24 d’abril 2012

HONEY BEES: A HISTORY

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Long known as the angels of agriculture, honey bees have received global attention due to losses attributed to a combination of factors: Colony Collapse Disorder, mites, deforestation and industrial agriculture. Honey bees provide pollination for crops, orchards and flowers; honey and wax for cosmetics, food and medicinal-religious objects; and inspiration to artists, architects and scientists.  

Conegudes des de fa temps com els àngels de l'agricultura, les abelles de la mel han rebut últimament una atenció mundial a causa de les pèrdues atribuïdes a una combinació de factors: el síndrome del desabellament, els àcars, la desforestació i l'agricultura industrial. Les abelles de la mel són les responsables de gran part de la pol·linització dels cultius, horts i flors. Per contra la mel i la cera són utilitzats en els cosmètics, alimentació, medicina i per celebracions religioses, essent font d'inspiració per a artistes, arquitectes i científics.
While there are thousands of insects in the Hymenoptera order (for example, wasps, sawflies and ants), honey bees are the only living members of the tribe Apini, within the family Apidae. The one genus of honey bee Apis can be divided into three branches based on how honey bees nest: the giant open-nesting honey bees Apis dorsata and Apis laboriosa; the dwarf, single-combed honey bees Apis florae and Apis andreniformis; and the cavity-nesting honey bees Apis cerana, Apis koschevnikovi, Apis nuluensis, Apis nigrocincta, and Apis mellifera. These nine species thrive in environmental extremes like deserts, rain forests and tundra, but most people only know Apis mellifera, the agricultural darling. 

Honey bees are eusocial. Adult bees are divided into a queen, female workers and male drones. The queen will leave the hive only once to mate with several drones, storing sperm in her spermatheca to last her lifetime. In order to rear and defend the eggs lain by the queen, worker bees develop stinging mechanisms, pollen baskets, dance languages and labor divisions. Tasks are divided according to age and colony needs. Younger worker bees tend to the queen, and older worker bees forage, construct wax cells, convert nectar into honey, clean cells and guard the hive. Ideally, a healthy hive is a collection of overlapping generations. 

Evolving from short-tongued, spheciform wasps, honey bees first appeared during the Cretaceous period about 130 million years ago. At that time, present-day continents such as Africa, India, South America, Australia and Antarctica formed a single landmass called Gondwana. Germinating in the warm dry Gondwanan climate, flowering plants called angiosperms developed colors and petal patterns to attract insects, which were more reliable than wind to transfer pollen. In addition to pollen, flowers eventually produced nectar, providing carbohydrates to their winged vectors. About 120 million years ago, the honey bee developed its morphologies specifically to collect pollen and nectar such as increased fuzziness, pollen baskets, longer tongues, and colonies to store supplies. 

As Gondwana gradually broke apart and temperatures cooled dramatically during the Oligocene-Miocene about 35-40 million years ago, European honey bees went extinct, while Indo-European honey bees survived and began to speciate. Open-nesting honey bees perhaps evolved before cavity-nesting bees, probably in India, but evidence is still lacking. In any event, a cavity-nesting honey bee spread east and north about six million years ago. During a Pleistocene warming about 2-3 million years ago, this bee spread west into Europe and thence into Africa to become Apis mellifera

Early civilizations quickly mastered honey hunting skills, shown in rock art in Africa, India and Spain. Egypt, Greece, Italy and Israel developed organized beekeeping centers until the Roman Empire dissolved in approximately 400 A.D. Christianity monasteries and convents then served as apiculture centers until Henry VIII closed them at the beginning of the Reformation. Science and technology provided the next insights into apiculture during the Enlightenment. 

Honey bees expanded to North America with human-assisted migration during the 17th century. Many Europeans fleeing wars, poverty, land laws or religious persecution brought extensive beekeeping skills to the United States during the next two centuries. Meanwhile, English colonists took bees to New Zealand, Australia and Tasmania, completing human-assisted migration of Apis mellifera around the globe. 

Beekeeping became commercially viable during the 19th century with four inventions: the moveable-frame hive, the smoker, the comb foundation maker, and the honey extractor. These inventions still support commercial apiculture. A fifth invention, a queen grafting tool, allows beekeepers to control genetic lines. 

Honey bees are such efficient pollinators that industrialized countries developed specialized agriculture dependent upon migratory pollination and one race of honey bee, Apis mellifera. Alarmed at the damage tracheal mites were doing to honey bees in Europe, the United States Congress passed a Honey Bee Restriction Act in 1922, in effect protecting Apis mellifera until tracheal and varroa mites arrived in the 1980s. U.S. beekeepers lost 50-80 percent of their colonies. The ban was partially rescinded in 2004. 

Rural economic development programs promote honey bees with mixed results. Honey and wax remain in high demand on global markets, and honey production tasks generate several lines of income. But different honey bee races can clash with pre-existing insect species. In the 1950s, the honey bee Apis mellifera scutellata (one type of African honey bee) was taken to Brazil via human assistance, creating ramifications for the endemic bee species in both South and North America. Similarly, Apis mellifera was introduced to India and China, but it competes with the smaller Apis florae for floral sources. 

Honey bees can adapt to minor changes in global warming, but Colony Collapse Disorder is the most recent bittersweet reminder that human society threatens honey bee habitats and breeding patterns on a global scale. Promoting genetic diversity of honey bees and providing safe environments are crucial steps toward future sustainable agriculture. 

Dr. Tammy Horn is the author of “Bees in America.”