Honeybees trained in Croatia to find land mines

Mirjana Filipovic is still haunted by the land mine blast that killed her boyfriend and blew off her left leg while on a fishing trip nearly a decade ago. It happened in a field that was supposedly de-mined.
Now, unlikely heroes may be coming to the rescue to prevent similar tragedies: sugar-craving honeybees. Croatian researchers are training them to find unexploded mines littering their country and the rest of the Balkans.
When Croatia joins the European Union on July 1, in addition to the beauty of its aquamarine Adriatic sea, deep blue mountain lakes and lush green forests, it will also bring numerous un-cleared minefields to the bloc's territory. About 750 square kilometres are still suspected to be filled with mines from the Balkan wars in the 1990s.

Nikola Kezic, an expert on the behaviour of honeybees, sat quietly together with a group of young researchers on a recent day in a large net tent filled with the buzzing insects on a grass field lined with acacia trees. The professor at Zagreb University outlined the idea for the experiment: Bees have a perfect sense of smell that can quickly detect the scent of the explosives. They are being trained to identify their food with the scent of TNT.
"Our basic conclusion is that the bees can clearly detect this target, and we are very satisfied," said Kezic, who leads a part of a larger multimillion-euro program, called "Tiramisu," sponsored by the EU to detect land mines on the continent.

Several feeding points were set up on the ground around the tent, but only a few have TNT particles in them. The method of training the bees by authenticating the scent of explosives with the food they eat appears to work: bees gather mainly at the pots containing a sugar solution mixed with TNT, and not the ones that have a different smell.

Kezic said the feeding points containing the TNT traces offer "a sugar solution as a reward, so they can find the food in the middle."
"It is not a problem for a bee to learn the smell of an explosive, which it can then search," Kezic said. "You can train a bee, but training their colony of thousands becomes a problem."

Croatian officials estimate that since the beginning of the Balkan wars in 1991, about 2,500 people have died from land mine explosions. During the four-year war, around 90,000 land mines were placed across the entire country, mostly at random and without any plan or existing maps.