Experiências em divulgação científica e sensibilização da população: importância do controle mecânico do vetor Aedes aegypti / Experiences in scientific outreach and public awareness: the importance of mechanical control of the Aedes aegypti vector / Experiencias en divulgación científica y sensibilización de la población: importancia del control mecánico del vector Aedes aegypti

Aedes aegypti é o principal vetor dos agentes etiológicos de dengue, zika e chikungunya, doenças para as quais não existem vacinas totalmente eficazes. Alternativas de controle visando mitigar essas arboviroses são primordiais. Entre essas, o controle mecânico aborda práticas de eliminação e/ou limpeza de criadouros do vetor. Neste relato, apresentamos e avaliamos criticamente ações realizadas pelo grupo, ocorridas entre 2016 e 2019, nas quais divulgamos informação científica clara através do diálogo com a população. Os métodos utilizados foram: 1) palestras em escolas (público infantojuvenil) utilizando slides, fotos e vídeos; 2) oficinas (público misto), estande com material in vivo do ciclo de vida do Aedes, jogos e desenhos. Analisamos dez palestras em escolas do ensino fundamental e médio e vinte oficinas realizadas em diferentes regiões do Brasil. Concluímos que tais ações e suas análises críticas devem ser realizadas continuamente para que sejam bem-sucedidas

Aedes aegypti is the main vector of dengue, zika, and chikungunya etiological agents, diseases for which no effective vaccines are available. Control alternatives aimed at mitigating these arboviruses are essential. Among such, mechanical control addresses practices of elimination and/or cleaning of vector breeding sites. Here, we presented and critically evaluated actions carried out by ourselves. These actions took place between 2016 and 2019, where we disseminated clear scientific information through dialogue with the population. The following methods were employed: 1) lectures in schools (children and youth audiences) using slides, photos, and videos; 2) workshops (mixed audience), stand with in vivo material from the Aedeslife cycle, games, and drawings. Ten lectures in elementary and high schools and twenty workshops held in different regions of Brazil were analyzed. It was concluded that such actions and their critical analyzes must be carried out continuously to be successful

Aedes aegypti es el principal vector de los agentes etiológicos del dengue, zika y chikungunya, enfermedades para las que no existen vacunas totalmente eficaces. Las alternativas de control para mitigar estas arbovirosis son fundamentales. El control mecánico, representa una de estas alternativas, aborda prácticas de eliminación y/o limpieza de criaderos del vector. En este informe presentamos y evaluamos de manera crítica las acciones realizadas por el grupo entre los años 2016 y 2019. Presentamos información científica clara a través del diálogo con la población mediante los siguientes métodos: 1) conferencias en escuelas (público infantil) utilizando diapositivas, fotos y videos; 2) Talleres (público mixto), stand con material in vivo del ciclo de vida del Aedes, juegos y dibujos. Analizamos diez conferencias en escuelas (primarias y secundarias) y veinte talleres realizados en diferentes regiones de Brasil. Concluimos que tales acciones y el análisis crítico de las mismas deben llevarse a cabo de manera continua para que resulten exitosas.

Molecular diversity of genes related to biological rhythms (period and timeless) and insecticide resistance (Na V and ace-1) in Anopheles darlingi

BACKGROUND Malaria is a public health concern in the Amazonian Region, where Anopheles darlingi is the main vector of Plasmodium spp. Several studies hypothesised the existence of cryptic species in An. darlingi, considering variations in behaviour, morphological and genetic aspects. Determining their overall genetic background for vector competence, insecticide resistance, and other elements is essential to better guide strategies for malaria control. OBJECTIVES This study aimed to evaluate the molecular diversity in genes related to behaviour and insecticide resistance, estimating genetic differentiation in An. darlingi populations from Amazonian localities in Brazil and Pacific Colombian region. METHODS We amplified, cloned and sequenced fragments of genes related to behaviour: timeless (tim) and period (per), and to insecticide resistance: voltage-gated sodium channel (Na V ) and acetylcholinesterase (ace-1) from 516 An. darlingi DNA samples from Manaus, Unini River, Jaú River and Porto Velho - Brazil, and Chocó - Colombia. We discriminated single nucleotide polymorphisms (SNPs), determined haplotypes and evaluate the phylogenetic relationship among the populations. FINDINGS The genes per, tim and ace-1 were more polymorphic than Na V . The classical kdr and ace-1 R mutations were not observed. Phylogenetic analyses suggested a significant differentiation between An. darlingi populations from Brazil and Colombia, except for the Na V gene. There was a geographic differentiation within Brazilian populations considering per and ace-1. CONCLUSIONS Our results add genetic data to the discussion about polymorphisms at population levels in An. darlingi. The search for insecticide resistance-related mechanisms should be extended to more populations, especially from localities with a vector control failure scenario.

Zika infection decreases Aedes aegypti locomotor activity but does not influence egg production or viability

BACKGROUND Zika has emerged as a new public health threat after the explosive epidemic in Brazil in 2015. It is an arbovirus transmitted mainly by Aedes aegypti mosquitoes. The knowledge of physiological, behavioural and biological features in virus-infected vectors may help the understanding of arbovirus transmission dynamics and elucidate their influence in vector capacity. OBJECTIVES We aimed to investigate the effects of Zika virus (ZIKV) infection in the behaviour of Ae. aegypti females by analysing the locomotor activity, egg production and viability. METHODOLOGY Ae. aegypti females were orally infected with ZIKV through an artificial feeder to access egg production, egg viability and locomotor activity. For egg production and viability assays, females were kept in cages containing an artificial site for oviposition and eggs were counted. Locomotor activity assays were performed in activity monitors and an average of 5th, 6th and 7th days after infective feeding was calculated. FINDINGS No significant difference in the number of eggs laid per females neither in their viability were found between ZIKV infected and non-infected females, regardless the tested pair of mosquito population and virus strain and the gonotrophic cycles. Locomotor activity assays were performed regardless of the locomotor activity in ZIKV infected females was observed, in both LD and DD conditions. MAIN CONCLUSIONS The lower locomotor activity may reduce the mobility of the mosquitoes and may explain case clustering within households reported during Zika outbreaks such as in Rio de Janeiro 2015. Nevertheless, the mosquitoes infected with ZIKV are still able to disseminate and to transmit the disease, especially in places where there are many oviposition sites.

The influence of a light and dark cycle on the egg laying activity of Aedes aegypti (Linnaeus, 1762) (Diptera: Culicidae)

BACKGROUND The epidemiological importance of the mosquito Aedes aegypti as a vector of multiple human pathogens has generated a growing number of studies on the physiology and behaviour of its blood-feeding females. The activity of oviposition is one of the critical elements contributing to the expansion of Ae. aegypti's populations. Although there is a vast literature about oviposition behaviour, significant specific knowledge about egg viability and female fertility under light and dark conditions is still lacking. OBJECTIVES We studied, in controlled laboratory conditions, the effect that light and dark cycles have on the efficiency of oviposition by Ae. aegypti females. METHODS Physiological assays were performed using synchronised eggs obtained from forced egg laying. The number and viability of eggs was analysed under three different light/dark regimes: LD12:12 (12 h of light and 12 h of dark), DD (constant darkness) and LL (constant light). FINDINGS and CONCLUSIONS Our results show that females prefer to lay their eggs in dark conditions, but maximising the number and viability of eggs requires the occurrence of a light/dark cycle. Ongoing research on this theme has the potential of contributing to the proposition of new strategies for control based on the failure of egg laying and hatching.

Circadian clock of Aedes aegypti: effects of blood-feeding, insemination and RNA interference

Mosquitoes are the culprits of some of the most important vector borne diseases. A species’ potential as a vector is directly dependent on their pattern of behaviour, which is known to change according to the female’s physiological status such as whether the female is virgin/mated and unfed/blood-fed. However, the molecular mechanism triggered by and/or responsible for such modulations in behaviour is poorly understood. Clock genes are known to be responsible for the control of circadian behaviour in several species. Here we investigate the impact mating and blood-feeding have upon the expression of these genes in the mosquito Aedes aegypti . We show that blood intake, but not insemination, is responsible for the down-regulation of clock genes. Using RNA interference, we observe a slight reduction in the evening activity peak in the fourth day after dstim injection. These data suggest that, as in Drosophila , clock gene expression, circadian behaviour and environmental light regimens are interconnected in Ae. aegypti .

Male accessory gland substances from Aedes albopictus affect the locomotor activity of Aedes aegypti females

Dengue is one of the world’s most important mosquito-borne diseases and is usually transmitted by one of two vector species: Aedes aegypti or Aedes albopictus . These two diurnal mosquitoes are frequently found coexisting in similar habitats, enabling interactions between adults, such as cross-mating. The objective of this study was to assess cross-mating between Ae. aegypti females and Ae. albopictus males under artificial conditions and evaluate the locomotor activity of Ae. aegypti virgin females injected with male accessory gland (MAG) homogenates to infer the physiological and behavioural responses to interspecific mating. After seven days of exposure, 3.3-16% of Ae. aegypti females mated with Ae. albopictus males. Virgin Ae. aegypti females injected with conspecific and heterospecific MAGs showed a general decrease in locomotor activity compared to controls and were refractory to mating with conspecific males. The reduction in diurnal locomotor activity induced by injections of conspecific or heterospecific MAGs is consistent with regulation of female reproductive activities by male substances, which are capable of sterilising female Ae. aegypti through satyrisation by Ae. albopictus .

Potential impact of a presumed increase in the biting activity of dengue-virus-infected Aedes aegypti (Diptera: Culicidae) females on virus transmission dynamics

Recently, we showed that infection with dengue virus increases the locomotor activity of Aedes aegypti females. We speculate that the observed increased locomotor activity could potentially increase the chances of finding a suitable host and, as a consequence, the relative biting rate of infected mosquitoes. We used a mathematical model to investigate the impact of the increased locomotor activity by assuming that this activity translated into an increased biting rate for infected mosquitoes. The results show that the increased biting rate resulted in dengue outbreaks with greater numbers of primary and secondary infections and with more severe biennial epidemics.

Spatiotemporal transcription of the P element and the 412 retrotransposon during embryogenesis of Drosophila melanogaster and D. willistoni

Transposable elements (TEs) are mobile nucleotide sequences which, through changing position in host genomes, partake in important evolutionary processes. The expression patterns of two TEs, P element transposon and 412 retrotransposon, were investigated during Drosophila melanogaster and D. willistoni embryogenesis, by means of embryo hybridization using riboprobes. Spatiotemporal transcription patterns for both TEs were similar to those of developmental genes. Although the two species shared the same P element transcription pattern, this was not so with 412 retrotransposon. These findings suggest that the regulatory sequences involved in the initial development of Drosophila spp are located in the transposable element sequences, and differences, such as in this case of the 412 retrotransposon, lead to losses or changes in their transcription patterns.