Carrion community and temperature influence oviposition preferences of forensically relevant blow flies (Diptera: Calliphoridae)

Oviposition behaviour can influence population dynamics, particularly in carrion insects. Although females should exhibit behaviours that will maximize the fitness of their offspring, females may display preferences in their oviposition choices. Oviposition preference can be influenced by abiotic factors, such as temperature and biotic factors, such as the presence of conspecifics or heterospecifics. The aim of this study was to examine the influence of species interactions and temperature on the oviposition behaviour of native blow flies Phormia regina Meigen and Lucilia sericata Meigen (Diptera: Calliphoridae). Oviposition behaviour on pig carcasses was observed under multiple species treatments (pure species and mixed species) as well as constant temperature treatments (15, 20, 25, 30 and 35°C). Cages of 100 females and 50 males for each treatment were provided with fresh liver for 5 days and were then exposed to a pig carcass. Observations were made as to the length of time until oviposition as well as the site selected for oviposition. An analysis of the oviposition data indicates that temperature has a significant effect on oviposition (F=13.82 _8,41 p=0.004) and on the length of time until the first oviposition event occurs (F=11.50 _14,75 p<0.0001). This study provides important information in community ecology and insect behaviour, but may also be applicable in investigations utilizing forensic entomology in which blow fly behaviour and development data are required to estimate the time since death.