Search

BACKGROUND: Aedes albopictus is an important vector for pathogens such as dengue, Zika, and chikungunya viruses. While insecticides is the mainstay for mosquito control, their widespread and excessive use has led to the increased resistance in Ae. albopictus globally. Gut symbiotic bacteria are believed to play a potential role in insect physiology, potentially linking to mosquitoes metabolic resistance against insecticides. METHODS: We investigated the role of symbiotic bacteria in the development of resistance in Ae. albopictus by comparing gut symbiotic bacteria between deltamethrin-sensitive and deltamethrin-resistant populations. Adults were reared from field-collected larvae. Sensitive and resistant mosquitoes were screened using 0.03% and 0.09% deltamethrin, respectively, on the basis of the World Health Organization (WHO) tube bioassay. Sensitive and resistant field-collected larvae were screened using 5 × LC50 (lethal concentration at 50% mortality) and 20 × LC50 concentration of deltamethrin, respectively. Laboratory strain deltamethrin-sensitive adults and larvae were used as controls. The DNA of gut samples from these mosquitoes were extracted using the magnetic bead method. Bacterial 16S rDNA was sequenced using BGISEQ method. We isolated and cultured gut microorganisms from adult and larvae mosquitoes using four different media: Luria Bertani (LB), brain heart infusion (BHI), nutrient agar (NA), and salmonella shigella (SS). RESULTS: Sequencing revealed significantly higher gut microbial diversity in field-resistant larvae compared with field-sensitive and laboratory-sensitive larvae (P

The vast majority of all global species have circadian rhythm cycles that allow them to adapt to natural environments. These regular rhythms are regulated by core clock genes and recent studies have also implicated roles for microRNAs in this regulation. Oviposition is an important circadian behavior in the reproductive cycle of insect vectors of diseases, and little is known about the rhythm or its regulation in mosquitoes. Aedes albopictus is a diurnal mosquito that transmits arboviruses and is the major cause of outbreaks of dengue fever in China. We analyzed the oviposition rhythm patterns of A. albopictus under different light/dark conditions and show that the mosquitoes have an oviposition peak between zeitgeber time 9 (ZT 9) and ZT 12. Furthermore, the antagomir-mediated knockdown of expression of the microRNA miR-2940-1 affected the oviposition rhythm of A. albopictus. These data support the conclusion that miR-2940-1 is involved in the regulation of oviposition rhythm in A. albopictus and provide a foundation for using oviposition rhythms as a new target for vector mosquito control.

The revival of the transmission dynamics of mosquito-borne diseases grants striking challenges to public health intensified by climate change worldwide. This inclusive review article examines multidimensional strategies and challenges linked to climate change and the epidemiology of mosquito-borne diseases such as malaria, dengue, Zika, chikungunya, and yellow fever. It delves into how the biology, pathogenic dynamics, and vector distribution of mosquitoes are influenced by continuously rising temperatures, modified rainfall patterns, and extreme climatic conditions. We also highlighted the high likelihood of malaria in Africa, dengue in Southeast Asia, and blowout of Aedes in North America and Europe. Modern predictive tools and developments in surveillance, including molecular gears, Geographic Information Systems (GIS), and remote sensing have boosted our capacity to predict epidemics. Integrated data management techniques and models based on climatic conditions provide a valuable understanding of public health planning. Based on recent data and expert ideas, the objective of this review is to provide a thoughtful understanding of existing landscape and upcoming directions in the control of mosquito-borne diseases regarding changing climate. This review determines emerging challenges and innovative vector control strategies in the changing climatic conditions to ensure public health. [ABSTRACT FROM AUTHOR]

Background: The biological larvicide Bacillus thuringiensis subsp. israelensis (Bti) represents a safe and effective alternative to chemical insecticides for mosquito control. Efficient control of mosquitoes implicates continuous and extensive application of Bti. This massive use of Bti imposes strong selective pressure, but the complex mode of action of the numerous synergistic Bti endotoxins lower the risk of the emergence of resistance. Although resistance to Bti has not been identified at the population level in nature, some larvae can survive Bti exposure, suggesting tolerance mechanisms. Here we investigated whether Bti-tolerant Aedes albopictus larvae experience any fitness costs. We also studied how this tolerance affects different aspects of the phenotype of the emerging adults that could be relevant for arboviral transmission. Methods: We exposed Ae. albopictus larvae to lethal concentration of Bti and studied the fitness and gut microbiota of tolerant larvae and their adult counterparts. We further compared the transcript abundance of nine key immunity genes in the gut of Bti-tolerant larvae and their emerging adults versus those not exposed to Bti. Results: Our results showed that Bti exposure has multifaceted impacts on Ae. albopictus mosquitoes during both larval and adult stages. The carry-over effect of Bti exposure on tolerant larvae manifested in reduced adult emergence rate, shorter lifespan, and decreased fecundity. Bti also alters the gut microbiota of both larvae and adults. We observed higher microbial diversity in Bti-tolerant larvae and changes in the richness of core microbiota. Bti infection and the altered microbiota triggered immune responses in the larval and adult guts. Conclusions: The observed reduction in mosquito fitness and changes in the composition of the microbiota of adults emerging from tolerant larvae could negatively influence mosquito vectorial capacity. Understanding these impacts is crucial for evaluating the broader implications of Bti-based insecticides in mosquito control programs. [ABSTRACT FROM AUTHOR]

Background: Algeria like other North African countries is experiencing recurrent episodes of West Nile Virus (WNV) emergences and new health threats associated with the introduction of Aedes albopictus in 2010 are to be feared. To improve the surveillance of mosquito-borne pathogens, we performed a study using innovative tools based on multiplex molecular methods. Methods: We combined two approaches: a high-throughput chip based on the BioMark Dynamic array system to detect arboviruses in mosquitoes, and a set of immunologic methods (ELISA, microsphere immunoassays (MIA) and virus microneutralization tests (MNT)) for serological surveys in animal hosts. We investigated two distinct regions: a first zone located in the coastal humid region and a second one in the Saharan desert region. Principal findings: We collected a total of 1,658 mosquitoes belonging to nine different species and found predominantly Culex pipienss. l. (56.5%) and Cx. perexiguus (27.5%). From 180 pools of 10 mosquitoes, we detected four arboviruses: Banna virus (BAV), chikungunya virus (CHIKV), Sindbis virus (SINV), and Usutu virus (USUV). Moreover, we examined 389 blood samples from equids and poultry and found that 52.4% were positive for flavivirus antibodies in ELISA, while 30.8% were positive for WNV and two chickens and two equids were positive for USUV by MNT and MIA respectively. Conclusions: To our knowledge, this is the first report of five arboviruses circulating in Algeria, with three reported for the first time (CHIKV, BAV, and USUV). Our study brings evidence that reinforcing surveillance using more discriminant tools may help in anticipating future emergences and propose adapted control measures. Author summary: Arboviruses are a significant threat to public health because of their epidemic and zoonotic potential. The geographical distribution of mosquito-borne diseases such as West Nile Fever has expanded over the last decades. Countries of the Mediterranean region are not spared. In this context, surveillance of the circulation of such viruses needs to be achieved before the appearing of human or animal cases. The aim of our study was to use innovative and highly efficient tools to highlight the circulation of arboviruses in mosquito vectors, animal reservoirs or exposed animals in Algeria. A total of 1,658 mosquitoes belonging to nine different species were collected and screened for arboviruses usinghighthroughput chips based on the BioMark Dynamic arrays system, capable of screening various arboviruses in a single experiment. Moreover, we analyzed 389 blood samples from equids and poultry using 3 different serologic methods. Our results bring, for the first time in Algeria, evidence of the cryptic circulation of 5 arboviruses: West Nile virus, chikungunya virus, Usutu virus, Sindbis virus and for the first time out of the Asian region, Banna virus. This approach, as an early warning system, is enabling for an early detection of pathogens circulation above-threshold before disease appearance in humans. [ABSTRACT FROM AUTHOR]

Temperature and water availability significantly influence mosquito population dynamics. We have developed a method, integrating experimental data with insights from mosquito and thermal biology, to calculate the basic reproduction number (RM) for urban mosquito species Aedes albopictus and Aedes aegypti. RM represents the number of female mosquitoes produced by one female during her lifespan, indicating suitability for growth. Environmental conditions, including temperature, rainfall and human density, influence RM by altering key mosquito life cycle traits. Validation using data from Spain and Europe confirms the approach's reliability. Our analysis suggests that temperature increases may not uniformly benefit Ae. albopictus proliferation but could boost Ae. aegypti expansion. We suggest using vector RM maps, leveraging climate and environmental data, to predict areas susceptible to invasive mosquito population growth. These maps aid resource allocation for intervention strategies, supporting effective vector surveillance and management efforts. [ABSTRACT FROM AUTHOR]

Natural products are thoroughly studied as valuable alternatives to synthetic insecticides. Heracleum persicum Desf. ex Fisch. (Apiaceae), commonly known as Golpar, is an Iranian medicinal plant largely employed as a spice, which has previously revealed insecticidal potential. The chemical composition of H. persicum essential oil (EO) was investigated by GC-MS and was mainly dominated by hexyl butyrate (36.1%) and octyl acetate (23.7%). The EO and its main esters were tested on three mosquito species. Aedes aegypti (L.) larvae were the most sensitive to all tested products. Lethal concentrations (LC50) of 59.09, 53.59, and 47.05 ppm were recorded for the EO, hexyl butyrate, and octyl acetate, respectively. Aedes albopictus (Skuse) and Anopheles gambiae Giles demonstrated comparable sensitivity to the EO, with LC50 values of 102.97 and 97.91 ppm, respectively, whereas the isolated constituents appeared more active on An. gambiae (LC50 of hexyl butyrate and octyl acetate of 70.97 and 60.71 ppm, respectively) with respect to Ae. albopictus (LC50 of hexyl butyrate and octyl acetate of 85.40 and 91.38 ppm, respectively). Low toxicity was registered for both EO and single components against human embryonic kidney (HEK293) cells. Overall, the H. persicum EO, hexyl butyrate, and octyl acetate could be further considered for larvicide development. [ABSTRACT FROM AUTHOR]

Background: In 2008–2010, Malaysia experienced a nationwide chikungunya virus (CHIKV) outbreak caused by the Indian Ocean lineage E1-226V (valine) variant, adapted to Aedes albopictus. In 2017–2022, transition to an E1-226A (alanine) variant occurred. Ae. albopictus prevails in rural areas, where most cases occurred during the E1-226V outbreak, while Ae. aegypti dominates urban areas. The shift in circulating CHIKV variants from E1-226V to E1-226A (2009–2022) was hypothesized to result in a transition from rural to urban CHIKV distribution, driven by differences in Ae. aegypti vector competence for the two variants. This study aimed to: (1) map the spatiotemporal spread of CHIKV cases in Malaysia between 2009–2022; and (2) compare replication of E1-226A and E1-226V variants in the midguts and head/thoraxes of Ae. aegypti. Methodology/Principal findings: Spatiotemporal analysis of national notified CHIKV case addresses was performed. Between 2009–2022, 12,446 CHIKV cases were reported, with peaks in 2009 and 2020, and a significant shift from predominantly rural cases in 2009–2011 (85.1% rural), to urban areas in 2017–2022 (86.1% urban; p<0.0001). Two Ae. aegypti strains, field-collected MC1 and laboratory Kuala Lumpur (KL) strains, were fed infectious blood containing constructed CHIKV clones, pCMV-p2020A (E1-226A) and pCMV-p2020V (E1-226V) to measure CHIKV replication by real-time PCR and/or virus titration. The pCMV-p2020A clone replicated better in Ae. aegypti cell line Aag2 and showed higher replication, infection and dissemination efficiency in both Ae. aegypti strains, compared to pCMV-p2020V. Conclusions/Significance: This study revealed that a change in circulating CHIKV variants can be associated with changes in vector competence and outbreak epidemiology. Continued genomic surveillance of arboviruses is important. Author summary: Chikungunya virus (CHIKV) causes fever, rash and joint pain in humans. CHIKV is spread by bites of infected Aedes (Ae.) aegypti and Ae. albopictus mosquitoes. In 2008–2010, CHIKV with an E1-226V mutation became highly adapted to Ae. albopictus and caused global outbreaks. In Malaysia, these major outbreaks occurred mainly in rural areas where this mosquito is most common. We found that a resurgence of CHIKV in 2017–2022 was associated with a different variant with an E1-226A mutation, which had a greater ability to replicate in the Ae. aegypti mosquito than the previous E1-226V variant. This mosquito is found mainly in urban areas, and by looking at geographical locations of reported CHIKV cases, we found that the case distribution had also shifted from rural to predominantly urban areas in 2017–2022. Genetic surveillance of CHIKV and other mosquito-borne viruses is important to identify genetic changes that may affect virus ability to infect different vectors, and disease numbers and distribution. [ABSTRACT FROM AUTHOR]

Background: Aedes albopictus (Skuse 1894) mosquitoes can transmit deadly arboviruses and are globally invasive due to their ability to survive in both tropical and temperate climates. Although adults cannot survive harsh winters, females are capable of anticipating seasonal change and producing overwintering diapause (DP) eggs that remain in a state of arrested development over the winter and hatch when favorable conditions return in the spring. While low temperatures can facilitate DP entry under short photoperiods, temperature signals alone are not sufficient to induce DP. Methodology/Principal findings: To identify maternal phenotypes predictive of DP egg production in laboratory conditions, we characterized aspects of maternal physiology and behavior to identify those that correlate with DP egg production and changes in photoperiod, versus changes in temperature. Neither changes in temperature nor photoperiod impacted protein preference, blood meal consumption, or total number of eggs produced per female. Egg retention and oviposition timing were influenced by temperature, independent of DP egg production. However, females housed under short photoperiod conditions showed increased starvation resistance, despite showing similar levels of locomotor activity and internal stores of triacylglycerols, glucose, glycogen, and trehalose compared to females housed in long photoperiods. Conclusions/Significance: These results suggest that temperature and photoperiod differentially affect maternal phenotypes and identify starvation resistance as a maternal phenotype that is influenced by photoperiod and correlates with DP egg status. Author summary: Aedes albopictus mosquitoes can survive in temperate climates because females are able to detect changes in temperature and day length in the autumn to produce "diapause" eggs that are provisioned with extra nutrients to survive harsh winters by remaining in a state of arrest and hatching in the spring. Although temperature and day length normally change in concert with each other throughout the year, studies have shown that day length is the most important cue used by female mosquitoes to initiate diapause egg production. In this study, the authors examined aspects of feeding and reproduction to determine which of these correlated with day length. Many aspects of reproduction were influenced by temperature; however, housing female mosquitoes under autumn-like short-day conditions led to increased starvation resistance. Surprisingly these females survive longer even though they do not appear to expend less energy compared to females housed in spring-like long-day conditions at the same temperature. This suggests that the mosquito mothers undergo changes in their metabolism that correlate with the production of DP eggs that can survive the winter. This new knowledge may lead to novel targets to disrupt seasonal reproduction in mosquitoes and limit the parts of the world where they can survive. [ABSTRACT FROM AUTHOR]

Background: Understanding of mosquito spatiotemporal dynamics is central to characterize candidate field sites for the sterile insect technique (SIT) testing, and is critical to the effective implementation and evaluation of pilot sterile male release programs. Here, we present a detailed description of Aedes albopictus (Skuse) egg-laying activity over a 6-year period in urban areas identified as potential SIT testing sites on Reunion Island. Method: Weekly entomological collections using ovitraps were carried out in residential and adjacent uninhabited habitats in two urban areas, Duparc and Bois Rouge, in the municipality of Sainte Marie, Reunion Island. Time-series data incorporating the frequency of positive ovitraps and the total number of eggs/ovitrap recorded each time at each locality during the study period from May 2013 to December 2018 were analyzed with multifaceted statistical approaches including descriptive statistics and spatiotemporal analyses incorporating the role of climatic factors on overall ovitrap productivity. Results: During the ovitrap survey, the proportion of egg-positive ovitraps differed among study sites (χ2 = 50.21, df = 2, P < 0.001), being relatively lower in Duparc (89.5%) than in Bois-Rouges (95.3%) and the adjacent buffer zone (91.2%). Within each neighborhood, Ae. albopictus egg abundance varied by month in a roughly seasonal pattern marked by a single peak occurring more regularly February each year, a decline at the onset of the austral winter in July, followed by a period of lower ovitrap productivity in August and September. Fluctuation in both positivity rate and eggs densities per ovitraps were related to annual and seasonal variations in local temperature and rainfall (P < 0.001 in all cases). The spatial analysis also captured substantial between- and within-habitats heterogeneity, whereby the overall ovitrap productivity was higher in residential areas than in the buffer zone. Conclusions: Collectively, these results reveal that the distribution of Ae. albopictus oviposition activity is shaped by local habitat heterogeneity and seasonal climatic factors. Overall, this study provides baseline insights into the reproductive dynamics of Ae. albopictus, which would assist in planning locally tailored SIT interventions, while addressing concerns related to focal areas of high egg-laying intensity and potential immigration of females from natural areas. [ABSTRACT FROM AUTHOR]

Background: Mosquitoes in nature may acquire multiple bloodmeals (BMs) over the course of their lifetime; however, incorporation of frequent feeding behavior in laboratory vector competence studies is rarely done. We have previously shown that acquisition of a second non-infectious BM can enhance early dissemination of Zika virus (ZIKV), dengue virus, and chikungunya virus in Aedes aegypti and ZIKV in Aedes albopictus mosquitoes, yet it is unknown if other taxonomically-diverse virus-vector pairings show a similar trend under a sequential feeding regimen. Methods: To test this, we evaluated the impact of a second noninfectious BM on the vector competence of Aedes aegypti and Anopheles quadrimaculatus for Mayaro virus, Culex quinquefasciatus for West Nile virus, Aedes triseriatus for La Crosse virus, and Aedes aegypti for Oropouche virus (OROV). Female mosquitoes were fed BMs containing these viruses and half of them were given a second noninfectious BM at 3 or 4-days post infection. Mosquitoes were harvested at various time points and assayed for virus infection in bodies and disseminated infection in legs by performing reverse transcription-quantitative polymerase chain reaction (RT-qPCR) assays. Results: We found that a second noninfectious BM had no impact on midgut infection rates but increased virus dissemination for all but one of the virus-vector pairings- Ae. aegypti and OROV. Unlike the other arboviruses under consideration, which are strictly mosquito-borne, biting midges (Culicoides spp.) serve as the main vector of OROV and this virus rarely disseminated to the mosquito leg tissue in our study. Conclusions: Taken together, our findings show that sequential blood feeding enhances virus dissemination across diverse arbovirus-vector pairings, representing three mosquito genera and virus families, but a second BM was insufficient to overcome a strong midgut virus escape barrier in a nonnatural virus–vector pairing. [ABSTRACT FROM AUTHOR]

Background: Vector-borne diseases cause morbidity and mortality globally. However, some areas are more impacted than others, especially with climate change. Controlling vectors remains the primary means to prevent these diseases, but new, more effective tools are needed. The World Health Organization (WHO) prioritized evaluating novel control methods, such as sterile insect technique (SIT) for control of Aedes-borne diseases. In response, a multiagency partnership between the U.S. Centers for Disease Control and Prevention (CDC), the Special Programme for Research and Training in Tropical Diseases (TDR), WHO, and the International Atomic Energy Agency (IAEA) supported the operational implementation and evaluation of SIT against Aedes aegypti and arboviral diseases in the Pacific through a consortium of regional partners (PAC-SIT Consortium). Main text: A workshop was held from 2 to 6 May 2023, during which PAC-SIT country participants, researchers, and stakeholders in SIT, scientific advisory committee members, and organizational partners came together to review the principles and components of SIT, share experiences, visit field sites and the SIT facility, and officially launch the PAC-SIT project. Working in groups focused on entomology, epidemiology, and community engagement, participants addressed challenges, priorities, and needs for SIT implementation. Conclusions: The PAC-SIT workshop brought together researchers and stakeholders engaged in evaluating SIT for arboviral diseases in the Pacific region and globally. This training workshop highlighted that many countries are actively engaged in building operational capacities and phased testing of SIT. The workshop identified a key need for robust larger-scale studies tied with epidemiological endpoints to provide evidence for the scalability and impact on mosquito-borne diseases. [ABSTRACT FROM AUTHOR]

Background: Dengue is a serious public health problem worldwide, including Panama. During the last years, the number of dengue cases has increased. This may be due to the presence of mosquito populations resistant to insecticides. The aim of this study was to characterize the resistance status, its enzymatic mechanisms and Kdr mutations in wild populations of Aedes aegypti and Aedes albopictus. Methods: Standard WHO bioassays were performed using insecticide-treated filter papers to determine resistance in populations Ae. aegypti and Ae. albopictus to pyrethroids insecticides, organophosphates, to the carbamate propoxur and to the organochlorine DDT. Biochemical assays were conducted to detect metabolic resistance mechanisms and real-time PCR was performed to determine the frequencies of the Kdr mutations Val1016IIe and F1534C. Results: The strains Ae. aegypti El Coco showed confirmed resistance to deltamethrin (78.5% mortality) and lambda-cyhalothrin (81%), Aguadulce to deltamethrin (79.3%), David to deltamethrin (74.8%) and lambda-cyhalothrin (87.5%) and Puerto Armuelles to permethrin (83%). Aedes aegypti El Empalme showed confirmed resistance to pirimiphos-methyl (62.3% mortality), chlorpyrifos-methyl (55.5%) and propoxur (85.3%). All strains of Ae. albopictus showed possible resistance to PYs and five strains to DDT. Only Ae. albopictus Canto del Llano showed confirmed resistance to pirimiphos-methyl (70% mortality) and malathion (62%). Esterase activity was variable across sites with the most frequent expression of α-EST compared to β-EST in Ae. aegypti populations. In Ae. Albopictus, the expressed enzymes were β-EST and MFOs. Through ANOVA, significant differences were established in the levels of enzymatic activity of α- and β-EST, MFOs and GST, with p < 0.001 in the Ae. aegypti and Ae. albopictus. The Kdr Val1016IIe mutation was detected in Ae. aegypti Aguadulce, El Coco and David. The odds ratio for the Val1016Ile mutation ranged from 0.8 to 20.8 in resistant mosquitoes, indicating the association between pyrethroid phenotypic resistance and the kdr mutation. Conclusion: The presence of a varied and generalized resistance, enzymatic mechanisms and the Val1016IIe mutation may be associated with the intensive use and possibly misuse of the different insecticides applied to control Aedes populations. These results highlight the need to develop a program for resistance management. Also, alternative approaches to mosquito control that do not involve insecticides should be explored. [ABSTRACT FROM AUTHOR]

Background: Dengue fever is one of the most prevalent mosquito-borne diseases in Cambodia. Until now, no specific vaccine nor antiviral treatment exists the virus causing Dengue fever. Consequently, its prevention relies only on vector control strategies. However, efficient vector control in turn relies on a good knowledge of the biology of the vector species. Therefore, this study aims to provide the first review of the distribution, ecology, meteorological impacts, trophic behavior, vector competence, vector control and insecticide resistance of dengue vector species in Cambodia. Methods: A systematic search of the Google Scholar and PubMed databases was conducted for relevant published articles. Of the 610 published articles originally identified, 70 articles were ultimately selected for inclusion in this review. We also included new data from unpublished research conducted in Cambodia between 2017 and 2023 related to dengue vector bionomics. Results: Eleven Aedes (Stegomyia) mosquito species have been recorded in Cambodia, including a new species described in 2024. Four species are associated with dengue virus transmission, among which Aedes aegypti and Ae. albopictus are the main vectors and Ae. malayensis and Ae. scutellaris are considered to be potential vectors. Aedes aegypti and Ae. albopictus are present in all provinces of Cambodia. Aedes albopictus shows a preference for forest, rural and suburban areas, while Ae. aegypti is mostly found in urban and suburban areas. The distribution of these two species is also influenced by meteorological factors, seasonality and the availability of breeding habitats and blood meals. Both species are predominant during the rainy season, and their respective density is impacted by precipitation and temperature. Aedes aegypti is characterized as anthropophilic, while Ae. albopictus exhibits zooanthropophilic behavior, and both species have been observed to be predominantly diurnal. In addition, they were found to be highly resistant to the insecticides used in Cambodia for their control, such as temephos for larvae and deltamethrin and permethrin for adult mosquitoes. Conclusions: This review provides extensive and important knowledge on dengue vectors in Cambodia. This knowledge is derived not only from published research articles but also from many recent studies in Cambodia on the bionomics of dengue vector species. The review provides valuable information for use by public health authorities on dengue virus transmission and to develop better vector control strategies in the country. [ABSTRACT FROM AUTHOR]

Simple Summary: The role of mosquito eggs in disease transmission is not well understood, despite reports of virus vertical transmission and their ability to survive dry periods in a dormant stage. Additionally, field evidence shows that new generations of mosquitoes often reappear weeks or months later in certain city areas. This may be because both species follow an "R strategy" reproduction pattern, laying many eggs to ensure survival in a harsh environment. This study was conducted in southern Mexico in 2023 and focused on the egg-laying activity of Ae. aegypti and Ae. albopictus mosquitoes during the dry inter-epidemic season. Ovitraps were used in the backyards of the houses to identify egg species, and further larval containers were surveyed. Most of the larval habitats were containers smaller than 1 L, commonly not treated as they were considered trash. Even though homeowners volunteer to remove them during government cleaning community-based campaigns, city waste disposal trucks transporting these containers do not take any measures to destroy the tiny eggs. We conclude with the urgent need to develop an egg-killing treatment, which could significantly enhance vector reduction and achieve a total stage strategy within the Integrated Vector Control Programs. Although integrated management and control programs implement intense control measures for adult, pupal, larval, and breeding sites during outbreaks, there is a lack of studies to understand the role of the vector egg stage in disease dynamics. This study aimed to assess the dry season quiescent Aedes aegypti and Aedes albopictus egg populations in houses and backyards in Tapachula, southern Mexico. Two hundred and fifty ovitraps were placed in 125 homes in the Las Americas neighborhood. A total of 7290 eggs were collected from 211 (84.4%) ovitraps. Only 5667 (77.7%) hatched under insectary water immersion and food supply conditions, with 4031 (71.1%) identified as Ae. aegypti, and 1636 (28.8%) as Ae. albopictus, respectively. The remaining 1623 (22.3%) did not hatch due to Delayed Hatching and/or quiescence tropical stage. Eighty-three larval containers were sampled with desiccated eggs during the dry season; most of them were described as trash waste because larvicides are only used for larger containers of 5–10 L. Evolutionary characteristics for the two species including partial egg hatching, ambient-regulated quiescence, the ability of the embryo to survive for a more extended period intra-seasonally, the egg sticking to inner container walls, demands urgent operational research to achieve successful egg-proof larval container methods. [ABSTRACT FROM AUTHOR]

Simple Summary: Household surveys of communities for potential oviposition containers by mosquito control teams offer effective mechanisms for reducing arbovirus transmission. Here, we combined standard community surveys with GIS mapping to identify premises with Aedes-positive containers and classify container types near the end of the dry season in Trinidad, West Indies. The entomological indices based on key containers (tanks, drums, tubs/basins/buckets) showed that two of the four locations surveyed were already at a high risk for arbovirus transmission going into the wet season. GIS mapping provided inspection teams with specific locations that had Aedes-positive containers and highlighted premises that were not accessible. This information can facilitate the identification of areas within communities that may be at greater risk and should be prioritized for future surveys and control efforts; it also highlights the need to inform and increase community participation. Dengue and other arboviruses remain a global threat, and enhanced efforts to control the mosquitoes that transmit them are urgently needed. A survey of potential manmade Aedes aegypti (L.) and Aedes albopictus (Skuse) oviposition containers was performed in four communities near the end of the typical dry season in 2018 in Trinidad, West Indies. The purpose was to conduct individual premise surveys and use GIS mapping to visualize premises within communities that had Aedes-positive containers, as this information could be used for the prioritization of mosquito control efforts in potential high risk areas as the wet season progressed. Accessible premises were surveyed following standard inspection protocols used by the Insect Vector Control Division (IVCD), Ministry of Health (MOH). The results indicated that two of the four locations would be at high risk for arbovirus transmission going into the wet season. The GIS mapping of premises with Aedes-positive containers facilitated the identification of potential hot spots for arbovirus transmission risk within communities that should be prioritized for enhanced monitoring and vector control efforts, emphasizing the need to increase community participation in standard surveys by IVCD. [ABSTRACT FROM AUTHOR]

Usutu virus (USUV) is an emerging mosquito-transmitted flavivirus with increasing incidence of human infection and geographic expansion, thus posing a potential threat to public health. In this study, we established a comprehensive spatiotemporal database encompassing USUV infections in vectors, animals, and humans worldwide by an extensive literature search. Based on this database, we characterized the geographic distribution and epidemiological features of USUV infections. By employing boosted regression tree (BRT) models, we projected the distributions of three main vectors (Culex pipiens, Aedes albopictus, and Culiseta longiareolata) and three main hosts (Turdus merula, Passer domesticus, and Ardea cinerea) to obtain the mosquito index and bird index. These indices were further incorporated as predictors into the USUV infection models. Through an ensemble learning model, we achieved a decent model performance, with an area under the curve (AUC) of 0.992. The mosquito index contributed significantly, with relative contributions estimated at 25.51%. Our estimations revealed a potential exposure area for USUV spanning 1.80 million km2 globally with approximately 1.04 billion people at risk. This can guide future surveillance efforts for USUV infections, especially for countries located within high-risk areas and those that have not yet conducted surveillance activities. [ABSTRACT FROM AUTHOR]

Background: The invasive mosquito Aedes albopictus is a major concern for human and animal health given its high potential to spread over large geographical distances, adapt to various habitats and food sources, and act as a vector for pathogens. It is crucial to understand how this species establishes ecological relationships at different locations, as it determines its role in transmission of diseases. Methods: Based on published blood meal surveys, a meta-analysis was performed to investigate how host diversity changes along the process of invasion at a large scale. For 48 independent localities, the Shannon diversity index was calculated and was then assessed against several moderator variables describing invasion status, habitat type, methodology, survey year and the year of introduction for invasive populations. Results: Diet diversity was higher in the invasive than in the native populations when the strong habitat effects were held constant. Furthermore, the year of introduction also had a significant role, as invasive populations that had been established earlier had wider diet diversity than more recent populations. Conclusions: Invasive Ae. albopictus has considerable ecological flexibility. The species' ability to adapt to various food sources goes hand in hand with its successful worldwide dispersion, which has strong implications for its role in pathogen transmission. [ABSTRACT FROM AUTHOR]

Aedes aegypti and Aedes albopictus mosquitoes spread major vector-borne viral diseases in tropical and sub-tropical regions of the globe. In this study, we sequenced the genome of Indian Ae. aegypti and Ae. albopictus and mapped to their reference genomes. Comparative genomics were performed between our strain and the reference strains. A total of 14,416,484 single nucleotide polymorphisms (SNPs) and 156,487 insertions and deletions (InDels) were found in Ae. aegypti, and 28,940,433 SNPs and 188,987 InDels in Ae. albopictus. Particular emphasis was given to gene families involved in mosquito digestion, development, and innate immunity, which could be putative candidates for vector control. Serine protease cascades and their inhibitors called serpins, play a central role in these processes. We extracted high-impact variants in genes associated with serine proteases and serpins. This study reports for the first time a high coverage genome sequence data of an Indian Ae. albopictus mosquito. The results from this study will provide insights into Indian Aedes specific polymorphisms and the evolution of immune related genes in mosquitoes, which can serve as a resource for future comparative genomics and those pursuing the development of targeted biopesticides for effective mosquito control strategies. [ABSTRACT FROM AUTHOR]

Background: Disease-vector mosquito monitoring is an essential prerequisite to optimize control interventions and evidence-based risk predictions. However, conventional entomological monitoring methods are labor- and time-consuming and do not allow high temporal/spatial resolution. In 2022, a novel system coupling an optical sensor with machine learning technologies (VECTRACK) proved effective in counting and identifying Aedes albopictus and Culex pipiens adult females and males. Here, we carried out the first extensive field evaluation of the VECTRACK system to assess: (i) whether the catching capacity of a commercial BG-Mosquitaire trap (BGM) for adult mosquito equipped with VECTRACK (BGM + VECT) was affected by the sensor; (ii) the accuracy of the VECTRACK algorithm in correctly classifying the target mosquito species genus and sex; (iii) Ae. albopictus capture rate of BGM with or without VECTRACK. Methods: The same experimental design was implemented in four areas in northern (Bergamo and Padua districts), central (Rome) and southern (Procida Island, Naples) Italy. In each area, three types of traps—one BGM, one BGM + VECT and the combination of four sticky traps (STs)—were rotated each 48 h in three different sites. Each sampling scheme was replicated three times/area. Collected mosquitoes were counted and identified by both the VECTRACK algorithm and operator-mediated morphological examination. The performance of the VECTRACK system was assessed by generalized linear mixed and linear regression models. Aedes albopictus capture rates of BGMs were calculated based on the known capture rate of ST. Results: A total of 3829 mosquitoes (90.2% Ae. albopictus) were captured in 18 collection-days/trap/site. BGM and BGM + VECT showed a similar performance in collecting target mosquitoes. Results show high correlation between visual and automatic identification methods (Spearman Ae. albopictus: females = 0.97; males = 0.89; P < 0.0001) and low count errors. Moreover, the results allowed quantifying the heterogeneous effectiveness associated with different trap types in collecting Ae. albopictus and predicting estimates of its absolute density. Conclusions: Obtained results strongly support the VECTRACK system as a powerful tool for mosquito monitoring and research, and its applicability over a range of ecological conditions, accounting for its high potential for continuous monitoring with minimal human effort. [ABSTRACT FROM AUTHOR]

Background: Dengue, a mosquito-borne viral disease, has occurred in many cities in China, and it tends to spread to higher latitudes (Huang et al., 2023). Xi'an, situated in central-west China, has witnessed an increase imported cases in the past few years, raising concerns of local dengue transmission. It is crucial to investigate the population density of Aedes albopictus and its insecticides resistance to enhance early warning of dengue fever. Methods: Eight sampling sites in eight counties (YT, BL, WY, CH, YL, LN, LT, ZZ) of Xi'an city were surveyed by larval dipping and human-baited double net trap biweekly from June 2021 to September 2022. The Breteau Index (BI, number of positive containers per 100 houses) and Container Index (CI, the percentage of containers containing larvae or pupae) were used to assess larval density, and the human-baited double net trap (HDN, the number of Ae. albopictus females collected per person per hour) to indicate human bating rate (HBR). Meanwhile, the association between the meteorological factors and mosquito density was analyzed. The Ae. albopictus adult insecticides resistance was evaluated by the World Health Organization (WHO) standard resistance bioassay. Adult females were exposed to insecticide-impregnated paper for 1 h, then transferred to the recovery tube, and mortality rate was calculated after 24 h. According to the Implementation Plan for National Vector Surveillance (2016), resistance status was classified into three levels based on mortality: <80% mortality as resistant, between 80% and 98% mortality as possibly resistant, and >98% mortality as sensitive. Results: From June 2021 to September 2022, a total of 1,065 houses were surveyed for water holding containers, and 99 of 430 water holding containers were checked to be positive for Ae. albopictus larvae and pupae. A total of 1,048 Ae. albopictus females were collected. The average BI, CI and HBR were 10.39, 21.41, and 11.20 female/man/hour in 2021 and 8.86, 20.86, and 11.63 f/m/h in 2022, respectively. The findings showed that the BI exceeded 5 in most months and reached above 20 in specific months. The CI varied in different months and monitoring sites, with the highest CI in August 2021 and July 2022. The discarded tires had the highest positivity rate, with up to 40.32% testing positive for Ae. albopictus larvae. The monthly average temperature showed a positive correlation with CI (r = 0.77), and the monthly BI was positively associated with CI (r = 0.93). The BI, CI, and HBR were significantly higher in the rainy season than other seasons. The bioassay results showed that the mortality rate of Ae. albopictus at the YT monitoring site was 76.92%, indicating resistance to deltamethrin. The mortality rate of Ae. Albopictus at BL, WY, CH, YL, LN, LT, and ZZ sampling sites were varying from 81.25%∼100%, suggesting possibly resistant or still sensitive to beta-cypermethrin, alpha-cypermethrin, malathion, chlorpyrifos, and propoxur. [ABSTRACT FROM AUTHOR]

Mosquito‐borne viruses continue to affect billions of people globally, posing a severe health risk and an economic burden. Aedes albopictus (Skuse), a highly invasive mosquito species, has repeatedly invaded and increased its presence, serving as a key vector of dengue virus, yellow fever virus (YFV), Zika virus (ZIKV), and Chikungunya virus (CHIKV), causing frequent outbreaks of related viral diseases. This study investigated the impact of larval diet quantity on larval duration and adult body size. The effect of adult mosquito body size on various aspects of Ae. albopictus was also examined, including blood‐feeding behavior, follicular development, reproductive capacity, egg retention capacity, preoviposition period, and fecundity. These diverse characteristics all have an effect on arboviruses transmission. The changes in body size (small, medium, and large) are obtained by providing different quantities of larval diet (low, average, and high). The results indicate that the quantity of larval diet directly impacts the adult body size while inversely affecting the larval duration. Furthermore, a positive correlation exists between adult body size and wing length, implying that wing length could be a reliable indicator of adult body size and rearing conditions during the developmental stages. Large females exhibited higher numbers of follicles and greater fecundity. Moreover, a significant correlation was observed between follicle number before the first blood meal and total egg number. In contrast, increasing wing length decreased the number of blood meals, egg retention, and the preoviposition period. The tendency of small females to perform multiple feedings was greater than that of large females. Small females exhibited a higher propensity for multiple feeding activities when compared to their larger counterparts. Most medium‐sized females (92.8%) deposited eggs in their ovaries, however, 7.2% retained a few. In contrast, most large females (87.4%) had complete ovary egg‐laying, whereas a minority (12.6%) retained some of their eggs. About 35.2% of small females showed ovarian egg retention, while 64.8% successfully laid all their eggs. After the first blood meal, the oviposition rate was 92% for large females, 88% for medium females, and 76% for small females. About 69.86% of the follicles in large females underwent vitellogenesis. This finding suggests that small females with low energy reserves exhibited incomplete oviposition and multiple blood feedings to increase their reproductive capacity. Research Highlights: Add more information about arbovirus epidemics and their consequences.Aedes albopictus is a global invasive species that transmit dengue virus, CHIKV, YFV, and ZIKV.A negative correlation was observed between body size, egg retention, and multiple blood feedings in Aedes albopictus.Size of the female's body was positively correlated with fecundity, while it was negatively correlated with the preoviposition period.Size‐dependent multiple blood feeding affects vector‐host contact frequency. [ABSTRACT FROM AUTHOR]

West Nile virus (WNV) is a mosquito-borne pathogen with a worldwide distribution. Climate change and human activities have driven the expansion of WNV into new territories in Europe during the last two decades. Romania is endemic for WNV circulation since at least 1996 when the presence of lineage 1 was documented during an unprecedented outbreak. Lineage 2 was first identified in this country during a second significant human outbreak in 2010. Its continuous circulation is marked by clade replacement, and even co-circulation of different strains of the same clade was observed until 2016. The present study aims to fill the information gap regarding the WNV strains that were circulating in Romania between 2017 and 2023, providing chiefly viral sequences obtained from mosquito samples collected in the Bucharest metropolitan area, complemented by human and bird viral sequences. WNV was detected mainly in Culex pipiens mosquitoes, the vectors of this virus in the region, but also in the invasive Aedes albopictus mosquito species. Lineage 2 WNV was identified in mosquito samples collected between 2017 and 2023, as well as in human sera from patients in southern and central Romania during the outbreaks of 2017 and 2018. Both 2a and 2b sub-lineages were identified, with evidence of multiple clusters and sub-clusters within sub-lineage 2a, highlighting the complex and dynamic circulation of WNV in Romania, as a consequence of distinct introduction events from neighboring countries followed by in situ evolution. [ABSTRACT FROM AUTHOR]

BACKGROUND: Releasing large numbers of Aedes albopictus males, carrying the artificially introduced Wolbachia 'wPip' strain, results in a decrease in the reproductive capacity of wild females due to a phenomenon known as cytoplasmic incompatibility (CI). This vector control strategy is referred to as the incompatible insect technique (IIT). However, its widespread implementation faces various challenges, including the complexity of removing fertile females from the males intended for release. Here, we present the results of semi‐field experiments comparing the impact of minimal female co‐release on two IIT modes: unidirectional CI‐based (UnCI IIT) and bidirectional CI‐based (BiCI IIT), specifically targeting Ae. albopictus. RESULTS: The contamination of 'wPip' infected females (2%) during male releases significantly weakened the overall effectiveness of IIT, emphasizing the need for thorough sex separation. Specifically, with UnCI IIT, despite the low rate of co‐released females, there was a gradual rise in 'wPip' infection frequency, resulting in more compatible mating and subsequently higher rates of egg hatching. Conversely, this pattern was effectively mitigated in BiCI IIT owing to the reciprocal sterility between the wild‐type and the 'wPip' infected populations. CONCLUSION: Through an experimental approach, conducted in a semi‐field setting, we have contributed to advancing scientific understanding regarding the potential outcomes of implementing the IIT strategy in the absence of a complete sexing system. The results suggest that safety measures for mitigating the potential impacts of co‐released females can be tailored according to the specific type of IIT being utilized. © 2024 Society of Chemical Industry. [ABSTRACT FROM AUTHOR]

BACKGROUND: Vector mosquito control is important for preventing and controlling mosquito‐borne infectious diseases. This study designed and developed a mosquito killer (MK) with a specific light wavelength, simulated human body temperature, human odor, and a photocatalyst to stimulate CO2 based on the physiological characteristics and ecological habits of mosquitoes. We tested the trapping effect of individual and multiple mosquito‐trapping elements of the MK through two‐way selection experiments and compared them with several commercial mosquito traps. RESULTS: The 365 nm wavelength MK was significantly more effective than the 395 nm (Cx. quinquefasciatus: 62.00% vs. 34.25%; Ae. albopictus: 50.75% vs 45.00%, An. sinensis: 49.75% vs 39.00%). Mosquitoes captured by the MK with heaters at 365 nm were significantly more than those captured by the MK without heaters at 365 nm. A trap with a 365 nm wavelength, heating element, and lure showed significantly better capture effectiveness than MK with a 365 nm wavelength, heating element, but without lure (Cx. quinquefasciatus: 67.00% vs. 29.75%, Ae. albopictus: 60.25% vs 36.25%, An. sinensis: 49.75% vs 39.75%). The coated photocatalyst trap with a 365 nm wavelength, heating element, and lure showed significantly better capture effectiveness than the trap without coating (Cx. quinquefasciatus: 54.25% vs. 42.50%; Ae. albopictus: 53.50% vs 44.00%, An. sinensis: 50.00% vs 41.25%). This trap demonstrated a significantly better capture advantage for Cx. quinquefasciatus and Ae. albopictus compared to the three commercial products. CONCLUSION: The developed mosquito trap with multiple attractant factors significantly enhanced the capture effectiveness of common mosquitoes. © 2024 Society of Chemical Industry. [ABSTRACT FROM AUTHOR]

Background: Insecticide resistance poses a significant challenge in the implementation of vector-borne disease control strategies. We have assessed the resistance levels of Aedes albopictus to deltamethrin and pyriproxyfen (PPF) in Fujian Province (China) and investigated the correlation between these resistance levels and mutations in the voltage-gated sodium channel (VGSC). Methods: The WHO bioassay protocol was used to evaluate the resistance coefficient of Ae. albopictus to deltamethrin and PPF, comparing a susceptible population from the Foshan (FS) area with wild populations from the Sanming (SM), Quanzhou (QZ), Zhangzhou (ZZ), Putian (PT) and Fuzhou (FZ) areas in Fujian Province. Genomic DNA was analyzed by PCR and sequencing to detect knockdown resistance (kdr) in the VGSC, specifically at the pyrethroid resistance alleles V1016V, I1532I and F1534F. Molecular docking was also performed to analyze the binding interactions of PPF and its metabolite 4'-OH-PPF to cytochrome P450 (CYP) 2C19, 2C9 and 3A4 and Ae. albopictus methoprene-tolerant receptors (AeMet), respectively. Results: The analysis of resistance to deltamethrin and PPF among Ae. albopictus populations from the various regions revealed that except for the sensitive population in FS and the SM population, the remaining four regional populations demonstrated resistance levels ranging from 4.31- to 18.87-fold for deltamethrin and from 2.85– to 3.62-fold for PPF. Specifically, the FZ and PT populations exhibited high resistance to deltamethrin, whereas the ZZ and QZ populations approached moderate resistance levels. Also, the resistance of the FZ, PT and ZZ populations to PPF increased slowly but consistently with the increasing trend of deltamethrin resistance. Genomic analysis identified multiple non-synonymous mutations within the VGSC gene; the F1534S and F1534L mutations showed significant resistance to deltamethrin in Ae. albopictus. Molecular docking results revealed that PPF and its metabolite 4'-OH-PPF bind to the Ae. albopictus AeMet receptor and CYP2C19. Conclusions: The wild Ae. albopictus populations of Fujian Province showed varying degrees of resistance to deltamethrin and PPF and a trend of cross-resistance to deltamethrin and PPF. Increased vigilance is needed for potential higher levels of cross-resistance, especially in the PT and FZ regions. [ABSTRACT FROM AUTHOR]

Climatic, ecological, and socioeconomic factors are facilitating the spread of mosquito-borne diseases, heightening the importance of vector surveillance and control. Citizen science is proving to be an effective tool to track mosquito populations, but methods are needed to detect and account for small scale sampling biases in citizen science surveillance. In this article we combine two types of traditional mosquito surveillance records with data from the Mosquito Alert citizen science system to explore the ways in which the socioeconomic characteristics of urban neighborhoods result in sampling biases in citizen scientists' mosquito reports, while also shaping the spatial distribution of mosquito populations themselves. We use Barcelona, Spain, as an example, and focus on Aedes albopictus, an invasive vector species of concern worldwide. Our results suggest citizen scientists' sampling effort is focused more in Barcelona's lower and middle income census tracts than in its higher income ones, whereas Ae. albopictus populations are concentrated in the city's upper-middle income tracts. High resolution estimates of the spatial distribution of Ae. albopictus risk can be improved by controlling for citizen scientists' sampling effort, making it possible to provide better insights for efficiently targeting control efforts. Our methodology can be replicated in other cities faced with vector mosquitoes to improve public health responses to mosquito-borne diseases, which impose massive burdens on communities worldwide. [ABSTRACT FROM AUTHOR]

Dengue virus (DENV) is the most prevalent mosquito-borne Flavivirus that affects humans worldwide. Aedes albopictus, which is naturally infected with the bacteria Wolbachia, is considered to be a secondary vector of DENV. However, it was responsible for a recent DENV outbreak of unprecedented magnitude in Reunion Island, a French island in the South West Indian Ocean. Moreover, the distribution of the cases during this epidemic showed a spatially heterogeneous pattern across the island, leading to questions about the differential vector competence of mosquito populations from different geographic areas. The aim of this study was to gain a better understanding of the vector competence of the Ae. albopictus populations from Reunion Island for local DENV epidemic strains, while considering their infection by Wolbachia. Experimental infections were conducted using ten populations of Ae. albopictus sampled across Reunion Island and exposed to three DENV strains: one strain of DENV serotype 1 (DENV-1) and two strains of DENV serotype 2 (DENV-2). We analyzed three vector competence parameters including infection rate, dissemination efficiency and transmission efficiency, at different days post-exposition (dpe). We also assessed whether there was a correlation between the density of Wolbachia and viral load/vector competence parameters. Our results show that the Ae. albopictus populations tested were not able to transmit the two DENV-2 strains, while transmission efficiencies up to 40.79% were observed for the DENV-1 strain, probably due to difference in viral titres. Statistical analyses showed that the parameters mosquito population, generation, dpe and area of sampling significantly affect the transmission efficiencies of DENV-1. Although the density of Wolbachia varied according to mosquito population, no significant correlation was found between Wolbachia density and either viral load or vector competence parameters for DENV-1. Our results highlight the importance of using natural mosquito populations for a better understanding of transmission patterns of dengue. [ABSTRACT FROM AUTHOR]

Background: Aedes albopictus, commonly known as the Asian tiger mosquito, has become one of the most invasive mosquito species. Over the last 5 decades, it has been introduced and established in various tropical and temperate regions worldwide. First reported in Europe in 1979 in Albania and later in Italy in 1990, the species is now established in 13 European Union (EU)/European Economic Area (EEA) countries and 337 regions (2023). In Portugal, Ae. albopictus was first detected in the Algarve and Penafiel regions in 2017, followed by Alentejo in 2022 and Lisbon in 2023. This mosquito species poses a significant public health risk as a vector for numerous pathogenic viruses, including dengue, Zika, and chikungunya. Methods: Aedes albopictus collected in Lisbon in 2023 were analyzed using cytochrome c oxidase I (COX) gene sequencing to understand their genetic relationships. Results: Our data indicate that the Ae. albopictus mosquito populations detected in three locations in Lisbon in 2023 correspond to recent but distinct introduction events. Conclusions: Although there has been no local transmission of Aedes-transmitted viruses in mainland Portugal to date, the spread of the mosquito and increased international travel increase the risk of Aedes-borne disease outbreaks. The ongoing spread of Ae. albopictus in the country and the confirmed multiple introductions in new locations raise awareness of the need to monitor mosquito vectors to control and prevent autochthonous Aedes-borne disease outbreaks. [ABSTRACT FROM AUTHOR]

Vector-borne diseases leave a large footprint on global health. Notable culprits include West Nile virus (WNV), St. Louis encephalitis virus (SLEV), and Japanese encephalitis virus (JEV), all transmitted by Culex mosquitoes. Chemical insecticides have been widely used to reduce the spread of mosquito-borne diseases. Still, mosquitoes are becoming more and more resistant to most chemical insecticides which cause particular harm to the ecology. Wolbachia belongs to the family Ehrlichiaceae in the order Rickettsiales and is a matrilineally inherited endosymbiont present in 60% of insects in nature. Wolbachia is capable of inducing a wide range of reproductive abnormalities in its hosts, such as cytoplasmic incompatibility, and can alter mosquito resistance to pathogen infection. Wolbachia has been proposed as a biological alternative to chemical vector control, and specific research progress and effectiveness have been achieved. Despite the importance of Wolbachia, this strategy has not been tested in Culex pipiens pallens, the most prevalent mosquito species in Shandong Province, China. Little is known about how the mass release of Wolbachia-infected mosquitoes may impact the genetic structure of Culex pipiens pallens, and how the symbiotic bacterium Wolbachia interacts with mitochondria during host mosquito transmission. Based on the population genetic structure of Culex pipiens pallens in Shandong Province, this study investigated the infection rate and infection type of Wolbachia in Shandong Province and jointly analysed the evolutionary relationship between the host mosquito and the symbiotic bacterium Wolbachia. Our study showed that Wolbachia naturally infected by Culex pipiens pallens in Shandong Province was less homologous to Wolbachia infected by Aedes albopictus released from mosquito factory in Guangzhou. Our results also show that Culex pipiens pallens is undergoing demographic expansion in Shandong Province. The overall Wolbachia infection rate of Culex pipiens pallens was 92.8%, and a total of 15 WSP haplotypes were detected. We found that the genetic diversity of Wolbachia was low in Culex pipiens pallens from Shandong Province, and the mosquitoes were infected only with type B Wolbachia. Visualizing the relationship between Culex pipiens pallens and Wolbachia using a tanglegram revealed patterns of widespread associations. A specific coevolutionary relationship exists between the host mosquito and Wolbachia. Knowledge of this mosquito–Wolbachia relationship will provide essential scientific information required for Wolbachia-based vector control approaches in Shandong Province and will lead to a better understanding of the diversity and evolution of Wolbachia for its utility as a biocontrol agent. Author summary: This study was the first to investigate the population genetic structure and Wolbachia infection of Culex pipiens pallens in Shandong Province, providing a basis for mosquito-borne control and disease prevention. The joint analysis of Wolbachia and mitochondrial markers highlighted the coevolutionary relationship between Wolbachia and its host. It also provided the scientific basis for green precision prevention and control of mosquito-borne bacteria and viruses. [ABSTRACT FROM AUTHOR]

Background: Anopheles stephensi is an invasive malaria vector in Africa that threatens to put an additional 126 million people at risk of malaria if it continues to spread. The island nation of Mauritius is highly connected to Asia and Africa and is at risk of introduction due to this connectivity. For early detection of An. stephensi, the Vector Biology and Control Division under the Ministry of Health in Mauritius, leveraged a well-established Aedes program, as An. stephensi is known to share Aedes habitats. These efforts triggered multisectoral coordination and cascading benefits of integrated vector and One Health approaches. Methods: Beginning June 2021, entomological surveys were conducted at points of entry (seaport, airport) and on ships transporting livestock in collaboration with the Civil Aviation Department, the Mauritian Port Authority and National Veterinary Services. A total of 18, 39, 723 mosquito larval surveys were respectively conducted in the airport, seaport, and other localities in Mauritius while two, 20, and 26 adult mosquito surveys were respectively conducted in the airport, seaport, and twenty-six animal assembly points. Alongside adult mosquito surveys, surveillance of vectors of veterinary importance (e.g.- Culicoides spp.) was also carried out in collaboration with National Parks and Conservation Service and land owners. Results: A total of 8,428 adult mosquitoes were collected and 1,844 larval habitats were positive for mosquitoes. All collected mosquitoes were morphologically identified and 151 Anopheles and 339 Aedes mosquitoes were also molecularly characterized. Mosquito species detected were Aedes albopictus, Anopheles arabiensis, An. coustani, An. merus, Culex quinquefasciatus, Cx. thalassius and Lutzia tigripes. Anopheles stephensi was not detected. The One Health approach was shared with the French Agricultural Research Centre for International Development (CIRAD), strengthening collaboration between Mauritius and Réunion Island on vector surveillance at entry points and insecticide resistance monitoring. The Indian Ocean Commission (IOC) was also alerted to the risk of An. stephensi, leading to regional efforts supporting trainings and development of a response strategy to An. stephensi bringing together stakeholders from Comoros, Madagascar, Mauritius, Réunion Island and Seychelles. Conclusions: Mauritius is a model system showing how existing public health entomology capabilities can be used to enhance vector surveillance and control and create multisectoral networks to respond to any emerging public and veterinary health vector-borne disease threat. Author summary: The malaria mosquito, Anopheles stephensi, is an invasive species in Africa where it threatens to put an additional 126 million people at risk of malaria if it continues to spread throughout the continent. The island nation of Mauritius is highly connected to Asia and Africa through maritime trade and therefore may be at risk of An. stephensi introduction and establishment. Mauritius implemented a One Health approach, enhancing entomological surveillance at entry points and collaborating across sectors (e.g. veterinary services, sea and airport authorities, national parks and conservation, communities, etc.) conducted extensive integrated vector surveillance, inspecting 85,071 larval habitats, and analyzing 8,428 adult mosquitoes morphologically and molecularly. Although An. stephensi was not detected, the initiative catalyzed and strengthened multisectoral partnerships nationally and across the Indian Ocean region member states (Comoros, Madagascar, Mauritius, Réunion Island and Seychelles). Leveraging the threat of An. stephensi, Mauritius exemplifies utilizing existing capabilities to create multisectoral networks for effective vector surveillance and response. [ABSTRACT FROM AUTHOR]

The incidence of vector-borne disease is on the rise globally, with burdens increasing in endemic countries and outbreaks occurring in new locations. Effective mitigation and intervention strategies require models that accurately predict both spatial and temporal changes in disease dynamics, but this remains challenging due to the complex and interactive relationships between environmental variation and the vector traits that govern the transmission of vector-borne diseases. Predictions of disease risk in the literature typically assume that vector traits vary instantaneously and independently of population density, and therefore do not capture the delayed response of these same traits to past biotic and abiotic environments. We argue here that to produce accurate predictions of disease risk it is necessary to account for environmentally driven and delayed instances of phenotypic plasticity. To show this, we develop a stage and phenotypically structured model for the invasive mosquito vector, Aedes albopictus, and dengue, the second most prevalent human vector-borne disease worldwide. We find that environmental variation drives a dynamic phenotypic structure in the mosquito population, which accurately predicts global patterns of mosquito trait-abundance dynamics. In turn, this interacts with disease transmission to capture historic dengue outbreaks. By comparing the model to a suite of simpler models, we reveal that it is the delayed phenotypic structure that is critical for accurate prediction. Consequently, the incorporation of vector trait relationships into transmission models is critical to improvement of early warning systems that inform mitigation and control strategies. There is a need for accurate models to predict disease dynamics by considering the interactions between environment and vector traits. This study finds that incorporating delayed phenotypic plasticity in mosquito traits significantly enhances the accuracy of dengue risk predictions. [ABSTRACT FROM AUTHOR]

The mosquito microbiome significantly influences vector competence, including in Aedes albopictus, a globally invasive vector. Describing the microbiome and Wolbachia strains of Ae. albopictus from different regions can guide area-specific control strategies. Mosquito samples from Spain and São Tomé were analyzed using 16S rRNA gene sequencing and metagenomic sequencing. Wolbachia infection patterns were observed by sex and population. Female mosquitoes were blood-fed, a factor considered in analyzing their microbiota. Results revealed a dominance of dual Wolbachia infections, strains A and B, in the microbiome of both populations of Ae. albopictus, especially among females. Both populations shared a core microbiome, although 5 and 9 other genera were only present in Spain and São Tomé populations, respectively. Genera like Pelomonas and Nevskia were identified for the first time in Aedes mosquitoes. This study is the first to describe the Ae. albopictus bacteriome in Spain and São Tomé, offering insights for the development of targeted mosquito control strategies. Understanding the specific microbiome composition can help in designing more effective interventions, such as microbiome manipulation and Wolbachia-based approaches, to reduce vector competence and transmission potential of these mosquitoes. [ABSTRACT FROM AUTHOR]

Background: C-type lectins (CTLs) are a large family of proteins with sugar-binding activity. CTLs contain an evolutionarily conserved C-type lectin domain (CTLD) that binds microbial carbohydrates in a calcium-dependent manner, thereby playing a key role in both microbial pathogenesis and innate immune responses. Aedes albopictus is an important vector for transmitting dengue virus (DENV) worldwide. Currently, the molecular characteristics and functions of CTLs in Ae. albopictus are largely unknown. Methods: Transcripts encoding CTL proteins in the Ae. albopictus genome assembly were analyzed via sequence blast. Phylogenetic analysis and molecular characterization were performed to identify the functional domains of the CTLs. Quantitative analysis was performed to determine the gene expression features of CTLs during mosquito development and in different tissues of female adults after blood feeding. In addition, the functional role of CTLs in response to DENV infection was investigated in Ae. albopictus mosquito cells. Results: We identified 39 transcripts encoding CTL proteins in the Ae. albopictus transcriptome. Aedes albopictus CTLs are classified into three groups based on the number of CTLDs and the domain architecture. These included 29 CTL-Ss (single-CTLDs), 1 immulectins (dual-CTLD) and 9 CTL-Xs (CTLDs with other domains). Phylogenetic analysis and structural modeling indicated that CTLs in Ae. albopictus are highly conserved with the homologous CTLs in Aedes aegypti. The expression profile assay revealed differential expression patterns of CTLs in both developmental stages and in adult female tissues. Knockdown and overexpression of three CTLs (CTL-S12, S17 and S19) confirmed that they can promote dengue virus infection in Ae. albopictus cells. Conclusions: The CTL genes in Ae. albopictus mosquito and other mosquito species are evolutionarily conserved and exhibit different developmental and tissue expression features. The functional assay indicated that three CTLs in Ae. albopictus mosquitoes are involved in promoting dengue virus infection. Our study revealed that CTLs play important roles in both the physiological processes and viral infection in mosquito vectors. [ABSTRACT FROM AUTHOR]

Background and Aim: Lymphatic filariasis (LF) is a vector-borne disease in various regions of Indonesia. The transmission dynamics within a locality are intricately linked to the presence of the pathogen (microfilaria), definitive host (humans), intermediate host (mosquitoes), reservoir, and environmental factors. The geographic landscape of Central Bengkulu Regency, which is characterized by plantations, marshlands, and forests, serves as a suitable habitat for mosquitoes. Understanding species diversity, vector behaviors, habitat characteristics, and microfilarial presence is crucial for devising effective and efficient control strategies. This study aimed to identify species diversity, assess biting patterns, characterize larval habitats, and detect microfilarial presence in mosquitoes. Materials and Methods: Mosquito collection was conducted using human landing collection (HLC) and resting collection indoors and outdoors for 6 months at a frequency of twice monthly from November 2022 to May 2023. The larvae were collected using dippers and pipettes. Adult mosquitoes and larvae were identified at the species level and analyzed using diversity indices. The measured larval bioecological parameters included physical, chemical, and biological conditions. The mosquito density obtained through HLC was calculated using the man-hour density (MHD) and man-biting rate (MBR) formulas. The presence of microfilaria was confirmed using a polymerase chain reaction. Results: A total of 808 adult mosquitoes from five genera and 18 species were captured, along with 485 larvae from four genera and eight species. The mosquito diversity was moderate. The dominant adult species included Armigeres subalbatus (44.8%), whereas Aedes albopictus (25.4%) and Ar. subalbatus (22.3%) were abundant larvae. The highest larval density was observed in natural ponds. The average MBR was three mosquitoes per person per night, with fluctuating nightly activity (mean MHD of 1.8 mosquitoes per person per hour). Larval habitats had temperatures of 25.4°C–28.7°C, illumination of 224–674 lx, and pH of 7.1–7.9, with over half being turbid and nearly two-thirds lacking predators. Microfilariae were not detected in the tested mosquitoes. Conclusion: The presence of mosquitoes, their habitat, and the high density of Ar. subalbatus contributes to the transmission of LF in Central Bengkulu Regency, Indonesia. [ABSTRACT FROM AUTHOR]

Rising temperatures are predicted to expand the range of Aedes aegypti and Aedes albopictus, potentially leading to new areas vulnerable to dengue outbreaks. The recent arrival of Aedes aegypti in Upper Egypt underscores this emerging threat, with documented outbreaks in the Red Sea Governorate (2017) serving as evidence. To address this, a cross-sectional surveillance study was conducted during the summer of 2023 in Hurghada City, Egypt, to identify established dengue vectors and their breeding sites. The presence of Aedes aegypti was confirmed, and entomological indices were calculated to assess vector distribution. Risk maps were generated to evaluate potential risks across the city. The study confirms the establishment of Aedes aegypti in Hurghada and provides valuable data for assessing future vector distribution and potential dengue outbreaks. These findings contribute to understanding how global warming and socioeconomic factors influence dengue transmission and will aid in developing effective control measures to prevent future outbreaks in Hurghada. [ABSTRACT FROM AUTHOR]

Simple Summary: The study is about tracking different types of mosquitoes and the spread of the invasive Asian tiger mosquito on the remote Greek island of Kastellorizo. The research aims to understand how widespread these mosquitoes are and how prepared the local community is to deal with them. We conducted KAP (knowledge, attitude, practices) surveys, set up mosquito traps, and identified the types of mosquitoes found. The surveys revealed the need for increased public education about these health risks. The mosquito traps confirmed the presence of species such as Aedes albopictus, which can play a role in the spread of various diseases, along with other species like Culex pipiens, which is the main vector of West Nile virus. The study concludes that involving the community in mosquito monitoring is crucial in regard to helping control the mosquito population. These findings are valuable because they provide essential information for creating effective mosquito control strategies in isolated areas, ultimately helping to protect public health by reducing the risk of disease outbreaks. The expansion of the tiger mosquito, a vector that can transmit diseases such as dengue, chikungunya, and Zika virus, poses a growing threat to global health. This study focuses on the entomological surveillance of Kastellorizo, a remote Greek island affected by its expansion. This research employs a multifaceted approach, combining KAP survey (knowledge, attitude, practices), mosquito collection using adult traps and human landing catches, and morphological and molecular identification methods. Results from questionnaires reveal community awareness and preparedness gaps, emphasizing the need for targeted education. Mosquito collections confirm the presence of the Aedes albopictus, Aedes cretinus, and Culex pipiens mosquitoes, highlighting the importance of surveillance. This study underscores the significance of community engagement in entomological efforts and proposes a citizen science initiative for sustained monitoring. Overall, this research provides essential insights for developing effective mosquito control programs in remote island settings, thereby emphasizing the importance of adopting a One Health approach to mitigate the spread of vector-borne diseases. [ABSTRACT FROM AUTHOR]

Simple Summary: For the sterile insect technique to be successful, sterile male mosquitoes need to outcompete fertile males and mate with wild females. Some female insects, however, have been shown to be able to select for "better sperm" to secure high-quality offspring. This study used stable isotopes to mark the sperm of sterile and fertile males to find any evidence of female tiger mosquitoes selecting the fertile sperm over the sterile one when mated by both types of males. Although this study does not prove that a complex mechanism of sperm selection does not occur, we were not able to find any evidence that double-mated Aedes albopictus females favor fertile sperm for egg fertilization. The key to success in the application of the sterile insect technique (SIT) relies on the ability of released, sterile males to outcompete their fertile wild male counterparts to mate with wild females. However, many insect species exhibit multiple-mating behavior, which can be a way for females to select paternity for their progeny. This study aims to recognize the consequences of potential double-matings during an SIT program and to detect any evidence of sperm selection favoring sperm from fertile mates. This report provides a descriptive analysis of the storage and use of sperm by female Aedes albopictus. Stable isotopes were used to mark the sperm of fertile and sterile males. Mated females were allowed to oviposit before dissecting the spermathecae to link the presence of each type of sperm to the sterility of the eggs laid. It was found that sperm in females inseminated by both males was distributed in the three spermathecae with no obvious pattern, mostly mixed but also separately, and no evidence of any mechanism for sperm selection, sperm precedence, or sperm competition in Ae. albopictus females could be found. The fact that only a few double-mated females were double-inseminated and could also produce semi-sterile eggs, together with the finding that the sperm of sterile males appeared to be no less viable than that of fertile males, is an encouraging outcome for SIT approaches. [ABSTRACT FROM AUTHOR]

Simple Summary: Aedes albopictus mosquitoes spread arboviruses like dengue, Zika, or chikungunya. The Sterile Insect Technique (SIT) can be used as a prevention and control tool against Ae. albopictus populations. Mark–release–recapture (MRR) trials are fundamental to estimate the size of the wild population in target areas and to determine the dispersal capacity and survival of sterile males in open field conditions. Environmental conditions can affect the MRR trial's results; thus, the influence of climatic factors on the first MRR trial with Ae. albopictus marked sterile males conducted in Portugal was analyzed. In October 2022, for three consecutive weeks at two different release points, 84,000 sterile males were released over 50 ha of the study area, in the municipality of Faro, Southern Portugal, and mosquitoes were recaptured by human landing collection (HLC) one, two, four, and six days after release. Distance travelled, daily survival, and life expectancy in the field were estimated for the released sterile males and the influence of climatic factors was analyzed. Despite no statistically significant association being found with humidity, temperature, and precipitation, it is crucial to plan MRRs, considering weather conditions for a more efficient application of the SIT in an integrated vector management program. Aedes albopictus is considered one of the major invasive species in the world and can transmit viruses such as dengue, Zika, or chikungunya. The Sterile Insect Technique (SIT) can be used to suppress the native populations of Ae. albopictus. Mark–release–recapture (MRR) studies are crucial to support the development of the release strategy during the SIT application. Meanwhile, weather conditions can affect the MRR trial's results and it is critical to understand the influence of climatic factors on the results. In October 2022, 84,000 irradiated sterile males were released for three consecutive weeks in Faro, Southern Portugal. Mosquitoes were recaptured by human landing collection (HLC) one, two, four, and six days after release. Generalized linear models with a negative binomial family and log function were used to estimate the factors associated with the number of recaptured mosquitoes, prevalence ratios, and the 95% confidence intervals (CIs). A total of 84,000 sterile male mosquitoes were released, with 528 recaptured (0.8%) by HLC. The prevalence of recaptured mosquitoes was 23% lower when the wind intensity was moderate. Marked sterile males had an average median distance travelled of 88.7 m. The median probability of daily survival and the average life expectancy were 61.6% and 2.1 days, respectively. The wild male population estimate was 443.33 males/ha. Despite no statistically significant association being found with humidity, temperature, and precipitation, it is important to consider weather conditions during MRR trial analyses to obtain the best determinant estimation and a more efficient application of the SIT in an integrated vector management program. [ABSTRACT FROM AUTHOR]

Viral diseases like yellow fever, dengue, and Zika have an alarming impact on public health. These diseases can be transmitted by Aedes mosquito species, such as Ae. albopictus, which is now found in many countries outside its original range. Xenorhabdus and Photorhabdus spp. are enteric bacterial symbionts of insect-preying nematodes and are known to produce an array of natural products with various activities including larvicidal activity. In this study, the effects of natural products produced by four Xenorhabdus and one Photorhabdus bacteria on the ovipositional behavior of Ae. albopictus mosquitoes were assessed. Utilizing a binary choice assay in insect cages, gravid female mosquitoes were presented with two oviposition cups containing water supplemented with varying concentrations of bacterial supernatants (50–1% concentrations) versus control medium. After 72 h, the eggs deposited on filter papers were counted. The oviposition attractant index (OAI) feature of the bacterial supernatant was evaluated using the number of eggs laid in the cups. Notably, all tested supernatants exhibited concentration-dependent deterrence of oviposition. Xenorhabdus cabanillasii displayed the strongest deterrent effect, inhibiting egg-laying at 50–5% concentrations (OAI: − 0.87 to − 0.35), followed by X. nematophila (50–10%, OAI: − 0.82 to − 0.52). Xenorhabdus szentirmaii, X. doucetiae, and P. kayaii showed significant deterrence at ≥ 20% concentrations. Using promoter exchange mutants generated by the easyPACId approach, fabclavine from X. szentirmaii was identified as the bioactive compound with evident deterrent effects. Such deterrents targeting egg-laying could be valuable for controlling populations by disrupting their breeding in suitable habitats. [ABSTRACT FROM AUTHOR]

Background: Mosquito-borne orthobunyaviruses are a growing priority for public and animal health in Canada. It is anticipated that disease incidence will increase due to a warming climate, given that habitats are expanding for reservoir hosts and vectors, particularly in Canada. Little is known about the ecology of primary vectors that perpetuate these orthobunyaviruses, including the viral transmission cycle and the impact of climatic and landscape factors. Methods: A scoping review was conducted to describe the current state of knowledge on the epidemiology of orthobunyaviruses relevant to Canada. The Preferred Reporting Items for Systematic Reviews and Meta-Analyses extension for Scoping Reviews guidelines was used to characterize studies focused on vector species. A literature search was conducted in six databases and gray literature. Eligible studies characterized orthobunyavirus epidemiology related to vector species, including viral competency, geospatial distributions, seasonal trends, and/or risk factors. Results: A total of 1734 unique citations were identified. Screening of these citations revealed 172 relevant studies, from which 87 studies presented primary data related to vectors. The orthobunyaviruses included Cache Valley virus (CVV), Jamestown Canyon virus (JCV), Snowshoe Hare virus (SHV), and La Crosse virus (LACV). Surveillance was the predominant study focus, with most citations representing the United States, specifically, LACV surveillance in Tennessee, followed by CVV and JCV in Connecticut. Orthobunyaviruses were detected in many mosquito species across multiple genera, with high vector specificity only being reported for LACV, which included Aedes triseriatus, Aedes albopictus, and Aedes japonicus. Peridomestic areas were positively associated with infected mosquitoes compared with dense forests. Orthobunyavirus infections, coinfections, and gut microbiota affected mosquito feeding and breeding behavior. Conclusion: Knowledge gaps included Canadian surveillance data, disease modeling, and risk projections. Further research in these areas, especially accounting for climate change, is needed to guide health policy for prevention of orthobunyaviral disease. [ABSTRACT FROM AUTHOR]

Background: This study conducted in the departments of Oueme and Plateau aims to assess the presence of the dengue virus and its different serotypes in Aedes aegypti and Aedes albopictus, as well as the epidemic risk incurred by the populations. Methods: Collections of adult mosquitoes using human landing catches (HLC) were carried out in six communes, three (Porto-Novo, Adjarra, and Avrankou) in the Oueme department and the rest (Ifangni, Kétou, and Pobè) in the Plateau department. Pools of ten Aedes mosquitoes were formed, and stored at −80°C in RNA later. RT-PCR was used to detect dengue virus, and conventional PCR for the different serotypes. Inspection of water containers and collection of Aedes larvae was performed inside and around each house to calculate the stegomyan indices. Results: In the six communes, the dengue virus was present both in Ae. aegypti and Ae. albopictus. Combined data of the two Aedes species at the communes level revealed infection rates ranging from 80.00% (95% CI: 61.43–92.29) to 96.67% (95% CI: 82.78–99.92). In all the communes, the values of stegomyan indices reached the WHO threshold, which indicates the existence of the risk of an arbovirus epidemic. In addition, the infection rates were similar for Ae. aegypti [88.19% (95% CI: 81.27–93.24)] and Ae. albopictus [86.79% (95% CI: 74.66–94.52)]. The three virus serotypes detected in the pools of Aedes were DENV-1, DENV-3, and DENV-4, with a high prevalence for the first two. Conclusion: This study revealed that three serotypes (DENV-1, DENV-3, and DENV-4) of dengue virus circulate in Ae. aegypti and Ae. albopictus in the departments of Oueme and Plateau. Moreover, the risk of transmission of arboviruses was globally high and variable from commune to commune. This information is essential for informed decision-making in the preventive control of the disease. [ABSTRACT FROM AUTHOR]

Insects geographically separated into island and mainland populations often exhibit phenotypic variations, a phenomenon known as insular conditions. These conditions can lead to rapid evolutionary changes that affect the morphological characteristics of mosquito vectors. Nevertheless, studies that specifically examine phenotype differences between island and mainland mosquito populations have been limited. In this study, wing variation in size and shape was investigated using the geometric morphometric (GM) technique in two dominant mosquito vectors, Aedes albopictus and Armigeres subalbatus, in the Ranong and Trat archipelagos of Thailand. Significant differences in average wing centroid size (CS) were found in 6 out of 15 population pairs for Ae. albopictus (p < 0.05) and in 5 population pairs for Ar. subalbatus (p < 0.05). After removing the allometric effect, canonical variate analyses (CVA) based on wing shape analysis revealed overlap across all populations for both Ae. albopictus and Ar. subalbatus. However, the statistical analysis indicated that Ar. subalbatus exhibited wing shape differences across all populations (p < 0.05), and most Ae. albopictus populations also displayed distinct wing shapes (p < 0.05), except for the populations from Chang Island and the mainland of Ranong, which showed no significant differences (p > 0.05). These findings enhance our understanding of mosquito adaptability in island regions and provide valuable data for the surveillance and monitoring of vector evolution. [ABSTRACT FROM AUTHOR]

Aedes albopictus is highly prevalent in the northern part of West Bengal and is considered to be responsible for the recent dengue outbreaks in this region. Control of this vector is largely relied on the use of synthetic pyrethroids, which can lead to the development of resistance. In the present study, larvae of three wild Ae. albopictus populations from the dengue‐endemic regions were screened for deltamethrin resistance, and the role of cytochrome P450 monooxygenases (CYPs) was investigated in deltamethrin exposed and unexposed larvae. Two populations were incipient resistant, and one population was completely resistant against deltamethrin. Monooxygenase titration assay revealed the involvement of CYPs in deltamethrin resistance along with an induction effect of deltamethrin exposure. Gene expression studies revealed differential expression of five CYP6 family genes, CYP6A8, CYP6P12, CYP6A14, CYP6N3 and CYP6N6, with high constitutive expression of CYP6A8 and CYP6P12 in all the populations before and after deltamethrin exposure. From these findings, it was evident that CYPs play an important role in the development of deltamethrin resistance in the Ae. albopictus populations in this region. [ABSTRACT FROM AUTHOR]

Dengue viruses are the causative agents of dengue fever, dengue hemorrhagic fever, and dengue shock syndrome, which are mainly transmitted by Aedes aegypti and Aedes albopictus mosquitoes, and cost billions of dollars annually in patient treatment and mosquito control. Progress in understanding DENV pathogenesis and developing effective treatments has been hampered by the lack of a suitable small pathological animal model. Until now, the candidate vaccine, antibody, and drug for DENV have not been effectively evaluated. Here, we analyzed the pathogenicity of DENV‐1 in type Ⅰ and type Ⅱ interferon receptor‐deficient mice (AGB6) by intraperitoneal inoculation. Infected mice showed such neurological symptoms as opisthotonus, hunching, ataxia, and paralysis of one or both hind limbs. Viremia can be detected 3 days after infection. It was found that 6.98 × 103 PFU or higher dose induce 100% mortality. To determine the cause of lethality in mice, heart, liver, spleen, lung, kidney, intestinal, and brain tissues were collected from AGB6 mice (at an attack dose of 6.98 × 103 PFU) for RNA quantification, and it was found that the viral load in brain tissues peaked at moribund states (14 dpi) and that the viral loads in the other tissues and organs decreased over time. Significant histopathologic changes were observed in brain tissue (hippocampal region and cerebral cortex). Hematological analysis showed hemorrhage and hemoconcentration in infected mice. DENV‐1 can be isolated from the brain tissue of infected mice. Subsequently, brain tissue transcriptome sequencing was performed to assess host response characteristics in infected AGB6 mice. Transcriptional patterns in brain tissue suggest that aberrant expression of pro‐inflammatory cytokines induces antiviral responses and tissue damage. Screening of hub genes and their characterization by qPCR and ELISA, it was hypothesized that IL‐6 and IFN‐γ might be the key factors in dengue virus‐induced inflammatory response. Therefore, this study provides an opportunity to decipher certain aspects of dengue pathogenesis further and provides a new platform for drug, antibody, and vaccine testing. [ABSTRACT FROM AUTHOR]

Dengue fever is an urban, tropical, and semi-tropical disease transmitted by Aedes aegypti and Aedes albopictus mosquitoes. One significant challenge lies in identifying reliable intra-urban indicators of their densities. Following standardized sampling protocols that adequately take into account the spatial heterogeneity of the geographical contexts which may influence mosquito habitats is therefore fundamental to compare studies and follow such relevant indicators. We develop a method for subdividing urban territory based on environmental factors which are susceptible to influence the density of potential mosquito-breeding containers. Indeed, the presence of these containers, most of which are produced by humans, is essential for the renewal of mosquito populations. Land-uses variables and their local variations are determinant in this analysis. Starting from each building and its immediate neighborhood described in terms of vegetation and open area, we computed the local landscape metrics of a million buildings in Bangkok. We then used segmentation and clustering techniques to generate homogeneous zones based on these components and physiognomy. Subsequently, a classification process was conducted to characterize these zones according to land-use and composition indicators. We applied this automatic clustering method within Bangkok's urban area. This classification built from hypotheses on the existence of links between the types of urban landscape and the presence of outdoor containers must be evaluated and will serve as a foundation for the spatial sampling of field studies for vector surveillance in Bangkok. The choice of sampling zones, even if it must be based on an administrative division due to the decentralization of health agencies in Bangkok, can then be enriched by this new, more functional division. This method, due to the genericity of the factors used, could be tested in other cities prone to dengue vectors. [ABSTRACT FROM AUTHOR]

BACKGROUND: In the perpetual struggle to manage mosquito populations, there has been increasing demand for the development of biopesticides to supplant/complement current products. The insecticidal potential of Xenorhabdus and Photorhabdus has long been recognized and is of interest for the control of important mosquitoes like Aedes albopictus which vectors over 20 different arboviruses of global public health concern. RESULTS: The larvicidal effects of cell‐free supernatants, cell growth cultures and cell mass of an extensive list of Xenorhabdus and Photorhabdus spp. was investigated. They were quite effective against Ae. albopictus causing larval mortality ranging between 52–100%. Three Photorhabdus spp. and 13 Xenorhabdus spp. release larvicidal compounds in cell‐free supernatants. Cell growth culture of all tested species exhibited larvicidal activity, except for Xenorhabdus sp. TS4. Twenty‐one Xenorhabdus and Photorhabdus bacterial cells (pellet) exhibited oral toxicity (59–91%) against exposed larvae. The effect of bacterial supernatants on the mosquito eggs were also assessed. Bacterial supernatants inhibited the hatching of mosquito eggs; when unhatched eggs were transferred to clean water, they all hatched. Using the easyPACId approach, the larvicidal compounds in bacterial supernatant were identified as fabclavine from X. szentirmaii and xencoumacin from X. nematophila (causing 98 and 70% mortality, respectively, after 48 h). Xenorhabdus cabanillasii and X. hominickii fabclavines were as effective as commercial Bacillus thuringiensis subsp. israelensis and spinosad products within 5 days post‐application (dpa). CONCLUSION: Fabclavine and xenocoumacin can be developed into novel biolarvicides, can be used as a model to synthesize other compounds or/and can be combined with other commercial biolarvicides. © 2024 The Authors. Pest Management Science published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry. [ABSTRACT FROM AUTHOR]

Abstract Background The biological larvicide Bacillus thuringiensis subsp. israelensis (Bti) represents a safe and effective alternative to chemical insecticides for mosquito control. Efficient control of mosquitoes implicates continuous and extensive application of Bti. This massive use of Bti imposes strong selective pressure, but the complex mode of action of the numerous synergistic Bti endotoxins lower the risk of the emergence of resistance. Although resistance to Bti has not been identified at the population level in nature, some larvae can survive Bti exposure, suggesting tolerance mechanisms. Here we investigated whether Bti-tolerant Aedes albopictus larvae experience any fitness costs. We also studied how this tolerance affects different aspects of the phenotype of the emerging adults that could be relevant for arboviral transmission. Methods We exposed Ae. albopictus larvae to lethal concentration of Bti and studied the fitness and gut microbiota of tolerant larvae and their adult counterparts. We further compared the transcript abundance of nine key immunity genes in the gut of Bti-tolerant larvae and their emerging adults versus those not exposed to Bti. Results Our results showed that Bti exposure has multifaceted impacts on Ae. albopictus mosquitoes during both larval and adult stages. The carry-over effect of Bti exposure on tolerant larvae manifested in reduced adult emergence rate, shorter lifespan, and decreased fecundity. Bti also alters the gut microbiota of both larvae and adults. We observed higher microbial diversity in Bti-tolerant larvae and changes in the richness of core microbiota. Bti infection and the altered microbiota triggered immune responses in the larval and adult guts. Conclusions The observed reduction in mosquito fitness and changes in the composition of the microbiota of adults emerging from tolerant larvae could negatively influence mosquito vectorial capacity. Understanding these impacts is crucial for evaluating the broader implications of Bti-based insecticides in mosquito control programs. Graphical Abstract