Blow flies may finally have a useful purpose — as chemical warfare investigators!

INDIANAPOLIS, Ind. — Pesky flies may finally have found a reason for you not to swat them — they can detect the use of chemical weapons! A new study finds blow flies are capable of tasting their way through a battlefield, looking for traces of chemical warfare agents and other toxins.

Researchers at the School of Science at Indiana University–Purdue University Indianapolis (IUPUI) found that the insects act like chemical sensors, literally tasting the environments they fly through, and then storing those chemical samples in their gut for up to two weeks.

Flies could find evidence of war crimes

Although international laws prohibit the use of chemical weapons, study authors say there’s evidence proving their use during the recent Syrian civil war and many people fear the same thing may happen in Ukraine at some point. The team adds that blow flies provide a safer alternative to sending people into hazardous areas as investigators look for these illegal weapons.

Blow flies are ubiquitous, and they are very adept at sampling the environment around us,” says Christine Picard, an associate professor of biology and director of the Forensic and Investigative Sciences Program at IUPUI, in a university release. “They will fly through the environment, taste it, and that information will be stored in their guts. Through a series of experiments, we were able to look at how different environmental factors would impact their detection of chemical weapon simulants.”

Flies can store the toxins before they disappear

Researchers conducted their experiments using chemical weapon simulants. Although they share similar features with actual chemical weapons and pesticides, they are not poisonous to people. The team notes that pesticides are also similar to chemical warfare agents in terms of their molecular behavior.

“We used a mass spectrometer to determine what chemicals were in the blow flies’ guts,” says Nick Manicke, an associate professor of chemistry and chemical biology and of forensic and investigative sciences. “We were able to detect the chemical warfare agent simulants, and also some of the things chemical agents get broken down into once they’re in the environment. If a fly were to come across a water source, with a chemical agent hydrolyzed in the water, we would find that in the fly.”

One of the problems in proving the use of chemical weapons is that they don’t linger in the environment for long. However, study authors found that a fly’s gut could preserve these traces for up to 14 days after the insect’s initial exposure.

“If an area is too dangerous, too remote or in an access-restricted area — or if one just wanted to collect samples covertly — then one just needs to put out some bait and the flies will come to the bait,” Manicke explains. “We can scan through big areas by drawing the flies into a trap and analyzing what is in their guts.”

Cleaning up the environment, too?

Researchers say blow flies could also help environmental scientists understand how pollutants like pesticides impact the planet.

“Due to the collaboration between Dr. Manicke and Dr. Picard, we were able to work on a project with the potential to make a direct impact,” says co-author and a Ph.D. student Sarah Dowling. “It is fulfilling to know that the work we did throughout this project could improve the safety of warfighters and others who deal with chemicals in the environment.”

The team will now apply their findings to a two-year study focusing on the detection of molecules from “insensitive munitions.” These are a new type of explosive that are less likely to detonate by accident. However, this means they also deposit more chemical residue into the environment.

The blow flies will head into remote and dangerous areas, looking for traces of these munition compounds, while scientists examine their impact of the local environment.

The study is published in the journal Environmental Science and Technology. The U.S. Defense Advanced Research Projects Agency funded the study.

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