Actividad repelente e insecticida de cuatro aceites esenciales de plantas recolectadas en Chocó-Colombia contra Tribolium castaneum / Repellent and insecticidal activity of four essential oils from plants recolleted in Chocó-Colombia against Tribolium castaneum

This study aimed to determine the repellent and insecticidal activity of four essential oils (EOs) from plants collected in the Chocó rain forest, Colombia, against T. castaneum . Conventional hydrodistillation was used to obtain the EOs. The repellent and insecticidal activities were evaluated by the preference area and gas dispersion methods, espectively. Statistical differences (p<0.05) were determined by applying a student's t-test. EOs of Siparuna guianensis, S. conica, Piper marginatum, and Nectandra acutifolia showed excellent repellent properties as the main findings, highlighting S. conicaEO with 84% repellency (1-hµL/cm2), while P. marginatum showed to be bioactive to the dose of 500 µL/mL (72 h), inducing mortality of 100% of the exposed population. In conclusion, the results evidenced the repellent properties of the EOs evaluated against T. castaneum , which allows us to conclude that these plant species are potential natural sources producing bio-repellents that contribute to the integrated control of T. castaneum.

Se evaluaron cuatro aceites esenciales (AEs) de plantas recolectadas en la selva pluvial del Chocó, Colombia, para determinar su actividad repelente e insecticida contra T. castaneum. Los AEs fueron obtenidos por hidrodestilación convencional. Las actividades repelentes e insecticidas se evaluaron por los métodos de área de preferencia y dispersión de gas, respectivamente. Las diferencias significativas (p<0,05) fueron determinadas aplicando una prueba t de student. Los AEs de Siparuna guianensis, S. conica, Piper marginatum y Nectandra acutifolia mostraron excelentes propiedades repelentes, destacando el AE de S. conicacon un 84% de repelencia (1µL/cm2), mientras que el AE de P. marginatummostró ser bioactivo a la dosis de 500 µL/mL (72 h) al inducir la mortalidad del 100% de la población expuesta. Se concluye que estas especies de plantas son fuentes naturales potencialmente viables para la producción de biorepelentes que contribuyan en el control integrado de T. castaneum.

Toxicity and larvicidal activity on Aedes aegypti of citronella essential oil submitted to enzymatic esterification / Toxicidade e atividade larvicida sobre Aedes aegypti de óleo essencial de citronella submetido à esterificação enzimática

Abstract The essential oil of citronella (Cymbopogon winterianus) has several biological activities, among them the insect repellent action. Some studies showed that cinnamic acid esters can be applied as natural pesticides, insecticides and fungicides. In this context, the objective of the present work was to evaluate the production of esters from citronella essential oil with cinnamic acid via enzymatic esterification. Besides, the essential oil toxicity before and after esterification against Artemia salina and larvicidal action on Aedes aegypti was investigated. Esters were produced using cinnamic acid as the acylating agent and citronella essential oil (3:1) in heptane and 15 wt% NS 88011 enzyme as biocatalysts, at 70 °C and 150 rpm. Conversion rates of citronellyl and geranyl cinnamates were 58.7 and 69.0% for NS 88011, respectively. For the toxicity to Artemia salina LC50 results of 5.29 μg mL-1 were obtained for the essential oil and 4.36 μg mL-1 for the esterified oils obtained with NS 88011. In the insecticidal activity against Aedes aegypti larvae, was obtained LC50 of 111.84 μg mL-1 for the essential oil of citronella and 86.30 μg mL-1 for the esterified oils obtained with the enzyme NS 88011, indicating high toxicity of the esters. The results demonstrated that the evaluated samples present potential of application as bioinsecticide.

Resumo O óleo essencial de citronela (Cymbopogon winterianus) possui diversas atividades biológicas, entre elas a ação repelente a insetos. Alguns estudos mostraram que os ésteres do ácido cinâmico podem ser aplicados como pesticidas naturais, inseticidas e fungicidas. Nesse contexto, o objetivo do presente trabalho foi avaliar a produção de ésteres a partir do óleo essencial de citronela com ácido cinâmico via esterificação enzimática. Além disso, foi investigada a toxicidade do óleo essencial antes e após a esterificação contra Artemia salina e a ação larvicida sobre Aedes aegypti. Os ésteres foram produzidos utilizando ácido cinâmico como agente acilante e óleo essencial de citronela (3: 1) em heptano e 15% em peso da enzima NS 88011 como biocatalisadores, a 70 ° C e 150 rpm. As taxas de conversão de cinamatos de citronelil e geranil foram 58,7 e 69,0% para NS 88011, respectivamente. Para a toxicidade sobre Artemia salina foram obtidos CL50 de 5,29 μg mL-1 para o óleo essencial e 4,36 μg mL-1 para os óleos esterificados com NS 88011. Na atividade inseticida contra larvas de Aedes aegypti, obteve-se CL50 de 111,84 μg mL-1 para o óleo essencial de citronela e 86,30 μg mL-1 para os óleos esterificados com a enzima NS 88011, indicando alta toxicidade dos ésteres. Os resultados demonstraram que as amostras avaliadas apresentam potencial de aplicação como bioinseticida.

Comparative study of the oil repellent activity of Copaifera officinalis Linnaeus and Copaifera reticulata Ducke front nymphs of Periplaneta americana Linnaeus

To control urban pests, especially cockroaches of the Periplaneta americana species, various pesticides have been developed that are increasingly potent and effective. However, the unrestrained application of pesticides has had negative consequences, such as the disappearance of some useful insect species and, consequently, the appearance of new pests, both in the countryside and cities. Due to the current scenario, it was necessary to search for new alternatives for the control of these insects. Among the species studied, Copaíba stood out. The oils were analyzed using GC-MS, b-caryophyllene and a-bergamotene being the predominant compounds. Repellency tests were performed with three different concentrations of C. officinalis and C. reticulata, 500 µg/mL, 250 µg/mL and 125 µg/mL, in triplicate. It can be observed that the oil of C. officinalis was more repellent to the nymphs at concentrations of 500 µg/mL and 250 µg/mL, however, when the behavior in nymphs exposed to the concentration of 125 µg/mL was compared, it was noted that C. reticulata oil was more repellent at this concentration. Copaifera has shown promising activity as a repellent against arthropods owing to the complex chemical composition of its oils

Smoke of Capsicum baccatum L. var. baccatum (Solanaceae) repels nymphs of triatoma infestans (Klug) (Hemiptera: Reduviidae) / Humo de capsicum baccatum L. var. baccatum (Solanaceae) repele las ninfas de Triatoma infestans (Klug) (Hemiptera: Reduviidae)

Control of the Chagas disease vector, Triatoma infestans (Klug) (Hemiptera: Reduviidae) with synthetic pesticides in Bolivia has become increasingly inefficient due to the development of resistance in the insects. In the Chaco region of Bolivia, guaraní populations have approached the problem by fumigating their houses with the smoke of native plants. Through interviews and field work with local guides, the main plant used by the guaraníes was collected and later identified as Capsicum baccatumL. var. baccatum (Solanaceae). In choice bioassays, filter papers exposed to the smoke of the plant repelled nymphs of T. infestans. Activity remained significant after storing the exposed filter papers for 9 days. Chemical analysis of smoke and literature data suggested that capsaicinoids present in the smoke were responsible for the repellent effect. The data presented provide a rationale for the use of C. baccatumvar. baccatumto control the Chagas vector bythe guaraní populations.

El control del vector de la enfermedad de Chagas, Triatoma infestans (Klug) (Hemiptera: Reduviidae) con plaguicidas sintéticos en Bolivia se ha vuelto cada vez más ineficiente debido al desarrollo de resistencias en los insectos. En la región del Chaco de Bolivia, las poblaciones guaraníes han abordado el problema fumigando sus casas con el humo de las plantas nativas. A través de entrevistas y trabajo de campo con guías locales, se recogió la principal planta utilizada por los guaraníes y posteriormente se identificó como Capsicum baccatumL. var. baccatum (Solanaceae). En bioensayos selectos, los papeles de filtro expuestos al humo de la planta repelieron a las ninfas de T. infestans. La actividad siguió siendo significativa después de almacenar los papeles de filtro expuestos durante 9 días. El análisis químico del humo y los datos de la literatura sugieren que los capsaicinoides presentes en el humo eran responsables del efecto repelente. Los datos presentados proporcionan una justificación para el uso de C. baccatum var. baccatum para el control del vector Chagas por las poblaciones guaraníes.

Tetradenia riparia leaves, flower buds, and stem essential oils to control of Aedes aegypti larvae

Abstract Tetradenia riparia (Hochst.) Codd (Lamiaceae) is a species native to the African continent and used as an insect repellent. The objective of the study was to evaluate the larvicidal potential of essential oils (EOs) from the leaves, flower buds, and stem of T. riparia, collected in winter against Aedes aegypti larvae. The EOs were extracted by hydrodistillation (3 h) and identified by GC/MS. The EOs were tested against larvae of A. aegypti at concentrations ranging from 12500 to 1.5 µg/mL for 24 h. The insecticide activity was evaluated by probit analysis, and the anticholinesterase activity was determined by bioautographic method. The results of the class projection indicated sesquiterpenes as the majority class, corresponding to 60.66% (leaves), 64.70% (flower buds) and 83.99% (stem), and the bioassays on A. aegypti larvae indicated LC50 of 1590, 675 and 665 µg/mL, respectively. The anticholinesterase activity indicated that the EO of the leaves inhibited the enzyme at a concentration of 780 µg/mL, and those from the flower buds and stem inhibited up to 1560 µg/mL. The results indicated weak activity of essential oils against A. aegypti larvae.

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.

Zuccagnia punctata Cav. Essential Oil into Poly(ε-caprolactone) Matrices as a Sustainable and Environmentally Friendly Strategy Biorepellent against Triatoma infestans (Klug) (Hemiptera, Reduviidae)

The main strategies against Triatoma infestans (primary vector responsible for the Chagas disease transmission) are the elimination or reduction of its abundance in homes through the application of insecticides or repellents with residual power, and environmental management through the improvement of housing. The use of plant-derived compounds as a source of therapeutic agents (i.e., essential oils from aromatic plants and their components) is a valuable alternative to conventional insecticides and repellents. Essential oil-based insect repellents are environmentally friendly and provide reliable personal protection against the bites of mosquitoes and other blood-sucking insects. This study investigates, for the first time to our knowledge, the potential repellent activity of Zuccagnia punctata essential oil (ZEO) and poly(ε-caprolactone) matrices loaded with ZEO (ZEOP) prepared by solvent casting. The analysis of its essential oil from aerial parts by GC­FID and GC-MS, MS allowed the identification of 25 constituents representing 99.5% of the composition. The main components of the oil were identified as (−)-5,6-dehydrocamphor (62.4%), alpha-pinene (9.1%), thuja-2, 4 (10)-diene (4.6%) and dihydroeugenol (4.5%). ZEOP matrices were homogeneous and opaque, with thickness of 800 ± 140 µm and encapsulation efficiency values above 98%. ZEO and ZEOP at the lowest dose (0.5% wt./wt., 96 h) showed a repellency of 33 and 73% respectively, while at the highest dose (1% wt./wt., 96 h) exhibited a repellent activity of 40 and 66 %, respectively. On the other hand, until 72 h, ZEO showed a strong repellent activity against T. infestans (88% repellency average; Class V) to both concentrations, compared with positive control N-N diethyl-3-methylbenzamide (DEET). The essential oils from the Andean flora have shown an excellent repellent activity, highlighting the repellent activity of Zuccagnia punctata. The effectiveness of ZEO was extended by its incorporation in polymeric systems and could have a potential home or peridomiciliary use, which might help prevent, or at least reduce, Chagas' disease transmission.

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.

Investigação do comportamento de tolerância ao N, N- dietilmetilbenzamida (DEET) em populações de Aedes aegypti (Diptera: Culicidae) / Investigation of tolerance behavior to N, N-diethylmethylbenzamide (DEET) in populations of Aedes aegypti (Diptera: Culicidae)

Aedes aegypti é um mosquito de grande interesse para saúde pública, pois é o vetor de arbovírus, como dengue, chikungunya e Zika. Para o controle desse vetor, são utilizados o controle biológico, mecânico e o controle químico, com utilização de inseticidas e repelentes. Os repelentes são considerados uma das melhores formas de se evitar as picadas das fêmeas, sendo os mais comercializados aqueles que possuem N,N-dietilmetilbenzamida (DEET) na fórmula, além de serem um dos mais estudados atualmente. Entretanto a resitência a alguns inseticidas como o piretroide, pode levar à alteração na atividade locomotora dos mosquitos. Deste modo, o presente trabalho tem como objetivo avaliar aspectos relacionados à tolerância ao DEET e à resistência a xenobióticos em cepas Ae. aegypti de campo (Laranjeiras) e de laboratório (Rockefeller). Foram realizados testes de repelência com Ae. aegypti para a resposta ao odor humano. Em cada teste, foram utilizadas 50 fêmeas, totalizando 700 fêmeas da população Laranjeiras e 1500 fêmeas para a população Rockefeller. As fêmeas foram colocadas em gaiolas de teste por cerca de duas horas, a fim de se adaptarem ao ambiente. Posteriormente, foi realizado o teste de repelência, que consistiu na exposição do mosquito a 0,5 mL de DEET (10% em etanol), este foi aplicado uniformemente pelo antebraço humano. Para diagnosticar a presença da mutação kdr na população de Laranjeiras foram analisadas 32 fêmeas dessa população. Para avaliar a atividade locomotora das fêmeas de Ae. aegypti Rockefeller e de Laranjeiras, foi utilizado o Drosophila Activity Monitor - Trikinetics. No período de setembro a novembro de 2019, foram instaladas 290 ovitrampas no município de Laranjeiras - SE, tendo sido verificado um total de 80,3% de palhetas com presença de ovos de Aedes, contabilizando 15.940 ovos. Após a realização dos bioensaios, foi possivel observar maior sensibilidade ao DEET nas fêmeas provinientes do campo. Além disso, também foi possivel observar a presença da mutação kdr e uma maior atividade locomotora nessa população. Dessa forma, nossos resultados sugerem que mosquitos resistentes podem ser mais suceptíveis ao DEET.

Aedes aegypti is a mosquito of great interest for public health, as it is the vector of arboviruses, such as dengue, chikungunya and Zika. Biological, mechanical and chemical control, with the use of insecticides and repellents, are used against this vector. Repellents are considered one of the best ways to avoid female bites, being those that have N, N-diethylmethylbenzamide (DEET) in the formula the most commercialized, as well as the most studied today. However, resistance to some insecticides such as pyrethroid, can lead to changes in the locomotor activity of mosquitoes. Thus, this study aims to evaluate aspects related to DEET tolerance and resistance to xenobiotics in field Ae. aegypti (Laranjeiras) and laboratory (Rockefeller) strains. Repellency tests were performed with Ae. aegypti for the response to human odor. In each test, 50 females were used, totaling 700 females from the Laranjeiras population and 1500 females from the Rockefeller population. The females were placed in test cages for about two hours in order to adapt to the environment. Subsequently, the repellency test was performed, which consisted of exposing the mosquito to 0.5 mL of DEET (10% in ethanol), which was applied evenly to the human forearm. To diagnose the presence of the kdr mutation in the population of Laranjeiras, 32 females from that population were analyzed. To evaluate the locomotor activity of Ae. aegypti Rockefeller and Laranjeiras females,, the Drosophila Activity Monitor - Trikinetics was used. In the period from September to November 2019, 290 ovitraps were installed in the municipality of Laranjeiras - SE, with a total of 80.3% of reeds with the presence of Aedes eggs, accounting for 15,940 eggs. After conducting the bioassays, it was possible to observe greater sensitivity to DEET in females from the field. In addition, it was also possible to observe the presence of the kdr mutation and greater locomotor activity in this population. Thus, our results suggest that resistant mosquitoes may be more susceptible to DEET.

Pyrethroid Resistance Associated With a Decreased DEET Repellency in the Common Bed Bug (Hemiptera: Cimicidae)

The global resurgence of the bed bug (Cimex lectularius L.) and the widespread resistance of this insect to pyrethroid insecticides have created the need to find alternatives to chemical control. Thus, synthetic or natural repellents have been considered as a suitable choice to control bed bug infestations. Repellents not only keep insects away from their hosts, but also allow a decrease in insecticide selection pressure. The aim of this study was to evaluate the repellence effectivity of DEET against two bed bug colonies from Argentina (a susceptible one and a fieldcollected pyrethroid-resistant one), under two starving periods. We found different repellent effects of DEET on the two C. lectularius colonies and no differences between the two starving periods. In fact, DEET had a lower effect on the insecticide-resistant colony. The methodology used in this study proved to be useful to test the variation of the effect of DEET between pyrethroid-susceptible and -resistant bed bugs.

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.

Persistence and efficacy of a new formulation based on dog allomonal repellents against Rhipicephalus sanguineus sensu lato tick / Persistência e eficácia de uma nova formulação baseada em repelentes alomônios de cães contra o carrapato Rhipicephalus sanguineus sensu lato

Abstract Beagles are less susceptible to Rhipicephalus sanguineus sensu lato tick due to the production of the allomones benzaldehyde and 2-hexanone. Our previous published work showed that these compounds can reduce tick burden on susceptible dogs. Here we tested the hypothesis that an increase in repellent dose and release rate could increase repellent efficacy and persistence. Slow-release formulations of these compounds, with higher doses and release rates, were tested on artificially-infested dogs. Ten dogs were randomly assigned to two groups with five dogs each. The treated group received collars with slow-release formulations of the compounds attached, while the control group received collars with clean formulations attached. Five environmental infestations were performed, with the number of ticks (at all stages) on the dogs being counted once a day for 40 days. No significant increase in repellent efficacy was observed with the higher doses and release rates, whereas a greater persistence in repellent activity was observed. Treatment with the formulations resulted in a two-to-three-fold reduction in the number of immature stage ticks for up to three weeks. However, the number of adults was similar in both groups. Loss of repellent activity after the third week of testing coincided with a marked change in the relative release rates for the two compounds. It is hypothesized that relative amounts, rather than absolute amounts, of repellent release from slow-release formulations are important for repellent activity. We also hypothesize that the avoidance of less-preferred hosts by ticks relies on olfactory-mediated perception of specific blends of volatile cues from less preferred hosts.

Resumo Beagles são menos suscetíveis ao carrapato Rhipicephalus sanguineus sensu lato devido à produção de benzaldeído e 2-hexanona. Nosso trabalho anterior já publicado mostrou que esses compostos podem reduzir a carga de carrapatos em cães suscetíveis. Aqui testamos a hipótese de que um aumento na dose destes repelentes e na taxa de liberação poderia aumentar a eficácia e a persistência do efeito repelente. As formulações de liberação lenta destes compostos, com doses e taxas de liberação mais elevadas foram testadas em cães infestados artificialmente. Dez cães foram distribuídos aleatoriamente em dois grupos com cinco cães cada. O grupo tratado recebeu colares contendo formulações de liberação lenta dos compostos, enquanto o grupo controle recebeu colares com formulações limpas. Cinco infestações ambientais foram realizadas, com o número de carrapatos (em todas as fases) nos cães sendo contados, uma vez ao dia, por 40 dias. Não se observou aumento significativo na eficácia do repelente com doses e taxas de liberação mais elevadas e, enquanto observou-se maior persistência na atividade repelente. O tratamento com as formulações resultou em uma redução de duas a três vezes no número de carrapatos dos estágios imaturos, por até três semanas. No entanto, o número de adultos foi semelhante em ambos os grupos. A perda de atividade repelente após a terceira semana de teste coincidiu com uma mudança nas taxas de liberação relativa para os dois compostos. A hipótese é que as quantidades relativas, ao invés das quantidades absolutas de liberação lenta, são importantes para a atividade repelente. Então, a hipótese é de que a repelência apresentada por hospedeiros menos susceptíveis aos carrapatos depende da percepção pelos carrapatos de misturas específicas de voláteis liberados por estes hospedeiros.

Insecticidal and repellent effect of cinnamon oil on flies associated with livestock / Efecto insecticida y repelente del aceite de canela sobre moscas asociadas con el ganado

Abstract Objective. Due to the increased parasitic resistance, there is a need to explore alternative insecticides, including natural products, such essential oils. In this sense, the aim of this study was to evaluate, for the first time, the insecticidal and repellent effect of Cinnamomun zeylanicum (free and nanoemulsion forms) in vitro and in vivo. Materials and methods. For that, the insecticidal effect of the free form was tested at 1.0, 5.0 and 10%, while the nanoemulsion form was tested at 0.5, 1.0 and 5.0% against adult house flies, Musca domestica. For validation of the test, the flies were sprayed with the diluent (water and triton 10%) and with blank nanoemulsion (without C. zeylanicum essential oil). Moreover, in vivo test was performed using cows naturally infested with Haemotobia irritans. Results. The results demonstrated that cinnamon oil (10%) and the nanoemulsion (5%) were 100% effective against M. domestica after 90 minutes of exposure. The repellent effect was tested in vivo using 5% of cinnamon oil on Holstein cows naturally infested by Haemotobia irritans. The flies were counted at 0, 1, 2, 3, 9 and 24 h after cinnamon oil treatment. It was verified significant decrease (p<0.05) in the number of flies on cows sprayed with cinnamon in all times. Conclusions. Based on these results, C. zeylanicum showed insecticidal effect (in vitro) against domestic flies and repellent effect (in vivo) against the horn fly.

Resumen Objetivo. Debido a la mayor resistencia parásita, hay una necesidad de explorar insecticidas alternativos, incluidos los productos naturales, tales como aceites esenciales. En este sentido, el objetivo de este estudio fue evaluar, para el primer equipo, el efecto insecticida y repelente de Cinnamomum zeylanicum (formas libres y nanoemulsión) in vitro e in vivo. Materiales y métodos. Para ello, el efecto insecticida de la forma libre se ensayó a 1.0, 5.0 y 10%, mientras que la forma nanoemulsión se ensayó a 0.5, 1.0 y 5.0% frente a las moscas domésticas adultas, Musca domestica. Para la validación de la prueba, las moscas fueron rociados con el diluyente (agua y triton 10%) y con nanoemulsión en blanco (sin aceite esencial de C. zeylanicum). También, fueron realizados pruebas in vivo usando vacas naturalmente infestadas con Haemotobia irritans. Resultados. Los resultados demostraron que el aceite de canela (10%) y la nanoemulsión (5%) fueron 100% eficaz contra M. domestica después de 90 minutos de exposición. El efecto repelente se ensayó in vivo usando 5% de aceite de canela en vacas Holstein, naturalmente infestados por Haemotobia irritans. Se contaron las moscas a las 0, 1, 2, 3, 9 y 24 h después del tratamiento el aceite de canela. Se verificó disminución significativa (p<0.05) en el número de moscas vivas de vacas canela pulverizada en todo momento. Conclusiones. En base a estos resultados, C. zeylanicum mostró un efecto insecticida (in vitro) contra las moscas domésticas y efecto repelente (in vivo) contra la mosca de los cuernos.

Stage-Dependent Expression of Deltamethrin Toxicity and Resistance in Triatoma infestans (Hemiptera: Reduviidae) From Argentina

Triatoma infestans Klug (Hemiptera: Reduviidae) is the main vector of Chagas disease in Latin America. This insect has been controlled with pyrethroids since the 1980s, although the emergence of resistance to deltamethrin has decreased control success in some areas of the Gran Chaco ecoregion. The response of T. infestans to deltamethrin was evaluated per developmental stage. In addition, we evaluated the possible stage-dependent expression of deltamethrin resistance. The bioassays were conducted by topical application of the insecticide in acetone. The drop size, age at the time of exposure, and mortality measuring time were standardized per stage. The lethal dose of deltamethrin moderately increased with the developmental stage. The resistance to deltamethrin was expressed in every instar, and was the highest in the fourth- and fifth-instar nymphs. While increasing, weight plays a relevant role in lethal dose stage dependency, a number of contributing factors such as degradative metabolism are probably involved in the variability of insecticide effect and resistance described for different T. infestans developmental stages. Possible explanations for these differences and their implications on resistance management and chemical control are discussed.

Repellent activity of essential oils extracted from five Artemisia species against Tribolium castaneum (Coleoptera: Tenebrionidae) / Actividad repelente de aceites esenciales extraídos de cinco especies de Artemisia contra Tribolium castaneum (Coleoptera: Tenebrionidae)

Artemisia genus (family Asteraceae) has been widely used as medicines and cosmetic. The chemical compositions of essential oils extracted from five Artemisia species (A. anethoides, A. giraldii, A. roxburghiana, A. rubripes and A. sacrorum) were analyzed and the repellent activities of five essential oils were investigated by testing percent repellency (PR) in petri dish against Tribolium castaneum. By GC-MS analysis, the common components of the five essential oils were eucalyptol (11.09%-50.05%), camphor (6.28%-33.10%), terpinen- 4-ol (2.46%-12.41%), ß-caryophyllene (0.63%-10.68%) and germacrene D (2.28%-10.01%). 3,3,6-trimethyl-1,4-heptadien-6-ol (11.72%), 2-isopropyl-5-methyl-3-cyclohexen-1-one (24.80%) and ß-farnesene (12.23%) were the characteristic compounds in essential oils of A. sacrorum, A. anethoides and A. rubripes respectively. The essential oils of five plants showed repellent activity against T. castaneum. The PR of others four essential oils were comparable with DEET expect for A. sacrorum. The results indicated that the essential oils of A. anethoides, A. giraldii, A. roxburghiana and A. rubripes had the potential to be developed as repellent for control of T. castaneum.

El género Artemisia (familia Asteraceae) ha sido ampliamente utilizado como medicamentos y cosméticos. Se analizaron las composiciones químicas de los aceites esenciales extraídos de cinco especies de Artemisia (A. anethoides, A. giraldii, A. roxburghiana, A. rubripes y A. sacrorum) y se investigaron las actividades repelentes de cinco aceites esenciales mediante la prueba de repelencia porcentual (PR) en placa de petri contra Tribolium castaneum. Por análisis GC-MS, los componentes comunes de los cinco aceites esenciales fueron eucaliptol (11,09% -50,05%), alcanfor (6,28% -33,10%), terpinen-4-ol (2,46% -12,41%), ß-cariofileno 0,63% -10,68%) y germacrén D (2,28% -10,01%). 3,3,6-trimetil-1,4-heptadien-6-ol (11,72%), 2-isopropil-5-metil-3-ciclohexen-1-ona (24,80%) y ß-farneseno (12,23%). Los compuestos característicos en los aceites esenciales de A. sacrorum, A. anethoides y A. rubripes respectivamente. Los aceites esenciales de cinco plantas mostraron actividad repelente contra T. castaneum. El PR de otros cuatro aceites esenciales eran comparables con DEET esperado para A. sacrorum. Los resultados indicaron que los aceites esenciales de A. anethoides, A. giraldii, A. roxburghiana y A. rubripes tienen el potencial de ser desarrollados como repelentes para el control de T. castaneum.

Aceites esenciales y sus componentes como una alternativa en el control de mosquitos vectores de enfermedades / Essential oils and their components as an alternative in the control of mosquito vectors of disease

Resumen Más de la mitad de la población humana está expuesta a contraer infecciones transmitidas por mosquitos. El cambio climático y la aparición de cepas resistentes a los insecticidas tradicionalmente utilizados han motivado la búsqueda de nuevos agentes capaces de controlar las poblaciones de mosquitos. Los aceites esenciales han resultado ser eficaces agentes repelentes y larvicidas. El objetivo de este trabajo fue revisar las investigaciones llevadas a cabo en los últimos años sobre la actividad larvicida de los aceites esenciales y sus componentes contra mosquitos de los géneros Aedes, Anopheles y Culex, así como los últimos reportes sobre su posible mecanismo de acción.

Abstract More than half of the human population is exposed to mosquito-borne infections. Climate change and the emergence of strains resistant to traditionally used insecticides have motivated the search of new agents for mosquito population control. Essential oils have been effective repellents and larvicidal agents. The aim of this work was to review research studies conducted in recent years on the larvicidal activity of essential oils and their components against Aedes, Anopheles and Culex mosquitoes, as well as the latest reports about their possible mechanism of action.

Serie parasitosis en dermatología: tungiasis / Dermatology iconography: tungiasis

La tungiasis es una ectoparasitosis causada por la penetración en la piel de la pulga hembra Tunga penetrans. Esta enfermedad no es específica del hombre y se distribuye en regiones cálidas y secas alrededor del mundo. Se adquiere por contacto directo con el suelo en donde habitan los parásitos adultos. En zonas endémicas, su alta prevalencia se asocia a pobreza y falta de acceso al sistema de salud. Además es frecuente entre viajeros que visitan regiones endémicas y que regresan a sus lugares de origen. Presentamos un caso típico de tungiasis en un paciente 39 años que había realizado un viaje reciente a zona endémica. (AU)

Tungiasis is an ectoparasitosis caused by penetration into the skin of the female flea Tunga penetrans. This disease is not human-specific and is distributed worldwide in warm, dry regions. It is acquired by direct contact with the soil where the adult parasites live. In endemic areas, its high prevalence is associated with poverty and lack of access to the health system. It is also frequent among travelers visiting endemic regions and returning to their places of origin. We present a typical case of tungiasis in a 39 year old patient who had made a recent trip to an endemic area. (AU)

Development and validation of an analytical method using High Performance Liquid Chromatography (HPLC) to determine ethyl butylacetylaminopropionate in topical repellent formulations

ABSTRACT Diseases caused by insects are frequent in poor countries, leading to epidemic scenarios in urban areas; e.g., Dengue, Zika and Chikungunya. For this reason, the development of a safe and efficient topical formulation is essential. Ethyl butylacetylaminopropionate (EB) is a mosquito repellent developed by Merck, which is used in products for adults, children and especially babies, due to its low allergenic potential. The aim of this work was to validate an analytical methodology to quantify EB in a new poloxamer-based formulation by high-performance liquid chromatography (HPLC). The quantification methodology was performed at 40 ºC using a Kromasil reverse-phase column (C18), with the dimensions of 250 x 4.6 mm. The mobile phase was acetonitrile:water (1:1) at a 1.0 mL/min flow-rate. The detector wavelength was set at 218 nm to detect EB. The methodology was considered validated since the results indicated linearity (R2>0.99), specificity, selectivity, precision and accuracy (active recovery between 98% and 102%). It also presented limits of detection and quantification of 0.255 µg/mL and 0.849 µg/mL, respectively. The present study demonstrated the EB vehiculated in poloxamer gel is promising as a new insect repellent formulation, since it could be quantified and quality control evaluated.