Potential for thermal refugia in a carrion fly system

Modeling blow fly development is important for understanding their role in nutrient recycling and in forensic entomology.  Recent modeling efforts have accounted for thermal preferences as an enhancement of accumulated degree-based attempts to estimate blow fly development.  However, such models may be challenged by conditions that alter thermal preferences.  Here we describe dynamics between the most common blow fly in Texas, Cochliomyia macellaria, and a relatively recently introduced facultative predator of other blow flies, Chrysomya rufifacies. Initially, introduction of the predator was thought to be a risk to the native fly.  However, these species coexist in Texas and we have considered a thermal hypothesis for why that may be: a thermal refuge for the prey species.  Through observations of museum specimens from Texas collections through laboratory studies of thermal tolerance in adults and larvae using ramping and static methods, an emergent picture of the competitive dynamic between the species is painted.  C. macellaria appears to be a relative thermal generalist with respect to C. rufifacies.  Seasonal variation in abundance indicates a season where C. macellaria can develop in the absence of competition with C. rufifacies.  In addition, laboratory studies indicate that C. macellaria has the potential to escape this competing predator when in cooler or hotter ends of its thermal performance curve.  This dynamic raises an important concern for predicting the development of either species – how much does the cooccurrence of these species alter the thermal preferences and developmental progress of either?