The bionomics and ecology of Culex salinarius Coq. (Diptera: Culicidae) in Chambers County, Texas

Abstract

In Chambers County, Texas, Culex salinarius larvae were widely distributed and found in a variety of aquatic habitats during cooler times of the year. However, during the summer they were generally restricted to cool aquatic habitats protected from exposure by direct sunlight. These protected habitats most commonly occur in the brackish marshes located along the coastal regions of the county. A fire effectively eliminated Cx. salinarius larval breeding within a brackish marsh during the summer of 1989 by removing the protective canopy of emergent vegetation thereby exposing water in breeding sites to the warming effects of direct sunlight. An attempt to use clear-cutting of vegetation to reduce Cx. salinarius breeding in this area was not successful. Adult populations were found year round in Chambers County with peak densities in April/May and September /October. Individual broods of mosquitoes were influenced by amount of rainfall and ambient temperatures. The largest females were collected in colder months and from light traps close to the coast of Chambers County. Regardless of the season, Cx. salinarius had two primary peaks of flight activity: one just after sunset and the other just before sunrise. These peaks are determined by changes in light intensity. During the colder months of the year these peaks occur closer to twilight hours of early evening and early morning than during the warmer months. Peaks in flight activity also occurred during the night and were influenced by the appearance of the full moon and low wind. Flight activity was reduced by high wind, heavy precipitation and cold temperatures. Fewer intermediate peaks in flight activity were observed on new moon nights than on full moon nights. Flight activity on full moon nights was strongly correlated with collections of females in CDC light traps. On new moon nights more female Cx. salinarius were collected by light trap than than by cartop trap.