The impact of sediment releases due to road construction on water chemistry and invertebrate communities was studied in a clear water river system in the tropical humid Bolivian Andes. Eight sites (2 reference, 1 source and 5 impacted along the main river) were sampled during the 1997 low flow season. Suspended sediment concentrations exhibited a 500-fold increase downstream from the source of pollution compared to the reference site, but recovered to natural levels within 90 km in the main river. Suspended solids had only a minor influence on other chemical parameters, but had a clear negative effect on invertebrate density (200-fold decrease in abundance) and diversity (6-fold decrease in number of taxa) in the main river. The most affected insects were epibenthic gatherers (e. g. Ephemeroptera: Leptohyphidae, Coleoptera: Elmidae), swimmers (Ephemeroptera: Leptophlebiidae), and scrapers (Coleoptera: Psephenidae, Trichoptera: Hydroptilidae). These families are therefore considered to be the best potential bio-indicators of sediment release impact in clear-water Andean rivers.

In the contemporary context of zoonosis emergence and spread, invasive species are a major issue since they represent potential pathogen hosts. Even though many progresses have been done to understand and predict spatial patterns of invasive species, the challenge to identify the underlying determinants of their distribution remains a central question in invasion biology. This is particularly exacerbated in the case of commensal species that strictly depend on humankind for dispersal and perennial establishment of new populations. The distribution of these species is predicted to be influenced by dispersal opportunities and conditions acting on establishment and proliferation, such as environmental characteristics, including spatio-temporal components of the human societies. We propose to contribute to the understanding of the recent spread of a major invasive rodent species, the black rat (Rattus rattus), in the changing southeastern of Senegal. We address the factors that promote the dispersal and distribution of this invasive rodent from the perspective of human geography. We first describe characteristics of human settlements in terms of social and spatial organization of human societies (i.e. economic activities, commercial and agricultural networks, roads connectivity). We then explore the relationship between these characteristics and the distribution of this invasive rodent. Finally we propose that historical and contemporary dynamics of human societies have contributed to the risk of invasion of the black rat. We argue that the diffusion processes of invasive species cannot be considered as a result of the spatial structure only (i.e. connectivity and distance), but as a part of the human territory that includes the social and spatial organization. Results suggest that the distribution of invasive rodents partly results from the contemporary and inherited human socio-spatial systems, beyond the existence of suitable ecological conditions that are classically investigated by biologists.

All stages of Simulium buissoni Roubaud, 1906 are redescribed. Larvae, pupae, and males of S. gallinum Edwards, 1932 are associated with the female holotype and all are fully described. Simulium adamsoni Edwards, 1932, the males of which have enlarged cerci, gonocoxae fused medially, and an enlarged keel-like ventral plate, is similarly redescribed. The female holotype and two paratypes of S. mumfordi Edwards, 1932 are fully redescribed. Males and females of S. hukaense Séchan, 1983 are associated with the pupae and larvae and described. Since all type material of this species is lost, a neotype is designated. Simulium uaense Séchan, 1983 is briefly mentioned. Three new species are described: S. pichoni Craig, Fossati, and Séchan, S. rivierei Craig, Fossati, and Séchan, and S. sechani Craig and Fossati. Brief comments are made concerning the bionomics and the relationships of the species.

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