title: Ecological characteristics of Simulium breeding sites in West Africa.
abstract: Twenty-nine taxa of Simulium were identified amongst 527 collections of larvae and pupae from untreated rivers and streams in Liberia (362 collections in 1967-71 & 1989), Togo (125 in 1979-81), Benin (35 in 1979-81) and Ghana (5 in 1980-81). Presence or absence of associations between different taxa were used to group them into six clusters using Ward agglomerative hierarchical cluster analysis. Environmental data associated with the pre-imaginal habitats were then analysed in relation to the six clusters by one way ANOVA. The results revealed significant effects in determining the clusters of maximum river width (all P<0.001 unless stated otherwise), water temperature, dry bulb air temperature, relative humidity, altitude, type of water (on a range from trickle to large river), water level, slope, current, vegetation, light conditions, discharge, length of breeding area, environs, terrain, river bed type (P<0.01), and the supports to which the insects were attached (P<0.01). When four non-significant contributors (wet bulb temperature, river features, height of waterfall and depth) were excluded and the reduced data-set analysed by principal components analysis (PCA), the first two principal components (PCs) accounted for 87% of the variance, with geographical features dominant in PC1 and hydrological characteristics in PC2. The analyses also revealed the ecological characteristics of each taxon's pre-imaginal habitats, which are discussed with particular reference to members of the Simulium damnosum species complex, whose breeding site distributions were further analysed by canonical correspondence analysis (CCA), a method also applied to the data on non-vector species.
authors.affiliation: Natural Resources Institute, University of Greenwich at Medway, Central Avenue, Chatham Maritime, Kent ME4 4TB, UK. Electronic address: r.a.cheke@greenwich.ac.uk.
authors.forename: Robert A
authors.initials: RA
authors.lastname: Cheke
authors.affiliation: Natural Resources Institute, University of Greenwich at Medway, Central Avenue, Chatham Maritime, Kent ME4 4TB, UK.
authors.forename: Stephen
authors.initials: S
authors.lastname: Young
authors.affiliation: Bernhard Nocht Institute for Tropical Medicine, Bernhard-Nocht-Str. 74, 20359, Hamburg, Germany.
authors.forename: Rolf
authors.initials: R
authors.lastname: Garms
mesh_terms: D000354:Africa, Western; D000531:Altitude; D000818:Animals; D001947:Breeding; D017753:Ecosystem; D007814:Larva / Q000145:classification; D011679:Pupa / Q000254:growth & development; D045483:Rivers; D012843:Simuliidae / Q000145:classification / Q000254:growth & development*; D013696:Temperature
keywords: CCA; Cluster analysis; Environmental variables; PCA; Simulium damnosum complex