Mosquito Samples Research Articles

Description of potential vectors of zoonotic filarial nematodes, Brugia pahangi, Setaria digitata, and Setaria labiatopapillosa in Thai mosquitoes

Filariasis is classified as a vector-borne zoonotic disease caused by several filarial nematodes. The disease is widely distributed in tropical and subtropical regions. Understanding the relationship between mosquito vectors, filarial parasites, and vertebrate hosts is therefore essential for determining the probability of disease transmission and, correspondingly, developing effective strategies for prevention and control of diseases. In this study, we aimed to investigate the infection of zoonotic filarial nematodes in field-caught mosquitoes, observe the potential vectors of filaria parasites in Thailand using a molecular-based survey, conduct a study of host-parasite relationship, and propose possible coevolution of the parasites and their hosts. Mosquitoes were collected around cattle farms in Bangkok, Nakhon Si Thammarat, Ratchaburi, and Lampang provinces from May to December 2021 using a CDC Backpack aspirator for 20–30 minutes in each area (intra-, peri-, and wild environment). All mosquitoes were identified and morphologically dissected to demonstrate the live larvae of the filarial nematode. Furthermore, all samples were tested for filarial infections using PCR and sequencing. A total of 1,273 adult female mosquitoes consisted of five species: 37.78% Culex quinquefasciatus, 22.47% Armigeres subalbatus, 4.71% Cx. tritaeniorhynchus, 19.72% Anopheles peditaeniatus, and 15.32% An. dirus. Larvae of Brugia pahangi and Setaria labiatopapillosa were found in Ar. subalbatus and An. dirus mosquitoes, respectively. All mosquito samples were processed by PCR of ITS1 and COXI genes for filaria nematode species identification. Both genes showed that B. pahangi was found in four mosquitoes of Ar. subalbatus from Nakhon Si Thammarat, S. digitata was detected in three samples of An. peditaeniatus from Lampang, and S. labiatopapillosa was detected in one of An. dirus from Ratchaburi. However, filarial nematodes were not found in all Culex species. This study infers that this is the first data regarding the circulation of Setaria parasites in Anopheles spp. from Thailand. The phylogenetic trees of the hosts and parasites are congruent. Moreover, the data could be used to develop more effective prevention and control strategies for zoonotic filarial nematodes before they spread in Thailand.

Detection of homozygous wildtype V1016V using allele-specific polymerase chain reaction in Aedes albopictus

Abstract. Setiawan AR, Fadila SZ, Sucipto TH, Fauziyah S, Madaniyah S, Dewi EC, Naw SW, Tukiran, Cahyaningrum SE. 2023. Detection of homozygous wildtype V1016V using allele-specific polymerase chain reaction in Aedes albopictus. Biodiversitas 24: 62-67. Aedes sp. is a carrier of several viruses that can infect humans and cause diseases such as zika, yellow fever, chikungunya, and dengue fever. Symptoms of dengue infection vary, consisting of classic dengue fever (DD), dengue hemorrhagic fever (DHF), and dengue shock syndrome. Insecticide spray can be used to manage Aedes mosquitoes chemically. Insecticide substances target nervous system proteins. Voltage-gated sodium channels (VGSC) are rendered inactive by pyrethroid binding. Knockdown is a signal indicating an insect has been knocked down in response to a specific insecticide. However, using insecticides for a long time can cause mosquitoes to become resistant. The pesticide resistance of mosquitoes is known as knockdown resistance (kdr). This study aims to detect kdr mutations (V1016G) in two male Aedes albopictusmosquitos named A1 and A2 collected from settlements in Kranggan, Sawahan, Surabaya, East Java, Indonesia, using allele-specific polymerase chain reaction (AS-PCR) assay. RNA was extracted from the two mosquito samples using an RNA extraction kit. After that, the extracted RNA was tested for kdr mutations using the AS-PCR method. After assaying, both samples are homozygous wildtype (V1016V) because the results showed bands appearing from samples A1 and A2 at 60 bp. On the other hand, this study has the potential to serve as preliminary monitoring for the program controlling vectors.

Entomological Survey for New Vector Incrimination and Re-Confirmation of Established Malaria Vectors in Endemic Areas of Bangladesh (4 Sentinel Sites)

In Bangladesh malaria is one of the major public health problems and there are 3 malaria endemic hill tract districts which are the major areas among the red zones of malaria enedemicity. This study was aimed at assessment of the new vector incrimination as well as re-confirmation of the established vectors in Naikhangchari, Thanchi, Laxmichari and Baghachari. The anopheline population were collected and tested to incriminate the vector of malaria and their role in transmission, to find out the sporozoite rate, determination of oocyst rate of parasite and entomological innocultaion rate was diagnosed. Anopheline mosquito samples were directly collected from the sites using human bait, cattle landing and CDC light traps. The collected mosquitoes were dissected to find out the sporozoite in the salivary gland, oocyst in the midgut and to see the ovary for determination of the mosquito’s status of parous or nail-parous to determine the length of gonotropic cycle. The highest collection of a primary vector An. philippinensis was in Laxmichari (186 samples) and the highest collection of a secondary vector species An. vagus was in Thanchi (392). After the dissection no sporozoite or oocyst were detected among the collected anopheles’ samples. The vectoral capacity of An. philippinesis should be re-evaluated in the further studies. The pick biting hours of An. philippinensis and An. vagus varied in the 3 study sites which is an important finding of this study.

Targeting a highly repetitive genomic sequence for sensitive and specific molecular detection of the filarial parasite Mansonella perstans from human blood and mosquitoes.

Mansonella perstans is among the most neglected of the neglected tropical diseases and is believed to cause more human infections than any other filarial pathogen in Africa. Based largely upon assumptions of limited infection-associated morbidity, this pathogen remains understudied, and many basic questions pertaining to its pathogenicity, distribution, prevalence, and vector-host relationships remain unanswered. However, in recent years, mounting evidence of the potential for increased Mansonella infection-associated disease has sparked a renewal in research interest. This, in turn, has produced a need for improved diagnostics, capable of providing more accurate pictures of infection prevalence, pathogen distribution, and vector-host interactions. Utilizing a previously described pipeline for the discovery of optimal molecular diagnostic targets, we identified a repetitive DNA sequence, and developed a corresponding assay, which allows for the sensitive and species-specific identification of M. perstans in human blood samples. Testing also demonstrated the ability to utilize this assay for the detection of M. perstans in field-collected mosquito samples. When testing both sample types, our repeat-targeting index assay outperformed a ribosomal sequence-targeting reference assay, facilitating the identification of additional M. perstans-positive samples falsely characterized as "negative" using the less sensitive detection method. Through the development of an assay based upon the systematic identification of an optimal DNA target sequence, our novel diagnostic assay will provide programmatic efforts with a sensitive and specific testing platform that is capable of accurately mapping M. perstans infection and determining prevalence. Furthermore, with the added ability to identify the presence of M. perstans in mosquito samples, this assay will help to define our knowledge of the relationships that exist between this pathogen and the various geographically relevant mosquito species, which have been surmised to represent potential secondary vectors under certain conditions. Detection of M. perstans in mosquitoes will also demonstrate proof-of-concept for the mosquito-based monitoring of filarial pathogens not vectored primarily by mosquitoes, an approach expanding opportunities for integrated surveillance.

Screening eaves of houses reduces indoor mosquito density in rural, western Kenya

Despite the scale-up of insecticide-treated nets and indoor residual spraying, the bulk of malaria transmission in western Kenya still occurs indoors, late at night. House improvement is a potential long-term solution to further reduce malaria transmission in the region. The impact of eave screening on mosquito densities was evaluated in two rural villages in western Kenya. One-hundred-and-twenty pairs of structurally similar, neighbouring houses were used in the study. In each pair, one house was randomly selected to receive eave screening at the beginning of the study while the other remained unscreened until the end of the sampling period. Mosquito sampling was performed monthly by motorized aspiration method for 4 months. The collected mosquitoes were analysed for species identification. Compared to unscreened houses, significantly fewer female Anopheles funestus (RR = 0.40, 95% CI 0.29-0.55), Anopheles gambiae Complex (RR = 0.46, 95% CI 0.34-0.62) and Culex species (RR = 0.53, 95% CI 0.45-0.61) were collected in screened houses. No significant differences in the densities of the mosquitoes were detected in outdoor collections. Significantly fewer Anopheles funestus were collected indoors from houses with painted walls (RR = 0.05, 95% CI 0.01-0.38) while cooking in the house was associated with significantly lower numbers of Anopheles gambiae Complex indoors (RR = 0.60, 95% CI 0.45-0.79). Nearly all house owners (99.6%) wanted their houses permanently screened, including 97.7% that indicated a willingness to use their own resources. However, 99.2% required training on house screening. The cost of screening a single house was estimated at KES6,162.38 (US$61.62). Simple house modification by eave screening has the potential to reduce the indoor occurrence of both Anopheles and Culex mosquito species. Community acceptance was very high although education and mobilization may be needed for community uptake of house modification for vector control. Intersectoral collaboration and favourable government policies on housing are important links towards the adoption of house improvements for malaria control.

Integrated survey of helminthic neglected tropical diseases and comparison of two mosquito sampling methods for lymphatic filariasis molecular xenomonitoring in the River Galana area, Kilifi County, coastal Kenya.

A lymphatic filariasis (LF) endemic focus along the River Galana/ Sabaki in Kilifi County, coastal Kenya, provided a platform to conduct an integrated survey for three helminthic neglected tropical diseases (NTDs), namely soil-transmitted helminthiasis (STH), schistosomiasis (SCH) and LF. Additionally, the study compared the performance of two mosquito trapping methods for LF molecular xenomonitoring (MX). Cross-sectional surveys measuring STH, SCH and LF prevalence were conducted in four villages. Mosquitoes were trapped using the CDC light trap (CDC-LT) and the Ifakara A tent trap (Ifakara-TT) methods and stored in pools which were tested for Wuchereria bancrofti DNA using the real-time polymerase chain reaction assay. A total of 907 people (436 adults; 471 children) participated in the parasitological testing. Among the STH infections, Trichuris trichiura and hookworms were most prevalent among the children and adult populations, respectively. The schistosome worm eggs detected belonged to the species Schistosoma haematobium and the prevalence of the infection was generally higher among the children compared with the adult population. The prevalence of LF infection among the adult population ranged from 1.8% to 7.6% across all 4 villages (P < 0.05). A total of 3,652 mosquitoes, including Anopheles, Culex, Mansonia, and Aedes species were collected. One mosquito pool consisting of Anopheles mosquitoes tested positive for filarial DNA out of 1,055 pools that were tested. The CDC-LT caught significantly more mosquitoes compared with the Ifakara-TT (P < 0.001). This study demonstrated that integrated epidemiological surveys using standard parasitological and entomological methods can provide useful information on co-endemic parasitic diseases which could help direct interventions and surveillance activities.

Host-Feeding Patterns of Mosquito Species in Aras Valley, Turkey

Identifying hosts of blood-feeding mosquito species is important to elucidate the role of vector species in disease transmission cycles. Herein, the aim was to identify the vertebrate hosts of mosquito species using the polymerase chain reaction-based reverse line blotting method. The mosquito species were Anopheles maculipennis sensu lato Meigen, 1818; Aedes caspius Pallas, 1771; Aedes vexans Meigen, 1830; Culex theileri Theobald, 1903; Anopheles hyrcanus Pallas 1771; Culex pipiens sensu lato Linnaeus, 1758; and Culiseta annulata Schrank, 1776, which were collected from the Aras Valley between July-August 2012 and June-September 2013. The analysis of mosquito blood-meal samples revealed several mammalian and avian host species. And also varying degrees of opportunistic mosquito feeding behavior in both birds and mammals were noted. These mosquito species fed on eight mammal species, i.e., humans, cows, sheep, horses, dogs, cats, goats, and porcupines, as well as avian species. Studies on the host-feeding patterns of blood-feeding vector arthropods may provide information about the vector potential of these species. However, the host-feeding patterns of the vector species are only one part of the vector capacity. To detect the exact potential of vector species, further studies are needed on vector competence for different pathogens.

Survey of Mosquito Larvae for Potential Nematode Parasitic Biological Control in Alachua County

There is an obvious and considerable interest in developing novel methods to control mosquito-borne diseases due to their impacts on mammalian hosts. Biological control practices are sustainable alternatives to chemical control of mosquito populations. Some nematodes are efficient insect parasites and represent a potential source of novel biological control agents. Such beneficial nematodes are potent biological control agents that can remove harmful pests whilst also preserving non-target insect populations. One such nematode, Romanomermis culicivorax, is a parasite of mosquito larvae, inducing paralysis and eventually killing its host. The potential success of a biological control agent can be informed from the current prevalence of native populations. Thus, we conducted a survey of parasitic nematodes in mosquito larvae in Alachua County. Twenty-five samples were obtained from all around Alachua County, with assistance from the Gainesville Department of Public Works Mosquito Control Section. Subsequent visual inspection and PCR for R. culicivorax were conducted to detect the presence of mosquito and nematode DNA in each sample. Out of the twenty-five mosquito samples tested, only one sample tested positive for the presence of the beneficial nematode. This sample was found in an apartment complex in proximity to Devil’s Millhopper Geological State Park. This work demonstrates the presence of mosquito parasitic nematodes in Alachua County, but at very low levels, potentially discouraging the use of such biological control practices. In addition, the proximity of the positive sample to the natural area may indicate the need to preserve such habitats for effective biological control measures.

Wolbachia infection in field-collected Aedes aegypti in Yunnan Province, southwestern China.

Wolbachia is gram-negative and common intracellular bacteria, which is maternally inherited endosymbionts and could expand their propagation in host populations by means of various manipulations. Recent reports reveal the natural infection of Wolbachia in Aedes Aegypti in Malaysia, India, Philippines, Thailand and the United States. At present, none of Wolbachia natural infection in Ae. aegypti has been reported in China. A total of 480 Ae. aegypti adult mosquitoes were collected from October and November 2018 based on the results of previous investigations and the distribution of Ae. aegypti in Yunnan. Each individual sample was processed and screened for the presence of Wolbachia by PCR with wsp primers. Phylogenetic trees for the wsp gene was constructed using the neighbour-joining method with 1,000 bootstrap replicates, and the p-distance distribution model of molecular evolution was applied. 24 individual adult mosquito samples and 10 sample sites were positive for Wolbachia infection. The Wolbachia infection rate (IR) of each population ranged from 0 - 41.7%. The infection rate of group A alone was 0%-10%, the infection rate of group B alone was 0%-7.7%, and the infection rate of co-infection with A and B was 0-33.3%. Wolbachia infection in wild Ae. aegypti in China is the first report based on PCR amplification of the Wolbachia wsp gene. The Wolbachia infection is 5%, and the wAlbA and wAlbB strains were found to be prevalent in the natural population of Ae. aegypti in Yunnan Province.

Method comparison for Japanese encephalitis virus detection in samples collected from the Indo-Pacific region.

Japanese encephalitis virus (JEV) is a mosquito-borne viral pathogen, which is becoming a growing public health concern throughout the Indo-Pacific. Five genotypes of JEV have been identified. Current vaccines are based on genotype III and provide a high degree of protection for four of the five known genotypes. RT-PCR, Magpix, Twist Biosciences Comprehensive Viral Research Panel (CVRP), and SISPA methods were used to detect JEV from mosquito samples collected in South Korea during 2021. These methods were compared to determine which method would be most effective for biosurveillance in the Indo-Pacific region. Our data showed that RT-PCR, Twist CVRP, and SISPA methods were all able to detect JEV genotype I, however, the proprietary Magpix panel was only able to detect JEV genotype III. Use of minION sequencing for pathogen detection in arthropod samples will require further method development. Biosurveillance of vectorborne pathogens remains an area of concern throughout the Indo-Pacific. RT-PCR was the most cost effective method used in the study, but TWIST CVRP allows for the identification of over 3,100 viral genomes. Further research and comparisons will be conducted to ensure optimal methods are used for large scale biosurveillance.

Modification of the Folmer primers for the cytochrome c oxidase gene facilitates identification of mosquitoes

BackgroundAccurate identification of mosquito species is essential for the development and optimization of strategies to control mosquitoes and mosquito-borne diseases. Problems with the morphological identification of mosquito species have led to the use of molecular identification techniques, in particular the Folmer cytochrome c oxidase subunit I (COI) PCR system (FCOS), originally designed to identify a range of other invertebrates.MethodsAs there can be difficulties identifying mosquitoes using FCOS, we re-evaluated the FCOS primers and developed a new COI-based SYBR PCR (the Auburn COI system—AUCOS) to improve the molecular identification of mosquitoes. Sequence data in GenBank for 33 species from 10 genera of mosquitoes were used to develop our AUCOS primers. Two molecular assays (AUCOS, FCOS) and morphological identification were carried out on mosquitoes collected from the field in Auburn, Alabama (USA) and on Saint Kitts.ResultsWith a convenience sample of individual mosquitoes comprising 19 species from six genera in Saint Kitts (n = 77) and Auburn (n = 48), our AUCOS provided higher-quality sequence data than FCOS. It also proved more sensitive than FCOS, successfully amplifying 67.5% (85/126) as opposed to 16.7% (21/126) of the samples. The species determined by morphology, or genus with damaged samples, matched that as determined by AUCOS for 84.9% (62/73) of the samples. Morphological classification was confirmed by FCOS with 81.0% (17/21) of samples producing utilizable sequences. While both FCOS and AUCOS correctly identified all the Aedes, Anopheles, Deinocerites, and Uranotaenia species in the study, identification of Culex species was less successful with both methods: 50.0% (3/6) by FCOS and 35.7% (5/14) by AUCOS.ConclusionsThe AUCOS DNA barcoding system for mosquito species described in this study is superior to the existing FCOS for the identification of mosquito species. As AUCOS and FCOS amplify the same variable region of the COI, the large amount of existing data on GenBank can be used to identify mosquito species with sequences produced by either PCR.Graphical

Malaria vector bionomics in Taita-Taveta County, coastal Kenya

BackgroundEstimation of the composition and densities of mosquito species populations is crucial for monitoring the epidemiology of mosquito-borne diseases and provide information on local vectors to public health officials and policy-makers. The aim of this study was to evaluate malaria vector bionomics in ecologically distinct sites in Taita-Taveta County, Kenya.MethodsAdult mosquitoes were collected using backpack aspirators and paired indoor/outdoor CDC light traps in 10 randomly selected households in six villages with distinct ecologies over a study period of 3 years. All Anopheles mosquitoes were morphotyped, and sibling species of Anopheles gambiae sensu lato (An. gambiae s.l.) were identified and separated by PCR analysis of extracted ribosomal DNA. All female anophelines were tested for sporozoite infectivity, with engorged females screened for blood-meal sources using the enzyme-linked immunosorbent assay technique. A subsample of those testing positive and those testing negative for Plasmodium in the ELISA were subjected to PCR assay.ResultsA total of eight different Anopheles species were collected both indoors and outdoors. Anopheles gambiae s.l. (82.6%, n = 5252) was the predominant species sensu lato, followed by Anopheles coustani sensu lato (An. coustani s.l.; (10.5%, n = 666) and Anopheles funestus sensu lato (An. funestus s.l.; 5.6%, n = 357). A subset of 683 mosquito samples representing An. gambiae s.l. (n = 580, approx. 11.0%) and An. funestus s.l. (n = 103, approx. 28.9%) were identified by molecular diagnostic assays into sibling species. The An. gambiae s.l. complex was composed of Anopheles arabiensis (62.5%, n = 363/580), An. gambiae sensu stricto (An. gambiae s.s.; 0.7%, n = 4/580), Anopheles merus (0.7%, n = 4/580) and Anopheles quadriannulatus (0.2%, n = 1/580), with the remaining samples (35.5%, n = 206/580) unamplified. Anopheles funestus s.l. was composed of An. rivulorum (14.6%, n = 15/103) and An. leesoni (11.6%, n = 12/103); the remaining samples were unamplified (73.8%, n = 76/103). A total of 981 samples were subjected to PCR analysis for malaria parasite detection; of these 16 (1.6%) were confirmed to be positive for Plasmodium falciparum. The overall human blood index was 0.13 (32/238).ConclusionsAnopheles gambiae, An. funestus and An. coustani are key malaria vectors in the Taveta region of Kenya, showing concurrent indoor and outdoor transmission. All of the vectors tested showed a higher propensity for bovine and goat blood than for human blood.Graphical

The Extraction of Zingiber Officinale Rosc as a Natural Insecticide for Aedes Aegypti Larvae

Dengue fever is a health problem in Indonesia, including in Gorontalo Province, with an incidence rate of 101.53 per 100,000 population. One of the efforts to prevent the incidence of dengue fever is the use of natural insecticides, including red ginger. This study aims to assess the effectiveness of red ginger juice on the mortality of Aedes aegypti mosquito larvae. This research took place at the Laboratory of the Department of Public Health, the State University of Gorontalo, in 2021 using a True Experiment design. The mosquito larvae samples used were 500 larvae of Aedes aegypti instar IV mosquitoes taken from endemic areas of dengue fever in Gorontalo. Data were analyzed using the One Way ANOVA statistical test. Red ginger extract was given in five concentrations, namely 60%, 70%, 80%, 90%, and 100%. The results showed an effect of red ginger extract on the mortality of Aedes aegypti mosquito larvae at each treatment concentration given (p-Value = 0.000). The higher the concentration level given, the higher the larval mortality rate will also be. Red ginger is expected to be used by the community to prevent dengue fever.

A prospective cohort study of Plasmodium falciparum malaria in three sites of Western Kenya

BackgroundMalaria in western Kenya is currently characterized by sustained high Plasmodial transmission and infection resurgence, despite positive responses in some areas following intensified malaria control interventions since 2006. This study aimed to evaluate long-term changes in malaria transmission profiles and to assess patterns of asymptomatic malaria infections in school children aged 5–15 years at three sites in western Kenya with heterogeneous malaria transmission and simultaneous malaria control interventions.MethodsThe study was conducted from 2018 to 2019 and is based on data taken every third year from 2005 to 2014 during a longitudinal parasitological and mosquito adult surveillance and malaria control programme that was initiated in 2002 in the villages of Kombewa, Iguhu, and Marani. Plasmodium spp. infections were determined using microscopy. Mosquito samples were identified to species and host blood meal source and sporozoite infections were assayed using polymerase chain reaction.ResultsPlasmodium falciparum was the only malaria parasite evaluated during this study (2018–2019). Asymptomatic malaria parasite prevalence in school children decreased in all sites from 2005 to 2008. However, since 2011, parasite prevalence has resurged by > 40% in Kombewa and Marani. Malaria vector densities showed similar reductions from 2005 to 2008 in all sites, rose steadily until 2014, and decreased again. Overall, Kombewa had a higher risk of infection compared to Iguhu (χ2 = 552.52, df = 1, P < 0.0001) and Marani (χ2 = 1127.99, df = 1, P < 0.0001). There was a significant difference in probability of non-infection during malaria episodes (log-rank test, χ2 = 617.59, df = 2, P < 0.0001) in the study sites, with Kombewa having the least median time of non-infection during malaria episodes. Gender bias toward males in infection was observed (χ2 = 27.17, df = 1, P < 0.0001). The annual entomological inoculation rates were 5.12, 3.65, and 0.50 infective bites/person/year at Kombewa, Iguhu, and Marani, respectively, during 2018 to 2019.ConclusionsMalaria prevalence in western Kenya remains high and has resurged in some sites despite continuous intervention efforts. Targeting malaria interventions to those with asymptomatic infections who serve as human reservoirs might decrease malaria transmission and prevent resurgences. Longitudinal monitoring enables detection of changes in parasitological and entomological profiles and provides core baseline data for the evaluation of vector interventions and guidance for future planning of malaria control.Graphical abstract

Geometric Morphometric Wing Analysis of Avian Malaria Vector, Culiseta longiareolata, from Two Locations in Algeria.

The application of geometric morphometry on mosquito wings (Culicidae) is considered a powerful tool for evaluating correlations between the phenotype (e.g., shape) and environmental or genetic variables. However, this has not been used to study the wings of the avian malaria vector, Culiseta longiareolata. Therefore, the goal of this study is to investigate the intra-specific wing variations between male and female Cs. longiareolata populations in different types of larval habitats and climatic conditions in Algeria. A total of 256 Cs. longiareolata mosquito samples were collected from January 2020 to July 2021 in three cities (Annaba, El-Tarf, and Guelma) of northeastern Algeria that have two distinct climatic condition levels (sub-humid and sub-arid) and different types of larval habitats (artificial and natural). Nineteen (19) wing landmarks (LMs) were digitized and analyzed based on geometric morphometry. Our results revealed differences in the wing shape of female and male mosquito populations, indicating sexual dimorphism. Moreover, canonical variance analysis (CVA) showed that factors, such as climatic conditions and type of larval habitats, also affect the wing shape of female and male Cs. longiareolata mosquito populations. Furthermore, the wing shape of male populations was more distinct compared with female populations.

Bacterial Community Diversity and Bacterial Interaction Network in Eight Mosquito Species.

Mosquitoes (Diptera: Culicidae) are found widely throughout the world. Several species can transmit pathogens to humans and other vertebrates. Mosquitoes harbor great amounts of bacteria, fungi, and viruses. The bacterial composition of the microbiota of these invertebrates is associated with several factors, such as larval habitat, environment, and species. Yet little is known about bacterial interaction networks in mosquitoes. This study investigates the bacterial communities of eight species of Culicidae collected in Vale do Ribeira (Southeastern São Paulo State) and verifies the bacterial interaction network in these species. Sequences of the 16S rRNA region from 111 mosquito samples were analyzed. Bacterial interaction networks were generated from Spearman correlation values. Proteobacteria was the predominant phylum in all species. Wolbachia was the predominant genus in Haemagogus leucocelaenus. Aedes scapularis, Aedes serratus, Psorophora ferox, and Haemagogus capricornii were the species that showed a greater number of bacterial interactions. Bacterial positive interactions were found in all mosquito species, whereas negative correlations were observed in Hg. leucocelaenus, Ae. scapularis, Ae. serratus, Ps. ferox, and Hg. capricornii. All bacterial interactions with Asaia and Wolbachia were negative in Aedes mosquitoes.

Entomological Surveillance of the Invasive Aedes Species at Higher-Priority Entry Points in Northern Iran: Exploratory Report on a Field Study.

Arboviral diseases such as dengue, Zika, and chikungunya are transmitted by Aedes aegypti and Ae albopictus and are emerging global public health concerns. This study aimed to provide up-to-date data on the occurrence of the invasive Aedes species in a given area as this is essential for planning and implementing timely control strategies. Entomological surveillance was planned and carried out monthly from May 2018 to December 2019 at higher-priority entry points in Guilan Province, Northern Iran, using ovitraps, larval collection, and human-baited traps. Species richness (R), Simpson (D), evenness (E), and Shannon-Wiener indexes (H̕) were measured to better understand the diversity of the Aedes species. The Spearman correlation coefficient and regression models were used for data analysis. We collected a total of 3964 mosquito samples including 17.20% (682/3964) belonging to the Aedes species, from 3 genera and 13 species, and morphologically identified them from May 2018 to December 2019. Ae vexans and Ae geniculatus, which showed a peak in activity levels and population in October (226/564, 40.07% and 26/103, 25.2%), were the eudominant species (D=75.7%; D=21.2%) with constant (C=100) and frequent (C=66.7%) distributions, respectively. The population of Ae vexans had a significant positive correlation with precipitation (r=0.521; P=.009) and relative humidity (r=0.510; P=.01), whereas it was inversely associated with temperature (r=-0.432; P=.04). The Shannon-Wiener Index was up to 0.84 and 1.04 in the city of Rasht and in July, respectively. The rarefaction curve showed sufficiency in sampling efforts by reaching the asymptotic line at all spatial and temporal scales, except in Rasht and in October. Although no specimens of the Ae aegypti and Aealbopictus species were collected, this surveillance provides a better understanding of the native Aedes species in the northern regions of Iran. These data will assist the health system in future arbovirus research, and in the implementation of effective vector control and prevention strategies, should Aeaegypti and Ae albopictus be found in the province.

Outdoor and early hour human biting activities of malaria mosquitoes and the suitability of clay pot for outdoor resting mosquito collection in malaria endemic villages of southern Rift Valley, Ethiopia

BackgroundSampling adult Anopheles mosquitoes is important for assessing vector density, estimating the sporozoite infection rate, and quantifying the impact of vector control interventions. The objective of this study was to assess the Anopheles mosquito species composition, and their outdoor and indoor biting activities, and to evaluate the suitability of clay pots for indoor and outdoor resting mosquito collections. MethodsTwo malaria-endemic villages in the Gamo zone were purposely selected. Forty clay pots were deployed for outdoor resting mosquitoes sampling and another forty for indoor resting sampling. Twenty pit shelters were constructed for outdoor resting mosquito collection. The human landing catch (HLC) technique was employed to collect indoor and outdoor host-seeking mosquitoes in two households in each village. Morphological identification of the Anopheles mosquito was done using an identification key. Enzyme-linked immunosorbent assay technique was used for blood meal origin and circumsporozoite proteins (CSP) test. Speciation of An. gambiae complex was done using polymerase chain reaction. A Chi-square test was used to compare the effectiveness of clay pot and pit shelters for outdoor resting sampling. ResultsA total of 904 female Anopheles mosquitoes comprising An. gambiae complex, An. pharoensis, An. tenebrosus, An. dencalicus and An. demelloni were sampled. The majority (64%) of them were sampled by the HLC technique. There was a slight difference between the outdoor clay pot (19%) and pit shelter (17%) collection. No Anopheles mosquitoes were collected indoor using clay pots. All mosquitoes were tested for CSPs, but none of them were found to be positive. Anopheles mosquitoes were tending to bite humans outdoor than indoors, and their peak biting hours was 10–11 pm. The human blood meal index of Anopheles mosquitoes was 0.07 from pit shelters and it was 0.04 from clay pots. The bovine blood meal index was 0.45 for mosquitoes from both pit shelters and clay pot collections. ConclusionAnopheles arabiensis was the predominant species and it was tending to bite cattle more than humans. Clay pot could be suitable for outdoor resting mosquito collection, but not for indoor resting species.

The Nutrient Composition of Three Mosquito (Diptera: Culicidae) Species, Aedes caspius, Anopheles hyrcanus, and Culex pipiens, Harvested from Rice Fields for Their Potential Utilization as Poultry Feed Ingredients

Increasing pressure on the world’s livestock production sector has stirred interest towards the exploration of insects as an alternative feed source. We examined the potential of wild-caught mosquitoes, harvested from rice-fields, to be utilised as poultry feed. Three mosquito species were identified in high abundance, namely Aedes caspius, Anopheles hyrcanus, and Culex pipiens, and their nutritional and microbiological profile was assessed at the species-level and as mixed samples collected from two different seasons (summer 2020 and 2021). Their nutritional potential was evaluated based on protein, fat, moisture and ash content, fatty acid and mineral profile, and antioxidant activity. The microbiological profile of each mosquito species was assessed by measuring the population of total viable count, Enterobacteriaceae, lactic acid bacteria, and coagulase-positive Staphylococci. Obtained values were compared to common edible insects and conventional livestock feedstuff. All mosquito samples presented an overall promising nutritional composition, stable between the two harvest seasons. Mosquitoes’ protein and fat content ranged from 54 to 62% and 16 to 28%, respectively. The examined species presented statistically significant differences in certain cases; Anopheles hyrcanus had the highest protein content (61.8% dry weight basis; dwb) and the highest antioxidant potential (45.9% ability to scavenge the DPPH radical). All mosquito samples were rich in minerals, containing high concentrations of calcium, phosphorus, and magnesium, minerals essential for poultry development. The GC/MS fatty acid profile revealed a high unsaturated character (65.2–71.5%), a predominance of palmitic (23.8–30.4%), palmitoleic (28.5–37.0%), and oleic (18.3–29.1%) acids, as well as the presence of essential linolenic (1.4–5.2%) and eicosipentanoic (1.5–2.4%) acids. The presence of microorganisms was confirmed across all species, at levels comparable to fresh food harvested from soil and farmed edible insects. Mosquitoes harvested from rice-fields exhibited an overall highly nutritious, stable profile, comparable and even superior to common feedstuff and edible insects, showing potential to be utilised as poultry feed components.

Screening of Circulation of Usutu and West Nile Viruses: A One Health Approach in Humans, Domestic Animals and Mosquitoes in Burkina Faso, West Africa.

Usutu virus (USUV) and West Nile virus (WNV) are phylogenetically closely related arboviruses. These viruses mainly follow an enzootic cycle involving mosquitoes and birds, but they occasionally infect humans and other mammals, inducing neurotropic disorders. Since the discovery of USUV, only two human cases have been reported in Africa, including one in Burkina Faso in 2004. Since then, no studies have been conducted to measure the extent of the circulation of this virus in Burkina Faso, and no study regarding the circulation of WNV has been conducted. Our study aimed to determine the seroprevalence of USUV and WNV in blood donations and in animals (horses, dogs, chickens and pigeons) and to perform molecular screening in patients with febrile fever and in Culex quinquefasciatus and Aedes aegypti mosquitoes. The prevalence of USUV and WNV was studied by serological (ELISA and microneutralization tests) and molecular analyses (RT-qPCR) of mosquito, dog, domestic bird, horse, and human samples in Burkina Faso between 2019 and 2021. We detected a very active transmission of both viruses in Burkina Faso. WNV and USUV seroprevalence is particularly high in humans (19.16% and 14.17%, respectively) and horses (17.28% and 6.17%). Molecular screening did not detect WNV or USUV in the mosquito or human samples tested. Our study shows an active spread of USUV and WNV in Burkina Faso, especially for WNV. This study highlights the value of developing surveillance programs to better prevent, detect, and alert people to USUV and WNV circulation in both primary and incidental hosts.