Distribution and Molecular Identification of Culex pipiens and Culex tritaeniorhynchus as Potential Vectors of Rift Valley Fever Virus in Jazan, Saudi Arabia

Entomologic investigations were conducted in the Al-Darb, Al-Reath, Al-Aridah, Abuareesh, Al-Ahad, Samttah, Sabyah, Damad and Beash areas by CO2-baited CDC miniature light traps in the Jazan region. Vectors were identified morphologically, as well as COI gene segment amplification and sequencing. The relative abundance (RA%) and pattern of occurrence (C%) were recorded. The presence of the Rift Valley fever virus (RVFV) in pooled mosquito samples was investigated by reverse transcriptase-polymerase chain reaction (RT-PCR). Culex pipiens (C. pipiens) and Culex tritaeniorhynchus (C. tritaeniorhynchus) were found with RA% values of 96% and 4%, respectively, in the region. Significant variations in vector population densities were observed in different districts. The C. pipiens was found highly abundant in all districts and RA% value (100%) was recorded in the Al-Darb, Al-Reath, Al-Aridah, Samttah and Damad areas, whereas RA% values (93.75%, 93.33%, 92.30% and 91.66%) were noted in Al-Ahad, Sabyah, Abuareesh and Beash districts, respectively. RA% values for C. tritaeniorhynchus were recorded as 8.33%, 7.70%, 6.66% and 6.25% in Beash, Abuareesh, Sabyah and Al-Ahad areas, respectively. The pattern of occurrence for C. pipiens and C. tritaeniorhynchus was recorded as 100% and 44.4% in the region. Phylogenetic analysis of C. pipiens and C. tritaeniorhynchus exhibited a close relationship with mosquitoes from Kenya and Turkey, respectively. All mosquito samples tested by RT-PCR were found negative for RVFV. In summary, the current study assessed the composition, abundance, distribution of different mosquito vectors and presence of RVFV in different areas of the Jazan region. Our data will help risk assessments of RVFV future re-emergence in the region.

Metagenomic sequencing reveals viral abundance and diversity in mosquitoes from the Shaanxi-Gansu-Ningxia region, China

Background Mosquitoes host and transmit numerous arthropod-borne viruses (arboviruses) that cause disease in both humans and animals. Effective surveillance of virome profiles in mosquitoes is vital to the prevention and control of mosquito-borne diseases in northwestern China, where epidemics occur frequently. Methods Mosquitoes were collected in the Shaanxi-Gansu-Ningxia region (Shaanxi Province, Gansu Province, and Ningxia Hui Autonomous Region) of China from June to August 2019. Morphological methods were used for taxonomic identification of mosquito species. High-throughput sequencing and metagenomic analysis were used to characterize mosquito viromes. Results A total of 22,959 mosquitoes were collected, including Culex pipiens (45.7%), Culex tritaeniorhynchus (40.6%), Anopheles sinensis (8.4%), Aedes (5.2%), and Armigeres subalbatus (0.1%). In total, 3,014,183 (0.95% of clean reads) viral sequences were identified and assigned to 116 viral species (including pathogens such as Japanese encephalitis virus and Getah virus) in 31 viral families, including Flaviviridae, Togaviridae, Phasmaviridae, Phenuiviridae, and some unclassified viruses. Mosquitoes collected in July (86 species in 26 families) showed greater viral diversity than those from June and August. Culex pipiens (69 species in 25 families) and Culex tritaeniorhynchus (73 species in 24 families) carried more viral species than Anopheles sinensis (50 species in 19 families) or Aedes (38 species in 20 families) mosquitoes. Conclusion Viral diversity and abundance were affected by mosquito species and collection time. The present study elucidates the virome compositions of various mosquito species in northwestern China, improving the understanding of virus transmission dynamics for comparison with those of disease outbreaks.

Spot Survei Entomologi Malaria di Daerah Epidemi di Kabupaten Kotabaru Kalimantan Selatan

Latar belakang: Indonesia menargetkan eliminasi malaria pada tahun 2030. Kabupaten Kotabaru merupakan daerah endemis malaria. Salah satu Desa Endemis yaitu Desa Batang Kulur yang terjadi peningkatan kasus signifikan sebanyak 12 kasus pada Bulan Maret 2019. Tujuan penelitian ini adalah untuk mengukur indeks entomologi, karakteristik, dan lingkungan habitat perkembangbiakan vektor malaria di Desa Batang Kulur.Metode: Kegiatan yang dilakukan yaitu penangkapan nyamuk dengan umpan orang, identifikasi dan pembedahan ovarium nyamuk untuk diketahui parusitas (pernah/tidak pernah bertelur) yang digunakan untuk memprediksi umur dan survei habitat perkembangbiakan vektor malaria.Hasil: Spesies dan komposisi nyamuk yang ditemukan yaitu Aedes vexans, Aedes albopictus, Culex quinquefasciatus, Culex tritaeniorhynchus, Culex vishnui, Mansonia dives dan Anopheles leucosphyrus. Kepadatan nyamuk Anopheles leucosphyrus 0,30 dan kepadatan permalam yaitu 2,67 dengan peluang hidup perhari 95% serta perkiraan umur populasi 21,54 hari. Fluktuasi Anopheles leucosphyrus mulai muncul pada jam 22.00 dan kembali meningkat pada jam 04.00. Tempat perindukan nyamuk yang ditemukan yaitu Habitat perkembang biakan nyamuk yang ditemukan ada 2 yaitu kolam dan mata air.Simpulan: Terdapat habitat perkembang biakan yang mendukung, peluang hidup 95% dan potensi umur nyamuk lebih dari masa inkubasi Plasmodium sehingga di Desa Batang Kulur merupakan daerah yang cocok untuk perkembangan vektor malaria. ABSTRACT Title: Investigation of Spot Survey of Malaria Entomological in Epedemic Areas in Kotabaru District, South KalimantanBackground: Indonesia is targeting malaria elimination by 2030. Kotabaru Regency is a malaria endemic area. One of the endemic villages, Batang Kulur Village, saw a significant increase of 12 cases in March 2019. The purpose of this study was to measure the entomological index, characteristics, and environment of the malaria vector breeding habitat in Batang Kulur Village.Method: Activities carried out include catching mosquitoes by baiting people, telephone and surgery for the mosquito ovaries to determine of parity (parous /nullyparous) which are used to predict age and survey the breeding habitats for malaria vectors.Result: The mosquito species and composition found were Aedes vexans, Aedes albopictus, Culex quinquefasciatus, Culex tritaeniorhynchus, Culex vishnui, Mansonia dives and Anopheles leucosphyrus. The density of the Anopheles leucosphyrus was 0.30 and the per night density was 2.67 with a 95% chance of survival per day and an estimated population age of 21.54 days. Anopheles leucosphyrus fluctuations began to appear at 22.00 and again increased at 04.00. The mosquito breeding places found were 2 mosquito breeding habitats, namely ponds and springs.Conclusion: There is a suitable breeding habitat, a 95% chance of survival and a potential age of mosquitoes that is more than the plasmodium incubation period so that in Batang Kulur Village is a suitable area for the development of malaria vectors.

Evaluating the competence of the primary vector, Culex tritaeniorhynchus, and the invasive mosquito species, Aedes japonicus japonicus, in transmitting three Japanese encephalitis virus genotypes

Japanese encephalitis virus (JEV) is maintained in an enzootic cycle between swine, water birds, and mosquitoes. JEV has circulated indigenously in Asia, with Culex tritaeniorhynchus as the primary vector. In some areas where the primary vector is scarce or absent, sporadic cases of Japanese encephalitis have been reported, with Aedes japonicus japonicus presumed to have the potential as a secondary vector. As one of the world’s most invasive culicid species, Ae. j. japonicus carries a considerable health risk for spreading diseases to wider areas, including Europe and North America. Thus, evaluation of its competency as a JEV vector, particularly in a native population, will be essential in preventing potential disease spread. In this study, the two mosquito species’ vector competence in transmitting three JEV genotypes (I, III, and V) was assessed, with Cx. tritaeniorhynchus serving as a point of reference. The mosquitoes were virus-fed and the infection rate (IR), dissemination rate (DR), and transmission rate (TR) evaluated individually by either RT-qPCR or focus forming assay. Results showed striking differences between the two species, with IR of 95% (261/274) and 9% (16/177) in Cx. tritaeniorhynchus and Ae. j. japonicus, respectively. Both mosquitoes were susceptible to all three JEV genotypes with significant differences in IR and mean viral titer. Results confirm the primary vector’s competence, but the fact that JEV was able to establish in Ae. j. japonicus is of public health significance, and with 2%–16% transmission rate it has the potential to successfully transmit JEV to the next host. This may explain the human cases and infrequent detection in primary vector-free areas. Importantly, Ae. j. japonicus could be a relevant vector spreading the disease into new areas, indicating the need for security measures in areas where the mosquito is distributed or where it may be introduced.

Mosquito Population Diversity and Abundance Patterns In Linzhi, Xizang, China

Background: In 2009, China CDC found the distribution of Culex tritaeniorhynchus and Aedes albopictus in Motuo county, Linzhi, Xizang and isolated the epidemic encephalitis V virus from Culex tritaeniorhynchus. However, with the road opend in Motuo County, the trade between people and mosquitoes transmission were more frequent. To illustrate patterns of mosquito population in Linzhi, Xizang, a mosquitoes surveillance was carried.Methods: Adult mosquitoes were collected by light traps and human landing catches, larva by container survey in six counties of Linzhi during August and September 2019. The trapped adult mosquitoes were initially counted and identified according to morphological criteria, and a part of mosquitoes were further identified by PCR. The monitoring data were recorded by Excel 2007, analyzed by SPSS 20.0 software and R.Results: Eight species of mosquitoes belonging to four genera were identified. Culex pipiens pallens (86.80%), Armigeres subalbalus (5.29%) and Aedes vexans (2.99%) were the top three species coolected by 164 light traps on 12 nights with the average mosquito density was 21.20 (mosquitoes per trap per night); Aedes albopictus were only collected in Chayu County Xiachayu Town by human landing catches with high average mosquito density (26.33 mosquitoes per hour per person). The larva were collected from waste tires, cement tanks and drums in Bomi, Milin and Lang Counties. The results of molecular identification are consistent with morphological identification. Aedes albopictus and Culex orientalis were newly recorded species for the first time. It is preliminarily speculated that there is a high potential risk of dengue fever in Xiachayu Town and a certain epidemic risk of Japanese encephalitis, while the risk of malaria is low in Linzhi.Conclusion: Mosquitoes had heterogeneous distribution throughout Linzhi, Xizang. The dominant mosquito species are Culex pipiens pallens. It is emphasized to carry out mosquito surveillance again during the peak period of mosquito activities so as to better understand the distribution and composition of local mosquitoes and assess the mosquito-borne disease risk in this area.

Molecular Characterization of Culturable Aerobic Bacteria in the Midgut of Field-Caught Culex tritaeniorhynchus, Culex gelidus, and Mansonia annulifera Mosquitoes in the Gampaha District of Sri Lanka

Background. Larval and adult mosquito stages harbor different extracellular microbes exhibiting various functions in their digestive tract including host-parasite interactions. Midgut symbiotic bacteria can be genetically exploited to express molecules within the vectors, altering vector competency and potential for disease transmission. Therefore, identification of mosquito gut inhabiting microbiota is of ample importance before developing novel vector control strategies that involve modification of vectors. Method. Adult mosquitoes of Culex tritaeniorhynchus, Culex gelidus, and Mansonia annulifera were collected from selected Medical Officer of Health (MOH) areas in the Gampaha district of Sri Lanka. Midgut lysates of the field-caught non-blood-fed female mosquitoes were cultured in Plate Count Agar medium, and Prokaryotic 16S ribosomal RNA partial genes of the isolated bacteria colonies were amplified followed by DNA sequencing. Diversity indices were used to assess the diversity and richness of the bacterial isolates in three mosquito species. The distribution pattern of bacterial isolates between different mosquito species was assessed by Distance-Based Redundancy Analysis (dbRDA). Results. A total of 20 bacterial species (Staphylococcus pasteuri, Bacillus megaterium, Staphylococcus cohnii, Pantoea dispersa, Staphylococcus chromogenes, Bacillus aquimaris, Staphylococcus arlettae, Staphylococcus sciuri, Staphylococcus warneri, Moraxella osloensis, Enterobacter sp., Klebsiella michiganensis, Staphylococcus hominis, Staphylococcus saprophyticus, Streptomyces sp., Bacillus niacin, Cedecea neteri, Micrococcus luteus, Lysinibacillus sphaericus, and Bacillus licheniformis) were identified. All of these species belonged to three phyla, Proteobacteria, Firmicutes, and Actinobacteria, out of which phylum Firmicutes (71.1%) was the most prominent. The least number of species was recorded from Actinobacteria. The relative distribution of midgut microbes in different mosquito species differed significantly among mosquito species (Chi-square, χ2=486.091; df=36; P≤0.001). Midgut microbiota of Cx. tritaeniorhynchus and Cx. gelidus indicated a similarity of 21.51%, while Ma. annulifera shared a similarity of 6.92% with the cluster of above two species. The gut microbiota of Cx. tritaeniorhynchus was also significantly more diverse and more evenly distributed compared to Ma. annulifera. Simpson’s diversity, Margalef’s diversity, and Menhinick’s diversity indices were higher in Cx. gelidus. Of the recorded species, P. dispersa and strains of nonpathogenic species in Bacillaceae family (B. megaterium, B. niacini, B. licheniformis, and L. sphaericus) can be recommended as potential candidates for paratransgenesis. Conclusion. The relative distribution of midgut microbes in different mosquito species differed significantly among the three studied adult mosquito species. The present data strongly encourage further investigations to explore the potential usage of these microbes through paratransgenic approach for novel eco-friendly vector control strategies.