Aging Blow Fly Eggs Using Gene Expression: A Feasibility Study

: Forensic entomology can aid death investigations by using predictable developmental changes to estimate the ages of flies associated with a body. In developmental stages that do not increase in size however, including the egg and pupa, it can be difficult to objectively refine an age estimate beyond the limits of the stage duration. Gene transcript levels, changing throughout development, represent a potential data source useful for objectively identify smaller units of developmental time. The expression of three genes (bcd, sll, cs) was profiled throughout the maturation of blow fly eggs to determine the feasibility of predicting age, identifying significant linear trends in expression during their development. Models estimating egg age made predictions within 2 h of true age when all expression data were available, while the presence/absence of cs transcripts identified two age classes, together indicating that gene expression can be used to more precisely predict blow fly age.