The role of the landscape in structuring immature mosquito assemblages in wetlands

Abstract

The distribution of mosquito populations is spatially heterogeneous and influenced by factors acting at a wide range of scales. The aim of this study was to assess the role of environmental heterogeneity at the landscape level in shaping the composition of immature mosquito communities inhabiting surface water habitats. The Parana´ Lower Delta (Argentina) is a temperate wetland that extends along a 18 north–south gradient and presents high landscape heterogeneity, due to the combined action of geomorphology, hydrology and human intervention. Immature mosquitoes were collected every 2 weeks (Nov 2011–April 2012) from surface water habitats within 11 peridomestic areas interspersed along a 75 km north–south transect. The environment was quantified by 24 variables regarding the geomorphology, geography, economic use, climate, landcover and topography of each site and its surroundings at three radii. The association between the mosquito assemblage and the environment was tested by two multivariate approaches, the community-based outlying mean index and by-species generalized linear models. The former explained 93.6 % of the marginality of all taxa as a function of the type and diversity of landcover, precipitation, presence of cattle and altitude. The niche of six species, most of which were floodwater mosquitoes of the genera Ochlerotatus and Psorophora, deviated significantly from uniformity. The by-species approach rendered significant models for four species as a function of landcover type and precipitation. Both methodologies were broadly consistent in pointing that landscape elements affect the distribution of immature mosquitoes, thereby shaping the composition of the mosquito assemblage in peridomestic environments within wetlands.