While human malaria transmission in Indonesia has declined, reported cases of zoonotic Plasmodium knowlesi are increasing. This study examined the larval habitats of malaria vectors in North Sumatra to assess the potential of larval source management as a control strategy for both human and zoonotic malaria vectors. Multiple larval habitat surveys in the areas surrounding two dusuns with documented human and zoonotic (P. knowlesi) malaria cases in Langkat Regency, North Sumatra, were conducted over 2 years, encompassing both wet and dry seasons. Larval habitats were characterized by mosquito immature presence and density, land-use type where found, aquatic habitat class (i.e., naturally occurring, man-made from natural materials or man-made from artificial materials), and habitat subclass for a range of abiotic and biotic parameters. A total of 1413 mosquito larvae and 98 pupae were collected. Anopheles larvae comprised 20.6% of all mosquito immatures. Anopheles maculatus comprised 65.3% of all immature anophelines, followed by Anopheles dirus (21.9%), Anopheles scanloni, Anopheles kochi, and Anopheles vagus in order of abundance. Habitat class predicted anopheline presence and density, with larvae occurring more frequently in naturally occurring habitats and man-made habitats from natural materials than in artificial man-made habitats (presence: generalized linear mixed model [GLMM] β = -1.45, P = 0.006; density: β = -1.42, P = 0.001). At the habitat subclass level, An. maculatus larvae were most frequently detected in natural habitats, particularly stream margins. Meanwhile, An. dirus larvae occurred approximately equally in natural habitats and man-made habitats from natural materials, with tire tracks being the most common habitat subclass. Four species (An. maculatus, An. dirus, An. scanloni, and An. kochi) were detected, albeit infrequently, in man-made habitats from artificial materials. In North Sumatra, anopheline vector species utilize a diverse range of larval habitats, including natural and man-made, on both natural substrates and artificial materials. Species-specific habitat preferences were observed: An. dirus was found in both natural and man-made habitats from natural materials, whereas An. maculatus was predominantly found in more dispersed and inaccessible natural sites, suggesting that larval control may be more challenging for An. maculatus than An. dirus.

Background: Indonesia has a large Muslim population, with a substantial proportion residing in areas that are vulnerable to malaria transmission. One such area is Trenggalek District, which is classified as a malaria-endemic region in East Java Province. Geographical conditions, occupational activities, and population mobility are factors that may influence malaria transmission dynamics in this region. Methods: This study employed a descriptive observational research design. Secondary data were obtained from the Environmental Health Engineering and Disease Control Agency (BBTKLPP) Surabaya. The data included information on the characteristics of malaria cases in Trenggalek District as well as the results of resistance testing of Anopheles vagus mosquitoes to 0.75% permethrin insecticide conducted in Pandean Village, Trenggalek District. Results: Trenggalek District is categorized as a low malaria endemic area, with most reported cases being imported, as no indigenous malaria cases have been identified to date. Malaria case trends from 2014 to 2017 exhibited fluctuating patterns. The majority of malaria patients were male (97.34%), with 59.88% working as farmers and 29.79% employed in the private sector. The insecticide resistance test showed that 100% of Anopheles vagus mosquitoes died within one hour of exposure to 0.75% permethrin, while no mortality was observed in the control group. Conclusion: Most malaria cases in Trenggalek District occurred among male individuals with high mobility, particularly those working as farmers or in the private sector, indicating a potential risk for the emergence of indigenous malaria transmission. Anopheles vagus mosquitoes in Pandean Village, Trenggalek District, remain susceptible to 0.75% permethrin insecticide. Keywords: Malaria cases; Trenggalek District; East Java; Anopheles vagus; permethrin resistance

Baseline genetic characterization of malaria vector populations provides critical data for evidence-based surveillance in persistent transmission foci. This pilot study generated preliminary genetic baseline data for Anopheles populations in the Menoreh Hills border region between Central Java and Yogyakarta provinces, Indonesia, addressing a key geographic gap in regional vector research. Adult female mosquitoes were collected from 3 houses with reported malaria cases in Ngadirejo Village using standardized entomological methods, including human landing, animal landing, and resting collections. Specimens were morphologically identified and molecularly characterized via ITS2 gene sequencing. Phylogenetic analyses were assessed using maximum likelihood methods, and genetic diversity indices were calculated to examine population structure. A total of 62 specimens representing 3 species were collected exclusively through animal landing collections: Anopheles vagus (48 specimens, 77.4%), Anopheles maculatus (9 specimens, 14.5%), and Anopheles kochi (5 specimens, 8.1%). An. kochi exhibited high haplotype diversity (Hd=0.709) with low nucleotide diversity (π=0.004), while An. maculatus showed lower haplotype diversity (Hd=0.480) and higher nucleotide diversity (π=0.026). Phylogenetic analysis revealed Purworejo specimens clustered with regional populations: An. kochi grouped within Clade I with Indonesian isolates; An. maculatus distributed across multiple clades; An. vagus formed a cohesive unit with other Indonesian populations. The exclusive success of animal landing collections in the Menoreh Hills highlands provides key methodological insights. This study offers essential baseline reference data, validates cost-effective genetic surveillance approaches, and supports future large-scale population connectivity studies across the Menoreh Hills malaria transmission complex.

BackgroundForeign migrant workers from malaria-endemic regions play a critical factor in the transmission of malaria to non-endemic areas, mainly due to their mobility while seeking employment opportunities. This risk is particularly heightened in areas where malaria vectors are present.MethodsThis study aimed to investigate the malaria vectors in two sub-districts in Khon Kaen Province, known for their factory areas and the significant presence of Myanmar migrant worker communities. The collection was carried out from June 2020 to May 2021. The black light traps (BLT) operated continuously from 6:00 pm to 6:00 am (12 h) and Kelambu trap (KT) were set up from 6:00 pm to 9:00 pm, with both traps set up once a month. A total of 679 female Anopheles mosquitoes were collected near the workplaces and dormitories of these workers. Subsequently, the collected female mosquitoes underwent morphological identification using Standard Thailand keys and polymerase chain reaction analysis with rDNA ITS2 primers.ResultsMorphological identification revealed that 201 (29.6%) belonged to the Barbirostris complex. The remaining Anopheles mosquitoes are in the subgroup Cellia, comprised 437 (64.4%) Anopheles vagus, 39 (5.7%) Anopheles subpictus, and 2 (0.3%) Anopheles annularis. To distinguish the Barbirostris complex, multiplex PCR based on ITS-2 sequences was conducted. Out of the 201 specimens examined, 153 (76.1%) as Anopheles campestris, 36 (17.9%) as Anopheles wejchoochotei, and 12 (6%) as Anopheles dissidens. Additionally, the subgroup Anopheles Cellia was confirmed using specific primers based on ITS-2 sequences.ConclusionsFrom the obtained results, An. campestris, An. wejchoochotei, An. vagus and An. annularis are reported as the malaria vectors in Thailand. The findings emphasized the important of addressing the presence of Anopheles malaria vectors, especially in the substantial migrant worker population originating from endemic areas. This situation raises concerns regarding the potential transmission of malaria infections to regions not traditionally affected by the disease. Epidemiological studies on malaria vectors should not solely concentrate on endemic regions but also extend to non-endemic areas because of the mobility of migrant workers throughout the country. This broader approach is crucial for implementing an effective malaria surveillance strategy.Graphical

Purworejo Regency, Central Java, remains an endemic malaria area in the elimination phase, with an Annual Parasite Incidence (API) exceeding the RPJMN 2018–2023 target of 0.07 per 1,000 at-risk population. The region's varied topography comprising coastal zones, lowlands, and hills supports diverse breeding habitats for Anopheles spp., increasing malaria transmission risk. This descriptive observational study with a cross-sectional design was conducted from May 2024 to March 2025 in the working area of the Ngombol Health Center. Ten villages were selected using proportional cluster sampling to identify potential Anopheles breeding sites. Field surveys were conducted, and data were analyzed using Geographic Information Systems (GIS). The study found swamps, rice fields, ponds, lagoons, and ditches as positive breeding habitats for Anopheles subpictus, Anopheles vagus, and Anopheles barbirostris. Environmental characteristics of these sites included temperatures of 28.2–31.3°C, humidity levels of 60–80%, pH values of 7.22–8.56, and altitudes between 4–13 meters above sea level. Buffer analysis revealed that breeding places within 1 KM of the coast, 500–1000 meters from rivers, and 200–500 meters from residential areas showed high larval densities. These findings underscore the importance of spatial mapping-based vector control strategies to reduce malaria transmission risk.

Impact of peri-urban pig farms on mosquito community structure in Yogyakarta, Indonesia

The genetic composition of Anopheles mosquitoes and the diverse population of gut-microbiota within the Anopheles subpictus and Anopheles vagus mosquitoes in Tamil Nadu, India

Abstract. Kermelita D, Hadi UK, Soviana S, Tiuria R, Novianto D. 2024. Species diversity, mosquito behavior, and microfilariae detection in vectors and reservoirs in filariasis-endemic areas of Bengkulu, Indonesia. Biodiversitas 25: 3125-3131. Filariasis, recognized by the WHO as a neglected tropical disease, remains a significant global health challenge, particularly in Southeast Asia. In Bengkulu Province, Indonesia, 66 cases of filariasis were reported between 2010 and 2020, with the highest prevalence found in Mukomuko and Seluma Districts. This study analyzed the vector behavior and detection of filariasis reservoirs in endemic areas of Bengkulu Province. Human landing and resting collections were employed for mosquito collection for 12 h (18:00-06:00), and blood sampling was performed on reservoir animals (Canis familiaris, Felis catus Linnaeus, 1758, and Macaca fascicularis (Raffles, 1821)). Mosquito diversity was analyzed using several diversity indices. Filaria larvae in mosquitoes were detected using Polymerase Chain Reaction (PCR) methods, and filaria in reservoir animals were detected using blood smears with Giemsa staining. The result showed that 17 mosquito species were captured in the filariasis-endemic regions of Bengkulu Province: Culex quinquefasciatus Say, 1823; Culex hutchinsoni Barraud, 1924; Culex gelidus Theobald, 1901; Culex pseudovishnui Colless, 1957; Culex vishnui Theobald, 1901; Armigeres subalbatus (Coquillett, 1898); Aedes aegypti (Linnaeus, 1762); Aedes albopictus (Skuse, 1894); Anopheles tessellatus Theobald, 1901; Anopheles vagus Döntiz, 1902; Anopheles minimus Theobald, 1901; Anopheles indefinitus (Ludlow, 1904); Anopheles sundaicus (Rodenwaldt, 1948); Anopheles barbirostris Wulp, 1884; Anopheles maculatus Theobald, 1901; Anopheles sp., and Mansonia annulata Leicester, 1908. Culex pseudovishnui exhibited the highest indoor density among the mosquito species, whereas C. quinquefasciatus exhibited the highest outdoor density. Filaria larvae were not detected in all mosquito sample pools based on the PCR results, whereas microfilariae of Dirofilaria immitis (Leidy, 1856) Railliet & Henry, 1911 were identified in the reservoir (Canine) blood samples. Thus, the presence of microfilariae in reservoir animals must be monitored because they can transmit filariasis to the community. Control strategies should be developed for endemic regions in Bengkulu Province.

Climate change will affect the physical and biological environment that supports the development of various infectious diseases, including malaria. Wajo District, particularly Inalipue Village in Tanasitolo Sub-district, faces a major challenge in controlling the malaria vector, the Anopheles mosquito. The main objective of this survey was to identify and understand the environmental factors that contribute to Anopheles mosquito population density in Inalipue Village. Data were obtained by capturing adult mosquitoes using the Human Landing Collection (HLC) method as well as surveying Anopheles mosquito larval breeding sites. Mosquito trapping was conducted inside and outside the house and around livestock pens. Anopheles barbirostris was the most dominant species, found in all capture methods with the highest Man Biting Rate (MBR) of 1.00 for outdoor capture. Anopheles nigerrimus and Anopheles vagus were also found, although in smaller numbers. Of the 17 breeding habitat sites, 5 showed positive larval results. Water temperature, pH, and the presence of flora and fauna in these habitats varied, but most had ideal conditions for mosquito breeding. Anopheles barbirostris shows high adaptation to a wide range of habitats, making it the main vector. These findings provide a strong basis for local governments and health agencies to plan and implement more effective and integrated malaria control programs.

BACKGROUNDAnopheles (An.) sp. transmits Plasmodium parasites that cause malaria. In its life cycle in the mosquito’s body, Plasmodium passes through 2 mosquito organs, namely the salivary glands and midgut. The bacterial community (symbiont bacteria) in these organs has been known to influence and/or inhibit the development of the Plasmodium life cycle by producing specific proteases. This research aims to isolate and characterize symbiotic bacteria with proteolytic activity from 2 important malaria vectors in Indonesia: An. sundaicus and An. vagus. METHODSA total of 183 bacterial originating from the salivary glands and midgut were successfully isolated. Initial screening was carried out based on morphological differences, followed by purification of the selected isolates to obtain single colonies. The selected isolates were then subjected to an initial proteolytic ability test using skim milk agar media. Only isolates with proteolytic activity were further characterized with the 16SrDNA molecular marker. The isolates were pabs5 from the salivary glands and pabs3 from the midgut of An. vagus, while pdbs3 and ecbs4 were isolates from the salivary glands and midgut of An. sundaicus. RESULTSMorphological and molecular characterization showed that both pabs5 and pabs3 isolates were Pseudomonas(Ps.) aeruginosa, while ecbs4 was Enterobacter cloacae and pdbs3 was Pantoea dispersa. These species werefirst discovered in Anopheles vagus and Anopheles sundaicus. CONCLUSIONThe ability of Ps. aeruginosa and Pantoea dispersa to produce proteases indicated their potential role in the exploration of new strategies to control mosquito vectors that transmit pathogens.

Malaria in eastern Indonesia remains high despite significant reduction and elimination in other parts of the country. A rapid entomological assessment was conducted in eight high malaria endemic regencies of Papua Province, Indonesia, to expedite malaria elimination efforts in this region. This study aims to characterize specific, actionable endpoints toward understanding where and when malaria transmission is happening, where interventions may function best, and identify gaps in protection that result in continued transmission. The entomological assessment included identifying potential vectors through human landing catch (HLC), indoor morning and night resting collections, identification of larval sites through surveillance of water bodies, and vector incrimination toward understanding exposure to malaria transmission. Human landing catches (HLCs) and larval collections identified 10 Anopheles species, namely Anopheles koliensis, Anopheles punctulatus, Anopheles farauti, Anopheles hinesorum, Anopheles longirostris, Anopheles peditaeniatus, Anopheles tesselatus, Anopheles vagus, Anopheles subpictus and Anopheles kochi. The most common and abundant species found overall were An. koliensis and An. punctulatus, while An. farauti was found in large numbers in the coastal areas of Mimika and Sarmi Regencies. Vector incrimination on Anopheles collected from HLCs and night indoor resting demonstrated that An. koliensis and An. punctulatus carried Plasmodium in Keerom, Jayapura, and Sarmi Regencies. Analysis of HLCs for the most common species revealed that the An. koliensis and An. punctulatus, bite indoors and outdoors at equal rates, while An. farauti predominantly bite outdoors. Larval surveillance demonstrated that most water bodies in and surrounding residential areas contained Anopheles larvae. This study demonstrated indoor and outdoor exposure to mosquito bites and gaps in protection, enabling exposure to infectious bites in all regencies. This explains why current malaria control efforts focusing on indoor protection have failed to substantially reduce malaria incidence in the region. Optimization of insecticide-treated bed nets (ITNs), as well as installment of mosquito screens in houses, may further reduce indoor transmission. For outdoor transmission, the use of community-centric approaches to reduce or eliminate larval sources within and surrounding the village through the guidance of locally stationed entomologists, along with Social and Behavior Change mediated health education towards the local adoption of mosquito protection tools during outdoor activities, may reduce malaria transmission.

Abstract. Ghofur A, Hadisaputro S, Sayono S. 2024. Detection of microfilaria L3 and insecticide resistance among wild-caught mosquito vectors in endemic areas of lymphatic filariasis. Biodiversitas 25: 1975-1983. The decline in the global prevalence of Lymphatic Filariasis (LF) is evident in the persistent endemic foci in Africa and Southeast Asia. In this context, the presence of infectious and insecticide-resistant mosquitoes and the annual biting rate in the area are key to microfilaria transmission. Therefore, this research aimed to determine insecticide resistance and microfilariae infection in mosquito vectors in endemic areas. In Jenggot and Medono Villages, twice entomological surveys were conducted based on six LF cases, where indoor and outdoor mosquito capturing was carried out in ten houses within a 100 m radius of each case as well as household interviews about insecticide use. In addition, laboratory works were performed for species identification and detection of ovarian dilatation, microfilariae infection, and knockdown resistance mutations. A total of 1,197 and 581 mosquitoes were distributed to five species and their proportions, namely Culex quinquefasciatus (69.59 and 65.40%), Cx. tritaeniorhynchus (5.76 and 0.00%), Cx. vishnui (5.85 and 27.54%), Anopheles vagus (0.58 and 0.00%), and Aedes aegypti (18.21 and 7.06%). The percentage of female mosquito infection, parity, and microfilaria were 66.25 and 86.00%, 63.37 and 70.95%, as well as 0.00 and 1.34%, respectively. Furthermore, TTA-TTT, TTA-CTA, and TTA-TGT base substitutions were reported in codon 1014 of Cx. quinquefasciatus VGSC gene with proportions of 81.66, 1.67, and 26.67%, respectively. The result showed that the vulnerability of the research location to transmission emphasized the necessity for early detection, vector control, and further analyses of the susceptibility of microfilariae to antiparasitic drugs.

Malaria is caused by Plasmodium infection transmitted Anopheles sp. One of the obstacles in malaria control is the variation of Anopheles sp. Species which have various characteristics and behaviour, so it’s very important to understand the species of Anopheles sp. with aim to develop the disease control program. This study was conducted in Kulon Progo Regency, Yogyakarta, one of the malaria endemic areas in Indonesia. Data collection of Anopheles sp. species diversity was carried out through landing collection inside and outside people’s homes at 18.00 - 06.00 WIB. Observations of abiotics factors in the habitat of Anopheles sp. larvae was carried out around the landing collection location. The result of research conducted in the Samigaluh, Kalibawang, and Pengasih Sub-Districts showed that the most common species found was Anopeheles vagus. The dominance of Anopheles vagus occurred in the Kalibawang and Pengasih dictricts, while in the Samigaluh Sub-Districts it became the second most among other species. Measurement of abiotic factors in the habitat of Anopheles sp. larvae through the parameters of temperature, air humidity, pH DO of water shows that the location where the larvae were found can support larval breeding and growth. That can be a factor in the large population of Anopheles sp., especially Anopheles vagus, which is a known vector of malarias based on research and its vectorial capacity.

BackgroundThe emergence of insecticide resistance and outdoor transmission in malaria-endemic areas underlines the urgent need to develop innovative tools, such as spatial repellents (SR), that may circumvent this residual transmission. With limited options for effective insecticides, regular resistance monitoring is warranted for selecting and using appropriate tools. This study evaluates the pyrethroid knockdown resistance (kdr) allele before and after implementing a transfluthrin-based spatial repellent (SR) intervention in placebo-treated clusters.MethodsThis study looks at the frequency distribution of the kdr allele in Sumba Island from June 2015 to August 2018. Insecticide susceptibility tests were carried out on female Anopheles sp. aged 3–5 days against permethrin 21.5 μg/ml, deltamethrin 12.5 μg/ml, and transfluthrin 10 μg/ml using CDC bottle assay. PCR sequencing of representative samples from adult mosquito collections and insecticide tests revealed the presence of kdr mutations (L1014F and L1014S) in the VGSC gene.ResultsA total of 12 Anopheles species, Anopheles tesselatus, Anopheles. aconitus, Anopheles barbirostris, Anopheles kochi, Anopheles annularis, Anopheles maculatus, Anopheles sundaicus, Anopheles flavirostris, Anopheles balabacensis, Anopheles indefinitus, Anopheles subpictus, and Anopheles vagus were analysed. Anopheles vagus and An. sundaicus predominated in the larval populations. Susceptibility assays for all insecticides identified fully susceptible phenotypes in all species examined. Anopheles increasing frequency of kdr mutant alleles during the 3 year SR deployment was observed in both SR-treated and placebo areas, a statistically significant increase occurred in each arm. However, it is unclear how significant SR is in causing the increase in mutant alleles. The L1014S, knockdown resistance east type (kdr-e) allele was detected for the first time among the mosquito samples in this study. The L1014F, knockdown resistance west type (kdr-w) allele and heteroduplex form (wild-type—mutant) were found in almost all Anopheles species examined, including An. vagus, An. aconitus, An. subpictus, An. tesselatus, An. annularis, An. flavirostris and An. sundaicus.ConclusionThe presence of fully susceptible phenotypes over time, along with an increase in the frequency distribution of the L1014F/S mutations post-intervention, suggest drivers of resistance external to the study, including pyrethroid use in agriculture and long-lasting insecticidal nets (LLINs). However, this does not negate possible SR impacts that support resistance. More studies that enable the comprehension of possible SR-based drivers of resistance in mosquitoes need to be conducted.

Mosquitoes are insects that are detrimental to human health because they act as disease vectors, such as dengue fever. Surabaya was known for its high risk of dengue fever. This study aims to describe the diversity of mosquitoes and breeding site distribution in Eastern Surabaya. The study was conducted in 2021 during the end of the wet season in different habitat types in the eastern Surabaya (residential, city park, bamboo forest, and mangrove forest). Eggs, larval, and adult-stage mosquitoes were collected and stored in the Entomology Laboratory for morphological identification. Adult mosquito was collected by using a sweep net and light trap method, while the larva and egg were collected incidentally from breeding sites. The diversity of mosquitoes in the Eastern Surabaya was determined by using the Shannon-Wiener diversity index (H’), dominance, species richness (R), and breeding site distribution. Eleven species were obtained in this study, namely Aedes aegypti, Aedes albopictus, Aedes annandalei, Anopheles subpictus, Anopheles vagus, Anopheles barbirostris, Culex bitaeniorhynchus, Culex pseudovishnui, Culex quinquefasciatus, Mansonia uniformis, and Malaya genurostris. The H’ index of 1.63 indicates the mosquito community was at a moderate level. The R-value of 1.56 indicates a low level of mosquito species richness. The most abundant species was Cx. quinquefasciatus (37.2%). Most of the breeding sites with mosquito larval infested were found in open areas (79.3%). These numbers mean the total of individuals of each species tends to be low and its dominance shows no effect on other species. The data on mosquito species and their distribution in Surabaya could be used as base information for vector control strategies.

This study aims to identify the species diversity, density, and their distribution and analyze mosquito larvae' habitat's physicochemical characteristics in the Dramaga sub-district, Bogor Regency rice fields.. This research used purposive sampling method by taking samples from 92 breeding site in four villages of Dramaga district. The physicochemical characteristics of larval habitats, including pH, temperature, Total Dissolve Solid (TDS), and Electrical Conductivity (EC) were measured in the field. Breeding site are marked using a Garmin Montana 680 GPS for further processing. Larvae were collected and identified until species level. The result showed Anopheles vagus, An. barbirostris, An. indefinitus, Culex. vishnui, Cx. fuscocephala, Cx. tritaeniorhynchus, Cx. sitiens, Cx. hutchinsoni, and Armigeres sp. were found in the rice fields of Dramaga district. The highest diversity and density of larvae was found in Cikarawang Village. The highest relative abundance of mosquitoes larvae were An. vagus and Cx. vishnui. The physicochemical characteristics of larval habitats such as pH, TDS, and EC, had no correlation with the larval abundance, however the temperature of larval habitat had a negative correlation between temperature and larval density.

This study aims to identify the species diversity, density, and their distribution and analyze mosquito larvae' habitat's physicochemical characteristics in the Dramaga sub-district, Bogor Regency rice fields.. This research used purposive sampling method by taking samples from 92 breeding site in four villages of Dramaga district. The physicochemical characteristics of larval habitats, including pH, temperature, Total Dissolve Solid (TDS), and Electrical Conductivity (EC) were measured in the field. Breeding site are marked using a Garmin Montana 680 GPS for further processing. Larvae were collected and identified until species level. The result showed Anopheles vagus, An. barbirostris, An. indefinitus, Culex. vishnui, Cx. fuscocephala, Cx. tritaeniorhynchus, Cx. sitiens, Cx. hutchinsoni, and Armigeres sp. were found in the rice fields of Dramaga district. The highest diversity and density of larvae was found in Cikarawang Village. The highest relative abundance of mosquitoes larvae were An. vagus and Cx. vishnui. The physicochemical characteristics of larval habitats such as pH, TDS, and EC, had no correlation with the larval abundance, however the temperature of larval habitat had a negative correlation between temperature and larval density.

Bacterial content of mosquitoes has given rise to the development of innovative tools that influence and seek to control malaria transmission. This study identified the bacterial microbiota in field-collected female adults of the Anopheles hyrcanus group and three Anopheles species, Anopheles nivipes, Anopheles philippinensis, and Anopheles vagus, from an endemic area in the southeastern part of Ubon Ratchathani Province, northeastern Thailand, near the Lao PDR-Cambodia-Thailand border. A total of 17 DNA libraries were generated from pooled female Anopheles abdomen samples (10 abdomens/ sample). The mosquito microbiota was characterized through the analysis of DNA sequences from the V3-V4 regions of the 16S rRNA gene, and data were analyzed in QIIME2. A total of 3,442 bacterial ASVs were obtained, revealing differences in the microbiota both within the same species/group and between different species/group. Statistical difference in alpha diversity was observed between An. hyrcanus group and An. vagus and between An. nivipes and An. vagus, and beta diversity analyses showed that the bacterial community of An. vagus was the most dissimilar from other species. The most abundant bacteria belonged to the Proteobacteria phylum (48%-75%) in which Pseudomonas, Serratia, and Pantoea were predominant genera among four Anopheles species/group. However, the most significantly abundant genus observed in each Anopheles species/group was as follows: Staphylococcus in the An. hyrcanus group, Pantoea in the An. nivipes, Rosenbergiella in An. philippinensis, and Pseudomonas in An. vagus. Particularly, Pseudomonas sp. was highly abundant in all Anopheles species except An. nivipes. The present study provides the first study on the microbiota of four potential malaria vectors as a starting step towards understanding the role of the microbiota on mosquito biology and ultimately the development of potential tools for malaria control.

Bacterial content of mosquitoes has given rise to the development of innovative tools that influence and seek to control malaria transmission. This study identified the bacterial microbiota in field-collected female adults of the Anopheles hyrcanus group and three Anopheles species, Anopheles nivipes, Anopheles philippinensis, and Anopheles vagus, from an endemic area in the southeastern part of Ubon Ratchathani Province, northeastern Thailand, near the Lao PDR-Cambodia-Thailand border. A total of 17 DNA libraries were generated from pooled female Anopheles abdomen samples (10 abdomens/ sample). The mosquito microbiota was characterized through the analysis of DNA sequences from the V3−V4 regions of the 16S rRNA gene, and data were analyzed in QIIME2. A total of 3,442 bacterial ASVs were obtained, revealing differences in the microbiota both within the same species/group and between different species/group. Statistical difference in alpha diversity was observed between An. hyrcanus group and An. vagus and between An. nivipes and An. vagus, and beta diversity analyses showed that the bacterial community of An. vagus was the most dissimilar from other species. The most abundant bacteria belonged to the Proteobacteria phylum (48%-75%) in which Pseudomonas, Serratia, and Pantoea were predominant genera among four Anopheles species/group. However, the most significantly abundant genus observed in each Anopheles species/group was as follows: Staphylococcus in the An. hyrcanus group, Pantoea in the An. nivipes, Rosenbergiella in An. philippinensis, and Pseudomonas in An. vagus. Particularly, Pseudomonas sp. was highly abundant in all Anopheles species except An. nivipes. The present study provides the first study on the microbiota of four potential malaria vectors as a starting step towards understanding the role of the microbiota on mosquito biology and ultimately the development of potential tools for malaria control.

BackgroundJoint efforts by government and non-government organizations have helped to reduce malaria in Bangladesh and set the country on a clear path to eventual malaria elimination. However, achieving that goal would be challenging without a comprehensive understanding of vector bionomics.MethodsTargeted capturing of Anopheles mosquitoes over a rainy season, utilizing specific sampling methods, including human landing catches (HLCs), CDC-light traps (CDC-LTs), and pyrethrum spray catches (PSCs) were aimed to characterize entomological drivers of transmission in four sites of Bandarban, Bangladesh.ResultsMolecular characterization of a subset of 4637 mosquitoes has demonstrated the presence of at least 17 species whose capture rates were representative of the rainy season. Species compositions and bionomic traits did not vary between sites with Anopheles maculatus having the highest landing rate by HLCs and Anopheles vagus having the highest capture rate with CDC-LTs. Interestingly, Anopheles species compositions and capture rates varied significantly (p < 0.05) for An. vagus, between HLCs and its often-used proxy—CDC-LTs- suggesting impacts on downstream analysis. CDC-LTs capture rates demonstrated differing compositions with indoor and outdoor biting rates. For example, Anopheles nigerrimus and Anopheles nivipes were more endophagic by HLCs and more exophagic by CDC-LTs. The use of a cow-baited CDC-LT also demonstrated significantly different results when compared to a human-baited CDC-LT considering the high degree of anthropophily in these species. The exception to both zoophily and indoor resting was An. vagus, which demonstrated both anthropophily and high resting rates indoors—pointing to this species being a possible primary vector at this site.ConclusionA diverse Anopheles fauna in Bandarban has been confirmed through molecular methods, highlighting the potential impact of sampling techniques. Given the complexity of the local ecosystem, a better understanding of mosquito behaviour and ecology is required to achieve the goal of malaria elimination in Bangladesh.