Table 1 Land-cover classes derived from VHR imagery, with suggested open alternatives, and knowledge relating to their influence on larval habitat suitability (from literature and experts)
Land-cover classes from VHR imagery | Alternative existing open product(s) | Larval habitat suitability—Sub-Saharan African cities | Larval habitat suitability—Dakar |
|---|---|---|---|
Buildings | Open buildings | Buildings are not among sites likely to provide artificial breeding sites [9] | Buildings do not provide suitable habitat conditions. There are very few water bodies on flat roofs and balconies [21] |
Swimming pools | n/a | Neglected swimming pools may provide larval habitat in affluent neighbourhoods [55, 56] | Swimming pools should not be discarded as potential breeding sites [57] |
Paved surface | OSM | Paved surfaces (e.g., roads and parking lots) are not cited among common artificial urban breeding sites [9] | Paved surface is unlikely to provide suitable conditions for the occurrence of breeding sites [21] |
Dumpsites | OSM | Breeding sites tend to be located close to human dwellings rather than in uninhabited areas such as the large city dumpsite [28] | |
Bare ground | Esri 2020 Land Cover, WorldCover | Puddles are typical breeding sites that can form on bare ground, in tyre tracks, potholes, footsteps and hoofsteps [9, 33, 59] | Temporary water bodies (e.g., puddles) can form on bare ground in the wet season [21] |
Grass | Esri 2020 Land Cover, WorldCover | Breeding sites can be found in flooded grassy areas [60, 61] | Flooded grassy areas, especially with low-floating vegetation, are suitable for anopheline larvae, but only when the vegetation cover is below 20% [10, 34] |
Scrub/shrub | Esri 2020 Land Cover, WorldCover | Scrub/shrub is not among features likely to provide natural breeding sites [9] | Breeding sites tend to be located close to human dwellings rather than in uninhabited land, such as areas covered in scrub/shrub [28] |
Trees | Esri 2020 Land Cover, WorldCover | Trees are not among features likely to provide natural breeding sites, but tree holes are cited in one study [9, 62] | The adaptation of anopheline larvae to new breeding sites such as tree holes has not yet been reported in Dakar [10, 34] |
Small water bodies  < 100 m2 | n/a | The An. gambiae complex of sub-Saharan Africa characteristically breeds in small water bodies [63, 64] | Small water bodies are more likely to host larvae than medium-sized and large water bodies [28] |
Medium water bodies 100 to 1000Â m2 | OSM, Esri 2020 Land Cover, WorldCover | Medium-sized water bodies can also be utilized as breeding sites [9] | |
Large water bodies  > 1000 m2 | OSM, Esri 2020 Land Cover, WorldCover | Large water bodies can also be utilized as breeding sites [9] | |
Water courses | OSM, Esri 2020 Land Cover, WorldCover | An. gambiae usually breeds in standing water rather than flowing water [33, 60]. However, river margins/banks can provide highly suitable habitats [64] | Backwaters, rather than flowing water, favour the occurrence of breeding sites [28]. There are few flowing water courses in Dakar, due to urbanization of low-lying lands and riverbeds during a long drought [65] |
Marine waters | n/a | An. gambiae usually breeds in freshwater [33]. Larval mortality increases with NaCl concentration [66] | Marine waters are not favourable to An. gambiae. An. melas is found in low numbers in such waters, but it is a less efficient malaria vector [34] |
Shadow | SRTM-derived shadow, using the GRASS GIS module r.sunmask | Water body exposure to sunlight is favourable, shade may reduce suitability [9, 33, 61, 67] | Larvae can be found in sunlit, partially shaded and shaded water bodies [28], but their presence is less likely in shaded water bodies [34] |