Chemical composition, in vitro larvicidal and antileishmanial activities of the essential oil from Citrus reticulata Blanco fruit peel / Composição química, atividades larvicida e leishmanicida in vitro do óleo essencial da casca do fruto de Citrus reticulata Blanco

Numerous studies have investigated the chemical composition and biological activities of essential oils from different Citrus species fruit peel, leaves and flowers. This paper aims to investigate the chemical composition, larvicidal and antileishmanial activities of essential oil from Citrus reticulata fruit peel (CR-EO). CR-EO was obtained by hydrodistillation in a Clevenger-type apparatus and its chemical composition was analyzed by GC-MS and GC-FID. Limonene (85.7%), ɣ-terpinene (6.7%) and myrcene (2.1%) were identified as its major components. CR-EO showed high activity against promastigote forms of Leishmania amazonensis (IC50 = 8.23 µg/mL). CR-EO also exhibited high larvicidal activity against third instar Aedes aegypti larvae at a lethal concentration (LC50 = 58.35 µg/mL) and 100% mortality at 150 µg/mL. This study suggests, for the first time, the potential use of CR-EO against this important mosquito-borne viral disease caused by the genus Aedes.

Numerosos estudos têm investigado a composição química e as atividades biológicas de óleos essenciais extraídos de cascas dos frutos, folhas e flores de diferentes espécies de Citrus. Este trabalho tem como objetivo investigar a composição química e as atividades larvicida e leishmanicida in vitro do óleo essencial das cascas dos frutos de Citrus reticulata (CR-EO). CR-EO foi obtido pela técnica de extração em aparelho Clevenger e sua composição química foi determinada por CG-EM e CG-DIC. Limoneno (85,7%), ɣ-terpineno (6,7%) and mirceno (2,1%) foram identificados como os constituintes majoritários. CR-EO mostrou alta atividade contra as formas promastigota de Leishmania amazonensis (CI50 = 8,23 µg/mL). CR-EO também exibiu alta atividade larvicida contra as larvas do terceiro estágio do Aedes aegypti com concentração letal (CL50 = 58,35 µg/mL) e mortalidade de 100% em 150 µg/mL. Este estudo sugere, pela primeira vez, o uso potencial de CR-EO contra esta importante doença viral transmitida por mosquitos do gênero Aedes.

Óleos essenciais e extratos vegetais como ferramentas alternativas ao controle químico de larvas de Aedes spp, Anopheles spp e Culex spp / Essential oils and plant extracts as alternative tools for chemical control of Aedes spp, Anopheles spp, and Culex spp

Objetivos: Realizar um levantamento das contribuições científicas produzidas entre 2017 e 2021 acerca do efeito larvicida de óleos essenciais e extratos vegetais no controle de Aedes spp, Anopheles spp e Culex spp. Métodos: de setembro a outubro de 2022, foi realizado um levantamento de artigos científicos publicados entre os anos de 2017 e 2021, nas bases de dados Portal Periódicos Capes, Scielo, Science Direct e Scopus. Foram utilizados os descritores "larvicide", "essential oil" e "plant extracts" com a interposição do operador boleano "AND". Resultados: inicialmente, foram obtidos 246 artigos, dos quais 110 foram excluídos (68 não estavam disponíveis na íntegra e 42 apareceram em mais de uma base de dados). Dos 136 artigos restantes, 36 foram excluídos por não terem realizado ensaio larvicida. Dos 100 artigos remanescentes, 63 foram excluídos por não mencionarem valores de CL50, enquanto 3 não especificaram a estrutura vegetal de obtenção dos produtos naturais, restando, portanto, 34 artigos para análise. Foram utilizadas 57 espécies vegetais para a obtenção dos produtos vegetais utilizados contra larvas de Aedes spp; 11 espécies nos ensaios contra Anopheles spp, e 36 espécies nos ensaios contra Culex spp. Os óleos essenciais predominaram nos ensaios contra Aedes spp, enquanto os extratos, contra Anopheles spp. A maior parte dos produtos testados exibiu CL50 < 100 ppm. Conclusão: a atividade larvicida demonstrada por uma grande variedade de extratos vegetais e óleos essenciais representa uma alternativa promissora ao tradicional controle químico feito à base de inseticidas sintéticos em programas de manejo integrado de vetores.

Objectives: Conduct a survey of the scientific contributions produced between 2017 and 2021 on the larvicidal effect of essential oils and plant extracts in the control of Aedes spp, Anopheles spp, and Culex spp. Methods: from September to October 2022, a survey was carried out of scientific articles published between 2017 and 2021 in the Portal Periódicos Capes, Scielo, Science Direct, and Scopus databases. The descriptors "larvicide", "essential oil" and "plant extracts" were used with the Boolean operator "AND". Results: initially, 246 articles were obtained, of which 110 were excluded (68 were not available, and 42 appeared in more than one database). Of the remaining 136 articles, 36 were excluded because they did not perform a larvicide assay. Of the 100 remaining articles, 63 were excluded for not mentioning LC50 values, while three did not specify the plant structure for obtaining natural products, thus leaving 34 articles for analysis. A total of 57 plant species were used to obtain plant products used against Aedes spp larvae; 11 species in the tests against Anopheles spp, and 36 species in the tests against Culex spp. Essential oils predominated in the tests against Aedes spp, while extracts against Anopheles spp. Most of the products tested exhibited an LC50 < 100 ppm. Conclusion: the larvicidal activity demonstrated by a wide variety of plant extracts and essential oils represents a promising alternative to traditional chemical control based on synthetic insecticides in integrated vector management programs.

Chemical composition and larvicidal activity of the essential oil of Pimenta dioica leaves / Composición química y actividad larvicida del aceite esencial de hojas de Pimenta dioica

In this study, we investigated the main constituent, the predominant class and biological activity of the essential oil extracted from the leaves of Pimenta dioica and the pattern of the major constituent against larvae in the third stage of Aedes aegypti. For this reason, we extracted the oil by hydrodistillation, identified its components by gas chromatography coupled with mass spectrometry (GC/MS) and calculated the lethal concentration (LC50) of the larvicidal activity using the Reed-Muench method. The results show that the oil consists mainly of eugenol, in which the phenylpropanoid class predominated and the lethal concentration, LC50, was 38.86 µg mL-1at a confidence level of 2.25 µg mL-1, while the eugenol standard presented LC5079.75 µg mL-1at a confidence level of 2.10 µg mL-1. Given the facts, we conclude that the oil is more active than the standard and that it has the potential to replace chemical larvicides.

En este estudio, investigamos el constituyente principal, la clase predominante y la actividad biológica del aceite esencial extraído de las hojas de Pimenta dioica y el patrón del constituyente principal contra las larvas en la tercera etapa de Aedes aegypti. Por este motivo, extrajimos el aceite por hidrodestilación, identificamos sus componentes mediante cromatografía de gases acoplada a espectrometría de masas (GC/MS) y calculamos la concentración letal (CL50) de la actividad larvicida mediante el método Reed-Muench. Los resultados muestran que el aceite está constituido principalmente por eugenol, en el que predominó la clase fenilpropanoide y la concentración letal, CL50, fue de 38,86 µg.mL-1 a un nivel de confianza de 2,25 µg.mL-1, mientras que el estándar de eugenol presentó CL50 79,75 µg.mL -1 a un nivel de confianza de 2,10 µg.mL-1. Dados los hechos, concluimos que el aceite es más activo que el estándar y que tiene el potencial de reemplazar los larvicidas químicos.

Chemical composition and insecticidal activity of Garcinia gardneriana (Planchon & Triana) Zappi (Clusiaceae) essential oil / Composición química y actividad insecticida del aceite esencial de Garcinia gardneriana (Planchon & Triana) Zappi (Clusiaceae)

The present study aimed to analyze the chemical composition of the essential oil from Garcinia gardneriana (Planchon & Triana) Zappi leaves and fruits, and to determine its acaricidal activity on Rhipicephalus microplusy larval packet test and larvicidal action on Aedes aegyptiby larval immersion test. The chemical analysis of the essential oil by gas chromatography-mass spectrometry identified sesquiterpene hydrocarbons and oxygenated sesquiterpenes in bacupari leaves and fruits, and α-cedrene, α-chamigrene, α-trans-bergamotene, and ß-curcumene as major compounds. Essential oil from leaves of G. gardneriana presented acaricidal activity on R. microplus (LC50= 4.8 mg/mL; LC99= 10.8 mg/mL) and larvicidal effect on A. aegypti (LC50= 5.4 mg/mL; LC99 = 11.6 mg/mL), where as essential oil from the fruits of G. gardneriana showed LC50= 4.6 mg/mL and LC99= 8.9 mg/mL against R. microplus and LC50= 6.4 mg/mL and LC99= 13.9 mg/mL against A. aegypti. These results thus demonstrate the potential acaricidal and larvicidal activity of essential oil of G. gardneriana, offering new perspectives for the realization of bioassays from this essential oil.

El presente estudio tuvo como objetivo analizar la composición química del aceite esencial de las hojas y frutos de Garcinia gardneriana (Planchon & Triana) Zappi, y determinar su actividad acaricida en Rhipicephalus microplus y larvicida en Aedes aegypti empleando la prueba de inmersión de larvas. El análisis químico del aceite esencial por cromatografía de gases-espectrometría de masas identificó hidrocarburos sesquiterpénicos y sesquiterpenos oxigenados en hojas y frutos de bacupari, y α-cedreno, α-chamigreno, α-trans-bergamoteno y ß-curcumeno como compuestos principales. El aceite esencial obtenido de las hojas de G. gardneriana presentó actividad acaricida en la garrapata del ganado (LC50= 4,8 mg/mL; LC99= 10,8 mg/mL) y actividad larvicida en A. aegypti (LC50= 5,4 mg/mL; LC99= 11,6 mg/mL), así como, el aceite esencial obtenido de los frutos de G. gardneriana mostró LC50= 4,6 mg/mL y LC99= 8,9 mg/mL contra las larvas de garrapatas de ganado y LC50= 6,4 mg/mL y LC99= 13,9 mg/mL en las larvas de A. aegypti. Por lo tanto, estos resultados demuestran la actividad acaricida y larvicida del aceite essencial de G. gardneriana, ofreciendo nuevas perspectivas para la realización de bioensayos a partir de este aceite esencial.

Insecticidal activity of Gallesia integrifolia (Phytolaccaceae) essential oil / Actividad insecticida del aceite esencial de Gallesia integrifolia (Phytolaccaceae)

This study evaluated the insecticidal activity of Gallesia integrifolia essential oil from fruits, leaves, and flowers against Aedes aegyptilarvae and pupae. The essential oil was obtained by hydrodistillation and characterized by gas chromatography-mass spectrometry. Sulfur compounds represented 95 to 99% of the essential oil from fruits, leaves, and flowers. Essential oil major compounds were 2,8-dithianonane (52.6%) in fruits, 3,5-dithiahexanol-5,5-dioxide (38.9%) in leaves, and methionine ethyl ester (45.3%) in flowers. The essential oils showed high activity against larvae, and low for pupae withLC99.9of 5.87 and 1476.67µg/mL from fruits; 0.0096 and 348.33 µg/mL from leaves and 0.021and 342.84 µg/mL from flowers, respectively. The main compound with insecticide activity is probably n-ethyl-1,3-dithioisoindole, from isoindole organothiophosphate class, found in greater amount in flower and leaf essential oil. The great insecticide activity of G. integrifolia essential oil suggests that this product is a natural insecticide.

Este estudio evaluó la actividad insecticida del aceite esencial de frutos, hojas y flores de Gallesia integrifolia contra larvas y pupas de Aedes aegypti. El aceite esencial se obtuvo por hidrodestilación y se caracterizó por cromatografía de gases acoplada a espectrometría de masas. Los compuestos de azufre representaron del 95 al 99% del aceite esencial de frutas, hojas y flores. Los compuestos principales del aceite esencial fueron 2,8-ditianonano (52,6%) en frutas, 3,5-ditiahexanol-5,5-dióxido (38,9%) en hojas y éster etílico de metionina (45,3%) en flores. Los aceites esenciales mostraron alta actividad contra larvas y baja para pupas con LC99.9de 5.87 y 1476.67µg/mL de frutos; 0,0096 y 348,33 µg/mL de hojas y 0,021 y342,84 µg/mL de flores, respectivamente. El principal compuesto con actividad insecticida es probablemente el n-etil-1,3-ditioisoindol, de la clase de los organotiofosfatos de isoindol, que se encuentra en mayor cantidad en el aceite esencial de flores y hojas. La gran actividad insecticida del aceite esencial de G. integrifolia sugiere que este producto es un insecticida natural.

Resistencia a insecticidas en Aedes aegypti y Aedes albopictus (Diptera: Culicidae) de Tapachula, Chiapas, México / Insecticide resistance in Aedes aegypti and Ae. albopictus (Diptera: Culicidae) populations from Tapachula, Chiapas, Mexico

Resumen: Objetivo: Determinar la resistencia a insecticidas en Ae. aegypti y Ae. albopictus de Tapachula, Chiapas, México. Material y métodos: Se utilizaron ovitrampas para obtener huevos de mosquitos Aedes y se realizaron pruebas de susceptibilidad (CDC) y ensayos enzimáticos con la primera generación. Resultados: Aedes aegypti mostró resistencia a deltametrina, permetrina, malatión, clorpirifos, temefos y a bendiocarb (CARB), mientras que Aedes albopictus a malatión y en menor grado a cloripirifos, temefos, permetrina y deltametrina. Ambas especies mostraron altos niveles de enzimas como citocomo P450 y glutatión S-tranferasa, mientras que los niveles de esterasas variaron por especie y sitio muestreado. Se detectó acetilcolinesterasa insensible a insecticidas en ambas especies. Conclusión: En un hábitat urbano de Tapachula, Chiapas, México donde se aplica control con insecticidas Ae. aegypti y Ae. albopictus sólo son susceptibles al propoxur.

Abstract: Objective: To determine the insecticide resistance status of Ae. aegypti and Ae. albopictus from Tapachula, México. Materials and methods: Mosquito eggs were collected with the use of ovitraps and CDC susceptibility bioassays and biochemical assays were conducted to determine resistance levels and resistance mechanisms, respectively. Results: Ae. aegypti showed resistance to deltamethrin and permethrin (PYRs), malathion, chlorpyrifos and temephos (OP), and to bendiocarb (CARB), while Ae. albopictus showed resistance to malathion and to a lesser intensity to chlorypirifos, temephos, permethrin and deltamethrin. Both species showed high levels of P450 and GSTs, while levels of esterases varied by species and collection site. Altered acethilcholinesterase was detected in both species. Conclusion: In an urban habitat from Tapachula, Chiapas, Mexico where vector control using insecticides takes place, Ae. aegypti and Ae. albopictus are only susceptible to propoxur.

Dinámica de aparición de criaderos de Aedes aegypti (Diptera: Culicidae) en la provincia La Habana, 2013-2017 / Dynamics of the appearance of breeding sites of Aedes aegypti (Diptera: Culicidae) in the province of Havana, 2013-1017

Introducción: El Programa Nacional de Control de Aedes aegypti realiza actividades de rutina para controlar la trasmisión de arbovirosis en el país, pero siempre quedan poblaciones residuales del vector, que demandan de una vigilancia entomológica sostenible. Objetivo: Determinar la presencia de estadios inmaduros de Ae. aegypti en la provincia La Habana en el periodo 2013-2017. Métodos: Se realizó un análisis del número de criaderos larvales, detectados por los trabajadores del Programa Nacional de Control de Ae. aegypti, en La provincia La Habana entre 2013-2017. La frecuencia de los muestreos fue mensual y se siguió la metodología de encuestas del programa. Resultados: Al analizar el número de criaderos larvales por meses de los 15 municipios de provincia La Habana, se observó un incremento de estos en el periodo de junio a octubre en todos los años y un pico entre los meses de enero a marzo en los años 2014, 2016 y 2017. La incidencia de Ae. aegypti resultó homogénea al comparar las medias por año, excepto para el año 2015 en el cual se observó una disminución significativa en el número de criaderos en comparación solo con el año 2017. Conclusiones: A pesar del esfuerzo que realizan los trabajadores del programa, no se ha logrado una disminución significativa de criaderos de Ae. aegypti, lo que evidencia la necesidad de fortalecer los sistemas de vigilancia y mantener la sostenibilidad de las acciones para controlar de forma efectiva la trasmisión de arbovirosis en la provincia La Habana(AU)

Introduction: The National Aedes aegypti Control Program carries out routine activities to control the transmission of arbovirus infections in the country. However, there still exist residual populations of the vector which require sustainable entomological surveillance. Objective: Determine the presence of immature stage Ae. aegypti in the province of Havana in the period 2013-2017. Methods: An analysis was conducted of the number of larval breeding sites detected by workers from the National Ae. aegypti Control Program in the province of Havana in the period 2013-2017. Sampling was performed on a monthly basis following the surveying methodology of the Program. Results: Analysis of the data on larval breeding sites per month in the 15 municipalities of the province of Havana revealed an increase in their number in the June-October period of every year, and a peak between the months of January and March in the years 2014, 2016 and 2017. Comparison of mean values per year found that incidence of Ae. aegypti was homogeneous, except for the year 2015, when a significant decrease was observed in the number of breeding sites only with respect to the year 2017. Conclusions: Despite the effort made by workers from the Program, a significant reduction has not been achieved in the number of Ae. aegypti breeding sites, which is evidence of the need to strengthen the surveillance systems and maintain the sustainability of the actions performed to effectively control the transmission of arbovirus infections in the Havana province(AU)

Larvicidal activity of piperovatine and dichloromethane extract from Piper corcovadensis roots against mosquitoes Aedes aegypti L / Actividad larvicida de piperovatina y extracto de diclorometano de las raíces de Piper corcovadensis contra mosquitos vectores del dengue Aedes aegypti L

The research of new substances capable of controlling the Aedes aegypti mosquito is urgent due to the increase in the transmission of the diseases such as dengue, chikungunya and Zika virus by the vector. Thus, the aim of this study was to evaluate the larvicidal activity of crude extract of Piper corcovadensis roots, a native plant from Brazil, and of the isolated compound piperovatine against larvae of A. aegypti by the larval immersion test. The lethal concentration that killed 50% (LC50) and 99% (LC99) of larvae was determined by Probit analysis. The results indicated high larvicidal activity on A. aegypti larvae for crude extract of Piper corcovadensis roots with LC50 of 4.86 µg/mL and LC99 of 15.50 µg/mL and piperovatine with LC50 of 17.78 µg/mL and LC99 of 48.55 µg/mL. This work opens new perspectives to the development of future products with crude extract of Piper corcovadensis roots and piperovatine that can be applied to mosquito control.

La investigación de nuevas sustancias capaces de controlar el mosquito Aedes aegypti es urgente debido al aumento en la transmisión de enfermedades como el dengue, el chikungunya y el virus Zika por el vector. Por lo tanto, el objetivo de este estudio fue evaluar la actividad larvicida del extracto crudo de las raíces de Piper corcovadensis, una planta nativa de Brasil, y del compuesto aislado piperovatine contra larvas de A. aegypti mediante la prueba de inmersión larvaria. La concentración letal que mató al 50% (LC50) y al 99% (LC99) de larvas se determinó mediante análisis Probit. Los resultados indicaron una alta actividad larvicida en larvas de A. aegypti para extracto crudo de las raíces de Piper corcovadensis con LC50 de 4.86 µg/mL y LC99 de 15.50 µg/mL y piperovatine con LC50 de 17.78 µg/mL y LC99 de 48.55 µg/mL. Este trabajo abre nuevas perspectivas para el desarrollo de futuros productos con extracto crudo de las raíces de Piper corcovadensis y piperovatine que pueden aplicarse al control de mosquitos.

Assessing the efficacy of two new formulations of larvicide pyriproxyfen for the control of Aedes aegypti using dissemination stations in two sites of Rio de Janeiro city

BACKGROUND Aedes aegypti is the primary transmitter of several arbovirus with great impact in human health. Controlling vector mosquitoes is an essential and complex task. One promising control method is to use mosquitoes as a vehicle to disseminate tiny particles of juvenile-killing insecticides, such as pyriproxyfen (PPF), to breeding sites. OBJECTIVES We aimed to investigate the capacity of Ae. aegypti to disseminate two new formulations of PPF in two sites of Rio de Janeiro city for assessment of the efficacy of these products. METHODS Dissemination stations impregnated with powder and liquid new formulations of PPF were installed in two test sites. Ovitraps were used in the test sites and in a control site for monitoring the presence of Ae. aegypti throughout eggs collection. FINDINGS Entomological indices indicated that the new formulations of PPF were efficient in reducing eggs abundance. Liquid formulation performed better than powder formulation. Ready-to-use formulations of PPF can be quickly applied in the field and can be replaced after a few months. MAIN CONCLUSIONS New formulations of PPF associated with mosquito dissemination approach make a valuable vector control strategy, managing to cover places of difficult access for whatever reason. New formulations application requires less labour, being economically attractive.

Susceptibility of Aedes aegypti populations to pyriproxyfen in the Federal District of Brazil

Abstract INTRODUCTION: In Brasilia, pyriproxyfen (PPF; 0.01 mg/L) has been used for the larval control of Aedes aegypti mosquitoes since 2016. Information on the susceptibility of Ae. aegypti to PPF, and the development of resistance in populations from the Federal District of Brazil (FD) is limited. It is essential to monitor the susceptibility of Ae. aegypti to insecticides in order to improve vector control strategies. This study aimed to evaluate the susceptibility of Ae. aegypti populations from five areas of Brasilia to PPF. METHODS: We performed dose-response tests to estimate the emergence inhibition and resistance ratio of each field population, including the Rockefeller reference population. We also analyzed egg positivity, and the density and mortality of larvae and pupae. RESULTS: Populations from Vila Planalto (RR50=1.7), Regiment Guards Cavalry (RR50=2.5), and Sub-secretary of Justice Complex (RR50=3.7) presented high susceptibility to PPF, while the RR values of populations from Lago Norte (RR50=7.7) and Varjão (RR50=5.9) were moderately high, suggesting the emergence of insipient resistance to PPF in Brasilia. At 30 ng/mL, the highest larvae mortality rate was 2.7% for the population from Lago Norte, while that of pupae was 92.1% for Varjão and Vila Planalto. CONCLUSIONS: The five populations of Ae. aegypti from the FD are susceptible to PPF and there is a need to monitor the susceptibility of Ae. aegypti in new areas of the FD.

Spatiotemporal multiple insecticide resistance in Aedes aegypti populations in French Guiana: need for alternative vector control

BACKGROUND Aedes aegypti is the sole vector of urban arboviruses in French Guiana. Overtime, the species has been responsible for the transmission of viruses during yellow fever, dengue, chikungunya and Zika outbreaks. Decades of vector control have produced resistant populations to deltamethrin, the sole molecule available to control adult mosquitoes in this French Territory. OBJECTIVES Our surveillance aimed to provide public health authorities with data on insecticide resistance in Ae. aegypti populations and other species of interest in French Guiana. Monitoring resistance to the insecticide used for vector control and to other molecule is a key component to develop an insecticide resistance management plan. METHODS In 2009, we started to monitor resistance phenotypes to deltamethrin and target-site mechanisms in Ae. aegypti populations across the territory using the WHO impregnated paper test and allelic discrimination assay. FINDINGS Eight years surveillance revealed well-installed resistance and the dramatic increase of alleles on the sodium voltage-gated gene, known to confer resistance to pyrethroids (PY). In addition, we observed that populations were resistant to malathion (organophosphorous, OP) and alpha-cypermethrin (PY). Some resistance was also detected to molecules from the carbamate family. Finally, those populations somehow recovered susceptibility against fenitrothion (OP). In addition, other species distributed in urban areas revealed to be also resistant to pyrethroids. CONCLUSION The resistance level can jeopardize the efficiency of chemical adult control in absence of other alternatives and conducts to strongly rely on larval control measures to reduce mosquito burden. Vector control strategies need to evolve to maintain or regain efficacy during epidemics.

Chemical composition and larvicidal activity of essential oils from Zingiber montanum (J. Koenig) Link ex. A. Dietr. against three mosquito vectors / Composición química y actividad larvicida de aceites esenciales de Zingiber montanum (J. Koenig) Link ex. A. Dietr. contra tres vectores de mosquitos

The chemical composition and larvicidal activity of essential oils derived from the leaves and rhizomes of Zingiber montanum (J. Koenig) Link ex. A. Dietr. were reported. The main compounds in the leaf oil were ß-pinene (13.8%), ß-phellandrene (11.3%) and α-pinene (7.3%) while the rhizome oil was dominated by sabinene (41.1%), terpinen-4-ol (22.7%) and (E)-nerolidol (14.3%). The minimum lethal concentration (larvicidal activity) LC50of the rhizome oil at 24 h against Aedes albopictus was 35.17 µg/mL, while LC50 values of 32.20 µg/mL and 31.12 µg/mL were obtained against Aedes aegypti and Culex quinquefasciatus respectively. At 48 h the oil displayed larvicidal action with LC50 values of 23.18 µg/mL, 25.58 µg/mL and 18.99 µg/mL respectively towards Ae. albopictus, Ae. Aegyptiand Cx. quinquefasciatus. The leaf oil did not exhibit significant mortality and larvicidal action. The results indicate the potential of rhizome essential oil of Z. montanumas a source of larvicidal agent.

En el presente trabajo se reportan la composición química y actividad larvicida de los aceites esenciales obtenidos de hojas y rizomas de Zingiber montanum (J. Koenig) Link ex. A. Dietr. Los principales compuestos en el aceite de hojas fueron ß-pineno (13.8%), ß-felandrene (11.3%) y α-pineno (7.3%); mientras que los más abundantes en el aceite de rizomas fueron sabineno (41.1%), terpinen-4-ol (22.7%) y (E)-nerolidol (14.3%). La concentración letal mínima (actividad larvicida) LC50 del aceite de riomas ante Aedes albopictus fue 35.17 µg/mL, mientras que los valores de LC50 de 32.20 µg/mL y 31.12 µg/mL fueron obtenidos ante Aedes aegyptiy Culex quinquefasciatus respectivamente. A las 48 horas, el aceite mostró acción larvicida con valores de LC50 de 23.18 µg/mL, 25.58 µg/mL y 18.99 µg/mL respectivamente, ante Ae. albopictus, Ae. Aegyptiand Cx. quinquefasciatus. El aceite de hojas no mostró mortalidad ni acción larvicida significativa. Los resultados indican el potencial del aceite esencial de rizomas de Z. montanum como una fuente de agentes larvicidas.

Evaluation of the larvicidal potential of root and leaf extracts of Saussurea costus (Falc. ) Lipsch. against three mosquito vectors: Anopheles stephensi, Aedes aegypti, and Culex quinquefasciatus

Abstract INTRODUCTION: The larvicidal potential of Saussurea costus (Falc.) Lipsch. was studied against the early 4th instar larvae of Anopheles stephensi Liston., Aedes aegypti Linn.,and Culex quinquefasciatus Say. because of the emergence of mosquito resistance to conventional synthetic insecticides. METHODS: At concentrations of 12.5-200 ppm, larvicidal activities were studied under laboratory conditions. RESULTS: After 24 h of exposure, the methanol extract of the roots recorded the highest larvicidal activity against An. stephensi, with LC50 and LC90values of 7.96 and 34.39 ppm, respectively. CONCLUSIONS: We are developing potent larvicidal compound(s) from S. costus for controlling the mosquito larval population.

Liaisons dangereuses: cross-border gene flow and dispersal of insecticide resistance-associated genes in the mosquito Aedes aegypti from Brazil and French Guiana

BACKGROUND In recent years, South America has suffered the burden of continuous high impact outbreaks of dengue, chikungunya and Zika. Aedes aegypti is the main mosquito vector of these arboviruses and its control is the only solution to reduce transmission. OBJECTIVES In order to improve vector control it is essential to study mosquito population genetics in order to better estimate the population structures and the geneflow among them. METHODS We have analysed microsatellites and knockdown resistance (kdr) mutations from a trans-border region in Amazonia between the state of Amapá (Brazil) and French Guiana (overseas territory of France), to provide further knowledge on these issues. These two countries have followed distinct vector control policies since last century. For population genetic analyses we evaluated variability in 13 well-established microsatellites loci in Ae. aegypti from French Guiana (Saint Georges and Cayenne) and Brazil (Oiapoque and Macapá). The occurrence and frequency of kdr mutations in these same populations were accessed by TaqMan genotype assays for the sites 1016 (Val/Ile) and 1534 (Phe/Cys). FINDINGS We have detected high levels of gene flow between the closest cross-border samples of Saint-Georges and Oiapoque. These results suggest one common origin of re-colonisation for the populations of French Guiana and Oiapoque in Brazil, and a different source for Macapá, more similar to the other northern Brazilian populations. Genotyping of the kdr mutations revealed distinct patterns for Cayenne and Macapá associated with their different insecticide use history, and an admixture zone between these two patterns in Saint Georges and Oiapoque, in accordance with population genetic results. MAIN CONCLUSIONS The present study highlights the need for regional-local vector surveillance and transnational collaboration between neighboring countries to assess the impact of implemented vector control strategies, promote timely actions and develop preparedness plans.

Estudo experimental sobre a ação de larvicidas em populações de Aedes aegypti do município de Itabuna, Bahia, em condições simuladas de campo / Estudio experimental sobre la acción de larvicidas en poblaciones de Aedes aegypti del municipio brasileño de Itabuna, BA, en condiciones simuladas de campo / Experimental study on the action of larvicides in Aedes aegypti populations collected in the Brazilian municipality of Itabuna, Bahia, under simulated field conditions

Objetivo: avaliar, em condições simuladas de campo, a eficácia do pyriproxyfen (hormônio juvenil), do novaluron (inibidor de quitina) e do spinosad (biolarvicida) no controle do Aedes aegypti. Métodos: exposição periódica de larvas de Ae. aeypti obtidas em Itabuna a recipientes tratados com os larvicidas, e comparação do efeito residual do tratamento com cepa Rockfeller. Resultados: o efeito inibitório na emergência de adultos, após 60 dias, foi de 89,5% spinosad, 96,5% novaluron e 75,4% pyriproxifen para larvas de Itabuna, não havendo diferença estatística (p=0,412) entre os tratamentos; spinosad e novaluron apresentaram maior percentual de mortalidade na fase larval, 98,8% e 97,9% respectivamente; pyriproxifen apresentou mortalidade maior na fase pupal, 95,1%. Conclusão: os três larvicidas apresentaram controle semelhante; no entanto, o pyriproxifen pode deixar a falsa impressão de positividade dos criadouros, por agir em fase pupal, comprometendo os indicadores de infestação que são parâmetros estratégicos para as ações de controle.

Objetivo: evaluar en condiciones simuladas de campo la eficacia del piriproxifén (hormona juvenil), novaluron (inhibidor de quitina) y spinosad (biolarvicida) en el control del Ae. Aegypti. Métodos: exposición periódica de larvas obtenidas de Itabuna, BA, Brasil, a recipientes tratados con larvicida y comparación del efecto residual con cepa Rockefeller. Resultados: el efecto inhibidor en la emergencia de adultos, después de 60 días, fue de 89,5% spinosad, 96,5% novaluron y 75,4% piriproxifén para larvas de Itabuna, no habiendo diferencia estadística (p=0,412) entre los tratamientos; spinosad y novaluron presentaron mayor mortalidad en la fase larval, 98,8% y 97,9% respectivamente; piriproxifén presentó mayor mortalidad en la fase de pupa, 95,1%. Conclusión: los tres larvicidas fueron eficaces en el control de larvas de Ae. Aegypti; sin embargo, piriproxifén puede dejar falsa positividad de los criaderos, por actuar en fase de pupa, comprometiendo los indicadores de infestación, parámetros estratégicos para las acciones de control.

Objective: to evaluate, under simulated field conditions, the efficacy of pyriproxyfen (juvenile hormone), novaluron (chitin inhibitor) and spinosad (biolarvicide) in controlling Aedes aegypti. Methods: periodic exposition of Ae. aegypti larvae collected in Itabuna, BA, Brazil, to recipients treated with larvicides and comparison of residual effect of treatment with the Rockefeller strain. Results: the inhibitory effect on adult emergence after 60 days was spinosad 89.5%, novaluron 96.5% and pyriproxifen 75.4% for Itabuna larvae, with no statistical difference (p=0.412) between treatments; spinosad and novaluron had a higher percentage of mortality in the larval stage, 98.8% and 97.9% respectively; pyriproxyfen showed higher mortality (95.1%) in the pupal stage. Conclusion: the three larvicides demonstrated similar control; however, pyriprofyxen might give a false impression of breeding ground positivity as it acts at the pupal stage, compromising the indicators of infestation that are strategic parameters for control actions.

Different susceptibilities of Aedes aegypti and Aedes albopictus larvae to plant-derived products

Abstract INTRODUCTION: Aedes aegypti and Aedes albopictus are important vectors that transmit arboviruses to human populations. METHODS: Natural products were obtained and tested against larvae collected from the field in Fortaleza, capital of Ceará state. RESULTS: The essential oils of Syzygium aromaticum (Ae. aegypti LC50 = 32.7 ppm and Ae. albopictus LC50 = 138.1 ppm) and Croton nepetaefolius (Ae. aegypti LC50 = 81.7 ppm and Ae. albopictus LC50 = 76.1 ppm) showed the most intense larvicidal activity. CONCLUSIONS: The essential oils and methyl esters showed greater larvicidal activity than did the ethanol extracts.

Larvicidal activity of essential oil from Vitex negundo and Vitex trifolia on dengue vector mosquito Aedes aegypti

Abstract INTRODUCTION: The ability of Vitex trifolia and Vitex negundo essential oils to kill Aedes aegypti and Culex quinquefasciatus larvae was evaluated. METHODS: The larvae were treated with their respective essential oils at 50-125 ppm concentration. RESULTS: LC50 and LC90 for V. trifolia against Ae. aegypti and C. quinquefasciatus, and those for V. negundo against Ae. aegypti were 57.7+0.4, 77.9+0.9 ppm and 55.17+3.14, 78.28+2.23 ppm, and 50.86+0.9, 73.12+1.3 ppm, respectively. Eucalyptol and caryophyllene were the major components in Vitex trifolia and Vitex negundo essential oil, respectively. CONCLUSIONS: This study revealed potential larvicidal properties of essential oil from V. trifolia.

Chemical composition, cytotoxicity and larvicidal activity against Aedes aegypti of essential oils from Vitex gardineriana Schauer / Composición química, citotoxicidad y actividad larvicida contra Aedes aegypti de aceites esenciales de Vitex gardneriana Schauer

Vitex gardneriana Schauer (Lamiaceae) popularly known as "jaramataia", is a shrub commonly found in caatinga biome located in Northeast Brazil. In folk medicine, its leaves have been used as analgesic and anti-inflammatory agents. The chemical composition of the essential oil from leaves obtained by hydrodistillation was analyzed and identified by GC-MS and GC-FID and showing a total of 26 constituents (95.9%) being 2 monoterpenes (0.4%) and 24 sesquiterpenes (95.4%). The main constituents identified were cis-calamenene (29.7%), 6,9-guaiadiene (14.5%) and caryophyllene oxide (14.0%). The essential oil has been demonstrated high larvicidal activity against Aedes aegypti (LC50 = 28.0 µg/mL). In the evaluation of the bioassay with Artemia salina the essential oil showed LC50 = 98.11 µg/mL. In addition, the essential oil did not show cytotoxicity (IC50 > 2.50 mg/mL) by the hemolysis assay.

Vitex gardneriana Schauer (Lamiaceae) popularmente conocido como "jaramataia", es un arbusto que se encuentra comúnmente en el bioma de caatinga ubicado en el noreste de Brasil. En medicina popular, sus hojas se han utilizado como analgésicos y agentes antiinflamatorios. La composición química de los aceites esenciales de las hojas obtenidas por hidrodestilación fue analizada e identificada por GC-MS y GC-FID y mostrando un total de 26 constituyentes (95.9%) siendo 2 monoterpenos (0.4%) y 24 sesquiterpenos (95.4%). Los componentes principales fueron cis-calamenene (29.7%), 6,9-guaiadiene (14.5%) y caryophyllene oxide (14.0%). El aceite esencial ha demostrado una alta actividad larvicida contra Aedes aegypti (CL50 = 28.0 µg/mL). En la evaluación del bioensayo con Artemia salina, el aceite esencial demostró CL50 = 98.11 µg/mL. Además, el aceite esencial no mostró citotoxicidad (IC50 > 2.5 mg / mL) mediante el ensayo de hemólisis.

A potent larvicidal agent against Aedes aegypti mosquito from cardanol

ABSTRACT Cardanol is a constituent of Cashew Nut Shell Liquid that presents larvicidal activity against Aedes aegypti. The isolation of cardanol is somewhat troublesome, however, in this work we describe an efficient and inexpensive method to obtain it as a pure material. The compound was used as starting material to make chemical transformation leading to saturated cardanol, epoxides and, halohydrins. These derivatives were tested for toxicity against Aedes aegypti larvae. The results showed that iodohydrins are very promising compounds for making commercial products to combat the vector mosquito larvae presenting a LC50 of 0.0023 ppm after 72 h of exposure.