Smart beesare facing lethal threat

BEE numbers are falling; honey producers, fruit-growers and farmers, all over the world, are worried.

Plants offer handouts of nectar to attract bees wasps and moths.

When a bee alights on a flower, its hairy body becomes coated with pollen and little sacs on its hind legs are filled with the powder.

Continuing on its rounds, the bee carries pollen from flower to flower and fertilisation occurs. With the decline in bee numbers, pollen distribution is failing and crop yields are down. Losses worldwide run to billions.

But why are bees in trouble? The culprits seem to be pesticides, poisons put out to kill weeds and harmful insects. In the case of the honey bee, there is another villain; a mite. Called after a Roman beekeeper, Marcus Terentius Varro, the tiny creepy-crawly, native to bee colonies in Asia, was accidentally introduced to the West. Asian bees can cope with Varroa, but our ones can’t. Colonies here are being decimated. The main defences against the pest are, unfortunately, chemicals. Now there’s concern about the side-effects of all these poisons on the bee’s tiny brain. Dr Chris Connolly, who is researching bees at Dundee University, told RTÉ’s Mooney Show that the problem “..may manifest at a number of behavioural levels; navigation (finding their way to food and returning home), communication (passing information regarding food supplies) and learning/memory (failure to remember food sources)”.

Bees are among the most remarkable creatures on Earth. Their intellectual abilities are mind-boggling. Consider the famous “bee waggle dance”, for the discovery of which Karl Ritter von Frisch shared the Nobel Prize for Medicine in 1973. Honey bees use dancing to tell each other about foraging locations. If a bee, returning to the colony after a sortie, walks vertically up a comb, it means that there’s a food source in the direction of the sun. If it alights at the top of the comb and walks vertically downwards, the source will be found by flying away from the sun. Directions to any point on the compass can be communicated by walking at the appropriate angle between the two. But the message does not end there. A bee tells its worker sisters the distance to the food by waggling its bottom as it walks. The farther away the nectar and pollen-laden flowers are, the more waggles are performed.

The 1,784m Schafberg Mountain in Austria has given its name to an experiment, the results of which would have astonished even von Frisch. There is only one source of bee food in the area. A colony was placed on the far side of the mountain so that the insects had to fly around the mountain to reach the flowers. This meant that the flight direction of a bee arriving back at the colony was not that of the foraging location. Also, the distance to the food, ‘as the crow flies’ directly across the mountain, was much shorter than the long-way-round route taken by the bees. What direction, the researches wanted to know, would bees indicate in the waggle dance on their return to the hive and how for away would they say the source lay?

Amazingly, the bees indicated the true direction of the source, as though the mountain was not there, but the distance they gave in their waggles was that for the journey around the mountain.

The calculations performed by a bee during even a normal excursion demand incredible mental gymnastics and the feats of memory required are extraordinary. A sortie may last more than an hour with the bee wandering over an area of several square kilometres. Choices must be made as to the best flowers to target, hundreds being visited in the process.

Sources and scents have to be noted and, all the while, the route being travelled is monitored so that the insect can navigate successfully back to the colony.

Consider the extra calculations required in the Schafberg experiment. The bee has to compensate for the gradual changes in direction it makes in flying around the mountain while still managing to keep tabs on the distance travelled. On return to the hive, it must work out the direction it would have flown were the mountain not in the way, an extraordinarily complex geometrical feat. We must stop poisoning bees.


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