency to avoid the compound was observed, albeit significance was not achieved in any case. The lack of repellence suggests that flies may respond to a combination of the volatile compounds found in P. galapageium, rather than to a single compound.

Actividad repelente e insecticida de dos aceites esenciales de Piper del Nor-Occidente del Pacífico Colombiano / Repellent and insecticidal activity of two Piper essential oils from the Nor-West Colombian Pacific

Introducción: El uso inapropiado de plaguicidas en alimentos y la resistencia que las plagas han adquirido frente a estos, han traído consigo problemas de salud pública; con el objetivo de disminuir el empleo de estas sustancias nocivas, se han realizado estudios biológicos con productos vegetales (aceites esenciales) los cuales han demostrado ser eficaces para controlar diferentes organismos. Objetivos: Esta investigación tiene como objetivo determinar la actividad repelente e insécticida de dos aceites esenciales del género Piper, procedentes del nor-occidente del Pacifico colombiano, sobre insectos que atacan productos almacenados. Materiales y métodos: Los aceites esenciales fueron extraidos por hidrodestilación convencional, la actividad repelente se trabajó aplicando el metodo de área de preferencia para la actividad insecticida por dispersión de gas, donde se obtuvieron los porcentajes de repelencia y mortalidad. Resultados: Se encontró a Piper obrutum como el aceite esencial más activo, presentando a la concentración de 1µL/cm2 porcentaje de repelencia de 85% y registrando una mortalidad del 25% a la concentración de 500µL/mL y 72h de exposición; mientras que, Piper littorale a este tiempo de exposición, produce una tasa de mortalidad mayor, con un porcentaje de 40%, pero la repelencia para esta especie fue menor con el 70% de los insectos repelidos. Conclusiones: Se infiere de esta investigación, que los aceites esenciales de Piper obrutum y Piper littorale poseen mejores propiedades repelentes que insecticidas y pueden emplearse en el desarrollo de repelentes, que se apliquen en el control integrado de plagas de productos almacenados.

Introduction: The inappropriate use of pesticides in food and the resistance that pests have acquired against them, have brought about public health problems; in order to reduce the use of these harmful substances, biological studies have been carried out with plant products (essential oils) which have proven to be effective in controlling different organisms. Objectives: The objective of this research is to determine the repellent and insecticidal activity of two essential oils of the Piper genus, from the northwest of the Colombian Pacific, on insects that attack stored products. Materials and methods: The essential oils were extracted by conventional hydrodistillation, the repellent activity was worked by applying the area of preference method and the insecticidal activity by gas dispersion, where the percentages of repellency and mortality were obtained. Results: Piper obrutum was found to be the most active essential oil, presenting at a concentration of 1µL/cm2 a repellency percentage of 85% and registering a mortality of 25% at a concentration of 500µL/mL and 72h of exposure; whereas, Piper littorale at this exposure time, produces a higher mortality rate, with a percentage of 40%, but the repellency for this species was lower with 70% of the repelled insects. Conclusions: It is inferred from this research, that the essential oils of Piper obrutum and Piper littorale have better repellent properties than insecticidal and can be used in the development of repellents, which are applied in the integrated pest control of stored products.

Efficacy and safety of repellents marketed in Brazil against bites from Aedes aegypti and Aedes albopictus: A systematic review.

BACKGROUND: Dengue, Zika and Chikungunya viruses represent a serious public health problem. No evidence is available on the efficacy of repellents commercially available in Brazil. This systematic review assessed the efficacy and safety of products containing repellents commercially available in Brazil for protection against bites from Aedes aegypti and Aedes albopictus. METHODS: We performed a systematic review using the CENTRAL, MEDLINE, EMBASE, CINAHL, Web of Science, AMED, LILACS and Scopus databases. Randomized clinical trials and non-randomized clinical trials comparing topical repellent products registered with the Brazilian Health Surveillance Agency were included. Main outcomes of interest investigated were adverse effects, percentage repellency and protection time against bites. Pairs of reviewers selected the studies, extracted the data and evaluated the risk of bias. RESULTS: Sixteen studies were included. No adverse effects were reported by the studies. Against Ae. aegypti: protection time using DEET (10% and 20%-spray) was similar to IR3535 (10% and 20%-spray) and longer than citronella (5%-spray). DEET (25%-solution) had longer protection time than eucalyptus (25%-solution), while DEET (20%-lotion) had longer protection time than citronella (10%-lotion). There was no difference in protection time between herbal repellents. DEET (7% and 15%- spray) had higher percentage repellency compared to both icaridin (7%-spray) and IR3535 (20%-spray). Against Ae. albopictus: DEET (15%-spray) had a similar protection time to icaridin (20%-spray), but longer than citronella (10%-spray). CONCLUSION: DEET proved more effective than the other synthetic and natural repellents marketed in Brazil for protecting against bites from the mosquito species investigated. All repellents studied exhibited satisfactory safety profile.

Respuesta de Aedes aegypti L. (Diptera: Culicidae) a transflutrina y linalol impregnados en diferentes tipos de tela / Response of Aedes aegypti L. (Diptera: Culicidae) to transfluthrin and linalool impregnated in different of fabric types

Resumen: Objetivo: Evaluar el efecto de repelencia espacial contra Ae. aegypti de dos compuestos químicos impregnados en diferentes tipos de telas. Material y métodos: El estudio se realizó en el periodo 2015-2016 en el Centro Regional de Investigación en Salud Pública, del Instituto Nacional de Salud Pública. Se utilizó el Sistema de Procesamiento de Alto-rendimiento para evaluar la respuesta de Ae. aegypti a transflutrina y linalol, impregnados individualmente a diferentes concentraciones en popelina, algodón y poliéster. También se determinó el efecto de sus mezclas, lavado sobre la residualidad y porcentaje de protección. Resultados: La mayor respuesta de repelencia espacial fue para el tratamiento linalol-algodón al 0.1% (RE= 70 ± 5.77%). La mezcla de linalol 0.1% y transflutrina 0.001% presentó un porcentaje de repelencia espacial similar para los tres tipos de tela. El tratamiento transflutrina-popelina 0.001% mantuvo una residualidad de cinco días. El linalol al 0.1% produjo 62.50% de protección en presencia de un estímulo de atracción. Conclusión: Se sugiere la impregnación de linalol al 0.1% en ropa como medida de protección de las picaduras de Ae. aegypti.

Abstract: Objective: Evaluate the effect of spatial repellency against Ae. aegypti of two chemical compounds impregnated in different types of fabrics. Materials and methods: The study was carried out in the year 2015-2016 in the Centro Regional de Investigación en Salud Pública, del Instituto Nacional de Salud Pública. The high-throughput screening system was used to evaluate the response of Ae. aegypti to transfluthrin and linalool, impregnated individually at different concentrations in poplin, cotton and polyester. The effect of their mixtures was also determined, washing on residuality and percentage of protection. Results: The highest spatial repellency response was for 0.1% linalool-cotton treatment (RE = 70 ± 5.77%). The mixture of 0.1% linalool and 0.001% transfluthrin presented a similar spatial repellence percentage for the three types of fabric. The transfluthrin-poplin treatment 0.001% maintained a residual of five days. 0.1% linalool produced a 62.50% protection in the presence of an attraction stimulus. Conclusion: It is suggested the impregnation of 0.1% linalool in clothing as a protection measure for Ae. aegypti.

[Response of Aedes aegypti L. (Diptera: Culicidae) to transfluthrin and linalool impregnated in different of fabric types.] / Respuesta de Aedes aegypti L. (Diptera: Culicidae) a transflutrina y linalol impregnados en diferentes tipos de tela.

OBJECTIVE: Evaluate the effect of spatial repellency against Ae. aegypti of two chemical compounds impregnated in different types of fabrics. MATERIALS AND METHODS: The study was carried out in the year 2015-2016 in the Centro Regional de Investigación en Salud Pública, del Instituto Nacional de Salud Pública. The high-throughput screening system was used to evaluate the response of Ae. aegypti to transfluthrin and linalool, impregnated individually at different concentrations in poplin, cotton and polyester. The effect of their mixtures was also determined, washing on residuality and percentage of protection. RESULTS: The highest spatial repellency response was for 0.1% linalool-cotton treatment (RE = 70 ± 5.77%). The mixture of 0.1% linalool and 0.001% transfluthrin presented a similar spatial repellence percentage for the three types of fabric. The transfluthrin-poplin treatment 0.001% maintained a residual of five days. 0.1% linalool produced a 62.50% protection in the presence of an attraction stimulus. CONCLUSIONS: It is suggested the impregnation of 0.1% linalool in clothing as a protection measure for Ae. aegypti.

OBJETIVO: Evaluar el efecto de repelencia espacial contra Ae. aegypti de dos compuestos químicos impregnados en diferentes tipos de telas. MATERIAL Y MÉTODOS: El estudio se realizó en el periodo 2015-2016 en el Centro Regional de Investigación en Salud Pública, del Instituto Nacional de Salud Pública. Se utilizó el Sistema de Procesamiento de Alto-rendimiento para evaluar la respuesta de Ae. aegypti a transflutrina y linalol, impregnados individualmente a diferentes concentraciones en popelina, algodón y poliéster. También se determinó el efecto de sus mezclas, lavado sobre la residualidad y porcentaje de protección. RESULTADOS: La mayor respuesta de repelencia espacial fue para el tratamiento linalol-algodón al 0.1% (RE= 70 ± 5.77%). La mezcla de linalol 0.1% y transflutrina 0.001% presentóun porcentaje de repelencia espacial similar para los tres tipos de tela. El tratamiento transflutrina-popelina 0.001%N mantuvo una residualidad de cinco días. El linalol al 0.1% produjo 62.50% de protección en presencia de un estímulo de atracción. CONCLUSIONES: Se sugiere la impregnación de linalol al 0.1% en ropa como medida de protección de las picaduras de Ae. aegypti.

The Behavioral Response of Blattella germanica (Blattodea: Ectobiidae) Exposed to DEET Varies Throughout Its Life Cycle.

The German cockroach, Blattella germanica L., is a hemimetabolous insect pest of economical and medical importance. N,N-diethyl-3-methylbenzamide (DEET) is an insect repellent whose effect on this species has received very little attention. The objective of this work was to determine whether the behavioral response of B. germanica to DEET varies along its life cycle. DEET repellence was assessed in small, medium, and large nymphs, and in adults of both sexes, all originated from the same laboratory colony (CIPEIN). The experimental arena consisted in a piece of filter paper treated with repellent on one half (195 µg/cm2) and solvent alone on the other half. A cockroach was placed on the filter paper, and its behavior was filmed. An image analyzer was used to quantify how long the insect spent on each side of the paper. As a control, a cockroach was exposed to a piece of filter paper treated with solvent (acetone) alone. Each assay was repeated independently six times. Distribution coefficient (DC) values were calculated, a parameter that ranges between 0 (attraction) and 1 (repellence). Small nymphs were more sensitive to DEET (mean DC = 0.93). The mean DC values of the other groups varied between 0.62 (medium nymphs) and 0.71 (male adults). The group of medium nymphs was the only one whose behavior was not significantly altered by exposure to DEET. The results show the importance of assessing insect repellents at different stages of the insect's life cycle in order to obtain a complete panorama of its effect.

Use of mosquito repellents to protect against Zika virus infection among pregnant women in Brazil.

OBJECTIVES: To evaluate the use of repellents among pregnant women as a protective measure against infection with the Zika virus. STUDY DESIGN: Pregnant women (n = 177) were interviewed between November 2016 and February 2017 at Basic Health Units in the city of Propriá, state of Sergipe, Brazil. Two units were located in rural areas and eight in urban regions. METHODS: Data were analysed using descriptive statistical methods, the Chi-squared test or Fisher's exact test and odds ratios. The independent variables were grouped by analysis of the main components, and adherence to the use of the repellent was analysed by the logistic regression method. RESULTS: A total of 100 women reported using repellents at the time of the interview (56%). The use of repellents was greater among women with higher levels of education (83%) than those with only high school (68%) or elementary school (36%) education. Women assisted by the income transfer programme (Bolsa Família) presented a 2.27 times greater chance of not using repellents compared with pregnant women who were not receiving benefits of the programme. Regarding the logistic regression model, we observed that low economic and social conditions of pregnant women, as well as their lack of advice, had a negative effect on the use of repellents. CONCLUSIONS: Repellents were generally used as a preventive measure in pregnant women with higher levels of schooling and fewer children. The relatively high cost of repellents was the main reason for non-use.

Personal protective measures of pregnant women against Zika virus infection / Medidas de proteção individual de gestantes contra a infecção pelo zika vírus

ABSTRACT OBJECTIVE To evaluate the adherence of pregnant women to personal protective measures against mosquito bites, recommended by the Ministry of Health, and to investigate the factors associated with the non-adoption of these measures. METHODS We interviewed 177 pregnant women between November 2016 and February 2017 in the 10 basic health units of the municipality of Propriá, state of Sergipe, two located in the rural area and eight in the urban area, during prenatal appointments, to raise information about the use of preventive measures against the vector transmission of Zika virus. Data were analyzed using descriptive statistical methods, chi-square test or Fisher's exact test, and the odds ratio was calculated. The independent variables were grouped by the analysis of principal components, and the dependents (the use of repellent, mosquito nets, garments, screens and insecticides) were analyzed using the logistic regression method. RESULTS Among the measures recommended by the Ministry of Health, mosquito nets were the most used by pregnant women living in rural areas and with low education level, while the repellents were more used by women in the urban area and with higher education level. Women in a vulnerable socio-economic situation presented a risk 2.4 times higher for not using screens in their homes, 1.9 times higher for not changing clothes and 2.5 times higher for not using repellent than pregnant women in better economic conditions. CONCLUSIONS The socioeconomic status of pregnant women, especially among the less privileged, influenced the use of protective measures against Zika virus, from the purchase of repellent, clothing, insecticides to other resources in the municipality of Propriá, SE.

RESUMO OBJETIVO Avaliar a adesão de gestantes às medidas de proteção individual contra picadas de mosquitos, recomendadas pelo Ministério da Saúde e investigar os fatores associados à não adoção dessas medidas. MÉTODOS Foram entrevistadas 177 gestantes entre novembro de 2016 e fevereiro de 2017 nas 10 unidades básicas de saúde da cidade de Propriá, SE, duas localizadas na zona rural e oito na zona urbana, durante as consultas de pré-natal, para levantar informações sobre o uso de medidas preventivas contra a transmissão vetorial do zika vírus. Os dados foram analisados utilizando métodos de estatística descritiva, teste do qui-quadrado ou teste exato de Fisher, e foi calculado o odds ratio . As variáveis independentes foram agrupadas por meio da análise de componentes principais, e as dependentes (uso de repelentes, mosquiteiros, vestimentas, telas e inseticidas) foram analisadas pelo método de regressão logística. RESULTADOS Entre as medidas recomendadas pelo Ministério da Saúde, o uso de mosquiteiros foi a mais utilizada por gestantes residentes na zona rural e de baixa escolaridade, enquanto os repelentes foram mais utilizados por mulheres da zona urbana e com maior tempo de estudo. Mulheres com situação socioeconômica vulnerável apresentaram risco 2,4 vezes maior de não utilizar telas em suas residências, 1,9 vezes maior de não mudar o modo de se vestir e 2,5 vezes maior de não usar repelentes do que gestantes em melhores condições econômicas. CONCLUSÕES A condição socioeconômica das gestantes, especialmente entre as mulheres menos favorecidas, influenciou o uso das medidas de proteção contra o zika vírus, desde a compra de repelentes, vestimentas, inseticidas até outros recursos na cidade de Propriá, SE.

Zein Nanoparticles as Eco-Friendly Carrier Systems for Botanical Repellents Aiming Sustainable Agriculture.

Botanical repellents represent one of the main ways of reducing the use of synthetic pesticides and the contamination of soil and hydric resources. However, the poor stability and rapid degradation of these compounds in the environment hinder their effective application in the field. Zein nanoparticles can be used as eco-friendly carrier systems to protect these substances against premature degradation, provide desirable release characteristics, and reduce toxicity in the environment and to humans. In this study, we describe the preparation and characterization of zein nanoparticles loaded with the main constituents of the essential oil of citronella (geraniol and R-citronellal). The phytotoxicity, cytotoxicity, and insect activity of the nanoparticles toward target and nontarget organisms were also evaluated. The botanical formulations showed high encapsulation efficiency (>90%) in the nanoparticles, good physicochemical stability, and effective protection of the repellents against UV degradation. Cytotoxicity and phytotoxicity assays showed that encapsulation of the botanical repellents decreased their toxicity. Repellent activity tests showed that nanoparticles containing the botanical repellents were highly repellent against the Tetranychus urticae Koch mite. This nanotechnological formulation offers a new option for the effective use of botanical repellents in agriculture, reducing toxicity, protecting against premature degradation, and providing effective pest control.

Neurotoxic Effects of Linalool and ß-Pinene on Tribolium castaneum Herbst.

Effective, ethical pest control requires the use of chemicals that are highly specific, safe, and ecofriendly. Linalool and ß-pinene occur naturally as major constituents of the essential oils of many plant species distributed throughout the world, and thus meet these requirements. These monoterpenes were tested as repellents against Tribolium castaneum, using the area preference method, after four hours of exposure and the effect transcriptional of genes associated with neurotransmission. Changes in gene expression of acetylcholinesterase (Ace1), GABA-gated anion channel splice variant 3a6a (Rdl), GABA-gated ion channel (Grd), glutamate-gated chloride channel (Glucl), and histamine-gated chloride channel 2 (Hiscl2) were assessed and the interaction with proteins important for the insect using in silico methods was also studied. For linalool and ß-pinene, the repellent concentration 50 (RC50) values were 0.11 µL/cm² and 0.03 µL/cm², respectively. Both compounds induced overexpression of Hiscl2 gen in adult insects, and ß-pinene also promoted the overexpression of Grd and the Ace1 gene. However, ß-pinene and linalool had little potential to dock on computer-generated models for GABA-gated ion channel LCCH3, nicotinic acetylcholine receptor subunits alpha1 and alpha2, and putative octopamine/tyramine receptor proteins from T. castaneum as their respective binding affinities were marginal, and therefore the repellent action probably involved mechanisms other than direct interaction with these targets. Results indicated that ß-pinene was more potent than linalool in inducing insect repellency, and also had a greater capacity to generate changes in the expression of genes involved in neuronal transmission.