Fitness trade-offs as a mechanism of coexistance within the family Calliphoridae: how to survive in a resource limited community

Within ecology, there are many systems where resource limitation acts as a driving force for competition and coexistence. Carrion represents an ephemeral resource where a unique insect community develops, exhibiting distinct changes in community composition over spatial and temporal scales. Within the carrion insect community, Calliphorids represent the primary resource colonizers responsible for the rapid removal of biomass during decomposition, where blow fly species commonly experience high levels of competition due to the nature of the resource and the number of larvae present. The effects of competition were investigated using two blow fly species: Phormia regina (Meigen) and Lucilia sericata (Meigen). A total of 400 first instar larvae were transferred to fetal pig carcasses (Sus scrofa (Linnaeus)), where the arrival sequence of each species varied. Larval, pupal and emergent adult mortality was measured as well as emergent adult fitness. Results indicate that L. sericata experiences a reduction in emergent adult fitness in the presence of P. regina. Alternately, P. regina experiences lower larval/pupal mortality, however, no reduction in adult fitness in the presence of L. sericata. Thus, L. sericata may act as a facilitator to promote the survival and fitness potential of P. regina, however, a reduction in adult fitness and, thus, a reduction in the colonization potential of the subsequent generation of L. sericata is exhibited. The different effects of competition on mortality and fitness demonstrated by these two blow fly species suggest that alternative strategies for survival can be adopted to allow for coexistence within the Calliphorid family.