BACKGROUND Aedes aegypti populations in Brazil have been subjected to insecticide selection pressures with variable levels and sources since 1967. Therefore, the Brazilian Ministry of Health (MoH) coordinated the activities of an Ae. aegypti insecticide resistance monitoring network (MoReNAa) from 1999 to 2012. OBJECTIVES The objective of this study was to consolidate all information available from between 1985 and 2017 regarding the resistance status and mechanisms of Brazilian Ae. aegypti populations against the main insecticide compounds used at the national level, including the larvicide temephos (an organophosphate) and the adulticide deltamethrin (a pyrethroid). METHODS Data were gathered from two sources: a bibliographic review of studies published from 1985 to 2017, and unpublished data produced by our team within the MoReNAa between 1998 and 2012. A total of 146 municipalities were included, many of which were evaluated several times, totalling 457 evaluations for temephos and 274 for deltamethrin. Insecticide resistance data from the five Brazilian regions were examined separately using annual records of both the MoH supply of insecticides to each state and the dengue incidence in each evaluated municipality. FINDINGS Ae. aegypti resistance to temephos and deltamethrin, the main larvicide and adulticide, respectively, employed against mosquitoes in Brazil for a long time, was found to be widespread in the country, although with some regional variations. Comparisons between metabolic and target-site resistance mechanisms showed that one or another of these was the main component of pesticide resistance in each studied population. MAIN CONCLUSIONS (i) A robust dataset on the assessments of the insecticide resistance of Brazilian Ae. aegypti populations performed since 1985 was made available through our study. (ii) Our findings call into question the efficacy of chemical control as the sole methodology of vector control. (iii) It is necessary to ensure that sustainable insecticide resistance monitoring is maintained as a key component of integrated vector management. (iv) Consideration of additional parameters, beyond the supply of insecticides distributed by the MoH or the diverse local dynamics of dengue incidence, is necessary to find consistent correlations with heterogeneous vector resistance profiles.

摘要 问题 2010年在亚马逊河城市博阿维斯塔爆发登革热期间检测到登革热病毒（DENV）血清分型-4。当时，巴西已经发生了DENV-1、DENV-2和DENV-3地方病。这是继1981年最初检测并消灭DENV-4之后，首次在该国发现DENV-4。 方法 为防止DENV-4在巴西的全面蔓延，加强了标准病媒控制措施。病媒控制专业...

Résumé Problème En 2010, le sérotype-4 du virus de la dengue (DENV) a été détecté pendant une épidémie de dengue dans la ville amazonienne de Boa Vista. À l'époque, le Brésil était déjà endémique pour les sérotypes DENV-1, DENV-2 et DENV-3. C'était la première fois que le sérotype DENV-4 était observé dans le pays après avoir été initialement détecté et éliminé en 1981. Approche Pour empêcher la propagation de DENV-4 dans tout le Brésil, les mesures standard de lutte antivectorielle ont été intensifiées. Des professionnels de la lutte antivectorielle ont rendu visite à 56 837 ménages dans 22 des 31 districts de Boa Vista pour éliminer les sites de reproduction des moustiques. Les ré...

Резюме Проблема В 2010 году, во время вспышки лихорадки денге в городе Боа-Виста в бассейне реки Амазонки, был обнаружен вирус денге 4-го серотипа (DENV-4). К этому времени Бр...

Problem In 2010, dengue virus (DENV) serotype–4 was detected during a dengue outbreak in the Amazonian city of Boa Vista. At that time Brazil was already endemic for DENV-1, DENV-2 and DENV-3. This was the first time DENV-4 was observed in the country after it was initially detected and eliminated in 1981. Approach To hinder the spread of DENV-4 throughout Brazil, standard vector control measures were intensified. Vector control professionals visited 56 837 households in 22 out of 31 districts of Boa Vista, to eliminate mosquito-breeding sites. Water storage containers were treated with the larvicide diflubenzuron, and deltamethrin was sprayed for adult Aedes aegypti mosquitoes. Fifteen days later, a second larvae survey and additional deltamethrin applications were performed. Local setting In Brazil, dengue vector control is managed at all three government levels. Regular surveillance of Aedes aegypti is done four to six times a year to strengthen mosquito control activities in areas with high-vector density. Educational dengue control campaigns in communities are scarce, especially between outbreaks. Relevant changes In spite of extensive implementation of all standard control actions recommended by the Brazilian dengue control programme, only a slight decrease in mosquito density was detected. Lessons learnt There is a need to redesign all levels of dengue control. Public consultation and engagement, behaviour change and actions that go beyond technical impositions are required. Vector control programme managers need to reflect on what constitutes good practices and whether intermittent information campaigns are effective measures for dengue prevention and control.

ملخص المشكلة في عام 2010، تم اكتشاف النمط المصلي 4 من فيروس حمى الضنك (DENV) خلال فاشية لحمى الضنك في مدينة بوا فيستا الواقعة على نهر الأمازون. وفي هذا الوقت، كانت الأنماط الم...

Resumen Situación En el año 2010 se detectó el serotipo 4 del virus del dengue (DENV) durante un brote de dengue en la ciudad amazónica de Boa Vista. En aquel momento, en Brasil ya eran endémicos los serotipos DENV-1, DENV-2 y DENV-3. Tras su detección inicial y eliminación en 1981, esta fue la primera vez que se volvía a observar el DENV-4 en el país. Enfoque Con objeto de impedir la propagación del DENV-4 por todo Brasil, se intensificaron las medidas de control vectorial estándar. Profesionales del control vectorial visitaron 56 837 hogares en 22 de los 31 distritos de Boa Vista para eliminar los criaderos de mosquitos. Los recipientes de almacenamiento de agua se trataron con el larvicida diflubenzuron, y se roció deltametrina contra los mosquitos adultos Aedes aegypti. Quince días más tarde se llevó a cabo una segunda encuesta de larvas y se realizaron aplicaciones adicionales de deltametrina. Marco regional En Brasil, el control vectorial del dengue se gestiona en los tres niveles gubernamentales. El control regular de Aedes aegypti se realiza de cuatro a seis veces al año para reforzar las actividades de control de los mosquitos en áreas con una densidad vectorial elevada. Las campañas educativas en las comunidades sobre el control del dengue son escasas, especialmente entre los brotes. Cambios importantes A pesar de la amplia aplicación de todas las acciones de control estándar recomendadas por el programa de control del dengue brasileño, únicamente se detectó una disminución leve en la densidad de mosquitos. Lecciones aprendidas Hay una necesidad de rediseñar todos los niveles de control del dengue. Son necesarios una consulta y compromiso públicos, un cambio en el comportamiento y acciones que vayan más allá de las imposiciones técnicas. Los directores de los programas de control vectorial deben reflexionar sobre qué constituye las buenas prácticas y si las campañas de información intermitentes son medidas eficaces para controlar y prevenir el dengue.

Currently, sticky traps are regularly employed to assist in the surveillance of Aedes aegypti infestation. We tested two alternative procedures for specimen identification performed by local health agents: directly in the field, as recommended by certain manufacturers, or after transportation to the laboratory. A total of 384 sticky traps (MosquiTRAP) were monitored monthly during one year in four geographically representative Brazilian municipalities. When the same samples were inspected in the field and in the laboratory, large differences were noted in the total number of mosquitoes recorded and in the number of specimens identified as Ae. aegypti by both procedures. Although field identification has the potential to speed vector surveillance, these results point to uncertainties in the evaluated protocol.

In Brazil, decades of dengue vector control using organophosphates and pyrethroids have led to dissemination of resistance. Although these insecticides have been employed for decades against Aedes aegypti in the country, knowledge of the impact of temephos resistance on vector viability is limited. We evaluated several fitness parameters in two Brazilian Ae. aegypti populations, both classified as deltamethrin resistant but with distinct resistant ratios (RR) for temephos. The insecticide-susceptible Rockefeller strain was used as an experimental control. The population presenting the higher temephos resistance level, Aparecida de Goiânia, state of Goiás (RR95 of 19.2), exhibited deficiency in the following four parameters: blood meal acceptance, amount of ingested blood, number of eggs and frequency of inseminated females. Mosquitoes from Boa Vista, state of Roraima, the population with lower temephos resistance level (RR95 of 7.4), presented impairment in only two parameters, blood meal acceptance and frequency of inseminated females. These results indicate that the overall fitness handicap was proportional to temephos resistance levels. However, it is unlikely that these disabilities can be attributed solely to temephos resistance, since both populations are also resistant to deltamethrin and harbour the kdr allele, which indicates resistance to pyrethroids. The effects of reduced fitness in resistant populations are discussed.

In this opinion paper, we discuss the potential and challenges of using the symbiont Wolbachia to block mosquito transmitted diseases such as dengue, malaria and chikungunya in Latin America.

The use of chemical insecticides continues to play a major role in the control of disease vector populations, which is leading to the global dissemination of insecticide resistance. A greater capacity to detoxify insecticides, due to an increase in the expression or activity of three major enzyme families, also known as metabolic resistance, is one major resistance mechanisms. The esterase family of enzymes hydrolyse ester bonds, which are present in a wide range of insecticides; therefore, these enzymes may be involved in resistance to the main chemicals employed in control programs. Historically, insecticide resistance has driven research on insect esterases and schemes for their classification. Currently, several different nomenclatures are used to describe the esterases of distinct species and a universal standard classification does not exist. The esterase gene family appears to be rapidly evolving and each insect species has a unique complement of detoxification genes with only a few orthologues across species. The examples listed in this review cover different aspects of their biochemical nature. However, they do not appear to contribute to reliably distinguish among the different resistance mechanisms. Presently, the phylogenetic criterion appears to be the best one for esterase classification. Joint genomic, biochemical and microarray studies will help unravel the classification of this complex gene family.

The mosquito Aedes aegypti is the main focus of dengue control campaigns. Because of widespread resistance against conventional chemical insecticides, chitin synthesis inhibitors (CSIs) are considered control alternatives. We evaluated the resistance status of four Brazilian Ae. aegypti populations to both the organophosphate temephos and the pyrethroid deltamethrin, which are used in Brazil to control larvae and adults, respectively. All vector populations exhibited high levels of temephos resistance and varying rates of alterations in their susceptibility to pyrethroids. The effect of the CSI novaluron on these populations was also investigated. Novaluron was effective against all populations under laboratory conditions. Field-simulated assays with partial water replacement were conducted to evaluate novaluron persistence. Bioassays were continued until an adult emergence inhibition of at least 70% was attained. We found a residual effect of eight weeks under indoor conditions and novaluron persisted for five-six weeks in assays conducted in an external area. Our data show that novaluron is effective against the Ae. aegypti populations tested, regardless of their resistance to conventional chemical insecticides.

The control of Aedes aegypti is impaired due to the development of resistance to chemical insecticides. Insect Growth Regulators (IGR) exhibit distinct mechanisms of action and are considered potential vector control alternatives. Studies regarding the effects of sublethal IGR doses on the viability of resulting adults will contribute to eval-uating their impact in the field. We analyzed several aspects of Ae. aegypti adults surviving exposure to a partially lethal dose of triflumuron, a chitin synthesis inhibitor. A highly significant difference in the proportion of males and females was noted in the triflumuron-exposed group (65.0% males) compared to the controls (50.2% males). Triflumuron affected adult longevity, particularly for females; after 16 days, only 29.2% of males and 13.8% of females were alive, in contrast with 94% survival of the control mosquitoes. The locomotor activity was reduced and the blood-feeding ability of the treated females was also affected (90.4% and 48.4% of the control and triflumuron-exposed females, respectively, successfully ingested blood). Triflumuron-surviving females ingested roughly 30% less blood and laid 25% fewer eggs than the control females. The treated males and females exhibited a diminished ability to copulate, resulting in less viable eggs.

Despite its vector importance little attention is given to Aedes aegypti embryonic development. In this study, temperature influence on time course of Ae. aegypti larvae hatching and egg viability were evaluated. The dormancy state at the end of embryogenesis could be interrupted with a proper stimulus. Temperatures tested ranged between 12-36°C; the maximum temperature limit is 35°C and the minimum one is below 12°C. Egg viability between 16-31°C was above 80%. The definition of physiological embryonic parameters at this temperature range corroborates Ae. aegypti presence on tropical and subtropical world regions.