Thermal ecophysiology of seven carrion‐feeding blowflies in Southern Africa

Abstract

AbstractA variety of temperature thresholds for larvae, pupae, and adults of seven African species of carrion‐feeding blowflies (Diptera: Calliphoridae) was measured and compared to understand their basic thermal biology and the influence of temperature on their behaviour. Calliphora croceipalpis (Jaennicke) had consistently lower temperature thresholds than all other species tested for all larval (42.9 °C), pupal (16.6 °C), and adult (45.6 °C) stages. Larvae (50.1 °C) and adults (53.4 °C) of Chrysomya marginalis (Robineau‐Desvoidy) had higher upper lethal temperature thresholds than all other species and weighed more than all other species. Pupae and adults of both Chrysomya albiceps (Wiedemann) and Lucilia sericata (Meigen) had similar temperature thresholds, whereas Chrysomya putoria (Wiedemann), Chrysomya chloropyga (Wiedemann), and Chrysomya megacephala (Fabricius) had inconsistent rank temperature thresholds between the larval, pupal, and adult stages. With a few minor exceptions, the nervous activity, muscle activity, and death thresholds in female adult flies responded at higher temperatures than conspecific male flies for all species tested. Similarly, female adult flies weighed consistently more than conspecific male flies for all species tested, except Ca. croceipalpis. These data suggest that there is a phylogenetic component to the thermal biology of blowflies, because Ca. croceipalpis belongs to a primarily Holarctic genus and shows adaptation to that climate even though it inhabits Africa. Comparisons between these temperature thresholds and the distributions of blowfly species present on three rhinoceros carcasses suggest that blowfly larvae with high upper lethal temperature thresholds (particularly C. marginalis) dominate in interspecific competition on the carcass by raising the temperature of the amassed maggots above the thresholds of other carrion‐feeding blowflies, through metabolically generated heat.