bims-mosdis 2022-01-16 papers

bims-mosdis

Biomed News

on Mosquito distribution and disease

Issue of 2022‒01‒16
23 papers selected by
Richard Halfpenny
Staffordshire University

A comparative study of dengue virus vectors in major parks and adjacent residential areas in Ho Chi Minh City, Vietnam.
Larval habitats, species composition and distribution of malaria vectors in regions with autochthonous and imported malaria in Roraima state, Brazil.
Habitat Segregation Patterns of Container Breeding Mosquitos: The Role of Urban Heat Islands, Vegetation Cover, and Income Disparity in Cemeteries of New Orleans.
Analysis of the Knockdown Resistance Locus (kdr) in Anopheles stephensi, An. arabiensis, and Culex pipiens s.l. for Insight Into the Evolution of Target-site Pyrethroid Resistance in Eastern Ethiopia.
The threat of mosquito-borne arboviral disease in Spain: A bibliographic review.
Seasonal Dynamics of Mosquito-Borne Viruses in the Southwestern Florida Everglades, 2016, 2017.
Blood meal analysis of Anopheles vectors of simian malaria based on laboratory and field studies.
Pyrethroid Susceptibility in Culex quinquefasciatus Say. (Diptera: Culicidae) Populations from Delta State, Niger-Delta Region, Nigeria.
Dengue virus infection modifies mosquito blood-feeding behavior to increase transmission to the host.
Diversity of Mosquitoes (Diptera: Culicidae) in the Bom Retiro Private Natural Heritage Reserve, Rio de Janeiro State, Brazil.
Ecological and environmental factors affecting transmission of sylvatic yellow fever in the 2017-2019 outbreak in the Atlantic Forest, Brazil.
Effect of larval density and additional anchoring surface on the life-history traits of a laboratory colonized Anopheles funestus strain.
Infectivity of Symptomatic Malaria Patients to Anopheles farauti Colony Mosquitoes in Papua New Guinea.
Evidence of pyrethroid resistance in Anopheles amharicus and Anopheles arabiensis from Arjo-Didessa irrigation scheme, Ethiopia.
Pyrethroid Resistance Intensity in Anopheles gambiae s.l. from Different Agricultural Production Zones in Benin, West Africa.
Local adaptation and colonization are potential factors affecting sexual competitiveness and mating choice in Anopheles coluzzii populations.
Epidemiology of West Nile virus in Africa: An underestimated threat.
Dengue surveillance using gravid oviposition sticky (GOS) trap and dengue non-structural 1 (NS1) antigen test in Malaysia: randomized controlled trial.
Insecticidal effects of a novel polyherbal formulation (HF7) against Culex pipiens L. (Diptera: Culicidae).
First records of Aedes pulcritarsis (Rondani, 1872) (Diptera: Culicidae) in Austria.
Dengue virus infections among European travellers, 2015 to 2019.
West Nile virus transmission potential in Portugal.
Virulence of entomopathogenic fungi against Culex pipiens: Impact on biomolecules availability and life table parameters.

PLoS Negl Trop Dis. 2022 Jan 12. 16(1): e0010119

A comparative study of dengue virus vectors in major parks and adjacent residential areas in Ho Chi Minh City, Vietnam.

Trang Thi Thuy Huynh, Noboru Minakawa.

The primary dengue virus vectors, Aedes aegypti and Aedes albopictus, are primarily daytime biting mosquitoes. The risk of infection is suspected to be considerable in urban parks due to visitor traffic. Despite the importance of vector control for reducing dengue transmission, little information is available on vector populations in urban parks. The present study characterized mosquito habitats and estimated vector densities in the major urban parks in Ho Chi Minh City, Vietnam and compared them with those in adjacent residential areas. The prevalences of habitats where Aedes larvae were found were 43% and 9% for the parks and residential areas, respectively. The difference was statistically significant (prevalence ratio [PR]: 5.00, 95% CI: 3.85-6.49). The prevalences of positive larval habitats were significantly greater in the parks for both species than the residential areas (PR: 1.52, 95% CI: 1.04-2.22 for A. aegypti, PR: 10.10, 95% CI: 7.23-14.12 for A. albopictus). Larvae of both species were positively associated with discarded containers and planters. Aedes albopictus larvae were negatively associated with indoor habitats, but positively associated with vegetation shade. The adult density of A. aegypti was significantly less in the parks compared with the residential areas (rate ratio [RR]; 0.09, 95% CI: 0.05-0.16), while the density of A. albopictus was significantly higher in the parks (RR: 9.99, 95% CI: 6.85-14.59). When the species were combined, the density was significantly higher in the parks (RR: 2.50, 95% CI: 1.92-3.25). The urban parks provide suitable environment for Aedes mosquitoes, and A. albopictus in particular. Virus vectors are abundant in the urban parks, and the current vector control programs need to have greater consideration of urban parks.

DOI: https://doi.org/10.1371/journal.pntd.0010119
Malar J. 2022 Jan 14. 21(1): 13

Larval habitats, species composition and distribution of malaria vectors in regions with autochthonous and imported malaria in Roraima state, Brazil.

Nathália Coelho Vargas de Almeida, Jaime Louzada, Maycon Sebastião Alberto Santos Neves, Thiago M Carvalho, Júlio Castro-Alves, Teresa Fernandes Silva-do-Nascimento, Ananias A Escalante, Joseli Oliveira-Ferreira.

  BACKGROUND: Malaria control requires local action. Assessing the vector diversity and abundance provides information on the local malariogenic potential or risk of transmission. This study aimed to determine the Anopheles species composition, habitats, seasonal occurrence, and distribution in areas with autochthonous and imported malaria cases in Roraima State.METHODS: A longitudinal study was conducted from January 2017 to October 2018, sampling larvae and adult mosquitoes in three municipalities of Roraima State: Boa Vista, Pacaraima and São João da Baliza. These areas have different risks of malaria importation. Four to six mosquito larval habitats were selected for larval sampling at each municipality, along with two additional sites for adult mosquito collection. All larval habitats were surveyed every two months using a standardized larval sampling methodology and MosqTent for adult mosquitoes.
RESULTS: A total of 544 Anopheles larvae and 1488 adult mosquitoes were collected from the three municipalities studied. Although the species abundance differed between municipalities, the larvae of Anopheles albitarsis s.l., Anopheles nuneztovari s.l. and Anopheles triannulatus s.l. were collected from all larval habitats studied while Anopheles darlingi were collected only from Boa Vista and São João da Baliza. Adults of 11 species of the genus Anopheles were collected, and the predominant species in Boa Vista was An. albitarsis (88.2%) followed by An. darlingi (6.9%), while in São João da Baliza, An. darlingi (85.6%) was the most predominant species followed by An. albitarsis s.l. (9.2%). In contrast, the most abundant species in Pacaraima was Anopheles braziliensis (62%), followed by Anopheles peryassui (18%). Overall, the majority of anophelines exhibited greater extradomicile than peridomicile-biting preference. Anopheles darlingi was the only species found indoors. Variability in biting times was observed among species and municipalities.
CONCLUSION: This study revealed the composition of anopheline species and habitats in Boa Vista, Pacaraima and São João da Baliza. The species sampled differed in their behaviour with only An. darlingi being found indoors. Anopheles darlingi appeared to be the most important vector in São João da Baliza, an area of autochthonous malaria, and An. albitarsis s.l. and An. braziliensis in areas of low transmission, although there were increasing reports of imported malaria. Understanding the diversity of vector species and their ecology is essential for designing effective vector control strategies for these municipalities.

Keywords:  Anopheles albitarsis s.l.; Anopheles darlingi; Human biting rate; Imported malaria; Larval habitats; Malaria vectors

DOI:  https://doi.org/10.1186/s12936-021-04033-1
Int J Environ Res Public Health. 2021 Dec 26. pii: 245. [Epub ahead of print]19(1):

Habitat Segregation Patterns of Container Breeding Mosquitos: The Role of Urban Heat Islands, Vegetation Cover, and Income Disparity in Cemeteries of New Orleans.

Rebeca de Jesús Crespo, Rachel Elba Rogers.

  Aedes aegypti and Aedes albopictus are important pathogen-carrying vectors that broadly exhibit similar habitat suitability, but that differ at fine spatial scales in terms of competitive advantage and tolerance to urban driven environmental parameters. This study evaluated how spatial and temporal patterns drive the assemblages of these competing species in cemeteries of New Orleans, LA, applying indicators of climatic variability, vegetation, and heat that may drive habitat selection at multiple scales. We found that Ae. aegypti was well predicted by urban heat islands (UHI) at the cemetery scale and by canopy cover directly above the cemetery vase. As predicted, UHI positively correlate to Ae. aegypti, but contrary to predictions, Ae. aegypti, was more often found under the canopy of trees in high heat cemeteries. Ae. albopictus was most often found in low heat cemeteries, but this relationship was not statistically significant, and their overall abundances in the city were lower than Ae. aegypti. Culex quinquefasciatus, another important disease vector, was also an abundant mosquito species during the sampling year, but we found that it was temporally segregated from Aedes species, showing a negative association to the climatic variables of maximum and minimum temperature, and these factors positively correlated to its more direct competitor Ae. albopictus. These findings help us understand the mechanism by which these three important vectors segregate both spatially and temporally across the city. Our study found that UHI at the cemetery scale was highly predictive of Ae. aegypti and strongly correlated to income level, with low-income cemeteries having higher UHI levels. Therefore, the effect of excessive heat, and the proliferation of the highly competent mosquito vector, Ae. aegypti, may represent an unequal disease burden for low-income neighborhoods of New Orleans that should be explored further. Our study highlights the importance of considering socioeconomic aspects as indirectly shaping spatial segregation dynamics of urban mosquito species.

Keywords:  Aedes aegypti; Aedes albopictus; New Orleans; cemeteries; income disparity vegetation cover; urban heat island (UHI)

DOI:  https://doi.org/10.3390/ijerph19010245
Am J Trop Med Hyg. 2022 Jan 10. pii: tpmd201357. [Epub ahead of print]

Analysis of the Knockdown Resistance Locus (kdr) in Anopheles stephensi, An. arabiensis, and Culex pipiens s.l. for Insight Into the Evolution of Target-site Pyrethroid Resistance in Eastern Ethiopia.

Tamar E Carter, Araya Gebresilassie, Shantoy Hansel, Lambodhar Damodaran, Callum Montgomery, Victoria Bonnell, Karen Lopez, Daniel Janies, Solomon Yared.

The malaria vector, Anopheles stephensi, which is typically restricted to South Asia and the Middle East, was recently detected in the Horn of Africa. Addressing the spread of this vector could involve integrated vector control that considers the status of insecticide resistance of multiple vector species in the region. Previous reports indicate that the knockdown resistance mutations (kdr) in the voltage-gated sodium channel (vgsc) are absent in both pyrethroid-resistant and pyrethroid-sensitive An. stephensi in eastern Ethiopia; however, similar information about other vector species in the same areas is limited. In this study, kdr and the neighboring intron were analyzed in An. stephensi, An. arabiensis, and Culex pipiens s.l. collected between 2016 and 2017 to determine the evolutionary history of kdr in eastern Ethiopia. A sequence analysis revealed that all of Cx. pipiens s.l. (N = 42) and 71.6% of the An. arabiensis (N = 67) carried kdr L1014F, which is known to confer target-site pyrethroid resistance. Intronic variation was only observed in An. stephensi (six segregating sites, three haplotypes), which was previously shown to have no kdr mutations. In addition, no evidence of non-neutral evolutionary processes was detected at the An. stephensi kdr intron, thereby further supporting the target-site mechanism not being a major resistance mechanism in this An. stephensi population. Overall, these results show key differences in the evolution of target-site pyrethroid/dichlorodiphenyltrichloroethane resistance mutations in populations of vector species from the same region. Variations in insecticide resistance mechanism profiles between eastern Ethiopian mosquito vectors may lead to different responses to insecticides used in integrated vector control.

DOI: https://doi.org/10.4269/ajtmh.20-1357
Med Clin (Barc). 2022 Jan 10. pii: S0025-7753(21)00668-0. [Epub ahead of print]

The threat of mosquito-borne arboviral disease in Spain: A bibliographic review.

Tanita Laycock, Clara Ureña Paniego, Jake Javier.

  Over the last two decades there has been an increase in outbreaks of arboviral diseases, being Spain at high risk for disease emergence. This paper reviews the current evidence regarding the transmissibility, disease epidemiology, control strategies and mosquito-borne disease drivers and maintaining factors in Spain. There is risk of autochthonous cases and outbreaks in Spain due to recent transmission occurrence. Recently, there has been an expansion of Aedes Albopticus, a vector for Dengue, Zika and Chikungunya; and Cullex spp., vector for West Nile Virus, already endemic in Spain. Their establishment has been facilitated by climate and environmental drivers. If climate change projections are to be met, an increase in disease transmission is to be expected, as well as the re-establishment of other vectors such as Aedes Aegypti. Our review supports the need to understand the threat of these emerging diseases and implement preventive strategies in order to minimise their impact.

Keywords:  Arbovirus; Cambio climático; Climate change; Emerging diseases; Enfermedades emergentes; España; Spain

DOI:  https://doi.org/10.1016/j.medcli.2021.10.014
Am J Trop Med Hyg. 2022 Jan 10. pii: tpmd201547. [Epub ahead of print]

Seasonal Dynamics of Mosquito-Borne Viruses in the Southwestern Florida Everglades, 2016, 2017.

John Anderson, Durland Fish, Philip Armstrong, Michael Misencik, Angela Bransfield, Francis Ferrandino, Theodore Andreadis, Mark Stenglein, Marylee Kapuscinski.

Mosquitoes were collected for 12 consecutive months beginning June 2016, from 11 locations in the Florida Everglades, Collier County, and tested for viruses by isolation in Vero cells and subsequent identification. One species complex and 31 species of mosquitoes were identified from 668,809 specimens. Ochlerotatus taeniorhynchus comprised 72.2% of the collection. Other notable species were Anopheles crucians complex, Culex nigripalpus, Cx. erraticus, and Cx. cedecei. Seven species of virus were identified from 110 isolations: Everglades, Gumbo Limbo, Mahogany Hammock, Pahayokee, Shark River, Tensaw, and West Nile viruses. Everglades, West Nile, Tensaw, and Mahogany Hammock viruses were most frequently isolated. Largest numbers of viruses were identified from Cx. cedecei, Cx. nigripalpus, and An. crucians complex. Five species of virus were isolated from Cx. cedecei. Viruses were isolated from mangrove, cypress swamp, hardwood hammock, and sawgrass habitats. West Nile virus was isolated August through October when Cx. nigripalpus was most abundant. Everglades virus was the most frequently isolated virus from nine species of mosquitoes collected from June through August. Tensaw virus was isolated primarily from Anopheles species. Isolations were made in July, August, January, February, and April, suggesting that this virus may be present in host-seeking mosquitoes throughout the year. Mahogany Hammock, Shark River, Gumbo Limbo, and Pahayokee viruses were isolated primarily from Cx. cedecei from June through December. Shotgun metagenomic sequencing was used to document that seven pools of Cx. cedecei were infected with two arboviruses. As communities expand into the Everglades, more humans will become exposed to arboviruses.

DOI: https://doi.org/10.4269/ajtmh.20-1547
Sci Rep. 2022 Jan 10. 12(1): 354

Blood meal analysis of Anopheles vectors of simian malaria based on laboratory and field studies.

Nantha Kumar Jeyaprakasam, Van Lun Low, Jonathan Wee Kent Liew, Sandthya Pramasivan, Wan-Yusoff Wan-Sulaiman, Atiporn Saeung, Indra Vythilingam.

Blood feeding and host-seeking behaviors of a mosquito play an imperative role in determining its vectorial capacity in transmitting pathogens. Unfortunately, limited information is available regarding blood feeding behavior of Anopheles species in Malaysia. Collection of resting Anopheles mosquitoes for blood meal analysis poses a great challenge especially for forest dwelling mosquitoes. Therefore, a laboratory-based study was conducted to evaluate the potential use of mosquitoes caught using human landing catch (HLC) for blood meal analysis, and subsequently to document blood feeding behavior of local Anopheles mosquitoes in Peninsular Malaysia. The laboratory-based experiment from this study revealed that mosquitoes caught using HLC had the potential to be used for blood meal analysis. Besides HLC, mosquitoes were also collected using manual aspirator and Mosquito Magnet. Overall, 47.4% of 321 field-caught Anopheles mosquitoes belonging to six species were positive for vertebrate host DNA in their blood meal. The most frequent blood meal source was human (45.9%) followed by wild boar (27.4%), dog (15.3%) and monkey (7.5%). Interestingly, only Anopheles cracens and Anopheles introlatus (Leucosphyrus Group) fed on monkey. This study further confirmed that members of the Leucosphyrus Group are the predominant vectors for knowlesi malaria transmission in Peninsular Malaysia mainly due to their simio-anthropophagic feeding behavior.

DOI: https://doi.org/10.1038/s41598-021-04106-w
J Med Entomol. 2022 Jan 13. pii: tjab217. [Epub ahead of print]

Pyrethroid Susceptibility in Culex quinquefasciatus Say. (Diptera: Culicidae) Populations from Delta State, Niger-Delta Region, Nigeria.

Chioma C Ojianwuna, Ahmed I Omotayo, Victor N Enwemiwe, Fouad A Adetoro, Destiny N Eyeboka, Kemi Adesalu, Allan Egedegbe, Eric Esiwo, Tolulope A Oyeniyi.

  The development of insecticide resistance in different species of mosquitoes to Pyrethroids is a major challenge for vector-borne diseases transmitted by mosquitoes. Failure of Pyrethroids in control of mosquitoes would impact negatively on the gains recorded in control of mosquito-borne diseases in previous years. In anticipation of a country-wide deployment of Pyrethroid-treated nets for control of mosquito-borne diseases in Nigeria, this study assessed susceptibility of Culex quinquefasciatus Say. (Diptera: Culicidae) to Pyrethroids in Owhelogbo, Ejeme and Oria-Abraka communities in Delta State, Niger-Delta, Nigeria. Three to five day old Cx. quinquefasciatus were exposed to Deltamethrin (0.05%), Permethrin (0.75%), and Alphacypermethrin (0.05%) using World Health Organization bioassay method. Polymerase chain reaction (PCR) was employed in characterization of species and knockdown mutation. Results revealed that Cx. quinquefasciatus were generally susceptible (98-100%) to Deltamethrin, Permethrin, and Alphacypermethrin in the three communities with the exception of Owhelogbo where resistance to Deltamethrin (97%) was suspected. Knockdown time to Deltamethrin (11.51, 11.23, and 12.68 min), Permethrin (28.75, 13.26, and 14.49 min), and Alphacypermethrin (15.07, 12.50, and 13.03 min) were considerably low for Owhelogbo, Ejeme, and Oria-Abraka Cx. quinquefasciatus populations, respectively. Species identification result showed that all amplified samples were Cx. quinquefasciatus; however, no kdr allele was found in the three populations. Deployment of pyrethroid-treated nets for control of mosquito-borne diseases in Niger-Delta region of Nigeria is capable of reducing burden of diseases transmitted by Cx. quinquefasciatus as well as addressing nuisance value of the vector; however, caution must be entertained so as not to increase selection pressure thereby aiding resistance development.

Keywords:   Culex quinquefasciatuss ; Delta; Nigeria; Pyrethroid resistance; knockdown mutation

DOI:  https://doi.org/10.1093/jme/tjab217
Proc Natl Acad Sci U S A. 2022 Jan 18. pii: e2117589119. [Epub ahead of print]119(3):

Dengue virus infection modifies mosquito blood-feeding behavior to increase transmission to the host.

Benjamin Wong Wei Xiang, Wilfried A A Saron, James C Stewart, Arthur Hain, Varsha Walvekar, Dorothée Missé, Fréderic Thomas, R Manjunatha Kini, Benjamin Roche, Adam Claridge-Chang, Ashley L St John, Julien Pompon.

  Mosquito blood-feeding behavior is a key determinant of the epidemiology of dengue viruses (DENV), the most-prevalent mosquito-borne viruses. However, despite its importance, how DENV infection influences mosquito blood-feeding and, consequently, transmission remains unclear. Here, we developed a high-resolution, video-based assay to observe the blood-feeding behavior of Aedes aegypti mosquitoes on mice. We then applied multivariate analysis on the high-throughput, unbiased data generated from the assay to ordinate behavioral parameters into complex behaviors. We showed that DENV infection increases mosquito attraction to the host and hinders its biting efficiency, the latter resulting in the infected mosquitoes biting more to reach similar blood repletion as uninfected mosquitoes. To examine how increased biting influences DENV transmission to the host, we established an in vivo transmission model with immuno-competent mice and demonstrated that successive short probes result in multiple transmissions. Finally, to determine how DENV-induced alterations of host-seeking and biting behaviors influence dengue epidemiology, we integrated the behavioral data within a mathematical model. We calculated that the number of infected hosts per infected mosquito, as determined by the reproduction rate, tripled when mosquito behavior was influenced by DENV infection. Taken together, this multidisciplinary study details how DENV infection modulates mosquito blood-feeding behavior to increase vector capacity, proportionally aggravating DENV epidemiology. By elucidating the contribution of mosquito behavioral alterations on DENV transmission to the host, these results will inform epidemiological modeling to tailor improved interventions against dengue.

Keywords:  blood-feeding behavior; dengue virus; epidemiology; mosquito; transmission

DOI:  https://doi.org/10.1073/pnas.2117589119
J Med Entomol. 2022 Jan 13. pii: tjab222. [Epub ahead of print]

Diversity of Mosquitoes (Diptera: Culicidae) in the Bom Retiro Private Natural Heritage Reserve, Rio de Janeiro State, Brazil.

Amanda Queiroz Bastos, Cecilia Ferreira de Mello, Júlia Dos Santos Silva, Hélcio Reinaldo Gil-Santana, Shayenne Olsson Freitas Silva, Jeronimo Alencar.

  This study registers the diversity of Culicidae in the Bom Retiro Private Natural Heritage Reserve (RPPNBR), Rio de Janeiro state, Brazil, based on the collection of the immature stages in natural and artificial larval habitats. Larvae and pupae were collected monthly at two sites of the RPPNBR from May 2014 to July 2015 using dippers and aquatic pipettes. The diversity of the mosquito community was described using the Shannon-Wiener Diversity Index (H'), as well as diversity, richness, and dominance of species found in different larval habitats (lake, bamboos, bromeliads, and artificial vessels). The Mann-Whitney test was used to calculate differences between the two natural and artificial habitats. Overall, 15,659 specimens belonging to 25 species, ten genera, and two subfamilies were collected. The most abundant species collected at sites that were reforested recently were Culex pleuristriatus Theobald, 1903, Limatus durhamii (Theobald, 1901), Aedes albopictus (Skuse, 1895), Culex neglectus (Lutz, 1904), and Culex retrosus (Lane & Whitman, 1951). In a forest preserved site, the most abundant species were Cx. neglectus, Culex iridescens (Lutz, 1905), Sabethes identicus (Dyar & Knab, 1907), Wyeomyia arthrostigma (Lutz, 1905), and Li. durhamii. With respect to larval habitats, 0.1% of the specimens were collected along the edge of a lake, 5.5% in bamboos, 35.9% in bromeliads, and 58.4% in artificial containers. Only 5.5% of the specimens were collected in the forest preserved site, with the remaining samples from the site with altered vegetation. A greater species richness and diversity were found in forest-altered sites compared to the forest preserved site. Several species were collected in the water accumulated in the nylon lids of plastic water tanks. Such vessels can promote an increase in mosquito population density in the environment surrounding the study area.

Keywords:  Atlantic Forest; abundance; distribution; immature; vector ecology

DOI:  https://doi.org/10.1093/jme/tjab222
Parasit Vectors. 2022 Jan 10. 15(1): 23

Ecological and environmental factors affecting transmission of sylvatic yellow fever in the 2017-2019 outbreak in the Atlantic Forest, Brazil.

Filipe Vieira Santos de Abreu, Cecilia Siliansky de Andreazzi, Maycon Sebastião Alberto Santos Neves, Patrícia Soares Meneguete, Mário Sérgio Ribeiro, Cristina Maria Giordano Dias, Monique de Albuquerque Motta, Christovam Barcellos, Anselmo Rocha Romão, Mônica de Avelar Figueiredo Mafra Magalhães, Ricardo Lourenço-de-Oliveira.

  BACKGROUND: Yellow fever virus (YFV) is an arbovirus that, despite the existence of a safe and effective vaccine, continues to cause outbreaks of varying dimensions in the Americas and Africa. Between 2017 and 2019, Brazil registered un unprecedented sylvatic YFV outbreak whose severity was the result of its spread into zones of the Atlantic Forest with no signals of viral circulation for nearly 80 years.METHODS: To investigate the influence of climatic, environmental, and ecological factors governing the dispersion and force of infection of YFV in a naïve area such as the landscape mosaic of Rio de Janeiro (RJ), we combined the analyses of a large set of data including entomological sampling performed before and during the 2017-2019 outbreak, with the geolocation of human and nonhuman primates (NHP) and mosquito infections.
RESULTS: A greater abundance of Haemagogus mosquitoes combined with lower richness and diversity of mosquito fauna increased the probability of finding a YFV-infected mosquito. Furthermore, the analysis of functional traits showed that certain functional groups, composed mainly of Aedini mosquitoes which includes Aedes and Haemagogus mosquitoes, are also more representative in areas where infected mosquitoes were found. Human and NHP infections were more common in two types of landscapes: large and continuous forest, capable of harboring many YFV hosts, and patches of small forest fragments, where environmental imbalance can lead to a greater density of the primary vectors and high human exposure. In both, we show that most human infections (~ 62%) occurred within an 11-km radius of the finding of an infected NHP, which is in line with the flight range of the primary vectors.
CONCLUSIONS: Together, our data suggest that entomological data and landscape composition analyses may help to predict areas permissive to yellow fever outbreaks, allowing protective measures to be taken to avoid human cases.

Keywords:  Functional traits; Haemagogus; Mosquito; Nonhuman primate

DOI:  https://doi.org/10.1186/s13071-021-05143-0
Med Vet Entomol. 2022 Jan 10.

Effect of larval density and additional anchoring surface on the life-history traits of a laboratory colonized Anopheles funestus strain.

Munyaradzi Prince Zengenene, Givemore Munhenga, Fredros Okumu, Lizette Leonie Koekemoer.

  Optimal rearing conditions, inclusive of larval rearing density, are critical for sustained mosquito productivity. There is limited information on favourable conditions for the larval rearing of Anopheles funestus, the dominant malaria vector in east and southern Africa. This work investigated the effects of larval rearing densities and additional anchoring surface on An. funestus development using a life table approach. Larval cohorts were reared at four different larval densities using the same rearing surface area, larval food concentrations and temperature conditions. Rearing larvae at high densities extended the larval developmental time and reduced adult productivity. Adding an extra larval anchoring surface when rearing larvae at high density resulted in extended larval developmental time, increased larval survivorship and produced bigger adults. These findings improve our understanding of the relationship between larval density and developmental traits in An. funestus and provides baseline information for An. funestus rearing under laboratory conditions.

Keywords:  anchoring surface; larvae; malaria vector; mosquito rearing; overcrowding

DOI:  https://doi.org/10.1111/mve.12563
Front Cell Infect Microbiol. 2021 ;11 771233

Infectivity of Symptomatic Malaria Patients to Anopheles farauti Colony Mosquitoes in Papua New Guinea.

Lincoln Timinao, Rebecca Vinit, Michelle Katusele, Tamarah Koleala, Elma Nate, Cyrille Czeher, Thomas R Burkot, Louis Schofield, Ingrid Felger, Ivo Mueller, Moses Laman, Leanne J Robinson, Stephan Karl.

  Plasmodium transmission from humans to mosquitoes is an understudied bottleneck in the transmission of malaria. Direct membrane feeding assays (DMFA) allow detailed malaria transmission studies from humans to mosquitoes. Especially for Plasmodium vivax, which cannot be cultured long-term under laboratory conditions, implementation of DMFAs requires proximity to P. vivax endemic areas. In this study, we investigated the infectivity of symptomatic Plasmodium infections to Anopheles farauti colony mosquitoes in Papua New Guinea (PNG). A total of 182 DMFAs were performed with venous blood collected from rapid diagnostic test (RDT) positive symptomatic malaria patients and subsequently analysed by light microscopy and quantitative real time polymerase chain reaction (qPCR). DMFAs resulted in mosquito infections in 20.9% (38/182) of cases. By light microscopy and qPCR, 10 - 11% of P. falciparum and 32 - 44% of P. vivax positive individuals infected An. farauti. Fifty-eight percent of P. vivax and 15% of P. falciparum gametocytaemic infections infected An farauti.

Keywords:  Anopheles farauti; Papua New Guinea; Plasmodium falciparum; Plasmodium vivax; direct membrane feeding assay; mosquitoes

DOI:  https://doi.org/10.3389/fcimb.2021.771233
PLoS One. 2022 ;17(1): e0261713

Evidence of pyrethroid resistance in Anopheles amharicus and Anopheles arabiensis from Arjo-Didessa irrigation scheme, Ethiopia.

Assalif Demissew, Abebe Animut, Solomon Kibret, Arega Tsegaye, Dawit Hawaria, Teshome Degefa, Hallelujah Getachew, Ming-Chieh Lee, Guiyun Yan, Delenasaw Yewhalaw.

BACKGROUND: Indoor residual spraying and insecticide-treated nets are among the key malaria control intervention tools. However, their efficacy is declining due to the development and spread of insecticide resistant vectors. In Ethiopia, several studies reported resistance of An. arabiensis to multiple insecticide classes. However, such data is scarce in irrigated areas of the country where insecticides, pesticides and herbicides are intensively used. Susceptibility of An. gambiae s.l. to existing and new insecticides and resistance mechanisms were assessed in Arjo-Didessa sugarcane plantation area, southwestern Ethiopia.METHODS: Adult An. gambiae s.l. reared from larval/pupal collections of Arjo-Didessa sugarcane irrigation area and its surrounding were tested for their susceptibility to selected insecticides. Randomly selected An. gambiae s.l. (dead and survived) samples were identified to species using species-specific polymerase chain reaction (PCR) and were further analyzed for the presence of knockdown resistance (kdr) alleles using allele-specific PCR.
RESULTS: Among the 214 An. gambiae s.l. samples analyzed by PCR, 89% (n = 190) were An. amharicus and 9% (n = 20) were An. arabiensis. Mortality rates of the An. gambiae s.l. exposed to deltamethrin and alphacypermethrin were 85% and 86.8%, respectively. On the other hand, mortalities against pirmiphos-methyl, bendiocarb, propoxur and clothianidin were 100%, 99%, 100% and 100%, respectively. Of those sub-samples (An. amharicus and An. arabiensis) examined for presence of kdr gene, none of them were found to carry the L1014F (West African) allelic mutation.
CONCLUSION: Anopheles amharicus and An. arabiensis from Arjo-Didessa sugarcane irrigation area were resistant to pyrethroids which might be synergized by extensive use of agricultural chemicals. Occurrence of pyrethroid resistant malaria vectors could challenge the ongoing malaria control and elimination program in the area unless resistance management strategies are implemented. Given the resistance of An. amharicus to pyrethroids, its behavior and vectorial capacity should be further investigated.

DOI: https://doi.org/10.1371/journal.pone.0261713
Vector Borne Zoonotic Dis. 2022 Jan;22(1): 39-47

Pyrethroid Resistance Intensity in Anopheles gambiae s.l. from Different Agricultural Production Zones in Benin, West Africa.

Hermann Watson Sagbohan, Casimir D Kpanou, Arthur Sovi, Razaki Osse, Aboubakar Sidick, Constantin Adoha, Boulais Yovogan, Albert S Salako, Idelphonse Ahogni, Arsène Fassinou, André Sominanhouin, Saïd Chitou, Germain G Padonou, Clément Agbangla, Martin Akogbeto.

  Agricultural production activities usually occur in Benin with the use of a huge amount of insecticides including pyrethroids for pest control. It is therefore important to regularly monitor pyrethroid resistance intensity in Anopheles gambiae s.l., the main malaria vector. This study was conducted in cereal, cotton, rice growing, and urban market gardening areas throughout the country in 2018 and 2019. Females An. gambiae s.l. field-collected as larvae were exposed to deltamethrin 1 × (0.05%), 2 × (0.1%), 5 × (0.25%), and 10 × (0.5%) and permethrin 1 × (0.75%), 2 × (1.5%), 5 × (3.75%), and 10 × (7.5%). Synergist assays were also performed using World Health Organization articles combining piperonyl butoxide (PBO) (4%) + deltamethrin 1 × and, PBO (4%) + Permethrin 1 × . Molecular species and L1014F kdr mutation were identified using PCR. Expression of metabolic enzymes was also assessed through biochemical tests. After exposure to permethrin and deltamethrin 10 × , An. gambiae s.l. displayed mortality rates <98%. Synergist assays induced significantly higher mortality rates than pyrethroids alone (p < 0.05). An. gambiae s.l. complex was composed of An. gambiae s.s., Anopheles coluzzii, and Anopheles arabiensis, with mean frequency of the L1014F kdr mutation >75%. Overexpression of nonspecific α and β esterases was observed in the cereal, cotton, and urban market gardening areas, while an overexpression of mixed function oxidases was observed in the cotton and rice growing areas. Overall, An. gambiae s.l. showed high resistance intensity to both deltamethrin and permethrin. The synergist and biochemical tests performed suggest that PBO long-lasting insecticidal nets may provide a greater control of pyrethroid-resistant mosquitoes.

Keywords:  An. gambiae s.l.; LLINs; PBO; pyrethroid resistance intensity

DOI:  https://doi.org/10.1089/vbz.2021.0066
Sci Rep. 2022 Jan 12. 12(1): 636

Local adaptation and colonization are potential factors affecting sexual competitiveness and mating choice in Anopheles coluzzii populations.

Charles Nignan, Bèwadéyir Serge Poda, Simon Péguédwindé Sawadogo, Hamidou Maïga, Kounbobr Roch Dabiré, Olivier Gnankine, Frédéric Tripet, Olivier Roux, Abdoulaye Diabaté.

The mating behaviour of the malaria vector Anopheles gambiae complex is an important aspect of its reproduction biology. The success of mosquito release programmes based on genetic control of malaria crucially depends on competitive mating between both laboratory-reared and wild individuals, and populations from different localities. It is known that intrinsic and extrinsic factors can influence the mating success. This study addressed some of the knowledge gaps about factors influcencing mosquito mating success. In semi-field conditions, the study compared the mating success of three laboratory-reared and wild allopatric An. coluzzii populations originating from ecologically different locations in Burkina Faso. Overall, it was found that colonization reduced the mating competitiveness of both males and females compared to that of wild type individuals. More importly, females were more likely to mate with males of their own population of origin, be it wild or colonised, suggesting that local adaptation affected mate choice. The observations of mating behaviour of colonized and local wild populations revealed that subtle differences in behaviour lead to significant levels of population-specific mating. This is the first study to highlight the importance of local adaptation in the mating success, thereby highlighting the importance of using local strains for mass-rearing and release of An. coluzzii in vector control programmes.

DOI: https://doi.org/10.1038/s41598-021-04704-8
PLoS Negl Trop Dis. 2022 Jan 10. 16(1): e0010075

Epidemiology of West Nile virus in Africa: An underestimated threat.

Giulia Mencattelli, Marie Henriette Dior Ndione, Roberto Rosà, Giovanni Marini, Cheikh Tidiane Diagne, Moussa Moise Diagne, Gamou Fall, Ousmane Faye, Mawlouth Diallo, Oumar Faye, Giovanni Savini, Annapaola Rizzoli.

BACKGROUND: West Nile virus is a mosquito-borne flavivirus which has been posing continuous challenges to public health worldwide due to the identification of new lineages and clades and its ability to invade and establish in an increasing number of countries. Its current distribution, genetic variability, ecology, and epidemiological pattern in the African continent are only partially known despite the general consensus on the urgency to obtain such information for quantifying the actual disease burden in Africa other than to predict future threats at global scale.METHODOLOGY AND PRINCIPAL FINDINGS: References were searched in PubMed and Google Scholar electronic databases on January 21, 2020, using selected keywords, without language and date restriction. Additional manual searches of reference list were carried out. Further references have been later added accordingly to experts' opinion. We included 153 scientific papers published between 1940 and 2021. This review highlights: (i) the co-circulation of WNV-lineages 1, 2, and 8 in the African continent; (ii) the presence of diverse WNV competent vectors in Africa, mainly belonging to the Culex genus; (iii) the lack of vector competence studies for several other mosquito species found naturally infected with WNV in Africa; (iv) the need of more competence studies to be addressed on ticks; (iv) evidence of circulation of WNV among humans, animals and vectors in at least 28 Countries; (v) the lack of knowledge on the epidemiological situation of WNV for 19 Countries and (vii) the importance of carrying out specific serological surveys in order to avoid possible bias on WNV circulation in Africa.
CONCLUSIONS: This study provides the state of art on WNV investigation carried out in Africa, highlighting several knowledge gaps regarding i) the current WNV distribution and genetic diversity, ii) its ecology and transmission chains including the role of different arthropods and vertebrate species as competent reservoirs, and iii) the real disease burden for humans and animals. This review highlights the needs for further research and coordinated surveillance efforts on WNV in Africa.

DOI: https://doi.org/10.1371/journal.pntd.0010075
Sci Rep. 2022 Jan 12. 12(1): 571

Dengue surveillance using gravid oviposition sticky (GOS) trap and dengue non-structural 1 (NS1) antigen test in Malaysia: randomized controlled trial.

Sivaneswari Selvarajoo, Jonathan Wee Kent Liew, Tock H Chua, Wing Tan, Rafdzah Ahmad Zaki, Romano Ngui, Wan Yusoff Wan Sulaiman, Poo Soon Ong, Indra Vythilingam.

Dengue remains a major public threat and existing dengue control/surveillance programs lack sensitivity and proactivity. More efficient methods are needed. A cluster randomized controlled trial was conducted for 18 months to determine the efficacy of using a combination of gravid oviposition sticky (GOS) traps and dengue non-structural 1 (NS1) antigen for early surveillance of dengue among Aedes mosquito. Eight residential apartments were randomly assigned into intervention and control groups. GOS traps were placed at the intervention apartments weekly to trap Aedes mosquitoes and these tested for dengue NS1 antigen. When dengue-positive pool was detected, the community were notified and advised to execute protective measures. Fewer dengue cases were recorded in the intervention group than the control. Detection of NS1-positive mosquitoes was significantly associated with GOS Aedes index (rs = 0.68, P < 0.01) and occurrence of dengue cases (rs = 0.31, P < 0.01). Participants' knowledge, attitude, and practice (KAP) toward dengue control indicated significant improvement for knowledge (P < 0.01), practice (P < 0.01) and total scores (P < 0.01). Most respondents thought this surveillance method is good (81.2%) and supported its use nationwide. Thus, GOS trap and dengue NS1 antigen test can supplement the current dengue surveillance/control, in alignment with the advocated integrated vector management for reducing Aedes-borne diseases.

DOI: https://doi.org/10.1038/s41598-021-04643-4
Saudi J Biol Sci. 2022 Jan;29(1): 279-286

Insecticidal effects of a novel polyherbal formulation (HF7) against Culex pipiens L. (Diptera: Culicidae).

Nael Abutaha, Fahd A Al-Mekhlafi, Mohammed S Al-Khalifa, Mohamed A Wadaan.

  Plant secondary metabolites represent the most efficient and convenient method to control and overcome environmental pollution and insecticidal resistance. This study explored the mosquitocidal activity of the combined extract of seven plants, (HF7) extracted using a Soxhlet extractor against Culex pipiens under laboratory conditions. Exposure of the 3rd instars of Cx. pipiens to HF7 hexane extract resulted in LC50:114.5 μg/mL and LC90:117.0 μg/mL values after 24 h. The ovicidal activities of hexane extract against Cx. pipiens eggs were 21.6%, 48.3%, and 71.6% at 187.5, 93.7, and 46.88 μg/mL, respectively. HF7-treated larvae showed the formation of irregular blebbing of epithelial cells toward the lumen and sloughing into the gut lumen. HF7 extract resulted in 100% adulticidal mortality at the concentration of 3.7 mg/test tube after 30 min of exposure. The IC50 of HF7 extract was 97.03 µg/ml against larvae, at which nuclear and morphological changes were observed. The spectroscopy spectrum of HF7 hexane extract disclosed the presence of 57 different secondary metabolites, among which the dominant compound was eugenol (32.3%). HF7 hexane extract could serve as a botanical insecticide for controlling Cx. pipiens and potentially other mosquito species.

Keywords:  Botanical pesticide; Culex pipiens; Cytotoxicity; Histopathology; Mosquito control

DOI:  https://doi.org/10.1016/j.sjbs.2021.08.101
Parasitol Res. 2022 Jan 15.

First records of Aedes pulcritarsis (Rondani, 1872) (Diptera: Culicidae) in Austria.

Karin Bakran-Lebl, Hans Jerrentrup, Eleni Daroglou, Wolf Peter Pfitzner, Hans-Peter Fuehrer, Franz Allerberger.

  Aedes pulcritarsis is a tree-hole breeding species with its main distribution in the Mediterranean area. Within the scope of two independent monitoring programmes, this mosquito species was detected for the first time in Austria, in the province of Lower Austria (2018, districts Mistelbach and Gaenserndorf; 2020, district Bruck an der Leitha). As the climatic and habitat situation in Central Europe seems to be generally suitable for this species, the most likely explanation for the species not being recorded previously is that it might have been overlooked in the past due to its specialized breeding habitat. However, further research on the distribution of Ae. pulcritarsis in Austria would be needed to support this hypothesis. The results from this study will contribute to the investigation of the northern distribution limit of Ae. pulcritarsis in Europe and possible changes thereof.

Keywords:  Aedes pulcritarsis; Austria; Mosquitoes; Species inventory

DOI:  https://doi.org/10.1007/s00436-022-07430-w
Euro Surveill. 2022 Jan;27(2):

Dengue virus infections among European travellers, 2015 to 2019.

Céline M Gossner, Nelly Fournet, Christina Frank, Beatriz Fernández-Martínez, Martina Del Manso, Joana Gomes Dias, Henriette de Valk.

  BackgroundDengue is a disease with major impacts on public health in tropical and subtropical countries. In Europe, in the past decade, few autochthonous outbreaks were described.AimWe aimed to identify factors associated with frequency of dengue virus infection among European travellers and at assessing how surveillance data could support preparedness against autochthonous outbreaks within Europe.MethodsWe performed a descriptive analysis of travel-related dengue cases reported by European countries from 2015 through 2019. Using flight passenger data, we calculated travellers' infection rates (TIR). We investigated the following associations: (i) between TIR and incidence rate in selected countries of infection and (ii) between number of travel-related cases and occurrence of autochthonous outbreaks within Europe.ResultsThere were 11,478 travel-related dengue cases and the TIR was 2.8 cases per 100,000 travellers. Most cases were infected in Asia (71%), predominantly in south-eastern Asia. The TIR was highest among travellers returning from Asia (6.1/100,000). There was an association between the incidence rate in the country of infection and the TIR but no association between the number of travel-related cases and occurrence of autochthonous outbreaks in Europe.ConclusionsThe likelihood of infection in travellers is a function of the ongoing epidemiological situation in the country of exposure. The number of travel-related cases alone is not sufficient to estimate the likelihood of autochthonous outbreaks where vectors are present in Europe. Additional contributing factors such as adequate vectorial capacity and suitable environmental conditions are required.

Keywords:  Europe; dengue; outbreak; surveillance; travel; travellers; vector-borne disease

DOI:  https://doi.org/10.2807/1560-7917.ES.2022.27.2.2001937
Commun Biol. 2022 Jan 10. 5(1): 6

West Nile virus transmission potential in Portugal.

José Lourenço, Sílvia C Barros, Líbia Zé-Zé, Daniel S C Damineli, Marta Giovanetti, Hugo C Osório, Fátima Amaro, Ana M Henriques, Fernanda Ramos, Tiago Luís, Margarida D Duarte, Teresa Fagulha, Maria J Alves, Uri Obolski.

It is unclear whether West Nile virus (WNV) circulates endemically in Portugal. Despite the country's adequate climate for transmission, Portugal has only reported four human WNV infections so far. We performed a review of WNV-related data (1966-2020), explored mosquito (2016-2019) and land type distributions (1992-2019), and used climate data (1981-2019) to estimate WNV transmission suitability in Portugal. Serological and molecular evidence of WNV circulation from animals and vectors was largely restricted to the south. Land type and climate-driven transmission suitability distributions, but not the distribution of WNV-capable vectors, were compatible with the North-South divide present in serological and molecular evidence of WNV circulation. Our study offers a comprehensive, data-informed perspective and review on the past epidemiology, surveillance and climate-driven transmission suitability of WNV in Portugal, highlighting the south as a subregion of importance. Given the recent WNV outbreaks across Europe, our results support a timely change towards local, active surveillance.

DOI: https://doi.org/10.1038/s42003-021-02969-3
Saudi J Biol Sci. 2022 Jan;29(1): 385-393

Virulence of entomopathogenic fungi against Culex pipiens: Impact on biomolecules availability and life table parameters.

Heba M Hamama, Ola H Zyaan, Ola A Abu Ali, Dalia I Saleh, Hend A Elakkad, Mohamed T El-Saadony, Shaimaa M Farag.

  Culex pipiens mosquitoes considered as vectors for many arboviruses such as the West Nile virus and encephalitis virus showing a global impact on human health. The natural management of the aquatic stages of this pest is crucial for maintaining an insecticide-free and sustained environment. The present work focused on studying the biological and biochemical effects of the entomopathogenic fungi: Metarhizium anisopliae, Beauveria bassiana, and Paecilomyces lilicanus, against 3rd instar larvae of Culex pipiens laboratory colony. The results revealed that M. anisopliae showed maximum larval mortality (88%) with the lowest lethal time (LT50) (22.6 hrs) at 108 spores/ml followed by B. bassiana (73.33%) with LT50 (38.35 hrs), while P. lilicanus showed minimum percent mortality (65%) with highest LT50 (51.5 hrs). The median lethal concentration (LC50) values were found to be 1.027 × 105 spores/ml for M. anisopliae, 1.24 × 106 spores/ml for B. bassiana, while it was 8.453 × 106 spores/ml for P. lilicanus. A reduction in female fecundity, number of hatched eggs, pupation and adult emergence percentage were recorded. The biochemical analysis of the treated larvae revealed different quantitative decrease in total soluble proteins, lipids, and carbohydrate hydrolyzing enzymes compared to control. Histopathological effects of fungal infection upon insect cuticles, muscles, and midgut were investigated. Based on the obtained results, M. anisopliae proved its superior virulent effect as a bio-control agent against Cx. pipiens.

Keywords:  Beauveria bassiana; Carbohydrate hydrolyzing enzymes; Culex pipiens; Entomopathogenic fungi; Metarhizium anisopliae; Paecilomyces lilicanus

DOI:  https://doi.org/10.1016/j.sjbs.2021.08.103