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The introduction of the bacterium Wolbachia (wMel strain) into Aedes aegypti mosquitoes reduces their capacity to transmit dengue and other arboviruses. Evidence of a reduction in dengue case incidence following field releases of wMel-infected Ae. aegypti has been reported previously from a cluster randomised controlled trial in Indonesia, and quasi-experimental studies in Indonesia and northern Australia. Following pilot releases in 2015-2016 and a period of intensive community engagement, deployments of adult wMel-infected Ae. aegypti mosquitoes were conducted in Niterói, Brazil during 2017-2019. Deployments were phased across four release zones, with a total area of 83 km2 and a residential population of approximately 373,000. A quasi-experimental design was used to evaluate the effectiveness of wMel deployments in reducing dengue, chikungunya and Zika incidence. An untreated control zone was pre-defined, which was comparable to the intervention area in historical dengue trends. The wMel intervention effect was estimated by controlled interrupted time series analysis of monthly dengue, chikungunya and Zika case notifications to the public health surveillance system before, during and after releases, from release zones and the control zone. Three years after commencement of releases, wMel introgression into local Ae. aegypti populations was heterogeneous throughout Niterói, reaching a high prevalence (>80%) in the earliest release zone, and more moderate levels (prevalence 40-70%) elsewhere. Despite this spatial heterogeneity in entomological outcomes, the wMel intervention was associated with a 69% reduction in dengue incidence (95% confidence interval 54%, 79%), a 56% reduction in chikungunya incidence (95%CI 16%, 77%) and a 37% reduction in Zika incidence (95%CI 1%, 60%), in the aggregate release area compared with the pre-defined control area. This significant intervention effect on dengue was replicated across all four release zones, and in three of four zones for chikungunya, though not in individual release zones for Zika. We demonstrate that wMel Wolbachia can be successfully introgressed into Ae. aegypti populations in a large and complex urban setting, and that a significant public health benefit from reduced incidence of Aedes-borne disease accrues even where the prevalence of wMel in local mosquito populations is moderate and spatially heterogeneous. These findings are consistent with the results of randomised and non-randomised field trials in Indonesia and northern Australia, and are supportive of the Wolbachia biocontrol method as a multivalent intervention against dengue, chikungunya and Zika.

Competition between mosquito species during the larval phase is a well-established mechanism structuring container mosquito communities, with invasive species often outperforming natives. We assessed the competitive outcome between 2 species that occur on the island of Puerto Rico, the historic invasive Aedes aegypti (L.) and the endemic Aedes mediovittatus (Coquillett) (Diptera: Culicidae). Trials were conducted under intra- and interspecific densities crossed with 2 amounts of 4 different leaf types serving as detrital resources for developing larvae; leaf types were representative of either urban or rural locations. Response variables included survival, male and female mass and development time, and a composite index of population growth ([lambda]'). We also measured tannin levels in detrital environments, a secondary metabolite that can negatively influence mosquito development and survival. The co-occurrence of Ae. aegypti and Ae. mediovittatus generally did not affect survival or population growth of Ae. mediovittatus, however the converse was not true. Specifically, Ae. aegypti suffered lower survival and lower population growth in the presence of Ae. mediovittatus compared to when it was alone. Tannin concentrations did not correspond to competitive outcomes, as the highest tannin levels occurred under the detrital conditions where mosquitoes had highest growth and survival, with no evidence of differences between urban or rural leaf types. This is the first study to quantify the competitive outcomes between these species, both of which are part of the dengue transmission cycle on the island, and our findings suggest that Ae. mediovittatus is capable of outcompeting Ae. aegypti under some resource environments.

Competition between mosquito species during the larval phase is a well-established mechanism structuring container mosquito communities, with invasive species often outperforming natives. We assessed the competitive outcome between 2 species that occur on the island of Puerto Rico, the historic invasive Aedes aegypti (L.) and the endemic Aedes mediovittatus (Coquillett) (Diptera: Culicidae). Trials were conducted under intra- and interspecific densities crossed with 2 amounts of 4 different leaf types serving as detrital resources for developing larvae; leaf types were representative of either urban or rural locations. Response variables included survival, male and female mass and development time, and a composite index of population growth ([lambda]'). We also measured tannin levels in detrital environments, a secondary metabolite that can negatively influence mosquito development and survival. The co-occurrence of Ae. aegypti and Ae. mediovittatus generally did not affect survival or population growth of Ae. mediovittatus, however the converse was not true. Specifically, Ae. aegypti suffered lower survival and lower population growth in the presence of Ae. mediovittatus compared to when it was alone. Tannin concentrations did not correspond to competitive outcomes, as the highest tannin levels occurred under the detrital conditions where mosquitoes had highest growth and survival, with no evidence of differences between urban or rural leaf types. This is the first study to quantify the competitive outcomes between these species, both of which are part of the dengue transmission cycle on the island, and our findings suggest that Ae. mediovittatus is capable of outcompeting Ae. aegypti under some resource environments. Key words: detritus, intraspecific, interspecific, resource, Stegomyia

Recent studies on invasive Aedes koreicus (Edwards 1917) have been conducted to elucidate the source population introduced to Europe. However, current information about the native range of Ae. koreicus is not consistent. The purpose of this study is to resolve confusion in the native distribution of Ae. koreicus by reviewing available literature from the first description of the species in its native range in 1917 to the first invasion in Europe in 2008. Aedes koreicus have been recorded in China, Japan, Korea, and eastern Russia. The 2 existing records of Ae. koreicus from Hokkaido, Japan, however, is likely due to the misidentification of 2 different morphologically similar species, Ae. koreicoides (Sasa, Kano & Hayashi 1950) and Aedes japonicus (Theobald 1901). Upon re-examination of published records, we conclude that the native distribution of Ae. koreicus is confined to continental eastern Asian regions, specifically China, Korea, and eastern Russia.

Twenty-seven villages were selected in southwest Burkina Faso to implement new vector control strategies in addition to long lasting insecticidal nets (LLINs) through a Randomized Controlled Trial (RCT). We conducted entomological surveys in the villages during the dry cold season (January 2017), dry hot season (March 2017) and rainy season (June 2017) to describe malaria vectors bionomics, insecticide resistance and transmission prior to this trial. We carried out hourly catches (from 17:00 to 09:00) inside and outside 4 houses in each village using the Human Landing Catch technique. Mosquitoes were identified using morphological taxonomic keys. Specimens belonging to the Anopheles gambiae complex and Anopheles funestus group were identified using molecular techniques as well as detection of Plasmodium falciparum infection and insecticide resistance target-site mutations. Eight Anopheles species were detected in the area. Anopheles funestus s.s was the main vector during the dry cold season. It was replaced by Anopheles coluzzii during the dry hot season whereas An. coluzzii and An. gambiae s.s. were the dominant species during the rainy season. Species composition of the Anopheles population varied significantly among seasons. All insecticide resistance mechanisms (kdr-w, kdr-e and ace-1 target site mutations) investigated were found in each members of the An. gambiae complex but at different frequencies. We observed early and late biting phenotypes in the main malaria vector species. Entomological inoculation rates were 2.61, 2.67 and 11.25 infected bites per human per month during dry cold season, dry hot season and rainy season, respectively. The entomological indicators of malaria transmission were high despite the universal coverage with LLINs. We detected early and late biting phenotypes in the main malaria vector species as well as physiological insecticide resistance mechanisms. These data will be used to evaluate the impact of complementary tools to LLINs in an upcoming RCT.

Important arboviral diseases, such as dengue, chikungunya, and Zika virus infections, are transmitted mainly by the Aedes aegypti vector. So far, controlling this vector species with current tools and strategies has not demonstrated sustainable and significant impacts. Our main objective was to evaluate whether open field release of sterile males, produced from combining the sterile insect technique using radiation with the insect incompatible technique through Wolbachia-induced incompatibility (SIT/IIT), could suppress natural populations of Ae. aegypti in semi-rural village settings in Thailand. Irradiated Wolbachia-infected Aedes aegypti males produced by the SIT/IIT approach were completely sterile and were able to compete with the wild fertile ones. Open field release of these sterile males was conducted in an ecologically isolated village in Chachoengsao Province, eastern Thailand. House-to-house visit and media reports resulted in community acceptance and public awareness of the technology. During intervention, approximately 100-200 sterile males were released weekly in each household. After 6 months of sterile male release, a significant reduction (p<0.05) of the mean egg hatch rate (84%) and the mean number of females per household (97.30%) was achieved in the treatment areas when compared to the control ones. Our study represents the first open field release of sterile Ae. aegypti males developed from a combined SIT/IIT approach. Entomological assessment using ovitraps, adult sticky traps, and portable vacuum aspirators confirmed the success in reducing natural populations of Ae. aegypti females in treated areas. Public awareness through media resulted in positive support for practical use of this strategy in wider areas. Further study using a systematic randomized trial is needed to determine whether this approach could have a significant impact on the diseases transmitted by Ae. aegypti vector.

Female Aedes aegypti (Linnaeus) mosquitoes integrate multiple sensory cues to locate human hosts for blood meals. Although male Ae. aegypti swarm around and land on humans in nature to mate, direct evidence of attraction to humans is limited. Male mosquito attraction to human host cues is often undetectable in confined laboratory assays, leading to a misconception that male mosquitoes are not attracted to humans. We used semifield experiments to demonstrate robust attraction of male Ae. aegypti to humans. Human-baited traps captured up to 25% of released males within 15 min, whereas control traps without humans as bait failed to capture males. Rapid attraction to humans was further demonstrated through videography. Males swarmed around and landed on human subjects, with no activity recorded in paired unbaited controls. Finally, we confirm the lack of discernible male attraction to humans in small laboratory cages. Our experiments demonstrate that both male and female Ae. aegypti show attraction to humans, but with clear sex-specific behavioral differences at short-range. Male mosquito attraction to humans is likely to be important for mating success in wild populations and its basis should be further explored. Our results highlight the importance of arena size and assay design for mosquito behavioral research. A better understanding of host cues that attract males could help us to improve mosquito surveillance and control.