How do invasive species affect native species? Experimental evidence from a carrion blowfly (Diptera: Calliphoridae) system

Abstract

1. The necrobiome is a unique microcosm in which various organisms interact and compete for access to an ephemeral resource, such as carrion, that ultimately determines the structure and composition of these assemblages.2. Blowfly species exhibit different competitive abilities which, when associated with other types of behaviour, such as predation or cannibalism, influence coexistence. Knowledge of the effects of competition between native and invasive species on development and survival is essential to understanding the dynamics of insect communities and to assess biological invasions.3. Laboratory experiments were performed to evaluate the effect of interspecific competition on the bionomics and survival of a native (Cochliomyia macellaria) and an invasive (Chrysomya rufifacies) blowfly species at different population densities.4. The deleterious effect of competition on the larval parameters of C. macellaria increased proportionally with increases in the larval density of C. rufifacies. When exposed to increased densities of C. rufifacies, larvae of C. macellaria accelerated their development and, as a trade‐off for this strategy, surviving adults were smaller and had reduced wing size, which were likely to reduce dispersal and reproductive capacity.5. Larval competition – both as species‐dependent and density‐dependent phenomena – influences morphological and biological traits of surviving individuals. The impact of the invasive species has consequences at the population level, such as displacement or local population depletion of native species, a phenomenon likely to occur in other systems involving insects and ephemeral resources.