Resource competition between two forensically important blow fly species (Diptera: Calliphoridae)

The colonization behaviour of two forensically important blow fly species (Diptera: Calliphoridae) were studied using the domestic fetal pig (Sus scrofa) as the resource type. In order to determine the colonization potential of Phormia regina (Meigen) and Lucilia sericata (Meigen), the species were separated as freshly emerged adults and placed in mesh cages to create five different treatment colonies where the sequence and species available for colonization varied. Once females were fully gravid, fetal pig carcasses (Sus scrofa) were placed within each treatment colony for 24–48 hours (depending upon treatment conditions) and colonization events and behavioral observations were recorded. After the designated colonization period ended, piglets were removed and egg mass surface area and depth were recorded. Results determined that egg laying locations differed between L. sericata and P. regina and also that the quantity of eggs deposited by females varied with respect to both species and introduction sequence, with L. sericata exhibiting a more aggressive colonization behaviour laying more eggs than P. regina. However, in treatments were P. regina was introduced subsequent to colonization of the resource by L. sericata, P. regina females laid significantly more eggs indicating that previous colonization by other blow fly species may act to increase survival of P. regina.