Testing the Relationship Between Dissolved Salts in Aquatic Habitats and Immature Populations of the <I>Culicoides variipennis</I> Complex (Diptera: Ceratopogonidae)

Abstract

Abstract Biting midges of the Nearctic Culicoides variipennis complex, C. sonorensis Wirth and Jones, C. variipennis (Coquillette), and C. occidentalis Wirth and Jones, are widespread and locally abundant throughout the United States. An understanding of environmental factors associated with the distributions of respective species is of value because risk for bluetongue disease in livestock is defined by the distribution of C. sonorensis, the primary vector of bluetongue viruses in the United States. This study tested the relationship between dissolved salts and immature populations of the C. variipennis complex by examining widespread and diverse aquatic habitats with larval populations and using discriminant analysis to classify larval habitats by species on the basis of soil chemistry. Aquatic habitats with immature C. sonorensis in British Columbia, Illinois, New Mexico, and Washington were moderate-high in levels of dissolved salts, as is typical for habitats with this species. In contrast, a nearby ...