title: Black-fly assemblage distribution patterns in streams in disturbed areas in southern Brazil.
abstract: Black flies (Simuliidae) are considered to be pests in rural and in some urban areas in the south of Brazil due to the bites of females. Little information exists on the factors that contribute to Simuliidae distribution in these areas. We sampled 39 streams in the state of Rio Grande do Sul in September 2004 to address ecological aspects. Of the 18 species collected, those that occurred in more than 50% of the streams were: Simulium subnigrum Lutz 1910, Simulium pertinax Kollar 1882, Simulium subpallidum Lutz 1910 and Simulium incrustatum Lutz 1910. Species richness was not influenced by any of the environmental or geographical variables considered, and there was no pattern of species co-occurrence, corroborating the hypothesis of a stochastic distribution of the Simuliidae assemblage. When analyzed individually, only three of seven species with occurrence frequency >30% were related to any of the variables measured. The probabilities of occurrence of Simulium jujuyense Paterson & Shannon 1927 and S. pertinax were higher in streams with high values of water pH and electrical conductivity, whereas the opposite was observed for S. incrustatum. Therefore, due to stochastic distribution, the population studies of Simuliidae are more suitable for predicting the occurrence of species in rural areas than are studies of assemblages.
authors.affiliation: Universidade Federal do Oeste do Pará, Instituto de Ciências e Tecnologia das Águas, Laboratório de Ecologia de Ictioplâncton e Invertebrados aquáticos, Anexo ao Campus Amazônia Boulevard, Av. Mendonça Furtado, 2946, Fátima, CEP 68040-470, Santarém, PA, Brazil. Electronic address: sheylacouceiro@yahoo.com.br.
authors.forename: Sheyla Regina Marques
authors.initials: SR
authors.lastname: Couceiro
authors.affiliation: Instituto Nacional de Pesquisas da Amazônia, Coordenação de Biodiversidade, Manaus, AM, Brazil. Electronic address: nhamada@inpa.gov.br.
authors.forename: Neusa
authors.initials: N
authors.lastname: Hamada
authors.affiliation: Governo do Estado do Rio Grande do Sul, Secretaria Estadual de Saúde, Porto Alegre, RS, Brazil. Electronic address: luciamardini@gmail.com.
authors.forename: Lúcia Beatriz
authors.initials: LB
authors.lastname: Sagot
authors.affiliation: Universidade Federal de São Carlos, Centro de Ciências Biológicas e da Saúde, São Carlos, SP, Brazil. Electronic address: mateuspepi@yahoo.com.br.
authors.forename: Mateus
authors.initials: M
authors.lastname: Pepinelli
mesh_terms: D000818:Animals; D001938:Brazil; D005260:Female; D007299:Insect Bites and Stings / Q000517:prevention & control*; D007300:Insect Control; D045483:Rivers; D012843:Simuliidae / Q000145:classification*; D014871:Water Microbiology
keywords: Aquatic ecosystems; Distribution; Disturbance; Neotropical; Rural areas; Simuliidae