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The mosquito-lethal effect of commercially available standard and long-lasting ivermectin formulations were evaluated in cattle and buffalo against wild-caught Anopheles on Sumba Island, Indonesia. Cattle have substantially higher blood-level concentrations of ivermectin compared to buffalo after receiving similar doses, irrespective of formulation. In total, nine Anopheles species were captured to assess the mosquito-lethal effects of ivermectin with susceptibility ranked from lowest to highest: An. flavirostris < An. aconitus < An. annularis < An. tessellatus < An. maculatus < An. sundaicus < An. vagus < An. kochi < An. barbirostris. The duration of mosquito-lethal effect of long-lasting ivermectin was superior to standard ivermectin and in cattle it well exceeded the WHO criteria for new endectocides having a mortality hazard ratio greater than 4 through 30 days after administration. Buffalo may require higher doses of long-lasting ivermectin to achieve similar mosquito-lethal effects observed in cattle. Of the four hosts evaluated buffalo were the most attractive to Anopheles followed by cattle then horse and finally humans. This study demonstrates, for the first time, the superiority of a commercially available long-lasting ivermectin formulation for the potential deployment of mass ivermectin treatment of livestock as a vector control tool for malaria elimination in Southeast Asia. [ABSTRACT FROM AUTHOR]

Dengue virus (DENV) is the most widespread mosquito-borne virus worldwide, but no antiviral therapies are available yet. The pan-serotype DENV inhibitor JNJ-A07 has shown potent activity in a mouse model. It remains unknown whether an antiviral drug ingested by mosquitoes could inhibit virus replication and thus reduce transmission to other hosts. Here, we investigated the antiviral activity of JNJ-A07 when administered in the blood meal to Aedes aegypti mosquitoes. JNJ-A07 blocked DENV-2 transmission by the mosquitoes in both pre-exposure and post-exposure settings. In addition, JNJ-A07 remained in the mosquito bodies for 7 days after blood meal. Reductions of DENV systemic infection in the mosquitoes suggested a potential for decreased proportions of DENV outbreaks in a simulated environment when the mosquitoes ingested JNJ-A07 via the blood meal. [ABSTRACT FROM AUTHOR]

Every day, hundreds of mosquito surveys are carried out around the world to inform policy and management decisions on how best to reduce or prevent the burden of mosquito-borne disease or mosquito nuisance. These surveys are usually time consuming and expensive. Mosquito surveillance is the essential component of vector management and control. However, surveillance is often carried out with a limited if not without a quantitative assessment of the sampling effort which can results in underpowered or overpowered studies, or certainly in overpowered studies when power analyses are carried out assuming independence in the measurements obtained from longitudinal and geographically proximal mosquito surveys. Many free, open-source and user-friendly tools to calculate statistical power are available, such as G*Power, glimmpse, powerandsamplesize.com website or R-cran packages (pwr and WebPower to name few of them). However, these tools may not be sufficient for powering mosquito surveys due to the additional properties of seasonal and spatially clustered repeated measurements required to reflect mosquito population dynamics. To facilitate power analysis for mosquito surveillance, we have developed TIMESS, a deployable browser-based Shiny app that estimates the number of repeated measurements and locations of mosquito surveys for a given effect size, power, significance level, seasonality and level of expected between-location clustering. In this article we describe TIMESS, its usage, strengths and limitations. [ABSTRACT FROM AUTHOR]

Background: Wolbachia incompatible insect technique (IIT) programs have been shown in field trials to be highly effective in suppressing populations of mosquitoes that carry diseases such as dengue, chikungunya, and Zika. However, the frequent and repeated release of Wolbachia-infected male mosquitoes makes such programs resource-intensive. While the need for optimization is recognized, potential strategies to optimize releases and reduce resource utilization have not been fully explored. Results: We developed a process-based model to study the spatio-temporal metapopulation dynamics of mosquitoes in a Wolbachia IIT program, which explicitly incorporates climatic influence in mosquito life-history traits. We then used the model to simulate various scale-down and redistribution strategies to optimize the existing program in Singapore. Specifically, the model was used to study the trade-offs between the intervention efficacy outcomes and resource requirements of various release program strategies, such as the total number of release events and the number of mosquitoes released. We found that scaling down releases in existing sites from twice a week to only once a week yielded small changes in suppression efficacy (from 87 to 80%), while requiring 44% fewer mosquitoes and release events. Additionally, redistributing mosquitoes from already suppressed areas and releasing them in new areas once a week led to a greater total suppressive efficacy (83% compared to 61%) while also yielding a 16% and 14% reduction in the number of mosquitoes and release events required, respectively. Conclusions: Both scale-down and redistribution strategies can be implemented to significantly reduce program resource requirements without compromising the suppressive efficacy of IIT. These findings will inform planners on ways to optimize existing and future IIT programs, potentially allowing for the wider adoption of this method for mosquito-borne disease control. [ABSTRACT FROM AUTHOR]

West Nile virus (WNV) is a flavivirus naturally circulating between mosquito vectors and birds, occasionally infecting horses and humans and causing epidemiologically relevant outbreaks. In Spain, the first big WNV outbreak was recorded in 2020, resulting in 77 people infected and 8 fatalities, most of them in southern Spain. Culex perexiguus was identified as the primary vector of WNV maintaining its enzootic circulation of the virus. Growing evidence highlights the role of mosquito microbiota as a key component determining the vectorial capacity of mosquitoes, largely contributing to disease epidemiology. Here, we develop, to our knowledge, the first identification of the microbiota composition of this mosquito vector under natural conditions and test for the potential relationship between mosquito microbiota composition and WNV infection. To do so, we collected mosquitoes in a natural area of southern Spain during the 2020 WNV outbreak and identified the microbiota composition of mosquitoes using a 16S rRNA gene metabarcoding approach. The microbiota of Cx. perexiguus was dominated by the phylum Proteobacteria. The most abundant families were Burkholderiaceae and Erwiniaceae, including the genera Burkholderia, Erwinia, and Pantoea. The genus Wolbachia, which use to dominate the microbiota of Cx. pipiens and negatively interact with WNV according to the literature, had a low prevalence and relative abundance in Cx. perexiguus and its abundance did not differ between WNV-positive and WNV-negative mosquito pools. The microbiota diversity and composition of Cx. perexiguus were not significantly related to the WNV infection status. These results provide the first identification of the mosquito microbiota in an endemic area of WNV circulation in Spain. [ABSTRACT FROM AUTHOR]

Background: Significant effort and resources have been invested to control malaria transmission in sub-Saharan Africa, but it remains a major public health problem. For the parasite to be transmitted, the female Anopheles vector must survive 10–14 days following an infective bite to allow Plasmodium gametocytes to develop into infectious sporozoites. The goal of this study was to assess factors associated with wild-caught Anopheles survival and infection following host-seeking and indoor resting. Methods: The study was conducted between January 2020 to March 2022 in a longitudinal cohort of 75 households in 5 villages including a total of 755 household members in Bungoma County, Kenya. Monthly adult mosquito collection was conducted by attenuated aspiration in all enrolled households, and mosquitoes were reared for 7 days. The daily mortality rate was determined through day 7. All mosquitoes were morphologically identified. Female Anopheles were dissected, and species-level members of the Anopheles gambiae complex were resolved by molecular methods. The abdomens of all samples were processed for Plasmodium falciparum oocyst detection by PCR. Results: Within a 25-month period, the total numbers of non-Anopheles and Anopheles mosquitoes collected indoors were 12,843 and 712, respectively. Anopheles gambiae and An. funestus were the major vectors, though their distributions varied between different villages; 61.2% (n = 436/712) of the Anopheles mosquitoes survived up to day 7, with the lowest mortality rate recorded on day 5 of captivity. The survival rate also varied between the different Anopheles species. Six hundred eighty-three of 712 mosquito abdomens were tested for P. falciparum; 7.8% (53/683) tested positive for P. falciparum, with An. funestus having a higher (10%) prevalence than An. gambiae s.s. (6.0%, p = 0.095, Pearson Chi-square test). The proportion of household members sleeping under a bednet the night before mosquito collection varied across time and village. Anopheles funestus survival times were refractory to household ITN usage, and An. gambaie s.s. survival was reduced only under very high (100%) ITN usage. Conclusions: Despite ITN usage, mosquitoes still acquired blood meals and P. falciparum infections. Survival differed across species and was inversely correlated with high ITN usage in the household but not oocyst development. [ABSTRACT FROM AUTHOR]

Background: The decision to imbibe a blood meal is predominantly dependent on the sensitivity and specificity of haematophagous arthropods to blood-derived adenine nucleotides, in particular adenosine triphosphate (ATP). Despite previous efforts to identify and characterise the specificity and sensitivity to ATP and other adenine nucleotides, as well as the role of other blood-derived phagostimulants across the Culicidae, comparisons across species remain difficult. Methods: The feeding response of the yellow fever mosquito Aedes aegypti and the African malaria vector Anopheles gambiae to adenine nucleotides in the presence of a carbonate buffer was assessed using a membrane feeding assay. The proportion of mosquitoes engorged and the volume imbibed by all mosquitoes was scored visually and spectrophotometrically. In addition, the proportion of prediuresing An. gambiae, as well as the volume engorged and prediuresed, was examined. Results: Aedes aegypti was more sensitive to adenine nucleotides than An. gambiae, but both species maintained specificity to these phagostimulants, demonstrating a dose-dependent bimodal feeding pattern, thereby expanding our understanding of the all-or-none blood-feeding hypothesis. Feeding on the bicarbonate buffer by An. gambiae—but not that of Ae. aegypti—demonstrated a species-specific variation in how blood phagostimulants are encoded. Adenine nucleotides, with and without bovine serum albumin, were observed to dose-dependently regulate the proportion of An. gambiae prediuresing and the volumes prediuresed but not volumes engorged. Conclusions: Taken together, the results of this study expand our understanding of how mosquitoes differentially assess and respond to blood meal constituents, and provide a basis for further physiological and molecular studies. [ABSTRACT FROM AUTHOR]

Wolbachia pipientis (= Wolbachia) has promise as a tool to suppress virus transmission by Aedes aegypti mosquitoes. However, Wolbachia can have variable effects on mosquito-borne viruses. This variation remains poorly characterized, yet the multimodal effects of Wolbachia on diverse pathogens could have important implications for public health. Here, we examine the effects of transient somatic infection with two strains of Wolbachia (wAlbB and wMel) on the alphaviruses Sindbis virus (SINV), O'nyong-nyong virus (ONNV), and Mayaro virus (MAYV) in Ae. aegypti. We found variable effects of Wolbachia including enhancement and suppression of viral infections, with some effects depending on Wolbachia strain. Both wAlbB- and wMel-infected mosquitoes showed enhancement of SINV infection rates one week post-infection, with wAlbB-infected mosquitoes also having higher viral titers than controls. Infection rates with ONNV were low across all treatments and no significant effects of Wolbachia were observed. The effects of Wolbachia on MAYV infections were strikingly strain-specific; wMel strongly blocked MAYV infections and suppressed viral titers, while wAlbB had more modest effects. The variable effects of Wolbachia on vector competence underscore the importance of further research into how this bacterium impacts the virome of wild mosquitoes including the emergent human pathogens they transmit. Author summary: In recent years, wild populations of Aedes aegypti mosquitoes in over a dozen countries have been deliberately infected with Wolbachia pipientis ("Wolbachia"); an intracellular bacterium that, in some circumstances, helps to curb the spread of mosquito-brone pathogens including dengue virus. But how does Wolbachia affect the ability of mosquitoes to become infected with and spread the many different viruses they encounter in nature? Here, we use transient somatic infections in Aedes aegypti to characterize the effects of Wolbachia on three different alphaviruses that cause illness in humans: Sindbis virus, O'nyong-nyong virus, and Mayaro virus. We find that transient Wolbachia infections have variable effects on these different pathogens, ranging from significant suppression of Mayaro virus to significant enhancement of Sindbis virus. Our research has important implications for the design of vector control strategies, and suggests further research is needed to understand how Wolbachia shapes the replication and transmission of diverse viruses in mosquitoes. [ABSTRACT FROM AUTHOR]

Precise mosquito identification is integral to effective arbovirus surveillance. Nonetheless, the conventional morphological approach to identifying mosquito species is laborious, demands expertise and presents challenges when specimens are damaged. DNA barcoding offers a promising alternative, surmounting challenges inherent in morphological identification. To integrate DNA barcoding into arbovirus surveillance effectively, a robust dataset of mosquito barcode sequences is required. This study established a comprehensive repository of Cytochrome Oxidase I (COI) barcodes, encompassing 177 samples representing 45 mosquito species from southern and northern Western Australia (WA), including 16 species which have not been previously barcoded. The average intraspecific and interspecific genetic distances were 1% and 6.8%, respectively. Anopheles annulipes sensu lato had the highest intraspecific distance at 9.1%, signifying a genetically diverse species. While validating the potential of COI barcodes to accurately differentiate mosquito species, we identified that some species pairs have low COI divergence. This includes Aedes clelandi and Ae. hesperonotius, Tripteroides atripes and Tp. punctolaeralis and Ae. turneri and Ae. stricklandi. In addition, we observed ambiguity in identification of the members of Culex sitiens subgroup (Cx. annulirostris, Cx. palpalis and Cx. sitiens) and three members of Cx. pipiens complex (Cx. australicus, Cx. globocoxitus, Cx. quinquefasciatus). In summary, despite presenting challenges in the identification of some mosquito species, the COI barcode accurately identified most of the species and generated a valuable resource that will support the WA arbovirus surveillance program and enhance public health intervention strategies for mosquito‐borne disease control. [ABSTRACT FROM AUTHOR]

The diversity and distribution of mosquitoes from Sonora, Mexico, was documented through entomologic surveys conducted in the four physiographic regions and sub-regions of Sonora: the Sonoran Plain, the Sierra Madre Occidental, the Northern Mountains and Plains, and the Pacific Coastal Plain. Immature stages were collected from aquatic habitats, while adult mosquitoes were collected using Shannon traps, resting in vegetation, and by human landing collections. Overall, 11,316 specimens, which comprised 493 larvae, 224 larval exuviae, 400 pupal exuviae, 33 pupae, 4552 females, 5607 males, and seven male genitalia, were identified. Two subfamilies: Anophelinae and Culicinae, seven tribes, 10 genera, 23 subgenera, and 56 species are reported below. Of these, one tribe, one genus, five subgenera, and 15 species were recorded for the first time in Sonora. Two species, Aedes deserticola Zavortink and Toxorhynchites septentrionalis (Dyar and Knab), are the first recordings of their kind nationwide. Toxorhynchites septentrionalis was also barcoded with the cytochrome oxidase subunit 1 (COI) gene. The presence of Psorophora columbiae (Dyar and Knab) is confirmed in Mexico. Taxonomic notes, new geographic distribution limits of mosquitoes in Sonora, and information regarding their importance as disease vectors are provided. By adding Ae. deserticola and Tx. septentrionalis and confirming Ps. columbiae in Mexico, there are currently 251 mosquito species in the Country. [ABSTRACT FROM AUTHOR]

The Zika virus, known for its potential to induce neurological conditions such as microcephaly when transmitted vertically from infected mothers to infants, has sparked widespread concerns globally. Motivated by this, we propose an optimal control problem for the prevention of vertical Zika transmission. The novelty of this study lies in its consideration of time-dependent control functions, namely, insecticide spraying and personal protective measures taken to safeguard pregnant women from infected mosquitoes. New results provide a way to minimize the number of infected pregnant women through the implementation of control strategies while simultaneously reducing both the associated costs of control measures and the mosquito population, resulting in a decline in microcephaly cases. [ABSTRACT FROM AUTHOR]

ABSTRACT: Context: Chikungunya's resurgence highlights reporting and awareness challenges. Aims: To analyze trends in 170 laboratory-confirmed Chikungunya cases in Urban Surat's Central Sentinel Surveillance (2016-2020), supplemented by a subset (n = 30) examining perceptions, attitudes, and risk reduction practices based on notification level. Results: Notification rates peaked in 2017 (1.14 cases/100,000). A high House Index (>1) was observed in 59% (2018) and 58% (2019) of cases. Seasonal peaks occurred in November (31%) and December (24.7%), with no private sector notifications. Highest case rates were in South (9.2) and Southeast (8.1) zones. Over half of the cases in Central (69.2%), Southeast (67.2%), and South (52.8%) zones had a House Index >1 (P = 0.001), indicating significant indoor mosquito breeding. Median age was 37 years (30-43), with females comprising 65.3% of cases. Awareness of mosquitoes as vectors (40%) and their day-biting behavior (26.7%) was low, despite familiarity with Abate larvicide (60%). Prevention methods included mosquito coils (76%) and fumigation (73%), with less emphasis on water change (40%) and container maintenance (23%). Only 13% perceived Chikungunya as preventable, with low readiness for community engagement (13%). Misconceptions included considering chemical fogging sufficient (63%) and neglecting water-logging as a health concern (40%). Few implemented risk reduction measures (23% removing stagnant water, 20% weekly water change). Conclusion: Fluctuating notifications and unnoticed surges in 2019-2020 underscore the need for continuous, standardized surveillance. Higher case rates in southern and central regions were linked to high indoor breeding. The lack of private sector reporting and underreporting indicate a need for integrated surveillance. Awareness and adoption of Aedes -specific risk reduction practices remain low, with persistent misconceptions and poor attitudes. [ABSTRACT FROM AUTHOR]

The complete mitochondrial genome of Culex hutchinsoni Barraud, 1924 was reported with 15,586 bp long. It contained 37 annotated genes and the control region, which is consistent with other mosquitoes. Most PCGs used typical ATN as start codons, while some special start codons were also used (i.e. TCG for COX1, TTG for ND1, GTG for ND5). Most PCGs terminated with TAA as well as some PCGs (COX1, COX2, COX3, ND3, ND4 and CYTB) terminated with TA-tRNA or T-tRNA. Cx. (Lophoceraomyia) was recovered as the sister group to Cx. (Culex), while Cx. hutchinsoni was recovered within the species group of Cx. pipiens. [ABSTRACT FROM AUTHOR]

Background: Mosquitoes serve as vectors for numerous pathogens, posing significant health risks to humans and animals. Understanding the complex interactions within mosquito microbiota is crucial for deciphering vector-pathogen dynamics and developing effective disease management strategies. Here, we investigated the nested patterns of Wolbachia endosymbionts and Escherichia-Shigella within the microbiota of laboratory-reared Culex pipiens f. molestus and Culex quinquefasciatus mosquitoes. We hypothesized that Wolbachia would exhibit a structured pattern reflective of its co-evolved relationship with both mosquito species, while Escherichia-Shigella would display a more dynamic pattern influenced by environmental factors. Results: Our analysis revealed different microbial compositions between the two mosquito species, although some microorganisms were common to both. Network analysis revealed distinct community structures and interaction patterns for these bacteria in the microbiota of each mosquito species. Escherichia-Shigella appeared prominently within major network modules in both mosquito species, particularly in module P4 of Cx. pipiens f. molestus, interacting with 93 nodes, and in module Q3 of Cx. quinquefasciatus, interacting with 161 nodes, sharing 55 nodes across both species. On the other hand, Wolbachia appeared in disparate modules: module P3 in Cx. pipiens f. molestus and a distinct module with a single additional taxon in Cx. quinquefasciatus, showing species-specific interactions and no shared taxa. Through computer simulations, we evaluated how the removal of Wolbachia or Escherichia-Shigella affects network robustness. In Cx. pipiens f. molestus, removal of Wolbachia led to a decrease in network connectivity, while Escherichia-Shigella removal had a minimal impact. Conversely, in Cx. quinquefasciatus, removal of Escherichia-Shigella resulted in decreased network stability, whereas Wolbachia removal had minimal effect. Conclusions: Contrary to our hypothesis, the findings indicate that Wolbachia displays a more dynamic pattern of associations within the microbiota of Culex pipiens f. molestus and Culex quinquefasciatus mosquitoes, than Escherichia-Shigella. The differential effects on network robustness upon Wolbachia or Escherichia-Shigella removal suggest that these bacteria play distinct roles in maintaining community stability within the microbiota of the two mosquito species. [ABSTRACT FROM AUTHOR]

Anophelinae mosquitoes are exposed to a variety of microbes including Plasmodium parasites that cause malaria. When infected, mosquitoes mount versatile immune responses, including the production of antimicrobial peptides. Cecropins are one of the most widely distributed families of antimicrobial peptides in insects and all previously studied Anopheles members are playing roles in adult mosquito immunity. We have identified and characterized a novel member of the Anopheles gambiae cecropin family, cecropin D (CecD), that is uniquely expressed and immune-responsive at late larval stages to promote microbial clearance through its broad-spectrum antibacterial activity during larval-pupal developmental transition. Interestingly, Cecropin D also exhibited highly potent activity against Plasmodium falciparum sporozoites, the malaria parasite stage that is transmitted from mosquitoes and infects humans and thereby holds promise as a malaria transmission-blocking agent. Finally, we have defined unequivocal cecropin-specific molecular signatures to systematically organize the diversity of the cecropin family in malaria vectors. Author summary: Anopheles mosquitoes that transmit the deadly malaria are exposed to a variety of microbes in their natural habitats. Mosquitoes use their innate immune system that also comprises antimicrobial peptides to fight infections with these microbes including the Plasmodium malaria parasite. Cecropins are one of the most widely distributed antimicrobial peptides in insects and all previously studied Anopheles cecropins are playing roles in adult mosquito immunity. We have identified and characterized a novel Anopheles gambiae cecropin, cecropin D (CecD), that is uniquely produced and immune-responsive at late larval stages to promote broad spectrum microbial clearance during larval-pupal developmental transition. Interestingly, Cecropin D also shows potent activity against Plasmodium falciparum sporozoites, the malaria parasite stage that is transmitted from mosquitoes to humans and could therefore be developed into a malaria control strategy. [ABSTRACT FROM AUTHOR]

Background: Despite the application of various tools for the control of vectors of Plasmodium falciparum, malaria remains the major killer disease in sub-Saharan Africa accounting for up to 90% of deaths due to the disease. Due to limitations of the useage of chemical insecticides such as resistance, negative impact on the environment and to nontarget organisms, the World Health Organization (WHO) requires that affected countries find alternative vector control tools. This study evaluated the effectiveness of (+)-usnic acid (UA) as an insecticide through oral administration to male and female Anopheles gambiae as an alternative or additional active ingredient to be used in toxic sugar bait. Methods: (+)-usnic acid was diluted using acetone at 5, 10, and 15 mg/ml concentrations in three replicates. A 5 ml mixture of 2% food dye and 10% sugar using chlorine-free water mixed with the dilutions of the (+)-usnic acid and negative control was made containing 2% food dye and 10% sugar solution. The preparations were soaked on a ball of cotton wool and placed over the net of a cup. 5 male and 5 non-blood-fed female newly hatched starved An. gambiae Kisumu strain were introduced together into a cup and monitored for knockdown and mortalities after 4, 24 48, and 72 h. The data were analysed using a multiple linear regression model using the lm function, a base R function and a posthoc test were conducted on the significant main effects and interaction terms using the emmeans function from the emmeans R package. All analyses were performed in RStudio using base R (version 4.3.3). Results: There was high mortality of both male and female An. gambiae after ingestion of the toxic sugar bait. 15 mg/ml usnic acid caused the highest mortality (50%) within the first 4 h compared to 5 and 10 mg/ml (+)-UA. There was a decline in the mortality rate with increased exposure time from 24 to 72 h, however, there was a significant difference in mortality at 5, 10 and 15 mg/ml. Acute toxicity was associated with ingestion of 15 mg/ml after 24 h. 72 h post-mortality was lower in all concentrations than in the control. High mortality was observed among females over the first 4 h (60%) compared to males (40%) due to higher feeding rate of the toxic agent. The proportion of dead males and females was equal after 24 h while after 48 h, the proportion of dead males was high.There was a significantly lower mortality rate after 72 h for both males and females (0 to 13.3%). Compared to all the treatments, high mortality of males was observed. Conclusions: The results of this study indicate that (+)-UA when administered as oral sugar bait to An. gambiae has insecticidal properties and is a suitable ingredient to be used as a toxic agent in the novel attractive toxic sugar bait for the control of malaria vectors. (+)-UA may be an alternative active ingredient as toxic bait in the effort to reduce and eliminate the transmission of Plasmodium falciparum in Africa. [ABSTRACT FROM AUTHOR]

This study delves into the often‐overlooked impact of immature mosquitoes on the dynamics of malaria transmission. By employing a mathematical model, we explore how these aquatic stages of the vector shape the spread of the disease. Our analytical findings are corroborated through numerical simulations conducted using the Runge–Kutta fourth‐order method in MATLAB. Our research highlights a critical factor in malaria epidemiology: the basic reproduction number R0. We demonstrate that when R0 is below unity R0<1, the disease‐free equilibrium exhibits local asymptotic stability. Conversely, when R0 surpasses unity R0>1, the disease‐free equilibrium becomes unstable, potentially resulting in sustained malaria transmission. Furthermore, our analysis covers equilibrium points, stability assessments, bifurcation phenomena, and sensitivity analyses. These insights shed light on essential aspects of malaria control strategies, offering valuable guidance for effective intervention measures. [ABSTRACT FROM AUTHOR]

Background: Plasmodium knowlesi, identified as the fifth human malaria parasite, has rapidly spread across various Southeast Asian countries, yet uncertainties persist regarding its human-mosquito-human transmission. Therefore, this study aims to explore the transmission potential of P. knowlesi from human blood to mosquitoes. Methods: A direct membrane-feeding assay was conducted by infecting laboratory-reared female Anopheles dirus mosquitoes with P. knowlesi-infected human blood from a single patient presenting with febrile malaria. Mosquitoes were dissected 7 days post-infection under a stereomicroscope to detect oocysts in the midgut, stained with mercurochrome. Salivary glands were examined 14 days post-infection for the presence of sporozoites. Malaria diagnosis employed microscopy by expert microscopists and nested PCR assays. Results: Upon dissecting 745 out of 1439 blood-fed An. dirus mosquitoes on day 7 post-infection, two oocysts were identified in the midguts of two mosquitoes (0.27%). An additional 694 mosquitoes were dissected for salivary glands on day 14 post-infection, with three mosquitoes (0.43%) exhibiting sporozoites. Further confirmation by nested-PCR assay verified these sporozoites as belonging to the P. knowlesi species. Conclusions: The findings underscore the potential transmission of P. knowlesi from human blood to mosquitoes. The significance of these findings necessitates further investigation, such as repeating similar experiments among natural vectors, to gain deeper insights into the transmission dynamics of P. knowlesi in Southeast Asia. [ABSTRACT FROM AUTHOR]

Accurate species identification of the mosquitoes in the genus Anopheles is of crucial importance to implement malaria control measures and monitor their effectiveness. We use a previously developed amplicon panel (ANOSPP) that retrieves sequence data from multiple short nuclear loci for any species in the genus. Species assignment is based on comparison of samples to a reference index using k-mer distance. Here, we provide a protocol to generate version controlled updates of the reference index and present its latest release, NNv2, which contains 91 species, compared to 56 species represented in its predecessor NNv1. With the updated reference index, we are able to assign samples to species level that previously could not be assigned. We discuss what happens if a species is not represented in the reference index and how this can be addressed in a future update. To demonstrate the increased power of NNv2, we showcase the assignments of 1789 wild-caught mosquitoes from Madagascar and demonstrate that we can detect within species population structure from the amplicon sequencing data. [ABSTRACT FROM AUTHOR]

Iranian mosquitoes (Diptera: Culicidae) include 73 species across eight genera. The fauna of mosquitoes in Guilan Province comprises 34 species classified into seven genera. A faunistic study of mosquitoes was conducted with emphasis on an aggressive biter mosquito reported by local people in Anzali and Rasht Cities of Guilan Province, northern Iran. Collections were made by hand catches using manual aspirators, light traps, BG lure traps and ovitraps during August-November 2023 in all 17 counties of the province. Species identification was carried out using morphological keys and molecular analysis of the barcode region of the cytochrome c oxidase subunit I (COI) gene. In total, 29 larvae and 896 adult specimens were collected which were not recognized as a species previously known to occur in the province. The aggressive biter mosquito was morphologically identified as Aedes albopictus (Skuse, 1895). The sequences of the barcode region of the COI gene of the species were generated for the first time in the country. This species was collected in 14 counties of the province. Thus, the mosquito fauna of Guilan Province increased to 35 species. [ABSTRACT FROM AUTHOR]

Simple Summary: Biting hematophagous dipterans are responsible for painful bites and blood spoliation; they induce behavioral modifications, anemia, and significant production losses in cattle. A feedlot of 100 feeder cattle would register a total loss of USD 16,000 within 5 months, which appears to be an unexpectedly huge loss caused by dipterans. Investing part of this money in fly control would probably be beneficial. In addition to blood pathogen transmission, insects of the order Diptera affect livestock through visual and contact harassment; blood-feeders are responsible for painful bites and blood despoliation, generating behavioral modifications, anemia, and production losses. Knowledge of their economic impact is a basis for cost-effective control. Here, we measured the global impact of diptera insects by comparing two batches of six feeder cattle, one in the open air and the other protected by a mosquito net. The analytical data were insect density in the open air and, for feeder cattle, tail flick counts, hematocrit values (Ht), feed intake, feed conversion ratio (FCR), and live body weight gain (LBWG). Over a period of five months, the results showed significant losses in the LBWG of cattle exposed to insects, estimated at 8.0 ± 1.5 kg/month [2.7; 13.3], with a total loss reaching 40.0 ± 5.5 kg/head. Main diurnal insects were Stomoxys spp. and Musca crassirostris. There was a strong correlation between fly density and diurnal tail flicks. Night trapping and tail flicks showed a potentially important role of mosquitoes to be further explored. The Ht levels of exposed animals were 3–4% lower than those of controls. FCRs indicated that exposed animals needed 33% more dry matter intake/kg of LBWG. An economic assessment showed that dipterans were responsible for a 10–11% loss in LBWG during the main growing period of feeder cattle (10–15 months). A feedlot of 100 calves would register a total loss of USD 16,000 within 5 months, which appears to be an unexpectedly huge loss caused by dipterans. Investing part of this money into fly control would probably be beneficial. [ABSTRACT FROM AUTHOR]

Orthoflaviviruses are arthropod-borne viruses that are transmitted by mosquitoes or ticks and cause a range of significant human diseases. Among the most important tick-borne orthoflaviviruses (TBFVs) is tick-borne encephalitis virus (TBEV), which is endemic in Eurasia, and Powassan virus, which is endemic in Asia and North America. There is a significant controversy regarding species assignment in the tick-borne encephalitis virus complex due to the complex phylogenetic, serological, ecological, and pathogenetic properties of viruses. Comparing the rate of non-synonymous to synonymous substitutions (dN/dS) over the course of tick-borne orthoflavivirus diversification suggests that there is a very strong stabilizing selection (Nei-Gojobori dN/dS < 0.1) among tick-borne orthoflaviviruses that differ by less than 13.5% amino acid/21.4% nucleotide sequences, and discretely more rapid accumulation of non-synonymous substitutions (dN/dS > 0.13) among more divergent viruses that belong to distinct species. This pattern was similarly observed in genome regions encoding structural (E) and non-structural (NS3) proteins. Below this distance threshold, viruses appear fit and strongly tied to their ecological niche, whereas above the threshold, a greater degree of adaptation appears necessary. This species criterion suggests that all subtypes of TBEV, all related ovine/caprine encephalomyelitis viruses, and Omsk hemorrhagic fever virus (OHFV) together correspond to a single species. Within this species, viruses make up 11 subtypes that are reliably segregated by a 10% nucleotide distance cut-off suggested earlier for TBEV. The same 10% subtype cut-off suggests that Powassan virus includes two subtypes, Powassan and Deer Tick virus. [ABSTRACT FROM AUTHOR]

Background: Surveillance of the host–anopheline mosquitoes' interaction is important for assessing malaria transmission risk and guiding vector control. We assume that changes in malaria vector species' feeding habits, as well as the surrounding environment, have a substantial impact on varied malaria transmission. In this study, we determined the vertebrate host feeding patterns of anopheline mosquitoes to characterize entomologic risk factors for malaria in Jabi Tehnan, Northwestern Ethiopia. Methods: Blood-fed anophelines surveyed during malaria surveillance in Jabi Tehnan district of northwestern Ethiopia were utilized in this study. They were collected using Centers for Disease Control and Prevention (CDC) light traps deployed in selected households per village, placed indoors and outdoors, spanning three agroecological settings (dry mountain, plateau, and semiarid highlands) between June 2020 and May 2021. The engorged mosquitoes were analyzed for host blood meal sources and Plasmodium infection via polymerase chain reaction (PCR) and/or sequencing. Infection rates and bovine and human blood indices were calculated and compared for abundant species; between indoors and outdoors and between agroecology using a chi-squared test for equality of proportion in R package at a significant level of p ≤ 0.05. Results: A total of 246 mosquitoes were successfully typed (indoor, 121; outdoor, 125), with greater relative abundance indoors in mountain and plateau highlands, and outdoors in semiarid areas. Despite ecological differences in blood-fed capture rates, cattle served as the most utilized blood meal source by 11 anopheline species with an overall bovine blood index (BBI) of 74.4%. This trend was dictated by Anopheles gambiae s.l. (198/246; BBI = 73.7%), which exhibited the most plastic feeding habits that included humans (human blood index = 15.7%) and other livestock and rodents. A total of five anopheline species (An. gambiae s.l., An. funestus s.l., An. coustani s.l., An. pretoriensis, and An. pharoensis) fed on humans, of which the first three were found infected with Plasmodium parasites. Most of the infected specimens were An. arabiensis (5.6%, 11/198) and had recently fed mainly on cattle (72.7%, 8/11); one each of infected An. funestus s.l. and An. coustani s.l. had fed on humans and cattle, respectively. Conclusions: The results demonstrate communal feeding on cattle by anophelines including primary and secondary malaria vectors. This study also indicates the importance of cattle-targeted interventions for sustainable control of malaria vectors in the study areas. [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]

The RNA genome of orthoflaviviruses encodes a methyltransferase within the non-structural protein NS5, which is involved in 2'-O-methylation of the 5'-terminal nucleotide of the viral genome resulting in a cap1 structure. While a 2'-O-unmethylated cap0 structure is recognized in vertebrates by the RNA sensor RIG-I, the cap1 structure allows orthoflaviviruses to evade the vertebrate innate immune system. Here, we analyzed whether the cap0 structure is also recognized in mosquitoes. Replication analyses of 2'-O-methyltransferase deficient yellow fever virus mutants (YFV NS5-E218A) of the vaccine 17D and the wild-type Asibi strain in mosquito cells revealed a distinct downregulation of the cap0 viruses. Interestingly, the level of inhibition differed for various mosquito cells. The most striking difference was found in Aedes albopictus-derived C6/36 cells with YFV-17D cap0 replication being completely blocked. Replication of YFV-Asibi cap0 was also suppressed in mosquito cells but to a lower extent. Analyses using chimeras between YFV-17D and YFV-Asibi suggest that a synergistic effect of several mutations across the viral genome accompanied by a faster initial growth rate of YFV-Asibi cap1 correlates with the lower level of YFV-Asibi cap0 attenuation. Viral growth analyses in Dicer-2 knockout cells demonstrated that Dicer-2 is entirely dispensable for attenuating the YFV cap0 viruses. Translation of a replication-incompetent cap0 reporter YFV-17D genome was reduced in mosquito cells, indicating a cap0 sensing translation regulation mechanism. Further, oral infection of Aedes aegypti mosquitoes resulted in lower infection rates for YFV-Asibi cap0. The latter is related to lower viral loads found in the midguts, which largely diminished dissemination to secondary tissues. After intrathoracic infection, YFV-Asibi cap0 replicated slower and to decreased amounts in secondary tissues compared to YFV-Asibi cap1. These results suggest the existence of an ubiquitously expressed innate antiviral protein recognizing 5'-terminal RNA cap-modifications in mosquitoes, both in the midgut as well as in secondary tissues. Author summary: Arthropod-borne viruses infect both mosquito and vertebrate hosts. One factor influencing the level of viral replication in the host is the ability of the virus to evade or counteract the host's immune system. In vertebrates, it was shown that orthoflaviviruses circumvent the innate immune system by capping their viral genome with a cap1 structure characterized by 2'-O-methylation of the 5'-terminal nucleotide. In contrast, viral genomes lacking 2'-O-methylation (cap0) are recognized as foreign and activate the vertebrate innate immune system. Here, we used yellow fever virus (YFV) strain 17D and Asibi mutants lacking 2'-O-methylation, as well as a cap0 reporter YFV genome, to analyze cap0 recognition in mosquito cells and living mosquitoes. The replication of the YFV cap0 mutants was profoundly impaired in different mosquito cells and cap0 YFV genomes showed reduced translation levels. Based on viral infection experiments in Aedes aegypti mosquitoes, we further demonstrate that these vector mosquitoes recognize the cap0 structure and that a potential recognizing effector protein is localized in the midgut as well as in secondary tissues. Our findings provide the basis for future studies investigating the recognition of foreign RNAs in mosquitoes and should contribute to establish methods to prevent transmission of arboviruses. [ABSTRACT FROM AUTHOR]

Phylogenetic analyses showed that the virus responsible for a May 2024 Oropouche fever outbreak in Cuba was closely related to viruses from Brazil in 2023. Pools of Ceratopogonidae spp. biting midges and Culex quinquefasciatus mosquitoes were positive for Oropouche viral RNA. No cases were severe. Virus extension to new areas may increase case numbers and severity [ABSTRACT FROM AUTHOR]

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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]

The global distribution of Aedes aegypti mosquitoes, particularly in tropical regions, poses a significant public health risk due to their apparent ability to transmit arboviruses such as West Nile virus (WNV). This study aimed to evaluate the vector competence of Ae. aegypti from São Tomé and Príncipe (STP) for the transmission of the WNV PT6.39 strain, considering its potential role as a bridge vector in a region where Culex quinquefasciatus would be the main vector. Aedes aegypti mosquitoes were collected, reared, and experimentally infected with WNV, with viral dissemination and transmission potential assessed 7, 14, and 21 days post infection (dpi). The results showed an increasing trend in infection rates, from 5% at 7 dpi to 35% at 21 dpi, with corresponding dissemination rates of 0%, 100%, and 43%. The transmission rates also increased from 0% at 7 dpi to 67% at 21 dpi, with a maximum transmission efficiency of 10% observed at the final time point. Although Ae. aegypti from STP demonstrated the potential to transmit WNV, the overall transmission efficiency remained relatively low. These findings provide necessary insights into the vector competence of Ae. aegypti in this region, highlighting the importance of continued monitoring and targeted vector control measures to mitigate the risk of potential WNV outbreaks. [ABSTRACT FROM AUTHOR]

Wolbachia are the most spread bacterial endosymbionts in the world. These bacteria can manipulate host reproduction or block virus transmission in mosquitoes. For this reason, Wolbachia-based strategies for vector control are seriously considered or have already been applied in several countries around the world. In South America, Wolbachia have been studied in human pathogen vectors such as sand flies and mosquitoes. In French Guiana, the diversity and distribution of Wolbachia are not well known in mosquitoes. In this study, we screened for Wolbachia natural infection in mosquitoes in French Guiana by using 16S rRNA, Wolbachia surface protein (WSP), and multi-locus sequence typing (MLST) molecular assays. A total of 29 out of 44 (65.9%) mosquito species were positive for natural Wolbachia infection according to the PCR results, and two Wolbachia strains co-infected three specimens of Mansonia titillans. Then, we analyzed the phylogenetic relationships among the Wolbachia detected. All of the tested specimens of Aedes aegypti, the major dengue vector of French Guiana, were negative. These results regarding Wolbachia strain, distribution, and prevalence in mosquitoes from French Guiana highlight Wolbachia–mosquito associations and pave the way for a future Wolbachia-based strategy for vector control in this Amazonian territory. [ABSTRACT FROM AUTHOR]

This study presented the first sequencing and analysis of the mitochondrial genome of Paraclius curvispinus Yang and Saigusa, 2001, a predator fly belonging to the family Dolichopodidae (long-legged fly). The complete mitochondrial genome of P. curvispinus was 16,882 bp long (GenBank accession number: PP498802), which contained 13 protein-coding genes, 22 tRNAs, 2 rRNAs, and a control region. The nucleotide composition of mitochondrial genome of P. curvispinus was 38.48% of A, 36.00% of T, 10.67% of G, and 14.85% of C. Maximum-likelihood (ML) analysis revealed the phylogenetic relationships within the subfamily Dolichopodinae, suggesting the following grouping: ((Dolichopus + Lichtwardtia)+((Hercostomus + Poecilobothrus)+ Gymnopternus))+ Paraclius. This study provides a basis for discussing the evolution of mosquito larval predation habits of Dolichopodinae. [ABSTRACT FROM AUTHOR]

Mosquitoes serve as vectors for many arthropod-borne viruses (arboviruses) that are responsible for millions of human infections and thousands of deaths each year. Among these arboviruses, O'nyong-nyong virus (ONNV) is an African alphavirus mainly transmitted by Anopheles mosquitoes. ONNV can be detected through serological or molecular tests, the first showing cross-reactivity to co-circulating alphaviruses and requiring technically demanding confirmation, while the latter, usually based on real-time PCR, are costly and demand specific equipment. Isothermal amplification approaches, such as Loop-Mediated Isothermal Amplification (LAMP), should therefore provide a cost-effective, sensitive, and specific alternative for virus detection, suitable for the resource-limited regions where ONNV circulates up to the present time. Here, we describe the development and optimization of a rapid and highly sensitive (10 pfu/reaction) RT-LAMP assay for ONNV detection. Additionally, we demonstrate that it is possible to bypass the RNA extraction step, reducing sample handling time and costs. The final RT-LAMPONNV is a promising field detection tool for ONNV, enabling a better understanding of its impact and serving as a point-of-care diagnostic method. [ABSTRACT FROM AUTHOR]

Malaria is a major international public health problem. The risk of acquiring malaria varies depending on the intensity of transmission and adherence to mosquito precautions and prophylaxis recommendations. Severe malaria can cause significant multiorgan dysfunction, including acute kidney injury (AKI). Intravenous artesunate is the treatment of choice for severe malaria in non-endemic areas. One of the possible events connected with the lifesaving effects of artemisins is post-artesunate haemolysis (PADH), which may be potentially dangerous and under-recognised. We present a case of a seafarer with severe Plasmodium falciparum malaria complicated with AKI and PADH, with a good response to steroid treatment. This case highlights the need for malaria prophylaxis in business travellers, e.g., seafarers to malara-endemic regions, and close supervision of patients with malaria even after the completion of antimalarial treatment due to the possibility of late complications. [ABSTRACT FROM AUTHOR]

Abstract Isolation mechanisms between mosquito species of the Anopheles gambiae complex, which includes major malaria vectors, remain poorly understood. In some cases, pre-zygotic barriers have been shown to limit gene flow between species of the complex, leading to a low level of hybridisation in nature. Post-zygotic mechanisms manifest with F1 hybrid males fully sterile and F1 hybrid females with reduced fertility. Genetic approaches combined with DNA sequencing techniques have highlighted the involvement of genomic regions in hybrid incompatibility with a predominant role of the X chromosome. In addition, differences in the phenotype of F1 hybrid males have been identified depending on the directionality of the parental cross used to generate them. All these studies have focused on the interaction of nuclear DNA elements in hybrid individuals. Given the role that mitochondrial DNA plays in genetic incompatibilities within other organisms and its unique inheritance pattern, commonly maternal, we conducted a genetic study that relied on the introgression of mitochondrial DNA between Anopheles gambiae and Anopheles arabiensis. The findings indicate that the mitochondrial switch does not appear to restore the fertility of F1 hybrid males, suggesting that mitochondrial DNA may not play a role in hybrid incompatibilities in these Anopheles species.

Abstract Background Wolbachia incompatible insect technique (IIT) programs have been shown in field trials to be highly effective in suppressing populations of mosquitoes that carry diseases such as dengue, chikungunya, and Zika. However, the frequent and repeated release of Wolbachia-infected male mosquitoes makes such programs resource-intensive. While the need for optimization is recognized, potential strategies to optimize releases and reduce resource utilization have not been fully explored. Results We developed a process-based model to study the spatio-temporal metapopulation dynamics of mosquitoes in a Wolbachia IIT program, which explicitly incorporates climatic influence in mosquito life-history traits. We then used the model to simulate various scale-down and redistribution strategies to optimize the existing program in Singapore. Specifically, the model was used to study the trade-offs between the intervention efficacy outcomes and resource requirements of various release program strategies, such as the total number of release events and the number of mosquitoes released. We found that scaling down releases in existing sites from twice a week to only once a week yielded small changes in suppression efficacy (from 87 to 80%), while requiring 44% fewer mosquitoes and release events. Additionally, redistributing mosquitoes from already suppressed areas and releasing them in new areas once a week led to a greater total suppressive efficacy (83% compared to 61%) while also yielding a 16% and 14% reduction in the number of mosquitoes and release events required, respectively. Conclusions Both scale-down and redistribution strategies can be implemented to significantly reduce program resource requirements without compromising the suppressive efficacy of IIT. These findings will inform planners on ways to optimize existing and future IIT programs, potentially allowing for the wider adoption of this method for mosquito-borne disease control.

Background: The general purpose of this study was to investigate the species diversity and characteristics of the larval habitats of culicids in important tourism centers of Fars province to design a comprehensive program to control them.Methods: In a cross-sectional study conducted from April to the end of September 2021, the species diversity of mosquito larvae and the characteristics of larval habitats were investigated. Mosquito larvae were collected using the dipping method and the characteristics of larval habitats such as permanent or temporary habitat, water running, intensity of sunlight, vegetation, habitat floor, turbidity, natural or artificial were recorded according to the hydro ecological characteristics.Results: Totally, 8825 specimens were collected and identified from 9 selected locations in Marvdasht city and 6 selected locations in Maharloo wetland. Collected species were Culex pipiens (39.77%), Culex sinaiticus (3.80%), Culex quinquefasciatus (23.68%), Culiseta longiareolata (17.52%), Uranotaenia unguiculata (9.02%), and Anopheles stephensi (6.21%). Most specimens (79%) were collected from natural habitats. There is a significant difference between the number of collected mosquitoes with the permanent habitat, stagnant water, partial sunlight, vegetation, turbidity, and natural habitat (P

Abstract Mosquito associated virus have always been a significant threat to global health. Metagenomics offers a straightforward and quantitative means to acquire the information of novel virus and has greatly enriched the content of mosquito associated virus databases. During an entomological surveillance for arthropod-borne viruses in China, we identified a previously unrecognized virus from mosquitoes, temporarily named Huajieling virus. In this study, a total of 3,960 mosquitoes were collected and then divided into 91 pools, according to location and species. QRT-PCR and nested PCR were performed to confirm the presence of Huajieling virus. Its genomic features and phylogenetic relationships were further analyzed. Our results showed that Huajieling virus was detected in 7 of the 91 mosquito pools and that the minimum infection rate (MIR) was 0.18% (7/3,960). One complete genome sequence and 2 viral partial sequences were obtained from the Huajieling virus-positive pools. Pairwise distances analysis indicated that these amplified sequences shared high nucleotide identity. Phylogenetic analysis demonstrated that Huajieling virus is most closely related to Wufeng shrew picorna-like virus 43, which belonging to Picornavirales. Further analyses indicated that Huajieling virus is a new member of unclassified Picornavirales, and is intermediate between the family Caliciviridae and Secoviridae in taxonomic status.

Abstract Background Mosquitoes serve as vectors for numerous pathogens, posing significant health risks to humans and animals. Understanding the complex interactions within mosquito microbiota is crucial for deciphering vector-pathogen dynamics and developing effective disease management strategies. Here, we investigated the nested patterns of Wolbachia endosymbionts and Escherichia-Shigella within the microbiota of laboratory-reared Culex pipiens f. molestus and Culex quinquefasciatus mosquitoes. We hypothesized that Wolbachia would exhibit a structured pattern reflective of its co-evolved relationship with both mosquito species, while Escherichia-Shigella would display a more dynamic pattern influenced by environmental factors. Results Our analysis revealed different microbial compositions between the two mosquito species, although some microorganisms were common to both. Network analysis revealed distinct community structures and interaction patterns for these bacteria in the microbiota of each mosquito species. Escherichia-Shigella appeared prominently within major network modules in both mosquito species, particularly in module P4 of Cx. pipiens f. molestus, interacting with 93 nodes, and in module Q3 of Cx. quinquefasciatus, interacting with 161 nodes, sharing 55 nodes across both species. On the other hand, Wolbachia appeared in disparate modules: module P3 in Cx. pipiens f. molestus and a distinct module with a single additional taxon in Cx. quinquefasciatus, showing species-specific interactions and no shared taxa. Through computer simulations, we evaluated how the removal of Wolbachia or Escherichia-Shigella affects network robustness. In Cx. pipiens f. molestus, removal of Wolbachia led to a decrease in network connectivity, while Escherichia-Shigella removal had a minimal impact. Conversely, in Cx. quinquefasciatus, removal of Escherichia-Shigella resulted in decreased network stability, whereas Wolbachia removal had minimal effect. Conclusions Contrary to our hypothesis, the findings indicate that Wolbachia displays a more dynamic pattern of associations within the microbiota of Culex pipiens f. molestus and Culex quinquefasciatus mosquitoes, than Escherichia-Shigella. The differential effects on network robustness upon Wolbachia or Escherichia-Shigella removal suggest that these bacteria play distinct roles in maintaining community stability within the microbiota of the two mosquito species.

Abstract Background Despite the application of various tools for the control of vectors of Plasmodium falciparum, malaria remains the major killer disease in sub-Saharan Africa accounting for up to 90% of deaths due to the disease. Due to limitations of the useage of chemical insecticides such as resistance, negative impact on the environment and to nontarget organisms, the World Health Organization (WHO) requires that affected countries find alternative vector control tools. This study evaluated the effectiveness of ( +)-usnic acid (UA) as an insecticide through oral administration to male and female Anopheles gambiae as an alternative or additional active ingredient to be used in toxic sugar bait. Methods ( +)-usnic acid was diluted using acetone at 5, 10, and 15 mg/ml concentrations in three replicates. A 5 ml mixture of 2% food dye and 10% sugar using chlorine-free water mixed with the dilutions of the ( +)-usnic acid and negative control was made containing 2% food dye and 10% sugar solution. The preparations were soaked on a ball of cotton wool and placed over the net of a cup. 5 male and 5 non-blood-fed female newly hatched starved An. gambiae Kisumu strain were introduced together into a cup and monitored for knockdown and mortalities after 4, 24 48, and 72 h. The data were analysed using a multiple linear regression model using the lm function, a base R function and a posthoc test were conducted on the significant main effects and interaction terms using the emmeans function from the emmeans R package. All analyses were performed in RStudio using base R (version 4.3.3). Results There was high mortality of both male and female An. gambiae after ingestion of the toxic sugar bait. 15 mg/ml usnic acid caused the highest mortality (50%) within the first 4 h compared to 5 and 10 mg/ml ( +)-UA. There was a decline in the mortality rate with increased exposure time from 24 to 72 h, however, there was a significant difference in mortality at 5, 10 and 15 mg/ml. Acute toxicity was associated with ingestion of 15 mg/ml after 24 h. 72 h post-mortality was lower in all concentrations than in the control. High mortality was observed among females over the first 4 h (60%) compared to males (40%) due to higher feeding rate of the toxic agent. The proportion of dead males and females was equal after 24 h while after 48 h, the proportion of dead males was high.There was a significantly lower mortality rate after 72 h for both males and females (0 to 13.3%). Compared to all the treatments, high mortality of males was observed. Conclusions The results of this study indicate that ( +)-UA when administered as oral sugar bait to An. gambiae has insecticidal properties and is a suitable ingredient to be used as a toxic agent in the novel attractive toxic sugar bait for the control of malaria vectors. ( +)-UA may be an alternative active ingredient as toxic bait in the effort to reduce and eliminate the transmission of Plasmodium falciparum in Africa.

Background Three types of equine encephalitis virus circulate in the Americas: Eastern equine encephalitis virus (EEEV), Western equine encephalitis virus (WEEV), and Venezuelan equine encephalitis virus (VEEV). These 3 related, [...]

In this paper, we establish and study a stochastic mosquito population suppression model incorporating the release of Wolbachia -infected males and time switching, where stochastic noises are given by independent standard Brownian motions. By combining the actual mosquito control strategy in Guangzhou, we assume that the waiting release period T between two consecutive releases of Wolbachia -infected males is less than the sexually active lifespan T ‾ of them. The existence and uniqueness of global positive solutions and stochastically ultimate boundedness for the stochastic model are obtained. Some sufficient conditions for the extinction and the existence of stochastic non-trivial periodic solutions are established. Furthermore, we assume that the release function is a general periodic function and some stochastic dynamical behaviors are obtained. Numerical examples are presented to illustrate the theoretical results. [ABSTRACT FROM AUTHOR]

Mosquitoes of the genus Aedes are the most important arthropod disease vector. Dengue virus (DENV) and Chikungunya virus (CHIKV) are the main arboviruses distributed throughout the world. Based on entomo-virological surveillance, appropriate public health strategies can be adopted to contain cases and control outbreaks. This study aims to show the potential performance of two new molecular methods for detecting DENV serotypes and CHIKV in mosquitoes. Mosquitoes were collected in urban and sylvatic areas of Bobo-Dioulasso, Burkina Faso, between July and August 2023. DENV and CHIKV were screened using new multiplex RT-PCR and RT-qPCR methods. A total of 2150 mosquitoes were trapped, consisting of 976 Aedes (959 Ae. aegypti, 6 Ae. furcifer, and 11 Ae. vittatus) and 1174 Culex sp. These were grouped into 39 pools, with each pool containing a maximum of 30 mosquitoes. Molecular screening revealed that 7.7% (3/39) of the pools were positive for DENV. Specifically, DENV-1 was detected in one pool (1/3), and DENV-3 was found in two pools (2/3). All pools tested negative for CHIKV. The overall minimum infection rate (MIR) of DENV in this study was 3.07 (95% CI: 2.24–19.86). This study shows the usefulness of our new molecular tools for the surveillance of DENV serotypes and CHIKV.

Abstract Background The core vector control tools used to reduce malaria prevalence are currently long-lasting insecticidal nets (LLINs), and indoor residual spraying (IRS). These interventions are hindered by insecticide resistance and behavioural adaptation by malaria vectors. Thus, for effective interruption of malaria transmission, there is a need to develop novel vector control interventions and technologies to address the above challenges. Larviciding using drones was experimented as an innovative tool that could complement existing indoor interventions to control malaria. Methods A non-randomized larviciding trial was carried out in irrigated rice fields in sub-urban Kigali, Rwanda. Potential mosquito larval habitats in study sites were mapped and subsequently sprayed using multirotor drones. Application of Bacillus thuringiensis var. israelensis (Bti) (Vectobac® WDG) was followed by entomological surveys that were performed every two weeks over a ten-month period. Sampling of mosquito larvae was done with dippers while adult mosquitoes were collected using CDC miniature light traps (CDC-LT) and pyrethrum spraying collection (PSC) methods. Malaria cases were routinely monitored through community health workers in villages surrounding the study sites. Results The abundance of all-species mosquito larvae, Anopheles larvae and all-species pupae declined by 68.1%, 74.6% and 99.6%, respectively. Larval density was reduced by 93.3% for total larvae, 95.3% for the Anopheles larvae and 61.9% for pupae. The total adult mosquitoes and Anopheles gambiae sensu lato collected using CDC-Light trap declined by 60.6% and 80% respectively. Malaria incidence also declined significantly between intervention and control sites (U = 20, z = − 2.268, p = 0.023). Conclusions The larviciding using drone technology implemented in Rwanda demonstrated a substantial reduction in abundance and density of mosquito larvae and, concomitant decline in adult mosquito populations and malaria incidences in villages contingent to the treatment sites. The scaling up of larval source management (LSM) has to be integrated in malaria programmes in targeted areas of malaria transmission in order to enhance the gains in malaria control.

Abstract Mosquito-borne diseases are a major global health threat. Traditional morphological or molecular methods for identifying mosquito species often require specialized expertise or expensive laboratory equipment. The use of convolutional neural networks (CNNs) to identify mosquito species based on images may offer a promising alternative, but their practical implementation often remains limited. This study explores the applicability of CNNs in classifying mosquito species. It compares the efficacy of body and wing depictions across three image collection methods: a smartphone, macro-lens attached to a smartphone and a professional stereomicroscope. The study included 796 specimens of four morphologically similar Aedes species, Aedes aegypti, Ae. albopictus, Ae. koreicus and Ae. japonicus japonicus. The findings of this study indicate that CNN models demonstrate superior performance in wing-based classification 87.6% (95% CI: 84.2–91.0) compared to body-based classification 78.9% (95% CI: 77.7–80.0). Nevertheless, there are notable limitations of CNNs as they perform reliably across multiple devices only when trained specifically on those devices, resulting in an average decline of mean accuracy by 14%, even with extensive image augmentation. Additionally, we also estimate the required training data volume for effective classification, noting a reduced requirement for wing-based classification compared to body-based methods. Our study underscores the viability of both body and wing classification methods for mosquito species identification while emphasizing the need to address practical constraints in developing accessible classification systems. Graphical abstract

In the current study, the effect of lethal concentrations of drug solutions and chemicals against pupae of Culex pipiens molestus mosquitoes was investigated after 24 hours and up to 3 days of the experiment using different concentrations. Regarding the drug solutions, the concentration of 100 ppm of the niclosamide drug solution showed a 100% lethal effect on the second day of the experiment, and the value of LC50 was 113.7 ppm. The concentration of 800 ppm of the sulfasalazine drug solution caused the death of all the pupa, with a death rate of 100% on the third day of the experiment, and the value of LC50 was 854.7 ppm. The concentration of 2000 ppm for both piperazine and isoniazid medicinal solutions caused a death rate of 100% on the second and third day of the experiment, respectively, and the LC50 value for both piperazine and isoniazid was 2220.7 and 2273.0 ppm, respectively. The concentration of 14,000 ppm of the drug solution 4-aminoantipyrine caused the death of all pupal mosquitoes on the second day of the experiment, and the value of LC50 was 14,360.0 ppm. As for solutions of chemicals, the concentration of 150 ppm of the chemical solution ethyl salicylate showed a lethal effect on all pupal mosquitoes, with a 100% death rate on the second day of the experiment, and the value of LC50 was 176.2 ppm. The death rate of mosquito pups reached 100% when using chemical solutions of thymol, sulfamic acid, sulfanilamide, and 2,6-dihydroxytoluene at concentrations of 240, 2000, 2500 and 10,000 ppm, respectively. The value of LC50 for each of thymol and sulfamic acid was, Sulfanilamide and 2,6-dihydroxytoluene 352.1, 2940.8, 2582.5 and 10750.0 ppm, respectively.

Abstract Humans have greatly altered earth’s terrestrial water cycle with the majority of fresh water being used for agriculture. Irrigation changes spatial and temporal water availability and alters mosquito abundance and phenology. Previous studies evaluating the effect of irrigation on mosquito abundance and mosquito-borne disease have shown inconsistent results and little is known about the effect of irrigation on variability in mosquito abundance. We examined the effect of irrigation, climate and land cover on mosquito abundance and human West Nile virus (WNV) disease cases across California. Irrigation made up nearly a third of total water inputs, and exceeded precipitation in some regions. Abundance of two key vectors of several arboviruses, including WNV, Culex tarsalis and the Culex pipiens complex, increased 17–21-fold with irrigation. Irrigation reduced seasonal variability in C. tarsalis abundance by 36.1%. Human WNV incidence increased with irrigation, which explained more than a third (34.2%) of the variation in WNV incidence among California counties. These results suggest that irrigation can increase and decouple mosquito populations from natural precipitation variability, resulting in sustained and increased disease burdens. Shifts in precipitation due to climate change are likely to result in increased irrigation in many arid regions which could increase mosquito populations and disease.

Culex interrogator is a culicid species that has recently been reported in the insular Caribbean, first in Cuba, specifically in the province of Santiago de Cuba, and shortly afterward in the Dominican Republic. This study’s objective is to report for the first time the presence of Cx. interrogator in the Cuban province of Camagüey and investigate its larval breeding sites in the urban environment. In 2022, visual inspections were conducted in all dwellings and facilities in the municipality of Camagüey, including intra- and peridomiciliary areas in the urban and suburban regions. In each positive mosquito reservoir, as many larvae and pupae as possible were collected. A total of 30 samples positive for Cx. interrogator (n = 155 larvae) were collected from 13 types of reservoirs. Ditches were the most frequent reservoir with the species present (n = 8; 26.66%), followed by ground-level tanks and sewage pits (n = 4; 13.33% each). All positive reservoirs were located in outdoor areas of dwellings. The discovery of this mosquito species in Camagüey, with many unknown aspects of its role as a vector, highlights the need for close monitoring and in-depth study.

Abstract Due to limitations in conventional disease vector control strategies including the rise of insecticide resistance in natural populations of mosquitoes, genetic control strategies using CRISPR gene drive systems have been under serious consideration. The identification of CRISPR target sites in mosquito populations is a key aspect for developing efficient genetic vector control strategies. While genome-wide Cas9 target sites have been explored in mosquitoes, a precise evaluation of target sites focused on coding sequence (CDS) is lacking. Additionally, target site polymorphisms have not been characterized for other nucleases such as Cas12a, which require a different DNA recognition site (PAM) and would expand the accessibility of mosquito genomes for genetic engineering. We undertook a comprehensive analysis of potential target sites for both Cas9 and Cas12a nucleases within the genomes of natural populations of Anopheles gambiae and Aedes aegypti from multiple continents. We demonstrate that using two nucleases increases the number of targets per gene. Also, we identified differences in nucleotide diversity between North American and African Aedes populations, impacting the abundance of good target sites with a minimal degree of polymorphisms that can affect the binding of gRNA. Lastly, we screened for gRNAs targeting sex-determination genes that could be widely applicable for developing field genetic control strategies. Overall, this work highlights the utility of employing both Cas9 and Cas12a nucleases and underscores the importance of designing universal genetic strategies adaptable to diverse mosquito populations.

Background: The efficacy of vector control tools depends on the behavior of the vector species. Many studies have sought to determine the feeding behavior of Anopheles mosquitoes in different settings of Ethiopia. We have performed a systematic review aimed to generate pooled evidence on the overall and species-specific blood meal sources of Anopheles mosquitoes in Ethiopia. Methods: A search for relevant articles was performed in two electronic databases (PubMed and Science Direct) and three search engines (Google Scholar, Research Gate and Google) between 11 March and 2 April 2024. Following the initial identification of articles, we used EndNote X8 software and removed duplicate articles and screened the remaining articles by careful reading of their titles and abstracts. The full text of articles that passed this screening phase was retrieved, read and evaluated against predetermined selection criteria. The final decision for inclusion in the systematic review was made after a methodological quality check using the JBI critical appraisal checklist. All relevant data were extracted from tables, figures and texts of the included articles using a premade template in Excel, and the data were analyzed using Stata version 14 software. Results: Of the 2431 studies identified, 27 met the inclusion criteria; all were published between 1997 and 2024. At 215 data points (frequency of tests of each Anopheles species by location and method of mosquito collections), 18,771 Anopheles mosquitoes belonging to 23 species or species complexes were tested for blood meal sources. The commonest sources of blood meals for Anopheles mosquitoes were bovine (36.0%, n = 6758) and human (29.4%, n = 5520). Among the tested anophelines, Anopheles (An.) arabiensis accounted for 67.9% (n = 12,741), followed by An. pharoensis, An. demeilloni and An. stephensi at 10.0%, 5.6% and 4.4%, respectively. Overall, there was no difference in the mean proportion of An. arabiensis detected with domestic animal blood (33.4%, 95% confidence interval [CI] 32.4–34.4%) and those detected with human blood (31.8%, 95% CI 30.9–32.8%). However, a greater proportion of the outdoor collected An. arabiensis were found to feed on bovines (47.9%, 95% CI 35.3–60.6) compared to humans (12.9%, 95% CI 0.8–24.9, P < 0.01). The foraging ratio (FR), which accounts for host availability, was greater for bovines (FR = 0.7) than for humans (FR = 0.2) for An. arabiensis, indicating preferential feeding on bovine hosts. This host preference was supported by the host preference index (human:bovine = 0.4). Anopheles pharoensis was detected with a slightly higher human blood index (53.5%, n = 1005) compared to bovine blood index (45.2%, n = 849). In contrast, An. demeilloni, An. coustani and An. marshalli were detected with a higher bovine blood index. Recently invaded urban malaria vector, An. stephensi was found with a higher ovine blood index. Conclusions: Bovine and human hosts are common sources of a blood meal for Anopheles mosquitoes. In terms of host availability, An. arabiensis showed preferential feeding on bovines/cattle. Targeting domestic animals, bovines and ovines with endectocides could supplement current vector control interventions. Study registration: The protocol of this study was registered on the International Prospective Register of Systematic Reviews, registration no. CRD42024515725. [ABSTRACT FROM AUTHOR]

Background: The core vector control tools used to reduce malaria prevalence are currently long-lasting insecticidal nets (LLINs), and indoor residual spraying (IRS). These interventions are hindered by insecticide resistance and behavioural adaptation by malaria vectors. Thus, for effective interruption of malaria transmission, there is a need to develop novel vector control interventions and technologies to address the above challenges. Larviciding using drones was experimented as an innovative tool that could complement existing indoor interventions to control malaria. Methods: A non-randomized larviciding trial was carried out in irrigated rice fields in sub-urban Kigali, Rwanda. Potential mosquito larval habitats in study sites were mapped and subsequently sprayed using multirotor drones. Application of Bacillus thuringiensis var. israelensis (Bti) (Vectobac® WDG) was followed by entomological surveys that were performed every two weeks over a ten-month period. Sampling of mosquito larvae was done with dippers while adult mosquitoes were collected using CDC miniature light traps (CDC-LT) and pyrethrum spraying collection (PSC) methods. Malaria cases were routinely monitored through community health workers in villages surrounding the study sites. Results: The abundance of all-species mosquito larvae, Anopheles larvae and all-species pupae declined by 68.1%, 74.6% and 99.6%, respectively. Larval density was reduced by 93.3% for total larvae, 95.3% for the Anopheles larvae and 61.9% for pupae. The total adult mosquitoes and Anopheles gambiae sensu lato collected using CDC-Light trap declined by 60.6% and 80% respectively. Malaria incidence also declined significantly between intervention and control sites (U = 20, z = − 2.268, p = 0.023). Conclusions: The larviciding using drone technology implemented in Rwanda demonstrated a substantial reduction in abundance and density of mosquito larvae and, concomitant decline in adult mosquito populations and malaria incidences in villages contingent to the treatment sites. The scaling up of larval source management (LSM) has to be integrated in malaria programmes in targeted areas of malaria transmission in order to enhance the gains in malaria control. [ABSTRACT FROM AUTHOR]