Bees drink nectar from flowers, either directly or regurgitated and sipped from the mouth of another bee. When nectar is in short supply, they sip honey that has been collected in the hive. Bees also require water, and Per Kryger and colleagues from the University of Aarhus in Denmark report that the task of foraging for water is carried out by approximately 1 percent of honey bees that are the same age as nectar and pollen foragers. In the desert, some bees forage for water as far as a mile from their colony, carrying it back home in a storage pouch, called a crop, located in their abdomen.
Adult bees have a tube-like proboscis with a tongue that sits inside it, and unlike butterflies and moths that use their proboscis like a straw to suck up watery nectar, almost all bees lap or lick up nectar that is more concentrated and sticky. This difference in the preferred consistency of the nectar is probably one of the many factors that determine which flowers will be a nectar source for each animal, allowing them to share the resources of the habitat.
A bee's tongue is encircled by rings of hairy cartilage at regular intervals, and the tip of the tongue is a small spoon-shaped lobe that is smooth on the underside and covered with branched spines along the edges and top. As the bee laps at fluids using muscles that control the tongue, a muscular sucking pump in the bee's head draws the liquid up through the proboscis. The food travels from the proboscis along a very narrow passageway through the bee's brain to the digestive system in the abdomen.
In a remarkable experiment in published in 2003, evolutionary biologist Brendan Borrell surgically removed the tongues from over seventy orchid bees, a species that has a proboscis that is longer than its body. These bees typically feed from flowers with thinner nectar than most bees prefer, and Borrell's experiments showed that these bees could effi- ciently drink the thin nectar without a tongue, strongly suggesting that sucking plays a big role in their normal eating. Bees with tongues to lap the nectar in the usual bee-like manner did better with thicker solutions.
As for all living things, bees' longevity is influenced by their environment as well as their genes. Under normal environmental conditions, a queen honey bee lives an average of one to two years, sometimes even longer. Unlike workers, who usually never develop a functional reproductive system, the honey bee queen remains reproductively viable throughout her life. This is quite unusual since most organisms have decreased longevity the more they reproduce, and the mechanisms behind the queen's longevity are being investigated.
Drones have a very limited but important role in the colony and a very limited life. Their only function is to mate with a virgin queen. Otherwise they have no function in the colony. If the drone is successful in mating, he will normally die soon afterward. If he has not successfully mated after a week or so of trying, the workers will withhold food or he will be driven out of the hive and killed because he is a drain on the group's reserves.
The hive bee caste consists of young worker bees and performs a variety of tasks inside the nest for from nine to forty days, usually ranging from eighteen to twenty-eight days. As they mature, they become members of the forager bee caste, the group that ventures outside the nest to engage in the riskier activities of guarding the nest and collecting nectar, pollen, and water. Foragers live for one or two weeks if they emerge from their pupal stage in the warm weather and if they begin foraging when nectar production is high. If they are diutinus, or "winter bees," having emerged in the fall and reached the foraging stage in the cold weather, they can live six months or more.
During the winter the colony is cold and inactive, and the winter bees live a quiet life inside the nest, eating only small amounts of honey, taking up their roles as foragers when flowers begin to bloom in the spring. Stig Omholt and Gro Amdam at the Agricultural University of Norway studied the role of a yolk protein called vitellogenin that they hypothesize plays a role as a lifespan-promoting protein. The age-based division of labor among worker bees, where the risky task of foraging is only taken on by older workers with depleted nutrient stores, seems to have evolved as a mechanism to conserve the resources of the colony. Healthy winter bees show few signs of aging during the long winter period of inactivity, although their protein stores become gradually reduced until pollen and nectar become available again in the spring.
Then they start nursing and foraging and their life ends in a few weeks following the usual warm weather cycle. The researchers calculated that if winter bees were prevented from becoming active, they could live more than two years based on the gradual rate of reduction of their protein supplies during the winter. Mapping the honey bee genome has made it possible to observe that genetic activity is quite different in young nurse bees compared to mature foragers. Although the normal aging process usually triggers this behavioral development from nurse to forager, a shortage of food can prematurely induce this transition because there is an increased need for foragers to search for food for the colony.
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