Honeybees have helped scientists to sniff out a trigger of long-term memory formation. Calcium has been linked to this type of memory for more than a decade, but only recently have researchers directly manipulated it in the honeybee (Apis mellifera) to show that it can activate the formation of such memories.
Jean-Christophe Sandoz and his colleagues at the University of Toulouse in France tested honeybees' memories by first training them to extend their probosces for a sugary reward when presented with a specific odour. They then exposed the bees to the same odour three days later to see whether the bees remembered it. Injecting the bees with a chemical that decreased calcium availability impaired the insects' ability to remember. Conversely, injecting chemicals that increased calcium levels improved their long-term memory.