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Emerging Microbes & Infections (2017) 6, e91; doi:10.1038/emi.2017.86; published online 18 October 2017.

Residual demography is a recent concept that has proved to be a useful tool to gain insights about the age distributions of wild populations, especially insects. We develop an operator equation that permits the derivation of functionals of the age distribution in wild populations, such as mean age, within the framework of residual demography. Our method combines information from an observed captive cohort, which consists of subjects that are sampled from the wild with unknown ages and then raised in the laboratory until death, and from a reference cohort that consists of subjects raised in the laboratory since birth of the same population. Targeting functionals such as the mean of the wild age distribution has the advantage of avoiding strong assumptions such as stationarity and stability of the population that one would need when targeting the entire survival distribution in the wild. Our main result characterizes the existence of a solution of the operator equation that yields the functional of interest. The proposed method also enjoys straightforward and easy implementation. A data example is included illustrating an application, where one aims to attain the mean age of mosquitoes in the wild, based on seasonal captive cohorts from Greece and a simulated reference cohort, separately for various summer and fall months.

Zika virus (ZIKV) is a flavivirus that has recently been associated with an increased incidence of neonatal microcephaly and other neurological disorders. The virus is primarily transmitted by mosquito bite, although other routes of infection have been implicated in some cases. The Aedes aegypti mosquito is considered to be the main vector to humans worldwide; however, there is evidence that other mosquito species, including Culex quinquefasciatus, transmit the virus. To test the potential of Cx. quinquefasciatus to transmit ZIKV, we experimentally compared the vector competence of laboratory-reared Ae. aegypti and Cx. quinquefasciatus. Interestingly, we were able to detect the presence of ZIKV in the midgut, salivary glands and saliva of artificially fed Cx. quinquefasciatus. In addition, we collected ZIKV-infected Cx. quinquefasciatus from urban areas with high microcephaly incidence in Recife, Brazil. Corroborating our experimental data from artificially fed mosquitoes, ZIKV was isolated from field-caught Cx. quinquefasciatus, and its genome was partially sequenced. Collectively, these findings indicate that there may be a wider range of ZIKV vectors than anticipated.

In China, the prevention and control of Zika virus disease has been a public health threat since the first imported case was reported in February 2016. To determine the vector competence of potential vector mosquito species, we experimentally infected Aedes aegypti, Ae. albopictus, and Culex quinquefasciatus mosquitoes and determined infection rates, dissemination rates, and transmission rates. We found the highest vector competence for the imported Zika virus in Ae. aegypti mosquitoes, some susceptibility of Ae. albopictus mosquitoes, but no transmission ability for Cx. quinquefasciatus mosquitoes. Considering that, in China, Ae. albopictus mosquitoes are widely distributed but Ae. aegypti mosquito distribution is limited, Ae. albopictus mosquitoes are a potential primary vector for Zika virus and should be targeted in vector control strategies.

The effects of microbial biopesticides used for mosquito control on autotrophic microorganisms such as nanophytoplankton are equivocal. We examined impacts of mosquito biopesticides and mosquito larvae on primary producers in two independent experiments. In the first experiment, we examined the effects of a commonly used microbial biopesticide formulation (VectoMax® CG) on a unicellular microalga, Selenastrum capricornatum Printz, under axenic laboratory conditions. The biopesticide treatments included two concentrations (0.008 and 0.016 g liter-1 ) of VectoMax® CG and two controls (one untreated and another with autoclaved 0.016 g VectoMax® CG liter-1 ) in replicated axenic experimental microcosms. Spectrophotometric analysis of chlorophyll a (proxy for algal biomass) and direct enumeration of algal cells following the treatments revealed no significant effects of the microbial biopesticide on algal population growth during the four-week study. In the second experiment, we tested the effects of different densities of Culex larvae on the population of S. capricornatum. Effects of mosquito larvae feeding on S. capricornatum were significant with a curvilinear relationship between larval density and algal abundance in the water column. Together, these studies demonstrated a lack of direct cytological/toxicological effects of Bacillus-based microbial pesticides on freshwater primary production and support the hypothesis that the reduction in algal primary production previously reported when Bti products were applied to aquatic environments was likely independent of the Bacillus-based larvicidal toxins. Instead, it was likely mediated by microbial interactions in the water column and the trophic cascade effects that resulted from the removal of larval mosquitoes. These studies suggest that mosquito larvae independent of pesticide application can influence primary production. Our method of evaluating biopesticides against small photoautotrophs can be very useful for studying the unintended effects on autotrophic microorganisms of other pesticides, including herbicides and pesticides applied to aquatic environments.

The World Health Organization (WHO) recommends that people travelling to or living in areas with Zika virus (ZIKV) outbreaks or epidemics adopt prophylactic measures to reduce or eliminate mosquito bites, including the use of insect repellents. It is, however, unknown whether repellents are effective against ZIKV-infected mosquitoes, in part because of the ethical concerns related to exposing a human subject's arm to infected mosquitoes in the standard arm-in-cage assay. We used a previously developed, human subject-free behavioural assay, which mimics a human subject to evaluate the top two recommended insect repellents. Our measurements showed that DEET provided significantly higher protection than picaridin provided against noninfected, host-seeking females of the southern house mosquito, Culex quinquefasciatus, and the yellow fever mosquito, Aedes aegypti. When tested at lower doses, we observed a significant reduction in DEET-elicited protection against ZIKV-infected yellow fever mosquitoes from old and recent laboratory colonies. The reduction in protection is more likely associated with aging than the virus infection and could be compensated by applying a 5x higher dose of DEET. A substantial protection against ZIKV-infected and old noninfected mosquitoes was achieved with 5% DEET, which corresponds approximately to a 30% dose in the conventional arm-in-cage assays.

The effect of global climate change on infectious disease remains hotly debated because multiple extrinsic and intrinsic drivers interact to influence transmission dynamics in nonlinear ways. The dominant drivers of widespread pathogens, like West Nile virus, can be challenging to identify due to regional variability in vector and host ecology, with past studies producing disparate findings. Here, we used analyses at national and state scales to examine a suite of climatic and intrinsic drivers of continental-scale West Nile virus epidemics, including an empirically derived mechanistic relationship between temperature and transmission potential that accounts for spatial variability in vectors. We found that drought was the primary climatic driver of increased West Nile virus epidemics, rather than within-season or winter temperatures, or precipitation independently. Local-scale data from one region suggested drought increased epidemics via changes in mosquito infection prevalence rather than mosquito abundance. In addition, human acquired immunity following regional epidemics limited subsequent transmission in many states. We show that over the next 30 years, increased drought severity from climate change could triple West Nile virus cases, but only in regions with low human immunity. These results illustrate how changes in drought severity can alter the transmission dynamics of vector-borne diseases.

Venezuelan equine encephalitis (VEE) complex alphaviruses are important re-emerging arboviruses that cause life-threatening disease in equids during epizootics as well as spillover human infections. We conducted a comprehensive analysis of VEE complex alphaviruses by sequencing the genomes of 94 strains and performing phylogenetic analyses of 130 isolates using complete open reading frames for the nonstructural and structural polyproteins. Our analyses confirmed purifying selection as a major mechanism influencing the evolution of these viruses as well as a confounding factor in molecular clock dating of ancestors. Times to most recent common ancestors (tMRCAs) could be robustly estimated only for the more recently diverged subtypes; the tMRCA of the ID/IAB/IC/II and IE clades of VEE virus (VEEV) were estimated at ca. 149-973 years ago. Evolution of the IE subtype has been characterized by a significant evolutionary shift from the rest of the VEEV complex, with an increase in structural protein substitutions that are unique to this group, possibly reflecting adaptation to its unique enzootic mosquito vector Culex (Melanoconion) taeniopus. Our inferred tree topologies suggest that VEEV is maintained primarily in situ, with only occasional spread to neighboring countries, probably reflecting the limited mobility of rodent hosts and mosquito vectors.

The insect repellent N,N-diethyl-3-methylbenzamide (DEET), is a multimodal compound that acts as a spatial repellent as well as an irritant (contact repellent), thus being perceived by the insect's olfactory and gustatory systems as an odorant and a tastant, respectively. Soon after DEET was developed, almost 6 decades ago, it was reported that it reduced mosquito feeding on blood mixed with this repellent. It is now known that the mosquito proboscis senses contact repellents with the tips (labella) of the labium, which remain in direct contact with the outer layers of the skin, while the stylets, including the feeding deterrent sensor (labrum), penetrate the skin. We designed a behavioral assay that allowed us to measure feeding deterrence without complications from contact or spatial repellency. Using the southern house mosquito, Culex quinquefasciatus, we demonstrate here that when DEET was mixed with blood and covered by Parafilm® layers, the mean number of landings and duration of contacts with surfaces covering blood mixed with DEET or blood plus solvent (dimethyl sulfoxide) did not differ significantly thus implying that DEET did not leak to the outer surface. The feeding times, however, were significantly different. When blood was mixed either with 0.1 or 1% DEET, female southern house mosquitoes spent significantly (P

BackgroundAvian malaria vector competence studies are needed to understand more succinctly complex avian parasite-vector-relations. The lack of vector competence trials may be attributed to the difficulty of obtaining gametocytes for the majority of Plasmodium species and lineages. To conduct avian malaria infectivity assays for those Plasmodium spp. and lineages that are refractory to in vitro cultivation, it is necessary to obtain and preserve for short periods sufficient viable merozoites to infect naïve donor birds to be used as gametocyte donors to infect mosquitoes. Currently, there is only one described method for long-term storage of Plasmodium spp.-infected wild avian blood and it is reliable at a parasitaemia of at least 1%. However, most naturally infected wild-caught birds have a parasitaemia of much less that 1%. To address this problem, a method for short-term storage of infected wild avian blood with low parasitaemia (even ≤ 0.0005%) has been explored and validated.MethodsTo obtain viable infective merozoites, blood was collected from wild birds using a syringe containing the anticoagulant and the red blood cell preservative citrate phosphate dextrose adenine solution (CPDA). Each blood sample was stored at 4 °C for up to 48 h providing sufficient time to determine the species and parasitaemia of Plasmodium spp. in the blood by morphological examination before injecting into donor canaries. Plasmodium spp.--infected blood was inoculated intravenously into canaries and once infection was established, Culex stigmatosoma, Cx. pipiens and Cx. quinquefasciatus mosquitoes were then allowed to feed on the infected canaries to validate the efficacy of this method for mosquito vector competence assays.ResultsStorage of Plasmodium spp.--infected donor blood at 4 °C yielded viable parasites for 48 h. All five experimentally-infected canaries developed clinical signs and were infectious. Pathologic examination of three canaries that later died revealed splenic lesions typical of avian malaria infection. Mosquito infectivity assays demonstrated that Cx. stigmatosoma and Cx. pipiens were competent vectors for Plasmodium cathemerium.ConclusionsA simple method of collecting and preserving avian whole blood with malaria parasites of low parasitaemia (≤ 0.0005%) was developed that remained viable for further experimental bird and mosquito infectivity assays. This method allows researchers interested in conducting infectivity assays on target Plasmodium spp. to collect these parasites directly from nature with minimal impact on wild birds.

BackgroundClimate change is predicted to alter the transmission of many vector-borne pathogens. The quantitative impact of climate change is usually estimated by measuring the temperature-performance relationships for a single population of vectors, and then mapping this relationship across a range of temperatures or locations. However, life history traits of different populations often differ significantly. Specifically, performance across a range of temperatures is likely to vary due to local adaptation to temperature and other factors. This variation can cause spatial variation in pathogen transmission and will influence the impact of climate change on the transmission of vector-borne pathogens.MethodsWe quantified variation in life history traits for four populations of Culex pipiens (Linnaeus) mosquitoes. The populations were distributed along altitudinal and latitudinal gradients in the eastern United States that spanned ~3 °C in mean summer temperature, which is similar to the magnitude of global warming expected in the next 3-5 decades. We measured larval and adult survival, development rate, and biting rate at six temperatures between 16 and 35 °C, in a common garden experiment.ResultsTemperature had strong and consistent non-linear effects on all four life history traits for all four populations. Adult female development time decreased monotonically with increasing temperature, with the largest decrease at cold temperatures. Daily juvenile and adult female survival also decreased with increasing temperature, but the largest decrease occurred at higher temperatures. There was significant among-population variation in the thermal response curves for the four life history traits across the four populations, with larval survival, adult survival, and development rate varying up to 45, 79, and 84 % among populations, respectively. However, variation was not correlated with local temperatures and thus did not support the local thermal adaptation hypothesis.ConclusionThese results suggest that the impact of climate change on vector-borne disease will be more variable than previous predictions, and our data provide an estimate of this uncertainty. In addition, the variation among populations that we observed will shape the response of vectors to changing climates.

Mosquitoes transmit major human diseases, resulting in millions of fatalities each year and the development of chemical insecticide resistance, leading to a rebound in vectorial capacity. Plants could be used as a mosquito repellent alternative. The purpose of this study was to evaluate the biocontrol potentiality of ethyl acetate extract of fruit pericarp of Alangium salviifolium against Culex quinquefasciatus larvae. 100% larval mortality was recorded after 72 h of exposure with 50, 40 ppm, and 30 ppm concentrations of ethyl acetate extract against 3rd instar mosquito larvae. The bioactive compound responsible for larval mortality was isolated by TLC (Rf value of 0.33). 3rd instar larvae were found to be the most susceptible (LC50 = 3.60 ppm) among all the instars and corresponding LC50 values were 4.45 ppm and 4.52 ppm for 2nd and 4th instars larvae respectively after 72 h of exposure. The mortality rate of all larval instars was directly proportional to the concentration of bioactive compounds. Three-way ANOVA analysis revealed that larval instars, the concentration of bioactive compound, and time of exposure had a significant effect on larval mortality. In the bioactive TLC fraction of A. salviifolium (Rf value of 0.33), FT-IR spectroscopy analysis revealed the presence of numerous functional groups. GC-MS analysis revealed the presence of Benzoyl bromide and 3-Amino -5 (2-Furyl) Pyrazole in the extract. The compounds were also studied on non-target organisms such as Anisops sardea, 4th instar larvae of Chironomus sp. and Diplonychus annulatum, and in all the cases no abnormalities were recorded.

Mosquito borne diseases pose a significant health risk for humans. In North America, Culex mosquitoes are a major vector for several diseases including West Nile Virus and St. Louis Encephalitis. In many instances, models used to predict the spread of mosquito borne disease rely on a quantification of mosquito abundance. In our work, we present a novel age-structured partial differential equation model for simulating Culex mosquito abundance. The model is constructed using a system of two dimensional coupled advection reaction equations, in which the first dimension represents the age of the mosquitoes within a growth-stage population and the second dimension is time. We form six mosquito growth-stage populations by subdividing the mosquito life cycle into six stages: egg, larvae/pupae, and four adult gonotrophic cycles. Each growth-stage population is coupled through the boundary conditions on the age of the mosquito, which advances the population through its life cycle. The model also includes a population of diapausing adults represented using an ordinary differential equation. The solution curves for each equation provide the distribution of mosquitoes over time for each growth-stage population. This model provides information on the relative abundance of mosquitoes as well as the abundance of mosquitoes at specific ages. We simulate mosquito abundance for the Greater Ontario Area and compare the simulated adult abundance to mosquito trap count data. The model produces mosquito abundance patterns similar to those observed in trap count data. • Age-structured model for Culex mosquito abundance. • Explicit tracking of age of mosquitoes within growth stages. • Continuous diapausing function allowing for multiple year simulations. • Simulated abundance patterns are reasonable as compared to mosquito trap count data. [ABSTRACT FROM AUTHOR]

Culex gelidus (Diptera: Culicidae), an important vector of the Japanese encephalitis virus (JEV), contributes to human viral encephalitis in many Asian countries, including Thailand. This study represents the first investigation of the demographic patterns of Cx. gelidus populations in Thailand using cytochrome c oxidase subunit I (COI) gene analysis and wing geometric morphometrics (GM). Mosquitoes were collected from 10 provinces across six regions of Thailand in 2022. Analysis of the COI sequences (n = 182) indicated high haplotype diversity (0.882) and low nucleotide diversity (0.006), with 72 haplotypes identified. The haplotype network demonstrated no profound splits among the geographic populations. Neutral tests, including Tajima's D and Fu's Fs , displayed negative values, with a significant result observed for Fu's Fs (−33.048, p < 0.05). The mismatch distribution analysis indicated that the population does not statistically deviate from a model of sudden population expansion (SSD = 0.010, p > 0.05; Rg = 0.022, p > 0.05). The estimations suggest that the Cx. gelidus population in Thailand began its expansion approximately between 459,243 and 707,011 years ago. The Mantel test showed no significant relationship between genetic and geographic distances (r = 0.048, p > 0.05). Significant phenotypic differences (based on wing shape) were observed among most populations. Additionally, in this study, we found no significant relationships between phenotypic and genetic distances (r = 0.250, p > 0.05). Understanding the genetic and morphological dynamics of Cx. gelidus is vital for developing targeted surveillance and vector control measures. This knowledge will also help to predict how future environmental changes might affect these populations, thereby informing long-term vector management strategies. [ABSTRACT FROM AUTHOR]

• Mosquito sounds are important for communication. • Mosquito produces highly species-specific and sex-specific sounds. • The sound profiles of 19 species of females and 9 species of males were generated. • Fundamental and harmonic frequencies are prominent for species, sex and fed-unfed identification. • The sound-based identification method enables automated surveillance. Mosquito surveillance for vector-borne disease management relies on traditional morphological and molecular techniques, which are tedious, time-consuming, and costly. The present study describes a simple and efficient recording device that analyzes mosquito sound to estimate species composition, male-female ratio, fed-unfed status, and harmonic convergence interaction using fundamental frequency (F 0) bandwidth, harmonics, amplitude, and combinations of these parameters. The study examined a total of 19 mosquito species, including 3 species of Aedes , 7 species of Anopheles , 1 species of Armigeres , 5 species of Culex , 1 species of Hulecoetomyia , and 2 species of Mansonia. Among them, the F 0 ranges between 269.09 ± 2.96 Hz (Anopheles culiciformis) to 567.51 ± 3.82 Hz (Aedes vittatus) and the harmonic band (hb) number ranges from 5 (An. culiciformis) to 12 (Ae. albopictus). In terms of species identification, the success rate was 95.32 % with F 0 , 84.79 % with F 0 - bandwidth, 84.79 % with harmonic band (hb) diversity, and 49.7 % with amplitude (dB). The species identification rate has gone up to 96.50 % and 97.66 % with the ratio and multiplication of F 0 and hb , respectively. This is because of the matrices that combine multiple sound attributes. Comparatively, combinations of the amplitude of the F 0 and the higher harmonic frequency band were non-significant for species identification (60.82 %). The fed females have shown a considerable increase in F 0 in comparison to the unfed. The males of all the species possessed significantly higher frequencies with respect to the females. Interestingly, the presence of male-female of Ae. vittatus together showed harmonic convergence between the 2nd and 3rd harmonic bands. In conclusion, the sound-based technology is simple, precise, and cost-effective and provides better resolution for species, sex, and fed-unfed status detection in comparison to conventional methods. Real-time surveillance of mosquitoes could potentially utilize this technology. [Display omitted] [ABSTRACT FROM AUTHOR]

Early detection of insecticide resistance is essential to develop resistance countermeasures and depends on accurate and rapid biological and biochemical tests to monitor resistance and detect associated mechanisms. Many such studies have measured activities of esterases, enzymes associated with resistance to ester- containing insecticides, using the model substrate, α-naphthyl acetate (α-NA). However, in the field, pests are exposed to ester-containing insecticides such as malathion, that are structurally distinct from α-NA. In the current study, malathion resistance in C. quinquefasciatus (3.2- to 10.4-fold) was highly associated with esterase activity measured with either α-NA (R2 = 0.92) or malathion (R2 = 0.90). In addition, genes encoding two esterases (i.e., EST-2 and EST-3) were over-expressed in field- collected strains, but only one (EST-3) was correlated with malathion hydrolysis (R2 = 0.94) and resistance (Rs = 0.96). These results suggest that, in the strains studied, α-NA is a valid surrogate for measuring malathion hydrolysis, and that heightened expression of an esterase gene is not necessarily associated with metabolic resistance to insecticidal esters. [Display omitted] • Resistance to malathion was detected in field- collected Culex quinquefasciatus • Malathion resistance was associated with heightened esterase activities towards a model substrate (1- naphthyl acetate) and an insecticide (malathion), and the two activities were highly correlated in the field strains. • Increased expression of genes encoding two esterases (EST-2 and EST-3) was measured in the field strains, and heightened expression of EST-3 (but not EST-2) was associated with resistance to malathion. [ABSTRACT FROM AUTHOR]

• First report on the detection of LSDV in the saliva of mosquitoes. • LSDV was detected in the saliva of Ae. aegypti as early as 2 dpi. • LSDV remained detectable in the mosquitoes until 14 dpi. • EIP of Cx. tritaeniorhynchus and Cx. quinquefasciatus was 8 and 14 dpi respectively. • All three mosquito species may serve as biological vectors of LSDV. Lumpy skin disease virus (LSDV) is a transboundary viral disease in cattle and water buffaloes. Although this Poxvirus is supposedly transmitted by mechanical vectors, only a few studies have investigated the role of local vectors in the transmission of LSDV. This study examined the infection, dissemination, and transmission rates of LSDV in Aedes aegypti, Culex tritaeniorhynchus, and Culex quinquefasciatus following artificial membrane feeding of 102.7, 103.7, 104.7 TCID 50 /mL LSDV in sheep blood. The results demonstrated that these mosquito species were susceptible to LSDV, with Cx tritaeniorhynchus exhibiting significantly different characteristics from Ae. aegypti and Cx. quinquefasciatus. These three mosquito species were susceptible to LSDV. Ae. aegypti showed it as early as 2 days post-infection (dpi), indicating swift dissemination in this particular species. The extrinsic incubation period (EIP) of LSDV in Cx. tritaeniorhynchus and Cx. quinquefasciatus was 8 and 14 dpi, respectively. Ingestion of different viral titers in blood did not affect the infection, dissemination, or transmission rates of Cx. tritaeniorhynchus and Cx. quinquefasciatus. All rates remained consistently high at 8–14 dpi for Cx. tritaeniorhynchus. In all three species, LSDV remained detectable until 14 dpi. The present findings indicate that, Ae. aegypti, Cx. tritaeniorhynchus , and Cx. quinquefasciatus may act as vectors during the LSDV outbreak; their involvement may extend beyond being solely mechanical vectors. [Display omitted] [ABSTRACT FROM AUTHOR]

West Nile virus is a flavivirus transmitted by mosquitoes, mainly of the genus Culex. In Brazil, serological studies have already indicated the circulation of the virus since 2003, with the first human case detected in 2014. The objective of the present paper is to report the first isolation of WNV in a Culex (Melanoconion) mosquito. Arthropods were collected by protected human attraction and CDC light bait, and taxonomically identified and analyzed by viral isolation, complement fixation and genomic sequencing tests. WNV was isolated from samples of Culex (Melanoconion) mosquitoes, and the sequencing analysis demonstrated that the isolated strain belonged to lineage 1a. The finding of the present study presents the first evidence of the isolation and genome sequencing of WNV in arthropods in Brazil.

Background: Different trapping devices and attractants are used in the mosquito surveillance programs currently running in Europe. Most of these devices target vector species belonging to the genera Culex or Aedes, and no studies have yet evaluated the effectiveness of different trapping devices for the specific targeting of Anopheles mosquito species, which are potential vectors of malaria in Europe. This study aims to fill this gap in knowledge by comparing the performance of trapping methods that are commonly used in European mosquito surveillance programs for Culex and Aedes for the specific collection of adults of species of the Anopheles maculipennis complex. Methods: The following combinations of traps and attractants were used: (i) BG-Sentinel 2 (BG trap) baited with a BG-Lure cartridge (BG + lure), (ii) BG trap baited with a BG-Lure cartridge and CO2 (BG + lure + CO2), (iii) Centers for Disease Control and Prevention-like trap (CDC trap) baited with CO2 (CDC + CO2), (iv) CDC trap used with light and baited with BG-Lure and CO2 (CDC light + lure + CO2). These combinations were compared in the field using a 4 × 4 Latin square study design. The trial was conducted in two sites in northeastern Italy in 2019. Anopheles species were identified morphologically and a sub-sample of An. maculipennis complex specimens were identified to species level by molecular analysis. Results: Forty-eight collections were performed on 12 different trapping days at each site, and a total of 1721 An. maculipennis complex specimens were captured. The molecular analysis of a sub-sample comprising 254 specimens identified both Anopheles messeae/Anopheles daciae (n = 103) and Anopheles maculipennis sensu stricto (n = 8) at site 1, while at site 2 only An. messeae/An. daciae (n = 143) was found. The four trapping devices differed with respect to the number of An. messeae/An. daciae captured. More mosquitoes were caught by the BG trap when it was used with additional lures (i.e. BG + lure + CO2) than without the attractant, CO2 [ratioBG+lure vs BG+lure+CO2 = 0.206, 95% confidence interval (CI) 0.101–0.420, P < 0.0001], while no significant differences were observed between CDC + CO2 and CDC light + lure + CO2 (P = 0.321). The addition of CO2 to BG + lure increased the ability of this combination to capture An. messeae/An. daciae by a factor of 4.85, and it also trapped more mosquitoes of other, non-target species (Culex pipiens, ratioBG+lure vs BG+lure+CO2 = 0.119, 95% CI 0.056–0.250, P < 0.0001; Ochlerotatus caspius, ratioBG+lure vs BG+lure+CO2 = 0.035, 95% CI 0.015–0.080, P < 0.0001). Conclusions: Our results show that both the BG-Sentinel and CDC trap can be used to effectively sample An. messeae/An. daciae, but that the combination of the BG-Sentinel trap with the BG-Lure and CO2 was the most effective means of achieving this. BG + lure + CO2 is considered the best combination for the routine monitoring of host-seeking An. maculipennis complex species such as An. messeae/An. daciae. The BG-Sentinel and CDC traps have value as alternative methods to human landing catches and manual aspiration for the standardized monitoring of Anopheles species in Europe. [ABSTRACT FROM AUTHOR]

Sindbis virus (SINV) is a zoonotic alphavirus (family Togaviridae, genus Alphavirus) that causes human diseases in Africa, Europe, Asia, and Australia. Occasionally, SINV outbreaks were reported in South Africa and northern Europe. Birds are the main amplifying hosts of SINV, while mosquitoes play the role of the primary vector. Culex mosquitoes were collected in Algeria and subsequently tested for SINV. SINV RNA was detected in 10 pools out of 40, from a total of 922 mosquitoes tested. A strain of SINV was isolated from a pool displaying high viral load. Whole-genome sequencing and phylogenetic analysis showed that the SINV Algeria isolate was most closely related to a Kenyan strain. This was the first record of SINV in Algeria and more broadly in northwestern Africa, which can be a potential risk for human health in the circulating area. Further studies are needed to measure the impact on public health through seroprevalence studies in Algeria. [ABSTRACT FROM AUTHOR]

Rift Valley Fever (RVF) and West Nile virus (WNV) are two important emerging Arboviruses transmitted by Aedes and Culex mosquitoes, typically Ae. caspius, Ae. detritus and Cx. pipiens in temperate regions. In Morocco, several outbreaks of WNV (1996, 2003 and 2010), affecting horses mostly, have been reported in north-western regions resulting in the death of 55 horses and one person cumulatively. Serological evidence of WNV local circulation, performed one year after the latest outbreak, revealed WNV neutralizing bodies in 59 out of 499 tested participants (El Rhaffouli et al., 2012). The country also shares common borders with northern Mauritania, where RVF is often documented. Human movement, livestock trade, climate changes and the availability of susceptible mosquito vectors are expected to increase the spread of these diseases in the country. Thus, in this study, we gathered a data set summarizing occurrences of Ae. caspius, Ae. detritus and Cx. pipiens in the country, and generated model prediction for their potential distribution under both current and future (2050) climate conditions, as a proxy to identify regions at-risk of RVF and WNV probable expansion. We found that the north-western regions (where the population is most concentrated), specifically along the Atlantic coastline, are highly suitable for Ae. caspius, Ae. detritus and Cx. pipiens, under present-day conditions. Future model scenarios anticipated possible range changes for the three mosquitoes under all climatic assumptions. All of the studied species are prospected to gain new areas that are currently not suitable, even under the most optimist scenario, thus placing additional human populations at risk. Our maps and predictions offer an opportunity to strategically target surveillance and control programmes. Public health officials, entomological surveillance and control delegation must augment efforts and continuously monitor these areas to reduce and minimize human infection risk. [ABSTRACT FROM AUTHOR]

Mosquitoes transmit a wide variety of devastating pathogens when they bite vertebrate hosts and feed on their blood. However, three entire mosquito genera and many individual species in other genera have evolved a nonbiting life history in which blood is not required to produce eggs. Our long‐term goal is to develop novel interventions that reduce or eliminate the biting behavior in vector mosquitoes. A previous study used biting and nonbiting populations of a nonvector mosquito, Wyeomyia smithii, as a model to uncover the transcriptional basis of the evolutionary transition from a biting to a nonbiting life history. Herein, we ask whether the molecular pathways that were differentially expressed due to differences in biting behavior in W. smithii are also differentially expressed between subspecies of Culex pipiens that are obligate biting (Culex pipiens pipiens) and facultatively nonbiting (Culex pipiens molestus). Results from RNAseq of adult heads show dramatic upregulation of transcripts in the ribosomal protein pathway in biting C. pipiens, recapitulating the results in W. smithii, and implicating the ancient and highly conserved ribosome as the intersection to understanding the evolutionary and physiological basis of blood feeding in mosquitoes. Biting Culex also strongly upregulate energy production pathways, including oxidative phosphorylation and the citric acid (TCA) cycle relative to nonbiters, a distinction that was not observed in W. smithii. Amino acid metabolism pathways were enriched for differentially expressed genes in biting versus nonbiting Culex. Relative to biters, nonbiting Culex upregulated sugar metabolism and transcripts contributing to reproductive allocation (vitellogenin and cathepsins). These results provide a foundation for developing strategies to determine the natural evolutionary transition between a biting and nonbiting life history in vector mosquitoes. [ABSTRACT FROM AUTHOR]

Simple Summary: The Flavivirus genus groups a wide range of species capable of infecting vertebrates and invertebrates, both terrestrial and aquatic. According to phylogenetic analyses, the flavivirus genomes cluster into three main branches; the first one containing viruses that infect vertebrates, also called arboviruses; the second called arbovirus-affiliated insect-specific flaviviruses or dual-host insect-specific flaviviruses (dISF), that preserve genomic similarity with arboviruses, but its replication is apparently restricted to invertebrates and insect-specific classical flaviviruses (ISF), with infection restricted to invertebrates. Culex Flavivirus (CxFV) is a classical insect-specific virus, which has aroused interest after the first indication that it can produce in nature superinfection exclusion of viruses of medical interest such as West Nile. Despite the detection of CxFV in different regions, CxFV ecology and the influence of co-circulation of arboviruses remains poorly understood. Therefore, our primary goals are to observe the occurrence of CxFV infection in mosquitoes trapped in an urban area of Rio de Janeiro, Brazil, characterize the virus circulation, and provide isolates. A prospective study was carried out for eight months on the Federal University of Rio de Janeiro campus trapping adult mosquitoes. The CxFV minimum infection rates were determined in this period, and the virus isolation process is fully described. Samples from this study were grouped into genotype 2, along with CxFV sequences from Latin America and Africa. Culex Flavivirus (CxFV) is a classical insect-specific virus, which has aroused interest after the first indication that it can produce in nature superinfection exclusion of viruses of medical interest such as West Nile. Despite the detection of CxFV in different regions, CxFV ecology and the influence of co-circulation of arboviruses remains poorly understood. Therefore, our primary goals are to observe the occurrence of CxFV infection in mosquitoes trapped in an urban area of Rio de Janeiro, Brazil, characterize the virus circulating, and provide isolates. A prospective study was carried out for eight months on the campus of the Federal University of Rio de Janeiro, trapping adult mosquitoes. The CxFV minimum infection rates were determined in this period, and the virus isolation process is fully described. Samples from this study were grouped into genotype 2, along with CxFV sequences from Latin America and Africa. [ABSTRACT FROM AUTHOR]

The control of mosquito populations using insecticides is increasingly threatened by the spread of resistance mechanisms. Dieldrin resistance, conferred by point mutations in the Rdl gene encoding the γ-aminobutyric acid receptor, has been reported at high prevalence in mosquito populations in response to selective pressures. In this study, we monitored spatio-temporal dynamics of the resistance-conferring Rdl R allele in Aedes (Stegomyia) albopictus (Skuse, 1895) and Culex (Culex) quinquefasciatus (Say, 1823) populations from Reunion Island. Specimens of both mosquito species were sampled over a 12-month period in three cities and in sites located at lower (<61 m) and higher (between 503 and 564 m) altitudes. Mosquitoes were genotyped using a molecular test detecting the alanine to serine substitution (A302S) in the Rdl gene. Overall, the Rdl R frequencies were higher in Cx. quinquefasciatus than Ae. albopictus. For both mosquito species, the Rdl R frequencies were significantly influenced by location and altitude with higher Rdl R frequencies in the most urbanized areas and at lower altitudes. This study highlights environmental factors that influence the dynamics of insecticide resistance genes, which is critical for the management of insecticide resistance and the implementation of alternative and efficient vector control strategies. [ABSTRACT FROM AUTHOR]

As one of the most widely distributed bacterial cytoplasmic symbionts on earth, Wolbachia pipientis Hertig serves as a model organism for the understanding of hostsymbiont interactions. Many mosquito species are infected with Wolbachia strains that induce a form of reproductive manipulation called cytoplasmic incompatibility, in which infected females gain a reproductive advantage over uninfected females in mixed infection populations. The selective advantage of cytoplasmic incompatibility often results in a population sweep of Wolbachia and co-transmitted mitochondrial genomes. Mitochondrial evolution and phylogenetic inferences drawn from mitochondrial gene sequences are thus potentially compromised by reproductive manipulating symbionts, like Wolbachia. Our initial analyses of phylogenetic patterns among collected Wolbachia-infected and uninfected mosquito species suggested significant Wolbachia-induced effects on mitochondrial evolutionary patterns. Discordant mitochondrial and nuclear phylogenies among Aedes and Culex species were associated with infections status, with a distinct mitochondrial clade of infected Aedes and Culex species, separate from uninfected species of the genera. Statistical analyses of molecular substitution among infected and uninfected sequence samples revealed elevated rates of substitution for the mitochondrial sequences of the discordant infected Aedes/Culex clade. Subsequent phylogenetic analyses suggested that the observed discordance could be attributed to long-branch attraction effects associated with elevated rates of substitution. Our results highlight the impact cytoplasmic selection can have on phylogenetic inference in limited sample sets with Wolbachia-infected and uninfected species. [ABSTRACT FROM AUTHOR]

Background: The Middle East Respiratory Syndrome coronavirus (MERS‐CoV) is still listed on the WHO Research and Development Blueprint of emerging pathogens. Dromedary camels remain the only known animal reservoir of the virus. The animal‐to‐animal as well as the animal‐to‐human transmission in the MERS‐CoV cycles were reported. However, many aspects of these transmission chains are not well studied. One of these directions is the potential roles of various species of arthropods in the transmission of the virus. Objectives: The main goal of the current work was to study the roles of several species of arthropods in the transmission of MERS‐CoV. Methodology: To achieve this goal, we identified some MERS‐CoV naturally infected dromedary camel populations. We conducted a longitudinal study among these animals for more than 2 months. This was done by repeated testing of nasal swabs biweekly from some selected animals in this population for the presence of MERS‐CoV‐RNAs by real‐time PCR. During the duration of this study, we collected several species of arthropods (Culicoides, Stomoxys, Musca domestica and some Culex species) that shared the habitat and were circulating in this farm during this longitudinal study. Results: Our results showing, despite the detection of the viral RNAs in some animals throughout this study, none of the examined species of arthropods tested positive for the viral RNA. Conclusions: These results are suggesting that at least the tested species of arthropods may not play roles in the transmission of MERS‐CoV. However, more large‐scale studies are required to explore any potential roles of arthropods in the transmission cycle of MERS‐CoV. [ABSTRACT FROM AUTHOR]

Multiple synthetic products are used against mosquitoes to kill them and inhibit the transmission of these vector-borne diseases. The continuous use of these products produces detrimental effects on the environment and non-target organisms, which also develops resistance in the mosquito. In the last few decades, there has been a continuous exploration of herbal extract-based insecticides. These plants extract essential oils that have emerged as a potential eco-friendly alternative for the killing of larvae, the immature form of adult mosquitoes. In this review article, we focused on the larvicidal activity (LC50 values) of plant extracts obtained from various parts of plants. We evaluated results obtained from numerous essential oil larvicidal activities against prominent vectors belonging to the genera Anopheles, Aedes, and Culex, among others, that had been reported in various scientific data bases. The mode of action of these plant extracts are also discussed with reference to insecticidal activity. The major limitation of essential oils with their overcome solutions through formulation development is also highlighted. This review article reported that essential oils are potential substitutes for the development of larvicides, which may be employed in vector-borne illness control programmes. Overall, this remarkable summary and organization of data may be used to design, develop, and optimise herbal-based formulations with potential larvicidal efficacy. [ABSTRACT FROM AUTHOR]

Background: The ministère de la Santé et des Services sociaux (MSSS) du Québec (Québec’s health authority) has expressed an interest in the development of an early warning tool to identify seasonal human outbreaks of West Nile virus infection in order to modulate public health interventions. The objective of this study was to determine if a user-friendly meteorological-based forecasting tool could be used to predict minimal infection rates for the Culex pipiens-restuans complex—a proxy of human risk—ahead of mosquito season. Methods: Annual minimal infection rate (number of positive pools/number of mosquitoes) was calculated for 856 mosquito traps set from 2003 to 2006 and 2013 to 2018 throughout the south of Québec’s. Coefficient of determination (R² ) were estimated using the validation dataset (one third of the database by random selection) with generalized estimation equations, which were prior fitted backwards with polynomial terms using the training dataset (two thirds of the database), in order to minimize the Bayesian information criteria. Mean temperatures and precipitation were grouped at five temporal scales (by month, by season and by 4, 6 and 10-months groupings). Results: Mean temperatures and cumulative precipitation from the previous months of March (R² =0.37), May (R² =0.36), December (R² =0.35) and the autumn season (R² =0.38) accounted for ~40% of Cx. pipiens-restuans annual minimal infection rates variations. Including the “year of sampling” variable in all regression models increased the predictive abilities (R² between 0.42 and 0.57). Conclusion: All regression models explored have too weak predictive abilities to be useful as a public health tool. Other factors implicated in the epidemiology of the West Nile virus need to be incorporated in a meteorological-based early warning model for it to be useful to the provincial health authorities. [ABSTRACT FROM AUTHOR]

Rift Valley fever (RVF) is a zoonotic disease caused by a virus mainly transmitted by Aedes and Culex mosquitoes. Infection leads to high abortion rates and considerable mortality in domestic livestock. The combination of viral circulation in Egypt and Libya and the existence of unregulated live animal trade routes through endemic areas raise concerns that the virus may spread to other Mediterranean countries, where there are mosquitoes potentially competent for RVF virus (RVFV) transmission. The competence of vectors for a given pathogen can be assessed through laboratory experiments, but results may vary greatly with the study design. This research aims to quantify the competence of five major potential RVFV vectors in the Mediterranean Basin, namely Aedes detritus, Ae. caspius, Ae. vexans, Culex pipiens and Cx. theileri, through a systematic literature review and meta-analysis. We first computed the infection rate, the dissemination rate among infected mosquitoes, the overall dissemination rate, the transmission rate among mosquitoes with a disseminated infection and the overall transmission rate for these five mosquito species. We next assessed the influence of laboratory study designs on the variability of these five parameters. According to experimental results and our analysis, Aedes caspius may be the most competent vector among the five species considered. [ABSTRACT FROM AUTHOR]

Ungulate malaria parasites and their vectors are among the least studied when compared to other medically important species. As a result, a thorough understanding of ungulate malaria parasites, hosts, and mosquito vectors has been lacking, necessitating additional research efforts. This study aimed to identify the vector(s) of Plasmodium bubalis. A total of 187 female mosquitoes (133 Anopheles spp., 24 Culex spp., 24 Aedes spp., and 6 Mansonia spp. collected from a buffalo farm in Thailand where concurrently collected water buffalo samples were examined and we found only Anopheles spp. samples were P. bubalis positive. Molecular identification of anopheline mosquito species was conducted by sequencing of the PCR products targeting cytochrome c oxidase subunit 1 (cox1), cytochrome c oxidase subunit 2 (cox2), and internal transcribed spacer 2 (ITS2) markers. We observed 5 distinct groups of anopheline mosquitoes: Barbirostris, Hyrcanus, Ludlowae, Funestus, and Jamesii groups. The Barbirostris group (Anopheles wejchoochotei or Anopheles campestris) and the Hyrcanus group (Anopheles peditaeniatus) were positive for P. bubalis. Thus, for the first time, our study implicated these anopheline mosquito species as probable vectors of P. bubalis in Thailand. [ABSTRACT FROM AUTHOR]

The geographic expansion of mosquitos is associated with a rising frequency of outbreaks of mosquito-borne diseases (MBD) worldwide. We collected occurrence locations and times of mosquito species, mosquito-borne arboviruses, and MBDs in the mainland of China in 1954−2020. We mapped the spatial distributions of mosquitoes and arboviruses at the county level, and we used machine learning algorithms to assess contributions of ecoclimatic, socioenvironmental, and biological factors to the spatial distributions of 26 predominant mosquito species and two MBDs associated with high disease burden. Altogether, 339 mosquito species and 35 arboviruses were mapped at the county level. Culex tritaeniorhynchus is found to harbor the highest variety of arboviruses (19 species), followed by Anopheles sinensis (11) and Culex pipiens quinquefasciatus (9). Temperature seasonality, annual precipitation, and mammalian richness were the three most important contributors to the spatial distributions of most of the 26 predominant mosquito species. The model-predicted suitable habitats are 60–664% larger in size than what have been observed, indicating the possibility of severe under-detection. The spatial distribution of major mosquito species in China is likely to be under-estimated by current field observations. More active surveillance is needed to investigate the mosquito species in specific areas where investigation is missing but model-predicted probability is high. [ABSTRACT FROM AUTHOR]

Objectives of the study was to evaluate larvicidal, pupicidal, repellence activities of Nicotiana plumbaginifolia leaf extracts (crude and solvents) and toxicity of smoke originated form dry leaves against rice field mosquito, Culex vishnui, vector of Japanese encephalitis. Larvicidal property of most effective extract was evaluated against third instar Cx. vishnui larvae under simulated semi-field condition. Crude extract of leaves exhibited remarkable larvicidal property. Amongst three used solvent extractives of leaves, ethyl acetate extractive showed best result in larvicidal test. In larvicidal bioassay, ethyl acetate extractive exhibited lowest LC50 and LC90 values, which were 7.237 ppm and 18.964 ppm respectively against the 1st instar larvae after 72 h of exposure. In pupicidal bioassay, LC50 and LC90 values were 111.20 ppm and 176.96 ppm respectively after 24 h of exposure. Remarkable (99.33%) repellency was found in 6% concentration of ethyl acetate extractive after 150 min of exposure. Smoke of N. plumbaginifolia dry leaves exhibited significant toxicity. Results of semi-field condition depicted that ethyl acetate extract was also highly effective under semi-field condition having highest mortality rate of 95.33 ± 0.33% at 500 ppm concentration against third instar Cx. vishnui larvae after 72 h exposure. The name of the isolated bioactive compound was "1-hexyl-2-nitrocyclohexane". However, the non-target organisms like, Damselfly nymph (Ischnura spp.: Odonata) and nymph of Hemipteran bug, Diplonychus spp. were found to be least toxic to the extracts. N. plumbaginifolia leaf has remarkable larvicidal, pupicidal, repellency and smoke toxic potentialities against Cx. vishnui. [ABSTRACT FROM AUTHOR]

Mosquitoes transmit major human diseases, resulting in millions of fatalities each year and the development of chemical insecticide resistance, leading to a rebound in vectorial capacity. Plants could be used as a mosquito repellent alternative. The purpose of this study was to evaluate the biocontrol potentiality of ethyl acetate extract of fruit pericarp QiAlnngium Snlviifolium against Culexquinquefnscintus larvae. 100% larval mortality was recorded after 72 h of exposure with 50, 40 ppm, and 30 ppm concentrations of ethyl acetate extract against 3rd instar mosquito larvae. The bioactive compound responsible for larval mortality was isolated by TLC (Rf value of 0.33). 3rd instar larvae were found to be the most susceptible (LC50 = 3.60 ppm) among all the instars and corresponding LC50 values were 4.45 ppm and 4.52 ppm for 2nd and 4th instars larvae respectively after 72 h of exposure. The mortality rate of all larval instars was directly proportional to the concentration of bioactive compounds. Three-way ANOVA analysis revealed that larval instars, the concentration of bioactive compound, and time of exposure had a significant effect on larval mortality. In the bioactive TLC fraction of A. Snlviifolium (Rf value of 0.33), FT-IR spectroscopy analysis revealed the presence of numerous functional groups. GC-MS analysis revealed the presence of Benzoyl bromide and 3-Amino -5 (2-Furyl) Pyrazole in the extract. The compounds were also studied on non-target organisms such as Anisops snrden, 4th instar larvae of Chironomus sp. and Diplonychus nnnulntum, and in all the cases no abnormalities were recorded. [ABSTRACT FROM AUTHOR]

The aqueous extract of Chara vulgaris algae and the leaves of the Myrtus communis plant was used and the calculation of the cumulative and non-cumulative effect of the effectiveness of these extracts was compared with the chemical insecticide Alpha-cypermethrin. The results showed the superiority of the insecticide over the algae and plant extracts. Myrtus, whether the effect is cumulative or non-cumulative, as results showed that the most affected phases were the first larval stage and for all treatments. While the fourth larval stage was less affected and the results showed phenotypic abnormalities in treated larvae with an increase in the number of days of the larval stage. The study showed the presence of compounds in the extract of leaves of Elias and Chara that included effective compounds including phenols, alkaloids, coumarines, clicosides, phenols, flavonoids, oils and tannins. [ABSTRACT FROM AUTHOR]

Background: Vector control strategies typically rely on pesticides to target mosquitoes involved in enzootic and zoonotic transmission of West Nile virus (WNV). Nevertheless, increasing insecticide resistance and a desire to reduce pesticide usage provide the impetus for developing alternative strategies. Ivermectin (IVM), an antiparasitic drug which is widely used in human and veterinary medicine, is a potential alternative for targeted control because Culex mosquitoes experience increased mortality following ingestion of IVM in bloodmeals. Methodology/Principal findings: We conducted a randomized field trial to investigate the impact of treating backyard chicken flocks with IVM in urban neighborhoods across Davis, California on mosquito populations and WNV transmission dynamics. We observed a significant reduction in WNV seroconversions in treated vs. untreated chickens, suggesting a reduction in WNV transmission intensity around treated flocks. We also detected a reduction in parity rates of Cx. tarsalis near treated vs. untreated flocks and increased mortality in wild mosquitoes following a bloodmeal on treated chickens (IVM serum concentration > 5ng/mL) vs. chickens with IVM serum concentrations < 5 ng/mL. However, we did not find a significant difference in abundance or infection prevalence in mosquitoes between treatment groups associated with the reductions in seroconversions. Mosquito immigration from surrounding larval habitat, relatively low WNV activity in the study area, and variable IVM serum concentrations likely contributed to uncertainty about the impact. Conclusions/Significance: Taken together, our results point to a reduction in WNV transmission due to the impact of IVM on Culex mosquito populations and support the ongoing investigation of oral administration of IVM to wild birds for local control of WNV transmission, although further work is needed to optimize dosing and understand effects on entomological endpoints. Author summary: Current mosquito control strategies aimed to prevent pathogen transmission to humans have limited ability to target mosquitoes involved in amplification and spillover transmission of pathogens like West Nile virus (WNV). Additionally, growing prevalence of insecticide resistance in mosquito populations limit the efficacy of these insecticide-based control strategies. Ivermectin (IVM) provides an alternative avenue for control by increasing the mortality of mosquitoes that ingest this drug in bloodmeals. Therefore, IVM treatment of avian species that account for the majority of mosquito bloodmeals during the WNV transmission season could be an effective control strategy. Building on pilot studies indicating the efficacy and feasibility of IVM-deployment for WNV control, we performed a randomized field trial to investigate the impact of IVM-treatment of backyard chickens on local population dynamics of Culex mosquitoes and WNV transmission. We were able to link changes in mosquito populations to reduction in WNV transmission, as measured by chicken seroconversions, through IVM-induced mortality in mosquitoes. However, further work is needed to identify the impact of treatment on mosquito abundance and infection prevalence to fully attribute observed changes to IVM administration. Overall, our results support IVM treatment as a potentially effective alternative to insecticide-based vector control strategies and one that can be used to target WNV transmission on the local scale. [ABSTRACT FROM AUTHOR]

Mosquitoes are important vectors that transmit pathogens to human and other vertebrates. Each mosquito species has specific ecological requirements and bionomic traits that impact human exposure to mosquito bites, and hence disease transmission and vector control. A study of human biting mosquitoes and their bionomic characteristics was conducted in West Sumba and Southwest Sumba Districts, Nusa Tenggara Timur Province, Indonesia from May 2015 to April 2018. Biweekly human landing catches (HLC) of night biting mosquitoes both indoors and outdoors caught a total of 73,507 mosquito specimens (59.7% non-Anopheles, 40.3% Anopheles). A minimum of 22 Culicinae species belonging to four genera (Aedes, Armigeres, Culex, Mansonia), and 13 Anophelinae species were identified. Culex quinquefasciatus was the dominant Culicinae species, Anopheles aconitus was the principal Anopheles species inland, while An. sundaicus was dominant closer to the coast. The overall human biting rate (HBR) was 10.548 bites per person per night (bpn) indoors and 10.551 bpn outdoors. Mosquitoes biting rates were slightly higher indoors for all genera with the exception of Anopheles, where biting rates were slightly higher outdoors. Diurnal and crepuscular Aedes and Armigeres demonstrated declining biting rates throughout the night while Culex and Anopheles biting rates peaked before midnight and then declined. Both anopheline and non-anopheline populations did not have a significant association with temperature (p = 0.3 and 0.88 respectively), or rainfall (p = 0.13 and 0.57 respectively). The point distribution of HBR and seasonal variables did not have a linear correlation. Data demonstrated similar mosquito–human interactions occurring outdoors and indoors and during early parts of the night implying both indoor and outdoor disease transmission potential in the area–pointing to the need for interventions in both spaces. Integrated vector analysis frameworks may enable better surveillance, monitoring and evaluation strategies for multiple diseases. Author summary: This study outlines the array of mosquitoes that bite humans at night on the island of Sumba, Indonesia, with data on behavioural traits that impact when and where disease transmission may occur. Biweekly human landing catches (HLCs) were performed in four selected houses in 12 clusters (villages) from sunset to sunrise over a three years period (May 2015 to April 2018). The collection and analysis of 73,507 mosquito specimens revealed the presence of various species of Anopheles, Aedes, Culex, Armigeres and Mansonia, that potentially transmit several diseases including malaria, filaria, dengue and other mosquito borne viral diseases. Even though these data represent only night-time collections, this represents a comprehensive geographic description and inventory of species, bionomics and temporal distribution of mosquitoes on the island of Sumba. Data demonstrate that the high diversity of species with associated diversity in behaviours results in mosquito-human contact occurring throughout the night and both indoors and outdoors–relevant to both disease transmission and intervention applicability. Vector specific behaviours are specifically relevant to intervention strategies for specific diseases. The use of molecular methods to determine and validate morphological identification of specimens resulted in the characterization of multiple novel sequences–indicating the presence of undescribed species, members of cryptic species complexes or species without molecular data. Species identification using molecular methods are essential towards determine vector species compositions–especially in areas where data is absent. Though the correlation between temperature, rainfall and HBR was not statistically significant, the presence of mosquito populations throughout the year allow for perennial transmission of mosquito-borne diseases. Overall, these findings represent baseline and novel data for Sumba and may be utilized to develop disease and vector-specific or integrated strategies that mitigate the transmission of mosquito borne diseases in Indonesia. [ABSTRACT FROM AUTHOR]

Background: Few studies have been conducted to investigate the distribution of mosquito vectors and the population structure of secondary vectors in the border region of Cambodia-Laos. The aim of this work was to study the mosquito diversity and molecular phylogeny of secondary vectors, i.e., Anopheles nivipes in this area. Methods: 1440 adult mosquitoes were trapped in the Cambodia-Laos border. mtDNA-COII were amplified and sequenced from 53 An. nivipes DNA samples. Together with COII sequences deposited in GenBank, a total of 86 COII sequences were used for examining population variations, genetic differentiation, spatial population structure, population expansion, and gene flow patterns. Results: The adult mosquitoes were classified into 5 genera and 27 species in this border region. The predominant genera were Culex (60.07%, 865/1440) and Anopheles (31.25%, 450/1440), and the major Anopheles species were An. nivipes (73.56%, 331/450) and Anopheles maculatus (14.22%, 64/450). Based on sequences analysis of COII, a high level of genetic differentiation was reported in two Northwest India (Cheema and Bathinda, Punjab) and Cambodia-Laos (Siem Pang, Stung treng) populations (FST = 0.97824, 0.97343, P < 0.05), as well as lower gene flow (Nm = 0.01112, 0.01365) in the An. nivipes populations. Phylogenetic analysis and SAMOVA revealed a gene barrier restricting gene flow among three An. nivipes populations. Mantel test suggested a significant correlation between geography and gene distance in all An. nivipes populations (Z = 44,983.1865, r = 0.5575, P = 0.0070). Neutrality test and Mismatch distribution revealed a recent population expansion of An. nivipes in the Cambodia-Laos population. Conclusions: Anopheles nivipes was one of the major Anopheles species in the Cambodia-Laos border. Based on sequences analysis of COII, a genetic barrier between Cambodia-Laos and two Indian populations was found, and a recent population expanding or selecting of An. nivipes occurred in the Cambodia-Laos population, suggesting that COII might be an effective marker for describing the molecular phylogeny of An. nivipes. Further investigation and continuous surveillance of An. nivipes are warranted in this region. [ABSTRACT FROM AUTHOR]

Herein we describe a previously uninvestigated salivary gland escape barrier (SEB) in Culex tarsalis mosquitoes infected with two different strains of Western equine encephalitis virus (WEEV). The WEEV strains were originally isolated either from mosquitoes (IMP181) or a human patient (McMillan). Both IMP181 and McMillan viruses were fully able to infect the salivary glands of Culex tarsalis after intrathoracic injection as determined by expression of mCherry fluorescent protein. IMP181, however, was better adapted to transmission as measured by virus titer in saliva as well as transmission rates in infected mosquitoes. We used chimeric recombinant WEEV strains to show that inclusion of IMP181-derived structural genes partially circumvents the SEB. [ABSTRACT FROM AUTHOR]

Mosquitoes are vectors of numerous pathogenic viruses and freshwater snails are intermediate hosts for several parasitic worms. There is a need for environmentally-benign botanical pesticides to augment or replace synthetic pesticides. In this research, essential oils from the leaves, stems, rhizomes, and roots of Alpinia galanga, an important Vietnamese medicinal plant, have been obtained by hydrodistillation and analyzed by gas chromatographic techniques. The essential oils were screened for mosquito larvicidal activity against Aedes aegypti and Culex quinquefasciatus, for molluscicidal activity against Gyraulus convexiusculus and Pomacea canaliculata, and for inhibition of acetylcholinesterase (AChE). The essential oils showed moderate to good pesticidal activities against these organisms. However, the oils also showed pronounced lethality to a non-target water bug, Diplonychus rusticus. [ABSTRACT FROM AUTHOR]

Reductions in aquatic habitat size facilitate encounters between predators and prey by reducing the height of the water column and the water volume. Here, we proposed to disentangle the effects of these mechanisms on predation rates and parameters of functional response curves of predators. We paired active-search predators (Buenoa, Hemiptera) or ambush predators (Pantala and Lestes, Odonata) with prey of different mobility types (Argyrodiaptomus, Copepoda; Culex, Diptera). Three treatments were established: high water column height and high water volume (H + V +), low water column height and high water volume (H − V +), and low water column height and low water volume (H − V−). We used contrast analysis to separate the effects of water column height (H + , H−) and water volume (V + , V−). Predation rates were higher in V− than in V + for Pantala and Buenoa consuming Argyrodiaptomus. In addition, we observed an increase in attack rates and a decrease in handling time in V− in relation to V + for Pantala and Lestes consuming Argyrodiaptomus. We concluded that reduction in the water volume was main responsible factor for the changes in predator–prey interactions. These changes depended on the prey behavior and predator foraging modes: ambush predators were the most benefited, and highly mobile prey were the most consumed. [ABSTRACT FROM AUTHOR]

Evidence suggests that pigs seroconvert after experimental exposure to Zika virus and are potential sentinels. We demonstrate that pigs are also susceptible to natural Zika virus infection, shown by the presence of antibodies in domestic pigs in Yucatan, Mexico. Zika virus RNA was detected in 5 species of mosquitoes collected inside pigpens.

An experimental infection approach was used to estimate the competence of the common mosquito, Culex pipiens, for hepatitis E virus replication and transmission, using an isolate of hepatitis E virus genotype 3 of human origin in varying infectious doses. The experimental approach was carried out in biosafety level 2 conditions on three batches of 120 Cx. pipiens females, each using an artificial feeding system containing the virus in aliquots of fresh avian blood. Mosquitoes from each batch were collected 1, 7, 14, and 21 days post-infection (dpi) and dissected. The proboscis was subjected to forced excretion of saliva to estimate potential virus transmission. HEV RNA presence in abdomen, thorax, and saliva samples was analyzed by PCR at the selected post-infection times. HEV RNA was detected in the abdomens of Cx. pipiens females collected 1 dpi in the two experimentally-infected batches, but not in the saliva or thorax. None of the samples collected 7–21 dpi were positive. Our results show that Cx. pipiens is not a competent vector for HEV, at least for zoonotic genotype 3.

Globalisation, climate change and international trade are the factors contributing to the spread of Aedes albopictus (Diptera: Culicidae) and Ae. aegypti into new areas. In newly invaded habitats, these non-native species can serve as arbovirus disease vectors or increase the risk of disease spill over. These mosquitoes continue to emerge in new areas where they have or will have overlapping ranges with other resident mosquito species. The study investigates how invasive Aedes mosquitoes compete with the native Culex pipiens in Türkiye, which might affect the overall mosquito population dynamics and disease transmission risks. Both Aedes species exhibited contrasting responses to interspecific competition with Cx. pipiens. While Ae. albopictus suffers reduced emergence primarily in larger containers with abundant food, Ae. aegypti surprisingly thrives in mixed cultures under all food conditions. Adult Cx. pipiens emergence drops by half against Ae. albopictus and under specific conditions with Ae. aegypti. Competition influences mosquito size differently across species and life stages. Culex pipiens females grow larger when competing with Ae. aegypti, potentially indicating resource advantage or compensatory strategies. However, Ae. albopictus size shows more nuanced responses, suggesting complex interactions at play. Understanding how invasive and native mosquitoes interact with each other can provide insights into how they adapt and coexist in shared habitats. This knowledge can inform effective control strategies. The study highlights the differential responses of invasive Aedes species and the potential for managing populations based on their competitive interactions with the native Cx. pipiens. It can contribute to improved monitoring and prediction systems for the spread of invasive mosquitoes and the associated disease risks., (© 2024 The Author(s). Medical and Veterinary Entomology published by John Wiley & Sons Ltd on behalf of Royal Entomological Society.)