Rabi A. Musah*, Samira Beyramysoltan, and Amy M. Osborne | University at Albany – State University of New York Jennifer Y. Rosati | John Jay College of Criminal Justice – City University of New York Abstract: Necrophagous insects that have colonized decomposing remains can play a critical role in forensic investigations, because their species identity can be used to estimate postmortem interval. However, insect evidence has the potential to reveal much more about the circumstances associated with a death. In this regard, it would be useful to be able to determine whether retrieved insect evidence fed on human verses animal remains, because this may be relevant to a crime. Recently, the mass spectral chemical fingerprints of insect species at various life stages, acquired by direct analysis in real time–high-resolution mass spectrometry (DART–HRMS), were shown to enable accurate determination of species identity. The presenters will report an investigation of whether these DART–HRMS chemical profiles can also reveal the food resource ingested by the flies. Eggs of three species (C. vicina, L. sericata, and P. regina) were reared on five resources: beef liver, pork chop, dog feces, chicken breast, and decaying tilapia. The emergent subsequent life stages were collected and stored in 70% aqueous ethanol until analysis. The DART–HRMS data of these samples were acquired from analysis of their aqueous ethanol suspensions. The data were binned and scaled, and the resulting matrix was explored by the multifactor Analysis of Variance (ANOVA) – Simultaneous Component Analysis technique to reveal variations in the chemical profiles that were a function of species and resource type. A fusion of partial least square-discriminant analysis and principal component analysis-discriminant analysis was performed to create a discriminative model for the reliable identification of not only species but also food resource using selected m/z values. The performance analysis of the method showed 95% and 52% accuracy by five-fold cross validation for larvae and adults, respectively. The results illustrated that the chemical profiles of adult samples were more influenced by external conditions than larva samples, which affected identification accuracy. Therefore, analysis of the larval life stage, which is the most commonly encountered insect form in forensic investigations, can be used not only for species determination but also for determination of resource substrate.