New Infrared Light Research on Blow Fly Larvae Reveals Clues to Time of
by Jo Ellen Nott
Texas A&M AgriLife Research has developed a new forensic tool that could revolutionize how investigators estimate time of death. Researchers have devised a technique using infrared light and machine learning to determine the sex of blow fly larvae found on human remains, a critical factor for accurate postmortem timelines.
Published in the Journal of Forensic Sciences, the study was led by doctoral student Aidan Holman under the supervision of Dmitry Kurouski, associate professor in the Department of Biochemistry and Biophysics. The research focused on the fact that male and female blow flies develop at different rates, a discrepancy that can skew postmortem estimates because their development rates are at least nine hours apart depending on temperature.
The study found that male larvae exhibited faster development and showed different levels of proteins and fats, which were reflected in their vibrational spectra. Before Holman’s research, distinguishing between male and female larvae was nearly impossible visually and required destructive molecular analysis.
The new, non-destructive method utilizes a handheld infrared spectroscopy device. It works by shining a light on live larvae and analyzing how their molecules respond, creating a unique “fingerprint.” The researchers then used machine learning models – Partial Least Squares Discriminant Analysis (“PLSDA”), eXtreme Gradient Boosting trees Discriminant Analysis (“XGBDA”), and Artificial Neural Networks Discriminant Analysis (“ANNDA”) – to sort the larvae based on these spectral fingerprints. Two of the models, PLSDA and ANNDA, achieved over 90% accuracy, with the most successful reaching 95%.
Unlike current lab methods, this technique is quick, portable, and allows for further testing on the same sample. Holman noted that the device could be used directly at a crime scene. Beyond its forensic applications, the technology could also be used in agriculture and biosecurity, such as in pest control efforts that rely on releasing sterile male insects to suppress populations.
This interdisciplinary project (biophysics, biochemistry and entomology) showcases how advanced analytical chemistry can be applied to solve practical problems in criminal investigations. By providing greater speed and objectivity, this method to determine the sex of blow fly larvae can lead to more accurate and reliable forensic analyses and ensure that justice is served more frequently.
Source: Forensic Mag
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