Predatory behavior of Synthesiomyia nudiseta larvae (Diptera: Muscidae) on several necrophagous blowfly species (Diptera: Calliphoridae)

Intraguild interactions play a prominent role in sarcosaprophagous communities, so intraspecific and interspecific competition phenomena between fly larvae take place. Synthesiomyia nudiseta is a species that has recently been recorded on human corpses in Europe, and it has been cited in forensic cases in Spain and Italy. The mature larvae are known to be facultative predators on necrophagous fly larvae, but their role as predators is unknown. The aim of this paper is to investigate the predatory behavior of S. nudiseta on the most abundant blowfly larvae in sarcosaprophagous communities in southwestern Europe (i.e., Chrysomya albiceps, Lucilia sericata, and Calliphora vicina). Intraspecific and interspecific competition experiments were carried out to study the effect of this species in the necrophagous diptera community. First-instar larvae were placed in plastic cups with the same amount of pig liver (15 g) at different densities (50, 100, 150, and 300 individuals/cup). Mortality in blowflies increased when S. nudiseta larvae were present: up to 98.40% in Ch. albiceps, 89.60% in L. sericata, and 84.93% in C. vicina. Pre-imaginal developmental time and adult wing size were analyzed and compared under each of the intraspecific and interspecific conditions; both variables were affected by competition in all cases. The implications of the presence of S. nudiseta for sarcosaprophagous community dynamics and its effect on the estimation of postmortem interval (PMI) are discussed.