Aggregation and Competition in Lucilia Sericata and Phormia Regina Meigen (diptera: Calliphoridae)

Blow flies (Diptera: Calliphoridae) are commonly used to estimate the post-mortem interval of unattended death when this interval is greater than 48 hours. This estimate utilizes the developmental biology and behaviour of these first arriving insects. Female blow flies typically engage in aggregated egg laying, resulting in larval feeding masses once the eggs hatch. The density of individuals from the same species and from other species of blow flies has the potential to impact developmental rates and survival between different developmental stages through competitive interactions. During larval feeding aggregations, the larvae are capable of generating internal heat temperatures that can exceed ambient temperatures by 20-30ºC. In order to withstand the thermal stress induced by this high internal temperature, maggots synthesize heat shock proteins. The aim of this research is to study the implications of spatial aggregation for larval competition on two forensically important blow flies Lucilia sericata Meigen (Diptera: Calliphoridae) and Phormia regina Meigen (Diptera: Calliphoridae). First instars approximately 2-3 hours old are transferred onto 50g of liver at several densities for pure and mixed laboratory cultures and reared at three different temperatures, 15°C, 25°C and 35°C. In pure cultures of Lucilia sericata and Phormia regina development rate and mortality increases with increasing temperature while adult size for both species decreased with increasing larval density. We will be measuring heat shock induced proteins synthesized during development at different densities of larvae. The results of this study will be used to refine estimates of post-mortem interval utilizing blow fly development and to potentially explain oviposition behaviour and larval behaviour during development. This research is particularly significant because of blow fly importance in the field of ecology, forensics, medical and veterinary science