1988/05/01 by Mark A. Barnby, Vincent H. Resh · 1 citation
Agricultural and Biological Sciences · #Diptera species taxonomy and behavior #Forensic Entomology and Diptera Studies #Insect behavior and control techniques
paper · doi:10.1093/aesa/81.3.437
Two species of brine fly (Diptera: Ephydridae), Paracoenia calida Mathis, which is endemic, and Ephydra goedeni Wirth, which is known from hot springs in several U.S. states, occur in high densities in the thermal (source temp. = 54°C), saline (22 parts per thousand [ppt] salinity) waters of Wilbur Hot Springs, Colusa County, Calif. Both populations are multicohort and multivoltine (based on the year-round presence of all life stages), yet their spatial distributions within the Wilbur Hot Springs thermal effluent are highly segregated. These result from species-specific differences in life history traits and larval physiological tolerances. For example, by ovipositing near the hot spring source, having larval metabolic rates that are independent of high temperatures, and using atmospheric oxygen for larval respiration, P. calida inhabits all but the hottest portions of the Wilbur Hot Springs effluent. In contrast, E. goedeni adults oviposit in cooler, more oxygen-rich pools than those occupied by P. calida. Larvae of E. goedeni are most abundant in these cooler (yet decidedly thermal) waters, perhaps because their metabolic rates increase at high temperatures and they use dissolved oxygen for respiration. However, unlike those of P. calida, larvae of E. goedeni can tolerate water salinities that differ from those at Wilbur Hot Springs. A comparison of physiological traits indicates that P. calida is more highly adapted for existence in thermal saline waters than E. goedeni; specialization for life under such severe and rare habitat conditions may account for the endemic distribution of P. calida.