Do native and invasive blow fly (Diptera: Calliphoridae) species differ in their preferential time of flight? Empirical evidence from a seasonally dry tropical forest

Abstract Since its establishment in the Americas, the invasive species Chrysomya albiceps has been displacing native species such as Cochliomyia macellaria . Behavioural traits associated with this phenomenon are poorly understood, particularly in semiarid environments, as in the Caatinga , the largest seasonally dry tropical forest in the world, endemic to Brazil, where resource availability is critical. Under hot and dry conditions, differences in flight activity may influence competitive abilities. We investigated the preferential time of flight of C. albiceps and C. macellaria in a fragment of Caatinga , based on the capture of adults in baited traps. Four diurnal treatments were used: 05:30 h to 08:30 h (early morning), 8:30 h to 11:30 h (late morning), 11:30 h to 14:30 h (early afternoon) and 14:30 h to 17:30 h (late afternoon), plus collections from 17:30 h to 05:30 h of the following day (night time). The results revealed that C. macellaria was almost three times more abundant than C. albiceps and that both species were least captured in the early morning and increasingly so during the day until the latter treatment. Curiously, no insect was collected in nocturnal samples. Contradictorily to our initial hypothesis, flies were mostly captured in the hottest and driest periods of the day. The similarity in flight temporal activity between the two species suggests that they may arrive at (and colonize) a substrate at the same time, with important implications for carrion ecology and forensic entomology.