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The University at Albany chemistry team process uses advanced mass spectrometry to identify insect eggs through their amino acid profiles. (Photo: Rabi Musah)

Corpse-eating insects and their eggs can sometimes be the only witnesses to a death investigation. Entomologists can pick apart the teeming collection of larvae, eggs and bugs and estimate a time of death, accounting for temperature and humidity. But the work involves carefully preserving the biological material in a special mixture called K.A.A.D. solution, and even growing some of the eggs to full adulthood to determine the exact species.

A chemist at the University at Albany and her team have a new solution: using direct analysis in real time with high resolution mass spectrometry (DART-HRMS) to identify amino acids in the bugs’ eggs. The method could provide near-instantaneous answers to the entomological questions right at a death scene.

“We want to make the process of insect egg profiling much easier, quicker and cheaper for investigators,” said Rabi Musah, an Albany organic chemist leading the team, in a school statement. “Our analysis is the first demonstration of a rapid chemical fingerprint-based method for blow fly species identification from eggs.”

Researcher Rabi Musah and her team have developed a method of quickly identifying insect eggs at crime scenes using high resolution mass spectrometry. (Photo: Courtesy of University at Albany)

Musah, along with Albany students Justine Giffen and Cameron Longo and colleague Jennifer Rosati at the John Jay College of Criminal Justice, published their findings in the latest issue of the journal Analytical Chemistry.

Using pieces of pork liver left out in the Manhattan area, they captured six blow fly species: Calliphora vicinia, Lucilia sericata, Lucilia coeruleiviridis and Phormia regina, as well as Sarcophagidae and Phoridae species. Back in the laboratory, they used fresh liver to allow the flies to lay new eggs.

Those eggs were then subjected to the DART-HRMS analysis.

The University at Albany chemistry team process uses advanced mass spectrometry to identify insect eggs through their amino acid profiles. (Photo: Rabi Musah)

The tool allowed them to identify the chemical signature within the eggs’ collection of amino acids, they report. For instance, the six species shared many compounds together including alanine, isoleucine and proline. But some other compounds were particular to species, like glutamine within the P. regina sample.

(Each species has its own part in the natureal processes of death. The Calliphoridae insects are typically the first to arrive, while the Phorids are present during later stages of decay, Musah said).

“Our approach circumvents many of the shortcomings of traditional analysis methods,” Musah said. “No sample preparation steps or specialized expertise is required. The eggs can be analyzed right away, in the form in which they are collected at a crime scene.”

Musah told Forensic Magazine that previously eggs had not appeared to be a source of forensic data - but with the use of the mass-spec tool, they have opened up a new avenue of analysis for death investigators.

"To our knowledge, no one had used DART-HRMS for analysis of insect eggs," she said.

“Differentiating insect eggs on corpses is of great forensic importance. Each species has its own development timeline, and therefore species identification of entomological evidence such as eggs can allow estimation of how long a body has been dead,” she added.

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