Community composition of carrion-breeding blowflies (Diptera: Calliphoridae) along an urban gradient in south-eastern Australia

Urbanisation is a process that results in rapid modification of the natural environment, dramatically altering community structure. Blowflies (Diptera: Calliphoridae) are common inhabitants of the urban ecosystem, although little is understood about their distributions or habitat preferences within the urban environment. Blowflies require carrion for development, and as carrion is an ephemeral resource, the effect of urbanisation on these flies may be expected to differ from insects that utilise more uniformly distributed resources. In this study, blowflies were captured at various locations along an urban gradient in the region of Sydney, Australia, during summer and winter. Four habitat categories were sampled: bush, farm, suburban and urban. Using analysis of similarities (ANOSIM), calliphorid assemblages differed between all habitats, except urban and suburban. Species associations with environmental variables were also analysed using canonical correspondence analysis (CCA). Calliphorid abundances were lower in the winter trapping period, compared with the summer trapping period. Chrysomya was the most abundant genus during summer, whilst Calliphora was the most abundant genus during the winter. Some species also displayed temporal changes in their habitat preferences and synanthropic behaviour. Other species were only present in the urban habitats during winter, suggesting that they rely on urban refuges at this time of year. The ecological effects of urbanisation were clearly observed in the present study, since three distinct calliphorid assemblages were found at three different levels of urbanisation within the urban gradient. This study provides information on blowfly responses to urbanisation of use to forensic and ecological entomologists.