Honey bees (genus Apis) are social insects in the family Apidae, order Hymenoptera; they are among the Aculeata (i.e., those having stingers). They evolved after the separation of the Americas and Australia from Eurasia/Africa and are native only in the Old World. The genus Apis probably first appeared in the Eocene, about 55 mya. Tropical species A. dorsata and A.florea existed by the end of the Oligocene 25 mya, and cavity-nesting A. mellifera and A. cerana, which can also live outside the tropics, were separate species by the end of the Pliocene about 2 mya. Therefore, the highly advanced cavity-nesting species have existed only perhaps a tenth as long as the open-nesting species, which were confined to the warmer tropics. The most important species to humans is A. mellifera, which has been introduced all over the world for use in beekeeping.
THE GENUS APIS
Known Species
The genus Apis contains 11 known species. A. mellifera ( Fig. 1 ) is the source of most of the world’s honey. It is native throughout Africa, the Middle East, and Europe except for the far north regions. All other Apis species are native to Asia. A. cerana which is kept in hives in the temperate zone as well as the tropics, is smaller than A. mellifera, and it makes smaller colonies. Other Asian species that build a multiple-comb nest in a cavity are A. koschevnikovi and A. nuluensis reported in Borneo and A. nigrocincta in Sulawesi.
FIGURE 1 Worker honey bees (Apis mellifera) on honeycomb.
Other Apis species native in parts of the Asian tropics build a single-comb nest in the open. The most important to humans is A. dorsata, a bee much larger than A. cerana. A. laboriosa, which is even larger, lives in parts of the Himalayas too high for A. dorsata. Much smaller than A. cerana, A. florea is widespread below around 500 m and can live in drier areas than A. dorsata. Mating, and How Reproductive Isolation Is Achieved
Honey bees mate in flight; the process has been studied in detail in A. mellifera, and involves three stages. A queen flies out when only a few days old, and drones that are flying in the area, attracted by the pheromones she produces, follow her. If a drone succeeds in clasping the queen with his legs, his endophallus is everted and mating occurs. When they separate, part of his genitalia remains in the queen, and he falls away and dies. She may mate more than once (usually on the same flight), and the semen she receives is stored in her spermatheca for use throughout her egg-laying life.
The main component of the pheromone attracting drones to the queen seems to be the same for all Apis species (9-oxo-”rans-decenoic acid). In an area with more than one species, reproductive isolation can be achieved if the drones of different species fly at different times of day.
APIS MELLIFERA Colony Life
The reproduction of individual bees takes place in the colony, and each colony normally contains a single mated female (the queen), many nonreproductive females (workers) and, during the reproductive season, a smaller number of reproductive males (drones). Colonies reproduce by swarming during a season when much food is available. The workers rear several young queens, each in a special queen cell. The old queen and perhaps half the workers of the colony leave as a swarm, which finds a new nest site. One of the young queens mates and heads the parent colony; the others are killed. Many aspects of the beekeeping cycle and social behavior of honey bee colonies have been studied in detail (see Further Reading).
In the tropics, temperatures are never too low for plants to flower or for bees to fly, and colony activity is governed by rainfall rather than temperature. There are two seasonal cycles in the year, so colonies do not grow as large, or store as much honey, as they do in temperate zones. If the stores of a colony of A. mellifera become low in a dearth period, the colony may leave its hive and fly to a nearby area where plants are starting to bloom, rebuilding its combs in a nest site there. Such movements are referred to as absconding or migration, and preventing them is an important part of beekeeping in tropical Africa.
Subspecies and Their Distribution
During the Ice Ages, geographical features in Europe, such as mountains, confined A. mellifera to several separate areas, where they diversified into a number of subspecies or races. The most important in world beekeeping, and their native areas, are A. mel-lifera ligustica (Italian) in northwestern Italy south of the Alps, A. mellifera carnica (Carnolian) in the eastern Alps and parts of the Balkans, A. mellifera caucasica (Caucasian) in Georgia and the Caucasus mountains between the Black Sea and the Caspian Sea, and also A. mellifera mellifera north of the Alps.
The first introductions of A. mellifera from Europe to new continents, after 1600, enabled future beekeeping industries to build up and flourish in many countries. Some of the subsequent introductions of A. mellifera carried diseases or parasites not previously present, and these caused much damage. From the late 1800s, after the movable-frame hive was devised, there was great interest in breeding more productive honey bees, and colonies of many races were transported from the Old World to other continents. Italian bees, especially, could store much honey in warm regions with consistently good nectar flows. During the 1900s, scientists introduced exotic species and races of honey bees into Europe for experimental purposes, but none is known to have survived in the wild.
Moving honey bees to new areas in tropical or subtropical environments can have wide-reaching effects. In 1956 a number of honey bee queens were transported from southern Africa to Brazil in an attempt to improve the beekeeping in that South American country, where bees of European origin performed poorly. Through an accident, a few of the African queens escaped with swarms, and this led to hybridization with bees of European origin. The consequent “Africanized” bees had characteristics that enabled them to become dominant over the “European” bees already in the American tropics, and they spread rapidly, reaching the Amazon by 1971, the north coast by 1977, Mexico by 1986, and then several southern U.S. states.
In warm regions, many native plants may be pollinated by small bees (Apoidea) whose populations are reduced if colonies of the larger A. mellifera are introduced, which in turn can endanger the reproduction of such native plants. This problem has been reported in Australia and Brazil.
A. mellifera is now used in beekeeping in almost every country in the world.
APIS CERANA AND RELATED SPECIES
Of the subspecies of A. cerana, the Asian hive bee, A. cer-ana indica is present from Yunnan in China through India to the Philippines. A. cerana cerana is in much of China, also the
Himalayas, Afghanistan, and the Russian Far East, and A. cerana japonica in Tsushima Island and Japan.
After A. mellifera was introduced in eastern Asia, A. cerana became restricted to areas with native flora. Then in 1985-1986, colonies of A. cerana were taken from one of the Indonesian islands to Irian Jaya, also Indonesian but part of New Guinea. The bees reached Papua New Guinea by 1987 and islands in the Torres Strait by 1993. By 2000 they were found (and killed) in Brisbane, Australia, and strenuous efforts are being taken to prevent any further entry and spread of this bee in Australia because it would probably carry the varroa mite, a pest that is of serious economic importance to beekeepers.
APIS DORSATA AND RELATED SPECIES
The large single-comb nests of the giant honey bee, A. dorsata, built in the open, are still the most important source of honey in India and some other tropical Asian countries. A. dorsata is present in most of the Indo-Malayan region, from the Indus River in the west to the eastern end of the Indonesian chain of islands, and from the Himalayas to Java in the south. A. breviligula is in the Philippines, and A. binghami in the Celebes. In the high Himalayas, A. laboriosa—a species even larger than A. dorsata—nests up to 3000m, whereas A. dorsata rarely nests above 1250m.
APIS FLOREA AND RELATED SPECIES
The area of the smaller A. florea extends as far northwest as Iran. It has also been reported around the Persian Gulf in Iran and Iraq, and in the Arabian peninsula. It reached parts of this last area, and also Sudan, by the aid of humans, and people may also have facilitated its spread along the coast, west of the Indus Valley. It is characteristically found in hot dry areas at altitudes below 500 m; in some localities it is the only honey bee that could survive. Its eastern range does not extend as far as that of A. dorsata, possibly because A. florea could not cross wide sea channels.
A. andreniformis, rather similar to A. florea, occurs in southern China, Myanmar (Burma), Palawan in the Philippines, Thailand, Indonesia, Laos, and Vietnam. It is likely that some early statements about A. florea in these areas refer instead to A. andreniformis.
