Possibly explaining the recent dramatic decline in their population, Croatian scientists have successfully used honeybees to sniff out land mines. A swarm of bees will be released, and then a heat-sensing camera will be used to track their movements to any mines that might be hidden below the soil.

During the Yugoslav Wars, which mired the Balkan peninsula during the 1990s and saw the dissolution of Yugoslavia into Serbia, Croatia, Bosnia, Slovenia, Montenegro, and Macedonia, 90,000 land mines were placed across what is now Croatia. Since 1991, about 2,500 people have died from land mine explosions. An extensive cleanup has occurred, but there’s still more than 450 square miles that are suspected to filled with mines. More importantly, though, there are areas that have been swept — but they still have mines that were missed by the sweepers, and people are still dying. Dijana Plestina, head of the Croatian de-mining bureau, suspects these mines are a large obstacle for the country’s continued growth. “While this exists, we are living in a kind of terror… And of course, that is unacceptable,” she says.

We have known for a long time that bees have a very acute sense of smell — rivaling, and sometimes bettering sniffer dogs. In the past, bees have been used to sniff out explosives, drugs, uranium, pregnant women, and diseases such as cancer. Training, as with most creatures, is easy: Classical (Pavlovian) conditioning is used, to associate the smell of a substance with their food source. The Croatian scientists mixed a sugar solution with a small amount of TNT — and after about five minutes of hunting for this doped sugar solution, the honeybees are trained to flock to the smell of TNT.

Once the bees have been trained, the Croatians will release the bees into areas that have already been de-mined by humans, and then track their movements with a heat-sensing camera. It is these regions where the most deaths occur, as people move freely and there aren’t any warning signs. The Croatians hope that the bees will help them discover mines that the humans may have missed. Unlike the unfortunate dogs and rats that came before them (pictured above), bees have the obvious advantage that they’re light enough to sniff out the mines without setting them off, too.

Moving forward, it sounds like the Croatians are still trying to prove that the honeybees are scientifically reliable before deploying them in the field. Other studies, though, have already confirmed that bees are accurate and reliable. The only real drawback of using bees (or wasps) over sniffer dogs is that they can only detect a single scent.

In the UK, there’s a firm called Inscentinel (!) that’s trying to commercialize the training and use of honeybees for sniffing substances. The video below details their technology — but be warned, it’s quite different from the Croatian technique, and altogether rather weird. For Inscentinel, sniffing out explosives is just the beginning: They see their bee-based sensor technology as a bona fide replacement for mass spectrometry, gas chromatography, and sniffer dogs in a wide range of applications.

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