Honeybees 101

Get to know your top pollinator. By Anna Mouton.

What is a honeybee?

Bees are a group of about 20 000 species of winged insects that include honeybees, bumblebees, stingless bees, mason bees, carpenter bees, leafcutter bees, and sweat bees. Most bees are solitary.

Honeybees are social. They form colonies with a fertile queen and many non-reproductive female workers who raise brood and gather food.

The honeybee genus Apis has eight species and 43 subspecies. The Western honeybee — Apis mellifera — and the Eastern honeybee — Apis cerana — are managed for crop pollination and honey production. Other species only occur as wild colonies.

Fossilised Apis date to at least 34 million years ago when forests of flowering trees dominated much of the earth, and modern birds and mammals began evolving. Genetic analysis suggests that honeybees originated in Africa.

Apis mellifera occurs naturally in Africa and Europe. The other Apis species occur in South and Southeast Asia.

The most recent evidence of an American species — Apis nearctica — is a 14-million-year-old fossil from Nevada. Honeybees next appeared in the Americas with the European introduction of Apis mellifera in 1622.

Honeybees and human beings have a long history. Rock paintings in France and Spain, dating back to around 7 000 BC, depict people collecting honey. Ancient Egyptian tomb paintings and hieroglyphs from before 2 600 BC show beekeeping.

In modern times, the world has more than 100 million managed honeybee hives, producing around 1.6 million tonnes of honey annually. Humans have now spread honeybees to every continent except Antarctica.

The Cape honeybee

The Cape honeybee — Apis mellifera capensis — is a subspecies of the Western honeybee. It occurs naturally on the coastal side of the Cape Fold mountains in the Western Cape and Eastern Cape. The African honeybee — Apis mellifera scutellata — occurs northwards throughout the rest of Africa.

Cape honeybees are adapted to temperate conditions. Their darker bodies are thought to help with temperature control, and they can fly in cooler weather.

They differ from all other honeybee subspecies in that workers can lay eggs that develop into female workers in the absence of a queen. In all other Apis mellifera subspecies, workers can only lay eggs that develop into male drones. Cape honeybee workers’ ability to generate more workers is why they can take over the hives of other honeybee subspecies.

Nectar and pollen

Plants produce nectar — a solution of roughly 20% sugars in water — to attract pollinators. Foraging bees use some nectar for energy and store the rest in a specialised honey stomach until they reach the hive. A bee can carry about half its body weight in nectar.

Returning foragers regurgitate the nectar to other workers, who store it in their honey stomachs. Enzymes in bees’ honey stomachs break down the complex sugars in nectar. Teams of hive bees repeatedly regurgitate and process the nectar to concentrate it.

Hive bees store honey in cells when it has a water content of about 70%. The bees dehydrate it further by beating their wings to circulate air — hive temperatures of 35 °C help evaporate honey moisture.

Honey’s final water content is 16%–18%. Spoilage organisms cannot grow in such highly concentrated sugar.

Like us, bees need proteins and fats in addition to carbohydrates. They get these macronutrients from pollen, which foragers collect in pollen baskets on their hind legs. Foragers don’t consume pollen directly but transfer it into open cells in the hive.

Hive bees mix pollen with nectar and saliva to initiate fermentation. The fermented mixture, bee bread, is the primary protein source for adults and developing bee larvae.

Behaviour

Temperature control

Bees are cold-blooded but can generate heat by vibrating their flight muscles. This is how workers maintain the hive temperature at 35 °C, which is the optimal temperature for brood development and wax creation. Worker bees also fan their wings to cool the hive on hot days.

Bees generally stop moving when outside temperatures drop below 7 °C–10 °C and slow down as temperatures exceed 38 °C.

Communication

The queen controls her workers by releasing pheromones. Workers also communicate through pheromones, allowing them to recognise colony members, signal alarm, coordinate defence, and organise colony activities.

Workers can distinguish between healthy and unhealthy brood cells based on their odour. They clean out unhealthy-smelling cells, which promotes control of parasitic mites, chalk brood, and American foul brood.

Foragers communicate location information through complex movements called bee dances. The dancing bee tells her co-workers in what direction and how far away resources such as food, water, or nesting sites are. She also releases pheromones during the dance.

Bees can elicit help from colony members in removing parasites through a grooming dance.

Life cycle

Honeybee colonies revolve around the queen. She is usually the only bee in the colony laying eggs that develop into workers. Queens can live for several years, whereas workers’ lives are generally measured in weeks.

A healthy colony will eventually fill its hive with honey and pollen. The queen now has nowhere to lay eggs, so she and about half her workers head out to start a new colony elsewhere — this is called swarming. Colonies can also sometimes lose their queen due to accidents or old age.

Young queens develop from the same eggs as workers but receive a different diet. When the colony needs a replacement queen, it raises several young queens. The first queen to emerge from pupation kills the others. If queens emerge simultaneously, they will fight until only one remains.

The single surviving queen starts her reign by establishing control over her workers through pheromones. She then flies off to mate with several males in a drone aggregation area. On her return, she settles down to a life of laying eggs and ruling workers.

Beekeepers increase their colonies by catching swarms or splitting hives. Read Prepare to Pollinate elsewhere in this issue for more information on hive management.