Mosquito species associated with a relic urban natural (run) site in College Station, Texas

Abstract

A qualitative study of the biodiversity of mosquito fauna was conducted in a relic natural creek bottom habitat inherent to the Kiwanis Nature Trail located in the College Hills residential area of College Stations Texas between Gilchrist and Francis Streets. During the different seasons ex-tending over a period beginning February 1993 and ending in March 1995, adult and larval mosquito specimens were collected, identified, and correlated with various habitat types occurring at the study site. Three main breeding areas were identified within the relic urban natural study site. These included shaded woodland, open grassland, and seasonal creek bottom areas. The woodland areas of the site contained depressions in the soil which served as floodwater-holding sites after heavy rains. The open grassland areas also contained various depressions and irregularities which served as floodwater-holding sites. The creekbed which passed through the wooded area frequently acted as a floodwater-holding site depending on rainfall, local irrigation runoff, and influxes of water from upstream. A total of 43 mosquito species were collected at the RUN site either as larvae, adults, or nth over the two year study period. As for the seasonal dynamics of larval mosquito populations occurring at the RUN site, larvae of floodwater species such as Aedes vexans Meigen and Ae. canadensls (Theobald), usually appeared first in the early spring after heavy rainfall followed by standing-water-breeders such as Culex salinarius Coquillett and Cx. restuans Theobald. This same sequence occurred in the various floodwater sites each time rains were sufficient to till the deeper depressions located in each of the areas studied at the site. After dry periods, such as occur in the slimmer, the cheeked would support the larva of floodwater species such as the aforementioned Ae. Texans when inundated by local runoff from rain or local water usage in the urban surrounding. These creekbed sites would then subsequently support standing-water-breeding species such as Cx. quinquefasciatus until such time that sites dried up. When water from upstream filled the creek, mosquito larva were at times found not to occur in the cheeked water. This was thought to be, in part, due to the influx of predatory minnows identified as Gambusia affinis brought into the study site via the water coming from upstream and in part, to some flushing out of the larval populations present in the creaked site before the upstream flooding occurred. Results of this study indicate that RUN sites do have great potential for supporting a large diversity of mosquito species in Central Texas; and creekbeds (especially those containing water only intermittently) in such settings can be prime larval development sites for both floodwater and standing water mosquito species.