Specific sodium channel gene mutations confer target site resistance to pyrethroid insecticides in mosquitoes and other insects. In Aedes mosquito species, multiple mutations that contribute to resistance vary in their importance around the world. Here, we characterize voltage sensitive sodium channel (Vssc) mutations in populations of Aedesaegypti from Kuala Lumpur, Malaysia, and look at their persistence in populations affected by ongoing Wolbachia releases (a dengue control measure). We also describe a Vssc mutation in Aedesalbopictus (F1534L) found for the first time in Malaysia. We show that there are three predominant Vssc haplotypes in Aedesaegypti in this region, which all persist with regular backcrossing, thereby maintaining the original genetic composition of the populations. We identify changes in genotype frequency in closed populations of Ae. aegypti maintained for multiple generations in laboratory culture, suggesting different fitness costs associated with the genotypes, some of which may be associated with the sex of the mosquito. Following population replacement of Ae. aegypti by Wolbachia in the target area, however, we find that the Vssc mutations have persisted at pre-release levels. Mosquitoes in two genotype classes demonstrate a type I pyrethroid resistance advantage over wildtype mosquitoes when exposed to 0.25% permethrin. This resistance advantage is even more pronounced with a type II pyrethroid, deltamethrin (0.03%). The results point to the importance of these mutations in pyrethroid resistance in mosquito populations and the need for regular backcrossing with male mosquitoes from the field to maintain similarity of genetic background and population integrity during Wolbachia releases.

Dengue is placing huge burdens on the Malaysian healthcare system as well as the economy. With the expansion in the number of high-rise residential buildings, particularly in the urban centers, the flight range and behavior of Aedes mosquitoes may be altered in this habitat type. In this study, we aimed to expand the understanding of the vertical distribution and dispersal of Aedes in nine selected high-rise residences in Kuala Lumpur, Selangor, and Johor using ovitraps as the sampling method. We discovered that Ae. aegypti is the predominant species in all study sites. Both Ae. aegypti and Ae. albopictus are most abundant within the first three levels and could be found up to level 21 (approximately 61.1–63.0 m). Pearson correlation analyses exhibited negative correlations in eight out of nine study sites between the ovitrap indexes (OIs) within each floor level, suggesting that Aedes density decreased as the building level increased. Our findings provide information to the public health authorities on ‘hot spot’ floors for effective suppression of dengue transmission.

Dengue is endemic in Malaysia, and vector control strategies are vital to reduce dengue transmission. The Wolbachia strain wAlbB carried by both sexes of Ae. aegypti was released in Mentari Court, a high-rise residential site, in October 2017 and stopped after 20 weeks. Wolbachia frequencies are still being monitored at multiple traps across this site, providing an opportunity to examine the spatiotemporal distribution of Wolbachia and mosquito density with respect to year, residential block, and floor, using spatial interpolation in ArcGIS, GLMs, and contingency analyses. In just 12 weeks, Wolbachia-infected mosquitoes were established right across the Mentari Court site with an overall infection frequency of >90%. To date, the Wolbachia frequency of Ae. aegypti has remained high in all areas across the site despite releases finishing four years ago. Nevertheless, the Wolbachia invaded more rapidly in some residential blocks than others, and also showed a relatively higher frequency on the eighth floor. The Ae. aegypti index tended to differ somewhat between residential blocks, whilst the Ae. albopictus index was relatively higher at the top and bottom floors of buildings. In Mentari Court, only a short release period was required to infiltrate Wolbachia completely and stably into the natural population. The results inform future releases in comparable sites in a dengue control programme.

Aedes aegypti (Ae. aegypti) is the primary vector for dengue, Zika and chikungunya, which represent major global public health concerns. The use of Wolbachia as a biological control agent in Ae. aegypti has gained significant international attention following the successful establishment of field-released mosquitoes in Australia, Malaysia, Brazil, Indonesia and Singapore. This study presents a comprehensive scientometric analysis of the research landscape of Wolbachia and Ae. aegypti. Data comprising 662 English-language publications from 2000 to 2025 were extracted from the Scopus database. Analytic tools, including VOSviewer and R-based Biblioshiny, were employed to quantify author productivity, transcontinental collaboration networks, thematic evolution, research gaps and future directions, while Bradford’s Law of Scattering was used to identify core dissemination channels. Publications have shown a steady upward trajectory since 2000, with an overall relative growth rate of 0.3%, while annual citations peaked in 2009 and 2011 (3337 and 3460 citations, respectively). The dataset strictly conformed to Bradford’s distribution (0.16% error), identifying PLOS Neglected Tropical Diseases (11.9%) and Parasites and Vectors (5.6%) as the core journals. Global research networks are predominantly led by Australia and the United States, supported primarily by the National Institutes of Health (14.8%) and the National Health and Medical Research Council (14.2%). Crucially, thematic analysis using a methodological triangulation approach demonstrates a progressive maturation in the field, shifting from foundational laboratory mechanisms toward large-scale deployment logistics and microbiome dynamics. Overall, this study highlights the intellectual landscape, underscores the vital role of global collaboration, and provides strategic insights to guide future evidence-based policies in Wolbachia–Aedes aegypti research.

In Aedes aegypti mosquitoes, introduction of certain strains of inherited Wolbachia symbionts results in transmission blocking of various viruses of public health importance, including dengue. This has resulted in a ‘replacement’ strategy for dengue control involving release of male and female mosquitoes, whereupon Wolbachia is able to spread through Ae. aegypti populations to high frequency and reduces the incidence of dengue. Wolbachia strain w AlbB is an effective transmission blocker and stable at high temperatures, making it very suitable for use in hot tropical climates. Following the first trial field releases of the w AlbB strain in Ae. aegypti in Malaysia, releases of w AlbB Ae. aegypti have for the first time become operationalized by the Malaysian health authorities. We report here on changes in dengue incidence based on a set of 20 releases sites and 76 control sites in high rise residential areas, which allows us to directly assess the impact of Wolbachia frequency on dengue incidence. The results indicate an average reduction in dengue of 62.4% (confidence intervals 50-71%); importantly the level of suppression increased with Wolbachia frequency, with suppression of 75.8% (confidence intervals 61-87%) estimated at 100% Wolbachia frequency. These findings emphasize the large impacts of w AlbB Wolbachia invasions on dengue incidence in an operational setting, with the expectation that the level of dengue will further decrease as wider areas are invaded.