Impact of heat shock and injury on the size and developmental progress of Cochliomyia macellaria (Fabricius) (Diptera: Calliphoridae), a forensically significant blow fly

Blow flies (Diptera: Calliphoridae) are commonly used to estimate the post-colonization interval, which can be used to infer the minimum elapsed time since death, if certain assumptions are met. To do so, forensic entomologists must first estimate the age of blow fly specimens using reference data based on size and developmental progress. However, these data sets are often collected in the laboratory under relatively benign conditions and do not account for stressful factors, such as high temperatures and predation, which may impact the size and development of blow flies. Some studies have documented predation of blow fly immatures in the field and laboratory while others have reported the upper thermal limits of some blow fly species. However, the impact of injury resulting from unsuccessful predation attempts and recovery following heat shock on the life history traits of blow flies have not been well studied. Therefore, this study attempts to mimic injury and heat shock in the laboratory to further explore the impact of these two factors on the life history traits of Cochliomyia macellaria (Diptera: Calliphoridae) (Fabricius). Following injury and heat shock of larvae, pupal size and development time were recorded. Overall, heat shock had a greater impact on pupal size and mean development times were longer among heat shock treatments. In addition, phenotypes associated with injury and heat shock were observed on pupae. If these phenotypes are observed on pupae collected for casework, estimates of blow fly specimen age should account for injury and/or heat shock.