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Fulltext Larvicidal and anti-termite activities of microbial biosurfactant produced by Enterobacter cloacae SJ2 isolated from marine sponge Clathria sp

Harikrishnan S, Sudarshan S, Sivasubramani K, Nandini MS, Narenkumar J, Ramachandran V, et al.

Sci Rep, 2023 Sep 13;13(1):15153.
PMID: 37704703 DOI: 10.1038/s41598-023-42475-6

The widespread use of synthetic pesticides has resulted in a number of issues, including a rise in insecticide-resistant organisms, environmental degradation, and a hazard to human health. As a result, new microbial derived insecticides that are safe for human health and the environment are urgently needed. In this study, rhamnolipid biosurfactants produced from Enterobacter cloacae SJ2 was used to evaluate the toxicity towards mosquito larvae (Culex quinquefasciatus) and termites (Odontotermes obesus). Results showed dose dependent mortality rate was observed between the treatments. The 48 h LC50 (median lethal concentration) values of the biosurfactant were determined for termite and mosquito larvae following the non-linear regression curve fit method. Results showed larvicidal activity and anti-termite activity of biosurfactants with 48 h LC50 value (95% confidence interval) of 26.49 mg/L (25.40 to 27.57) and 33.43 mg/L (31.09 to 35.68), respectively. According to a histopathological investigation, the biosurfactant treatment caused substantial tissue damage in cellular organelles of larvae and termites. The findings of this study suggest that the microbial biosurfactant produced by E. cloacae SJ2 is an excellent and potentially effective agent for controlling Cx. quinquefasciatus and O. obesus.

Matched MeSH terms: Culex*
Fulltext Identification of the Tembusu Virus in Mosquitoes in Northern Thailand

Hamel R, Vargas REM, Rajonhson DM, Yamanaka A, Jaroenpool J, Wichit S, et al.

Viruses, 2023 Jun 27;15(7).
PMID: 37515135 DOI: 10.3390/v15071447

Among emerging zoonotic pathogens, mosquito-borne viruses (MBVs) circulate between vertebrate animals and mosquitoes and represent a serious threat to humans via spillover from enzootic cycles to the human community. Active surveillance of MBVs in their vectors is therefore essential to better understand and prevent spillover and emergence, especially at the human-animal interface. In this study, we assessed the presence of MBVs using molecular and phylogenetic methods in mosquitoes collected along an ecological gradient ranging from rural urbanized areas to highland forest areas in northern Thailand. We have detected the presence of insect specific flaviviruses in our samples, and the presence of the emerging zoonotic Tembusu virus (TMUV). Reported for the first time in 1955 in Malaysia, TMUV remained for a long time in the shadow of other flaviviruses such as dengue virus or the Japanese encephalitis virus. In this study, we identified two new TMUV strains belonging to cluster 3, which seems to be endemic in rural areas of Thailand and highlighted the genetic specificities of this Thai cluster. Our results show the active circulation of this emerging flavivirus in Thailand and the need for continuous investigation on this poorly known but threatening virus in Asia.

Matched MeSH terms: Culex*
Insecticidal activity and physiopathological effects of Cotula cinerea crude extract against Culex pipiens

Trop Biomed, 2023 Jun 01;40(2):241-249.
PMID: 37650412 DOI: 10.47665/tb.40.2.016

The development of new alternatives strategies to synthetic insecticides aimed at reducing pest populations by developing pesticides based on plant extracts without negative effects in non target organisms and environment. The present study was undertaken in order to assess the insecticidal activity of the crude methanolic extract of the Algerian Asteraceae Cotula cinerea, against the larval and the pupal stage of Culex pipiens (Diptera: Culicidae). It is also to determine the chemical composition of the used extract, and to understand the mechanism of toxic action of the tested extract. Based on the preliminary tests, five concentrations of the crude methanolic extract of C. cinerea (0.62, 1.25, 2.50, 3.75, and 5 mg/mL) were tested for their insecticidal activity according to the protocol recommended by the World Health Organization. The chemical profile of the extract was also obtained by high performance liquid chromatography (HPLC). Histopathological effects and inhibition of acetylcholinesterase activity in treated mosquitoes with LC90 were examined to elucidate the mechanism of the toxic effect of the tested extract (48 h post treatment). Eight compounds have been identified by HPLC. That includes four flavonoids (rutin, quercetin, myrcetin and cathechin), three phenolic acids (benzoic acid, vanillic acid, p-coumaric acid) and one alkaloid (berberine). C. cinerea methanolic extract showed good larvicidal and pupicidal activities with LC50 and LC90 values of 1.10 and 4.37 mg/mL respectively against pupae, 24h post treatment and 1.26, 2.35 mg/mL respectively against the fourth instar larvae. Data of enzymatic assay performed on LC50 and LC90 pupae and larvae revealed prominent neurotoxic effects. C. cinerea extract reduced the activity of acetylcholinesterase (AChE) enzyme in a concentration dependent manner. Obtained inhibition percentages, 48 h after treatment, were 35.11 ± 7.44 and 51.83 ± 4.04% for pupal stage and 30.98 ± 2.97 % and 48.77 ± 4.72% for the fourth instar larvae for LC50 and LC90 values respectively. Treated larvae and pupae showed also histopathological damages in the pupal cuticle and larval midgut. The results of this study showed that C. cinerea crude methanolic extract could be considered as an eco-friendly alternative for mosquito control.

Matched MeSH terms: Culex*
Fulltext Circulation of West Nile virus in mosquitoes approximate to the migratory bird stopover in West Coast Malaysia

Natasha JA, Yasmin AR, Sharma RSK, Nur-Fazila SH, Nur-Mahiza MI, Arshad SS, et al.

PLoS Negl Trop Dis, 2023 Apr;17(4):e0011255.
PMID: 37023172 DOI: 10.1371/journal.pntd.0011255

Being a tropical country with a conducive environment for mosquitoes, mosquito-borne illnesses such as dengue, chikungunya, lymphatic filariasis, malaria, and Japanese encephalitis are prevalent in Malaysia. Recent studies reported asymptomatic infection of West Nile virus (WNV) in animals and humans, but none of the studies included mosquitoes, except for one report made half a century ago. Considering the scarcity of information, our study sampled mosquitoes near migratory bird stopover wetland areas of West Coast Malaysia located in the Kuala Gula Bird Sanctuary and Kapar Energy Venture, during the southward migration period in October 2017 and September 2018. Our previous publication reported that migratory birds were positive for WNV antibody and RNA. Using a nested RT-PCR analysis, WNV RNA was detected in 35 (12.8%) out of 285 mosquito pools consisting of 2,635 mosquitoes, most of which were Culex spp. (species). Sanger sequencing and phylogenetic analysis revealed that the sequences grouped within lineage 2 and shared 90.12%-97.01% similarity with sequences found locally as well as those from Africa, Germany, Romania, Italy, and Israel. Evidence of WNV in the mosquitoes substantiates the need for continued surveillance of WNV in Malaysia.

Matched MeSH terms: Culex*
Insecticidal activities of Streptomyces sp. KSF103 ethyl acetate extract against medically important mosquitoes and non-target organisms

Amelia-Yap ZH, Low VL, Saeung A, Ng FL, Chen CD, Hassandarvish P, et al.

Sci Rep, 2023 Jan 02;13(1):4.
PMID: 36593229 DOI: 10.1038/s41598-022-25387-9

A potentially novel actinobacterium isolated from forest soil, Streptomyces sp. KSF103 was evaluated for its insecticidal effect against several mosquito species namely Aedes aegypti, Aedes albopictus, Anopheles cracens and Culex quinquefasciatus. Mosquito larvae and adults were exposed to various concentrations of the ethyl acetate (EA) extract for 24 h. Considerable mortality was evident after the EA extract treatment for all four important vector mosquitoes. Larvicidal activity of the EA extract resulted in LC50 at 0.045 mg/mL and LC90 at 0.080 mg/mL for Ae. aegypti; LC50 at 0.060 mg/mL and LC90 at 0.247 mg/mL for Ae. albopictus; LC50 at 2.141 mg/mL and LC90 at 6.345 mg/mL for An. cracens; and LC50 at 0.272 mg/mL and LC90 at 0.980 mg/mL for Cx. quinquefasciatus. In adulticidal tests, the EA extract was the most toxic to Ae. albopictus adults (LD50 = 2.445 mg/mL; LD90 = 20.004 mg/mL), followed by An. cracens (LD50 = 5.121 mg/mL; LD90 = 147.854 mg/mL) and then Ae. aegypti (LD50 = 28.873 mg/mL; LD90 = 274.823 mg/mL). Additionally, the EA extract exhibited ovicidal activity against Ae. aegypti (LC50 = 0.715 mg/mL; LC90 = 6.956 mg/mL), Ae. albopictus (LC50 = 0.715 mg/mL; LC90 = 6.956 mg/mL), and An. cracens (LC50 = 0.715 mg/mL; LC90 = 6.956 mg/mL), evaluated up to 168 h post-treatment. It displayed no toxicity on the freshwater microalga Chlorella sp. Beijerinck UMACC 313, marine microalga Chlorella sp. Beijerinck UMACC 258 and the ant Odontoponera denticulata. In conclusion, the EA extract showed promising larvicidal, adulticidal and ovicidal activity against Ae. aegypti, Ae. albopictus, An. cracens, and Cx. quinquefasciatus (larvae only). The results suggest that the EA extract of Streptomyces sp. KSF103 has the potential to be used as an environmental-friendly approach in mosquito control. The current study would serve as an initial step toward complementing microbe-based bioinsecticides for synthetic insecticides against medically important mosquitoes.

Matched MeSH terms: Culex*
Phytochemical composition of almond oil from Melia azedarach L. and its larvicidal, ovicidal, repellent and enzyme activities in Culex pipiens L

Khaldi R, Rehimi N, Kharoubi R, Soltani N

Trop Biomed, 2022 Dec 01;39(4):531-538.
PMID: 36602212 DOI: 10.47665/tb.39.4.008

Melia azedarach L. (Meliaceae) is a botanical species with focal point of global research for its biological properties. The Melia azedarach tree is distinguished by its rapid growth, its adaptation to different temperate zones, as well as its insecticidal properties. All this made us think of exploiting it in biological control against different stages of mosquitoes. To this end, we aim, through the present work, to evaluate the effectiveness of Melia azedarach extracts against Culex pipiens mosquito. More specifically, our study focuses on determining the chemical composition of Melia almond oil, as well as the larvicidal, ovicidal and repellent activities on Culex pipiens L. mosquito as well as the activities of acetylcholinesterase (AChE) and glutathione-S-transferase (GST). Almond oil was extracted by a Soxhlet and subjected to gas chromatography-mass spectrometry (GC/MS). The yield was found to be 35.17%. The chemical composition revealed the presence of various phytoconstituents. A total of 7 compounds were identified, the main ones being 9,11-Octadecadienoic acid, methyl ester, (E,E)- (79.32%), 9-octadecenoic acid (Z)-, methyl ester (13.24%), hexadecanoic acid and methyl ester (3.69%). The larvicidal bioassays were performed according to the protocol recommended by the World Health Organization with concentrations varying from 20 to 80 mg/L depending on the exposure time (24, 48 and 72 hours). The almond oil exhibited remarkable larvicidal activity against fourth instar larvae and the lethal concentrations were determined (LC25= 23.70 mg/L, LC50=35.49 mg/L, LC90=79.61 mg/L). The results also showed that the oil caused an ovicidal activity with a significant effect on egg hatch. The recorded hatching percentages were respectively 88.79% and 72.40% for the LC25 and LC50, and this compared to the control series. Moreover, this oil exhibited significant repellency against adult mosquitoes. Furthermore, the enzymatic measurements performed on LC50 and LC90 treated larvae revealed a neurotoxic activity and a stimulation of the detoxification system as evidenced, respectively, by an inhibition of AChE and induction in GST activity. Overall, our data proved that Melia azedarach almond oil could be considered as a potent biorational alternative to synthetic insecticides for mosquito control.

Matched MeSH terms: Culex*
Fulltext Identification of potential vectors of Dirofilaria immitis and Brugia pahangi (Spirurida: Filariidae): First observation of infective third-stage larva of B. pahangi in Culex quinquefasciatus (Diptera: Culicidae)

Vinnie-Siow WY, Low VL, Tan TK, Wong ML, Leong CS, Ahmad NW, et al.

Pathog Glob Health, 2022 Sep;116(6):356-364.
PMID: 35287548 DOI: 10.1080/20477724.2022.2035624

Information on the mosquito species that transmit canine filariosis is scanty. Hence, an experimental study was conducted to identify the potential vectors responsible for the transmission of D. immitis Leidy and B. pahangi Buckley & Edeson. A total of 367 mosquitoes belonging to six species containing both laboratory and field strains (i.e. Aedes togoi Theobald, Aedes aegypti Linnaeus, Aedes albopictus Skuse, Culex quinquefasciatus Say, Culex vishnui Theobald and Anopheles dirus Peyton & Harrison) were used in this study. All mosquitoes were artificially fed on either D. immitis or B. pahangi microfilariae (mfs) infected blood by using the Hemotek™ membrane feeding system. Out of 367 mosquitoes, 228 (64.9%) were fully engorged. After feeding on D. immitis (20%) and B. pahangi (33%) mfs positive blood, the mortality rates for Cx. quinquefasciatus were found to be slightly lower than that of other species of mosquitoes. On the other hand, majority of An. dirus were found to be incapable to withstand the infection of mfs as the mortality rates were relatively high (D. immitis = 71.4%; B. pahangi = 100.0%). Brugia pahangi was detected in Ae. togoi and Cx. quinquefasciatus with infection rates of 50% and 25%, respectively. Aedes togoi was the only species infected with D. immitis with an infection rate of 69%. Our results showed that Ae. togoi was an excellent experimental vector for both D. immitis and B. pahangi. This study also documented the observation of B. pahangi, for the first time in the head region of Cx. quinquefasciatus under a laboratory setting.

Matched MeSH terms: Culex*
Fulltext An update on the mosquito fauna and mosquito-borne diseases distribution in Cameroon

Bamou R, Mayi MPA, Djiappi-Tchamen B, Nana-Ndjangwo SM, Nchoutpouen E, Cornel AJ, et al.

Parasit Vectors, 2021 Oct 11;14(1):527.
PMID: 34635176 DOI: 10.1186/s13071-021-04950-9

The expansion of mosquito-borne diseases such as dengue, yellow fever, and chikungunya in the past 15 years has ignited the need for active surveillance of common and neglected mosquito-borne infectious diseases. The surveillance should be designed to detect diseases and to provide relevant field-based data for developing and implementing effective control measures to prevent outbreaks before significant public health consequences can occur. Mosquitoes are important vectors of human and animal pathogens, and knowledge on their biodiversity and distribution in the Afrotropical region is needed for the development of evidence-based vector control strategies. Following a comprehensive literature search, an inventory of the diversity and distribution of mosquitoes as well as the different mosquito-borne diseases found in Cameroon was made. A total of 290 publications/reports and the mosquito catalogue website were consulted for the review. To date, about 307 species, four subspecies and one putative new species of Culicidae, comprising 60 species and one putative new species of Anopheles, 67 species and two subspecies of Culex, 77 species and one subspecies of Aedes, 31 species and one subspecies of Eretmapodites, two Mansonia, eight Coquillettidia, and 62 species with unknown medical and veterinary importance (Toxorhynchites, Uranotaenia, Mimomyia, Malaya, Hodgesia, Ficalbia, Orthopodomyia, Aedeomyia, and Culiseta and Lutzia) have been collected in Cameroon. Multiple mosquito species implicated in the transmission of pathogens within Anopheles, Culex, Aedes, Eretmapodites, Mansonia, and Coquillettidia have been reported in Cameroon. Furthermore, the presence of 26 human and zoonotic arboviral diseases, one helminthic disease, and two protozoal diseases has been reported. Information on the bionomics, taxonomy, and distribution of mosquito species will be useful for the development of integrated vector management programmes for the surveillance and elimination of mosquito-borne diseases in Cameroon.

Matched MeSH terms: Culex/parasitology; Culex/physiology; Culex/virology
Identification and characterization of long noncoding RNAs and their association with acquisition of blood meal in Culex quinquefasciatus

Azlan A, Halim MA, Mohamad F, Azzam G

Insect Sci, 2021 Aug;28(4):917-928.
PMID: 32621332 DOI: 10.1111/1744-7917.12847

The Southern house mosquito, Culex quinquefasciatus (Cx. quinquefasciatus) is an important vector that transmit multiple diseases including West Nile encephalitis, Japanese encephalitis, St. Louis encephalitis and lymphatic filariasis. Long noncoding RNAs (lncRNAs) involve in many biological processes such as development, infection, and virus-host interaction. However, there is no systematic identification and characterization of lncRNAs in Cx. quinquefasciatus. Here, we report the first lncRNA identification in Cx. quinquefasciatus. By using 31 public RNA-seq datasets, a total of 4763 novel lncRNA transcripts were identified, of which 3591, 569, and 603 were intergenic, intronic, and antisense respectively. Examination of genomic features revealed that Cx. quinquefasciatus shared similar characteristics with other species such as short in length, low GC content, low sequence conservation, and low coding potential. Furthermore, compared to protein-coding genes, Cx. quinquefasciatus lncRNAs had lower expression values, and tended to be expressed in temporally specific fashion. In addition, weighted correlation network and functional annotation analyses showed that lncRNAs may have roles in blood meal acquisition of adult female Cx. quinquefasciatus mosquitoes. This study presents the first systematic identification and analysis of Cx. quinquefasciatus lncRNAs and their association with blood feeding. Results generated from this study will facilitate future investigation on the function of Cx. quinquefasciatus lncRNAs.

Matched MeSH terms: Culex/genetics*; Culex/metabolism
Tiger nut (Cyperus esculentus) as a potential phytoinsecticide: larvicidal activity of crude extracts on Aedes aegypti and Culex quinquefasciatus (Diptera: Culicidae)

Avicor SW, Wajidi MFF, Achoribo ES, Ong MT, Hamzah SN

Trop Biomed, 2021 Jun 01;38(2):186-191.
PMID: 34172709 DOI: 10.47665/tb.38.2.056

Plants contain bioactive compounds and are constantly explored as safer alternatives to conventional insecticides. Despite numerous studies on many plants, information on the insecticidal potential of underutilised plants like tiger nut, Cyperus esculentus L., are scant, although their pharmacological potentials are well known. Hence, this study investigated the larvicidal potential of crude aqueous extracts of two C. esculentus varieties (black and yellow) on the mosquitoes Aedes aegypti (L.) and Culex quinquefasciatus (Say). Mosquito larvae were exposed to C. esculentus crude extracts using the larval bioassay technique of the World Health Organization. Differential larvicidal responses were observed in the test mosquitoes and extracts of Black Dried Tiger nuts (BDT) were more larvicidal than Yellow Dried Tiger nuts (YDT). Acute larval toxicity of the extracts was more pronounced on Cx. quinquefasciatus than Ae. aegypti. The results indicate the potential of C. esculentus (particularly BDT) as a source of mosquito bioinsecticide and merits further studies as a safer alternative to conventional insecticide-based vector control.

Matched MeSH terms: Culex*
Fulltext Checklist of the mosquito fauna (Diptera, Culicidae) of Cambodia

Maquart PO, Fontenille D, Rahola N, Yean S, Boyer S

Parasite, 2021;28:60.
PMID: 34374642 DOI: 10.1051/parasite/2021056

Between 2016 and 2020, the Medical and Veterinary Entomology unit of the Institut Pasteur du Cambodge collected over 230,000 mosquitoes. Based on this sampling effort, a checklist of 290 mosquito species in Cambodia is presented. This is the first attempt to list the Culicidae fauna of the country. We report 49 species for the first time in Cambodia. The 290 species belong to 20 genera: Aedeomyia (1 sp.), Aedes (55 spp.), Anopheles (53 spp.), Armigeres (26 spp.), Coquillettidia (3 spp.), Culex (57 spp.), Culiseta (1 sp.), Ficalbia (1 sp.), Heizmannia (10 spp.), Hodgesia (3 spp.), Lutzia (3 spp.), Malaya (2 spp.), Mansonia (5 spp.), Mimomyia (7 spp.), Orthopodomyia (3 spp.), Topomyia (4 spp.), Toxorhynchites (4 spp.), Tripteroides (6 spp.), Uranotaenia (27 spp.), and Verrallina (19 spp.). The Cambodian Culicidae fauna is discussed in its Southeast Asian context. Forty-three species are reported to be of medical importance, and are involved in the transmission of pathogens.

Matched MeSH terms: Culex*
Fulltext The potential use of Azolla pinnata as an alternative bio-insecticide

Ravi R, Rajendran D, Oh WD, Mat Rasat MS, Hamzah Z, Ishak IH, et al.

Sci Rep, 2020 11 06;10(1):19245.
PMID: 33159109 DOI: 10.1038/s41598-020-75054-0

Four different tests showed the effectiveness of Azolla pinnata plant extracts against Aedes aegypti and Aedes albopictus mosquitoes. In the adulticidal test, there was a significant increase in mortality as test concentration increases and A. pinnata extracts showed LC50 and LC95 values of 2572.45 and 6100.74 ppm, respectively, against Ae. aegypti and LC50 and LC95 values of 2329.34 and 5315.86 ppm, respectively, against Ae. albopictus. The ovicidal test showed 100% eggs mortality for both species tested for all the concentrations tested at 1500 ppm, 1000 ppm, 500 ppm, 250 ppm and 125 ppm. Both tested samples of Ae. aegypti and Ae. albopictus did not lay any eggs in the plastic cups filled with the A. pinnata extract but instead opted to lay eggs in the plastic cups filled with water during the oviposition deterrence test. Similarly, the non-choice test of Ae. aegypti mosquitoes laid eggs on the sucrose solution meant for the nutrient source of the mosquitoes instead of in the plastic cup that was designed to facilitate oviposition filled with the extract. This clearly indicates the presence of bioactive compounds which are responsible in adulticidal and ovicidal activity in Aedes mosquitoes and at the same time inducing repellence towards the mosquitoes. The LC-MS results showed mainly three important chemical compounds from A. pinnata extracts such as 1-(O-alpha-D-glucopyranosyl)-(1,3R,25R)-hexacosanetriol, Pyridate and Nicotinamide N-oxide. All these chemicals have been used for various applications such as both emulsion and non-emulsion type of cosmetics, against mosquito vector such as Culex pipens and Anopheles spp. Finally, the overall view of these chemical components from A. pinnata extracts has shown the potential for developing natural product against dengue vectors.

Matched MeSH terms: Culex/growth & development*
Fulltext New vectors in northern Sarawak, Malaysian Borneo, for the zoonotic malaria parasite, Plasmodium knowlesi

Ang JXD, Kadir KA, Mohamad DSA, Matusop A, Divis PCS, Yaman K, et al.

Parasit Vectors, 2020 Sep 15;13(1):472.
PMID: 32933567 DOI: 10.1186/s13071-020-04345-2

BACKGROUND: Plasmodium knowlesi is a significant cause of human malaria in Sarawak, Malaysian Borneo. Only one study has been previously undertaken in Sarawak to identify vectors of P. knowlesi, where Anopheles latens was incriminated as the vector in Kapit, central Sarawak. A study was therefore undertaken to identify malaria vectors in a different location in Sarawak.
METHODS: Mosquitoes found landing on humans and resting on leaves over a 5-day period at two sites in the Lawas District of northern Sarawak were collected and identified. DNA samples extracted from salivary glands of Anopheles mosquitoes were subjected to nested PCR malaria-detection assays. The small subunit ribosomal RNA (SSU rRNA) gene of Plasmodium was sequenced, and the internal transcribed spacer 2 (ITS2) and mitochondrial cytochrome c oxidase subunit 1 (cox1) gene of the mosquitoes were sequenced from the Plasmodium-positive samples for phylogenetic analysis.
RESULTS: Totals of 65 anophelines and 127 culicines were collected. By PCR, 6 An. balabacensis and 5 An. donaldi were found to have single P. knowlesi infections while 3 other An. balabacensis had either single, double or triple infections with P. inui, P. fieldi, P. cynomolgi and P. knowlesi. Phylogenetic analysis of the Plasmodium SSU rRNA gene confirmed 3 An. donaldi and 3 An. balabacensis with single P. knowlesi infections, while 3 other An. balabacensis had two or more Plasmodium species of P. inui, P. knowlesi, P. cynomolgi and some species of Plasmodium that could not be conclusively identified. Phylogenies inferred from the ITS2 and/or cox1 sequences of An. balabacensis and An. donaldi indicate that they are genetically indistinguishable from An. balabacensis and An. donaldi, respectively, found in Sabah, Malaysian Borneo.
CONCLUSIONS: Previously An. latens was identified as the vector for P. knowlesi in Kapit, central Sarawak, Malaysian Borneo, and now An. balabacensis and An. donaldi have been incriminated as vectors for zoonotic malaria in Lawas, northern Sarawak.

Matched MeSH terms: Culex/classification*; Culex/genetics; Culex/parasitology
Fulltext Charaterization of mosquito larval habitats in Qatar

Alkhayat FA, Ahmad AH, Rahim J, Dieng H, Ismail BA, Imran M, et al.

Saudi J Biol Sci, 2020 Sep;27(9):2358-2365.
PMID: 32884417 DOI: 10.1016/j.sjbs.2020.07.006

Mosquito borne diseases have remained a grave threat to human health and are posing a significant burden on health authorities around the globe. The understanding and insight of mosquito breeding habitats features is crucial for their effective management. Comprehensive larval surveys were carried out at 14 sites in Qatar. A total of 443 aquatic habitats were examined, among these 130 were found positive with Culex pipiens, Cx. quinquefasciatus, Cx. mattinglyi, Ochlerotatus dorsalis, Oc. caspius and Anopheles stephensi. The majority of positive breeding habitats were recorded in urban areas (67.6%), followed by livestock (13.8%), and least were in agriculture (10.7%). An. stephensi larvae were positively correlated with Cx. pipien, Cx. quinquefasciatus, and negatively with water salinity. Large and shaded habitats were the most preferred by An. stephensi. In addition, Cx. pipiens was positively associated with the turbidity and pH, and was negatively associated with vegetation and habitat size. A negative association of Cx. quinquefasciatus with dissolved oxygen, water temperature, and salinity, while positive with habitat surface area was observed. Oc. dorsalis was negatively correlated with pH, water temperature, depth, and habitat surface area, whereas salinity water was more preferable site for females to lay their eggs. These results demonstrate that environmental factors play a significant role in preference of both anopheline and culicine for oviposition, while their effective management must be developed as the most viable tool to minimize mosquito borne diseases.

Matched MeSH terms: Culex
Fulltext Detection of Japanese Encephalitis Virus in Culex Mosquitoes in Singapore

Yap G, Mailepessov D, Lim XF, Chan S, How CB, Humaidi M, et al.

Am J Trop Med Hyg, 2020 09;103(3):1234-1240.
PMID: 32700679 DOI: 10.4269/ajtmh.19-0377

Mosquito-borne flaviviruses are emerging pathogens of an increasing global public health concern because of their rapid increase in geographical range and the impact of climate change. Japanese encephalitis virus (JEV) and West Nile virus (WNV) are of concern because of the risk of reemergence and introduction by migratory birds. In Singapore, human WNV infection has never been reported and human JEV infection is rare. Four sentinel vector surveillance sites were established in Singapore to understand the potential risk posed by these viruses. Surveillance was carried out from August 2011 to December 2012 at Pulau Ubin, from March 2011 to March 2013 at an Avian Sanctuary (AS), from December 2010 from October 2012 at Murai Farmway, and from December 2010 to December 2013 at a nature reserve. The present study revealed active JEV transmission in Singapore through the detection of JEV genotype II in Culex tritaeniorhynchus collected from an Avian Sanctuary. Culex flavivirus (CxFV), similar to the Quang Binh virus isolated from Cx. tritaeniorhynchus in Vietnam and CxFV-LSFlaviV-A20-09 virus isolated in China, was also detected in Culex spp. (vishnui subgroup). No WNV was detected. This study demonstrates the important role that surveillance plays in public health and strongly suggests the circulation of JEV among wildlife in Singapore, despite the absence of reported human cases. A One Health approach involving surveillance, the collaboration between public health and wildlife managers, and control of mosquito populations remains the key measures in risk mitigation of JEV transmission in the enzootic cycle between birds and mosquitoes.

Matched MeSH terms: Culex/virology*
Fulltext Natural Wolbachia infection in field-collected Anopheles and other mosquito species from Malaysia

Wong ML, Liew JWK, Wong WK, Pramasivan S, Mohamed Hassan N, Wan Sulaiman WY, et al.

Parasit Vectors, 2020 Aug 12;13(1):414.
PMID: 32787974 DOI: 10.1186/s13071-020-04277-x

BACKGROUND: The endosymbiont bacterium Wolbachia is maternally inherited and naturally infects some filarial nematodes and a diverse range of arthropods, including mosquito vectors responsible for disease transmission in humans. Previously, it has been found infecting most mosquito species but absent in Anopheles and Aedes aegypti. However, recently these two mosquito species were found to be naturally infected with Wolbachia. We report here the extent of Wolbachia infections in field-collected mosquitoes from Malaysia based on PCR amplification of the Wolbachia wsp and 16S rRNA genes.
METHODS: The prevalence of Wolbachia in Culicinae mosquitoes was assessed via PCR with wsp primers. For some of the mosquitoes, in which the wsp primers failed to amplify a product, Wolbachia screening was performed using nested PCR targeting the 16S rRNA gene. Wolbachia sequences were aligned using Geneious 9.1.6 software, analyzed with BLAST, and the most similar sequences were downloaded. Phylogenetic analyses were carried out with MEGA 7.0 software. Graphs were drawn with GraphPad Prism 8.0 software.
RESULTS: A total of 217 adult mosquitoes representing 26 mosquito species were screened. Of these, infections with Wolbachia were detected in 4 and 15 mosquito species using wsp and 16S rRNA primers, respectively. To our knowledge, this is the first time Wolbachia was detected using 16S rRNA gene amplification, in some Anopheles species (some infected with Plasmodium), Culex sinensis, Culex vishnui, Culex pseudovishnui, Mansonia bonneae and Mansonia annulifera. Phylogenetic analysis based on wsp revealed Wolbachia from most of the mosquitoes belonged to Wolbachia Supergroup B. Based on 16S rRNA phylogenetic analysis, the Wolbachia strain from Anopheles mosquitoes were more closely related to Wolbachia infecting Anopheles from Africa than from Myanmar.
CONCLUSIONS: Wolbachia was found infecting Anopheles and other important disease vectors such as Mansonia. Since Wolbachia can affect its host by reducing the life span and provide resistance to pathogen infection, several studies have suggested it as a potential innovative tool for vector/vector-borne disease control. Therefore, it is important to carry out further studies on natural Wolbachia infection in vector mosquitoes' populations as well as their long-term effects in new hosts and pathogen suppression.

Matched MeSH terms: Culex/microbiology
Utilization of gum polysaccharide of Araucaria heterophylla and Azadirachta indica for encapsulation of cyfluthrin loaded super paramagnetic iron oxide nanoparticles for mosquito larvicidal activity

Samrot AV, Bhavya KS, Angalene JLA, Roshini SM, Preethi R, Steffi SM, et al.

Int J Biol Macromol, 2020 Jun 15;153:1024-1034.
PMID: 31751703 DOI: 10.1016/j.ijbiomac.2019.10.232

Surface engineering of super paramagnetic iron oxide nanoparticles (SPIONs) favor the tagging of any molecule or compound onto it, encapsulating them with a biopolymer make them biocompatible and favor slow release of loaded molecules. Recovery of SPIONs is easier as they obey to external magnetic field. In this study, SPIONS were used for mosquito larvicidal activity after surface engineered with oleic acid to favor the tagging of Cyfluthrin (mosquito larvicidal agent), it was then encapsulated with gum polysaccharide derived from Azadirachta indica and Araucaria heterophylla. Every stage of coreshell formation was microscopically and spectroscopically characterized. The coreshell SPIONs produced using Azadirachta indica and Araucaria heterophylla gum derived polysaccharide encapsulation were found to be the size around 80 nm. Thus, prepared coreshell SPIONs was subjected for mosquito larvicidal activity against Culex sp. The coreshell SPIONs was efficiently killing the mosquito larva and its impact was studied by percentage mortality studies.

Matched MeSH terms: Culex
Fulltext Entomological Surveillance Associated with Human Zika Cases in Miri Sarawak, Malaysia

Ali R, Azmi RA, Wasi Ahmad N, Abd Hadi A, Muhamed KA, Rasli R, et al.

Am J Trop Med Hyg, 2020 May;102(5):964-970.
PMID: 32228777 DOI: 10.4269/ajtmh.19-0339

Two confirmed human cases of Zika virus (ZIKV) were reported in the district of Miri, Sarawak, in 2016. Following that, a mosquito-based ZIKV surveillance study was conducted within 200-m radius from the case houses. Mosquito surveillance was conducted using five different methods, that is, biogents sentinel mosquito (BG) sentinel trap, modified sticky ovitrap, resting catch, larval surveillance, and conventional ovitrap. A total of 527 and 390 mosquito samples were obtained from the case houses in two localities, namely, Kampung Lopeng and Taman Shang Ri La, Miri, Sarawak, respectively. All mosquitoes collected were identified, which consisted of 11 species. Aedes albopictus, both the adult and larval stages, was the dominant species. Resting catch method obtained the highest number of adult mosquitoes (67%), whereas ovitrap showed the highest catch for larval mosquitoes (84%). Zika virus was detected in both adults and larvae of Ae. albopictus together with adults of Culex gelidus, and Culex quinquefasciatus using the real-time reverse transcriptase polymerase chain reaction (PCR) technique. It was noteworthy that Ae. albopictus positive with ZIKV were caught and obtained from four types of collection method. By contrast, Cx. gelidus and Culex quinquefasciatus adults collected from sticky ovitraps were also found positive with ZIKV. This study reveals vital information regarding the potential vectors of ZIKV and the possibility of transovarian transmission of the virus in Malaysia. These findings will be essentials for vector control program managers to devise preparedness and contingency plans of prevention and control of the arboviral disease.

Matched MeSH terms: Culex/virology
Fulltext Population structure and genetic diversity of Aedes aegypti and Aedes albopictus in Penang as revealed by mitochondrial DNA cytochrome oxidase I

Md Naim D, Kamal NZM, Mahboob S

Saudi J Biol Sci, 2020 Mar;27(3):953-967.
PMID: 32127775 DOI: 10.1016/j.sjbs.2020.01.021

The population genetics study is crucial as it helps in understanding the epidemiological aspects of dengue and help improving a vector control measures. This research aims to investigate the population genetics structure of two common species of Aedes mosquitoes in Penang; Aedes aegypti and Aedes albopictus using Cytochrome Oxidase I (COI) mitochondrial DNA (mtDNA) marker. Molecular investigations were derived from 440 bp and 418 bp mtDNA COI on 125 and 334 larvae of Aedes aegypti and Aedes albopictus respectively, from 32 locations in Penang. All samples were employed in the BLASTn for species identification. The haplotype diversity, nucleotide diversity, neutrality test and mismatch distribution analysis were conducted in DnaSP version 5.10.1. AMOVA analysis was conducted in ARLEQUIN version 3.5 and the phylogenetic reconstructions based on maximum likelihood (ML) and neighbor-joining (NJ) methods were implemented in MEGA X. The relationships among haplotypes were further tested by creating a minimum spanning tree using Network version 4.6.1. All samples were genetically identified and clustered into six distinct species. Among the species, Ae. albopictus was the most abundant (67.2%), followed by Ae. aegypti (25.2%) and the rest were counted for Culex sp. and Toxorhynchites sp. Both Ae. aegypti and Ae. albopictus show low nucleotide diversity (π) and high haplotype diversity (h), while the neutrality test shows a negative value in most of the population for both species. There are a total of 39 and 64 haplotypes recorded for Ae. aegypti and Ae. albopictus respectively. AMOVA analysis revealed that most of the variation occurred within population for both species. Mismatch distribution analysis showed bimodal characteristic of population differentiation for Ae. aegypti but Ae. albopictus showed unimodal characteristics of population differentiation. Genetic distance based on Tamura-Nei parameter showed low genetic divergent within population and high genetic divergent among population for both species. The maximum likelihood tree showed no obvious pattern of population genetic structure for both Ae. aegypti and Ae. albopictus from Penang and a moderate to high bootstrap values has supported this conclusion. The minimum spanning network for Ae. aegypti and Ae. albopictus showed five and three dominant haplotypes respectively, which indicates a mixture of haplotypes from the regions analysed. This study revealed that there is no population genetic structure exhibited by both Ae. aegypti and Ae. albopictus in Penang. Mutation has occurred rapidly in both species and this will be challenging in controlling the populations. However, further analysis needed to confirm this statement.

Matched MeSH terms: Culex
Gender beyond male and female: Occurrence of a gynandromorph in the Japanese encephalitis vector Culex sitiens (Diptera: Culicidae)

Low VL, Wong ML, Liew JWK, Pramasivan S, Jeyaprakasam NK, Vythilingam I

Acta Trop, 2020 Jan;201:105207.
PMID: 31586449 DOI: 10.1016/j.actatropica.2019.105207

A gynandromorph of Culex sitiens Wiedemann (Diptera: Culicidae) was attracted to a human during a mosquito surveillance programme conducted in Kuala Lipis, Pahang, Malaysia on July 20, 2019. Gynandromorphism was observed in antennae, maxillary palps, legs and wings of the specimen, with distinct male characters on the left and female characters on the right, though the left maxillary palp is slightly shorter than the proboscis of a typical male. The abdomen, however, displays well-developed male genitalia. This study represents the first report of oblique gynandromorphism in Cx. sitiens, one of the vectors of Japanese encephalitis in Asia.

Matched MeSH terms: Culex/classification*; Culex/genetics*

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