Underestimation of foraging behaviour by standard field methods in malaria vector mosquitoes in southern Africa

Das, Smita; Henning, Tyler C.; Simubali, Limonty; Hamapumbu, Harry; Lukwa, N.; Mamini, Edmore; Makuwaza, Aramu; Muleba, Mbanga; Norris, Douglas E.; Stevenson, Jennifer

doi:10.1186/s12936-014-0527-9

Cited by 19 publications

(27 citation statements)

References 40 publications

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“…Mammalian host was assessed for all anophelines due to the possibility that there may be mosquitoes that appear "unfed," but are actually fed as determined by molecular assays. 24,31,38 HBI was, therefore, calculated using PCR-confirmed blood meals.…”

Section: Seasonalmentioning

confidence: 99%

Habitat Partitioning of Malaria Vectors in Nchelenge District, Zambia

Das

Muleba

Stevenson

et al. 2016

The American Society of Tropical Medicine and Hygiene

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Abstract. Nchelenge District in Luapula Province, northern Zambia, experiences holoendemic malaria despite implementation of vector control programs. The major Anopheles vectors that contribute to Plasmodium falciparum transmission in this area had not previously been well defined. Three collections performed during the 2012 wet and dry seasons and the 2013 wet season revealed Anopheles funestus sensu stricto and Anopheles gambiae sensu stricto as the main vectors, where 80-85% of each collection was composed of An. funestus. Both vectors were found to be highly anthropophilic, and An. funestus has higher sporozoite infection rates (SIRs) and entomological inoculation rates (EIRs) year-round compared with An. gambiae: SIRs of 1.8-3.0% and 0-2.5%, respectively, and EIRs of 3.7-41.5 infectious bites per 6-month period (ib/p/6mo) and 0-5.9 ib/p/6mo, respectively. Spatial and temporal changes in each vector's dynamics and bionomics were also observed. Anopheles funestus was the predominant vector in the villages near Kenani Stream in both wet and dry seasons, whereas An. gambiae was found to be the main vector in areas near Lake Mweru during the wet season. The vector data illustrate the need for broader temporal and spatial sampling in Nchelenge and present unique opportunities to further our understanding of malarial transmission and implications for malarial control in high-risk areas.

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Section: Seasonalmentioning

confidence: 99%

Habitat Partitioning of Malaria Vectors in Nchelenge District, Zambia

Das

Muleba

Stevenson

et al. 2016

The American Society of Tropical Medicine and Hygiene

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“…Different Anopheles species vary in their malaria vectorial capacities as well as in their feeding and resting habits [11,47]. They may also have different insecticide susceptibility profiles and, therefore, their correct identification to species is vital for the implementation of an efficient vector control strategy based on accurate vector incrimination and appropriate use of insecticides.…”

Section: Discussionmentioning

confidence: 99%

“…gambiae complex and An. funestus group are often found in sympatry [11,47,48]. It is, therefore, likely that the collection of field samples could contain a mix of species, making accurate identification to species essential.…”

Section: Discussionmentioning

confidence: 99%

Member species of the Anopheles gambiae complex can be misidentified as Anopheles leesoni

Dahan-Moss

Hendershot

Dhoogra

et al. 2020

Malar J

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Background: Accurate Anopheles species identification is key for effective malaria vector control. Identification primarily depends on morphological analysis of field samples as well as molecular species-specific identifications. During an intra-laboratory assessment (proficiency testing) of the Anopheles funestus group multiplex PCR assay, it was noted that Anopheles arabiensis can be misidentified as Anopheles leesoni, a zoophilic member of the An. funestus group. The aim of this project was, therefore, to ascertain whether other members of the Anopheles gambiae complex can also be misidentified as An. leesoni when using the standard An. funestus multiplex PCR. Methods: The An. funestus multiplex PCR was used to amplify DNA from An. gambiae complex specimens. These included specimens from the laboratory colonies and field samples from the Democratic Republic of Congo. Amplified DNA from these specimens, using the universal (UV) and An. leesoni species-specific primers (LEES), were sequence analysed. Additionally, An. leesoni DNA was processed through the diagnostic An. gambiae multiplex PCR to determine if this species can be misidentified as a member of the An. gambiae complex. Results: Laboratory-colonized as well as field-collected samples of An. arabiensis, An. gambiae, Anopheles merus, Anopheles quadriannulatus, Anopheles coluzzii as well as Anopheles moucheti produced an amplicon of similar size to that of An. leesoni when using an An. funestus multiplex PCR. Sequence analysis confirmed that the UV and LEES primers amplify a segment of the ITS2 region of members of the An. gambiae complex and An. moucheti. The reverse was not true, i.e. the An. gambiae multiplex PCR does not amplify DNA from An. leesoni. Conclusion: This investigation shows that An. arabiensis, An. gambiae, An. merus, An. quadriannulatus, An. coluzzii and An. moucheti can be misidentified as An. leesoni when using An. funestus multiplex PCR. This shows the importance of identifying specimens using standard morphological dichotomous keys as far as possible prior to the use of appropriate PCR-based identification methods. Should there be doubt concerning field-collected specimens molecularly identified as An. leesoni, the An. gambiae multiplex PCR and sequencing of the internal transcribed spacer 2 (ITS2) can be used to eliminate false identifications.

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“…accounted for 29% and 9%, respectively, of limited indoor and outdoor catches of adult anophelines in Western Province villages in 2013 [48], they were not the most abundant species in that collection (some of which originated in our study area). All three of these species exhibit large human blood indices in Zambia [49], and although An. arabiensis is generally considered to be less anthropophilic than An.…”

Section: Discussionmentioning

confidence: 99%

Geographically extensive larval surveys reveal an unexpected scarcity of primary vector mosquitoes in a region of persistent malaria transmission in western Zambia

Cross¹,

Thomas

McKeown³

et al. 2020

Preprint

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Background: The Barotse floodplains of the upper Zambezi River and its tributaries are a highly dynamic environment, with seasonal flooding and transhumance presenting a shifting mosaic of potential larval habitat and human and livestock bloodmeals for malaria vector mosquitoes. However, limited entomological surveillance has been undertaken to characterise the vector community in these floodplains and their environs. Such information is necessary as, despite substantial deployment of insecticide-treated nets (ITNs) and indoor residual spraying (IRS) against Anopheles vectors, malaria transmission persists across Barotseland in Zambia’s Western Province.Methods: Geographically extensive larval surveys were undertaken in two health districts along 102 km of transects, at fine spatial resolution, during a dry season and following the peak of the successive wet season. Larvae were sampled within typical Anopheles flight range of human settlements and identified through genetic sequencing of cytochrome c oxidase I and internal transcribed spacer 2 regions of mitochondrial and nuclear DNA. This facilitated detailed comparison of taxon-specific abundance patterns between ecological zones differentiated by hydrological controls.Results: An unexpected paucity of primary vectors was revealed, with An. gambiae s.l. and An. funestus representing < 2% of 995 sequenced anophelines. Potential secondary vectors predominated in the vector community, primarily An. coustani group species and An. squamosus. Whilst the distribution of An. gambiae s.l. in the study area was highly clustered, secondary vector species were ubiquitous across the landscape in both dry and wet seasons, with some taxon-specific relationships between abundance and ecological zones by season.Conclusions: Larval survey results imply that residual transmission of malaria in Barotseland is being mediated predominantly by secondary vector species, whose known tendencies for crepuscular and outdoor biting renders them largely insensitive to prevalent vector control methods (ITNs and IRS). Alternative interventions may be required against this vector community to further reduce transmission. Larviciding is one potential supplementary intervention, although it presents a challenge in extensive wetlands such as those found in the Upper Zambezi catchment. However, the combination of advances in remote sensing of habitats, genetic identification of local vectors, and spatial modelling present a potential opportunity to optimise targeting of aerial spraying in these environments.

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Underestimation of foraging behaviour by standard field methods in malaria vector mosquitoes in southern Africa

Cited by 19 publications

References 40 publications

Habitat Partitioning of Malaria Vectors in Nchelenge District, Zambia

Habitat Partitioning of Malaria Vectors in Nchelenge District, Zambia

Member species of the Anopheles gambiae complex can be misidentified as Anopheles leesoni

Geographically extensive larval surveys reveal an unexpected scarcity of primary vector mosquitoes in a region of persistent malaria transmission in western Zambia

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