Multivariate analysis of relationships between habitats, environmental factors and occurrence of anopheline mosquito larvae Anopheles albimanus and A. pseudopunctipennis in southern Chiapas, Mexico

Samples for the two principal malaria vectors, Anopheles albimanus and A. pseudopunctipennis, were taken and 17 environmental factors were measured or estimated. Canonical correspondence analysis combined with a Monte Carlo permutation test revealed significant dependence of mosquito larval occurrence in environmental factors and habitat categories in the dry season and on environmental factors only in the wet season. There was a positive association between the habitat category "flooded or irrigated pastures' and A. albimanus occurrence in both seasons, and positive association between "estuaries' and A. albimanus occurrence in the dry season. The occurrence of A. albimanus was negatively associated with the habitat category "foothills' in both seasons, and negatively associated with the category "estuaries' in the wet season. In the dry season, the abundance of phytoplankton and cover of floating macrophytes were significantly greater for sampling sites where A. albimanus was present. Concentrations of K⁺, Ca²⁺ and PO₄-P and amount of phytoplankton were significantly higher and the amount of filamentous algae significantlylower for A. albimanus positive sites in the wet season. Altitude and the amount of filamentous algae were significantly higher, and Na⁺ concentration was significantly lower for sampling sites positive for A. pseudopunctipennis in the dry season. In the wet season, the mean abundance of filamentous algae in sites with A. pseudopunctipennis was significantly higher than in sites where this species was absent. -from Authors