One of the most important insects in the world is the bee, and the most common species of bee is the western honey bee. Naturally found in three continents the western honey bee pollinates roughly a third of all crops worldwide.
Taxonomy and Evolution
The western honey bee, Apis mellifera, is one of the roughly eight species of honeybee, all of which belong to the genus Apis. Despite being the bee we imagine when we say ‘bee’ honey bees are a minority among bees, their seven species merely a drop in the bucket of the 20,000 species of bee worldwide. Bees have an incredible evolutionary history as they evolved symbiotically with flowering plants. Sometime during the Cretaceous bees evolved from carnivorous wasps, potentially switching their diet as they ate insects covered in pollen, and began adapting to the evolution of flowering plants which had pollen readily available. These eusocial insects also benefited the plants as the early bees were good vectors for pollination, and flowering plants began evolving to better accommodate bees. Sometime around 39 million years ago the first honeybees appeared in the fossil record. Genome testing undertaken in 2021 found that the western honey bee evolved in southeast Asia around 7 million years ago and soon spread to Africa and Europe.
Not only is the western honey bee the most common bee species, it is also one of the most diverse. There are a staggering 31 subspecies of the western honey bee and several more hybrids between different subspecies. The most common is the European dark bee, Apis mellifera mellifera, which originated in central Asia but spread to Europe after the Ice Age. As it was readily domesticated it spread even further, first to Britain by the Romans, and then the world by European colonisation. The East African lowland honey bee, Apis mellifera scullata, is another common bee and was imported to Brazil in the 1950s. A few queens escaped, mated with European dark bees (already long imported), and produced the infamous Africanised honey bees – the infamously aggressive and invasive bee you hear in the news. They aren’t nearly as deadly as the media portrays them, but they are certainly more aggressive than the European dark bee.
Biology and Behaviour
The western honey bee is normally what we imagine when we think of bees. The bright yellow and bright stripes of bees aren’t actually present in the western honey bee; these bees are much darker with reddish-brown colouration. The queens are the largest reaching a max of 20 millimetres, whereas workers reach between 10 and 15 millimetres. Male bees are between 15 and 18 millimetres, but have larger eyes compared to the females – mostly to spot the queens during mating season. There are three types of bee in the colony: queen, worker, and drone. The queens are not only the largest bees but also the longest lived, having a 2-3 year lifespan, and are the only fertile female bees. She can lay up to 1,500 eggs in a day and can determine whether they are fertilised or not. Drones are the males. Born from unfertilised eggs they lack stings and are only there to mate with queens. Finally, fertilised but sterile females are the workers, and their jobs change as they age. First, they clean the hive and then help with feeding. As they age they take part in hive repair and growth, then the defence of the hive, and finally foraging. If you see a honey bee flying about it is more than likely an older worker. If a colony lacks a queen workers are capable of laying unfertilised eggs that will develop into drones. This can even happen if the queen is still around and healthy, and it can lead to clashes in a hive about which larvae receive care, the queens’ or the workers’.
During the spring and summer in cold climates and the wet season in more tropical climates the queens’ fertilised eggs, laid during the winter and dry season, hatch. To ensure queen bees develop larvae chosen to be queens are fed more royal jelly, richer in protein it gives these bees enough protein to develop eggs. Just before the new queens hatch from their pupal stage the old queen leaves the hive with two-thirds of the workers. When the new queens hatch a war breaks out. The queens will try and kill each other until only one queen is left. This will be the colony’s new queen, but she is still unfertilised. She will take a ‘nuptial flight’ where she will fly around and drones will attempt to mate with her. She may do this around four times. Lucky drones die shortly after mating and unlucky ones will try again until their own death in a few weeks. Now fertilised the queen will begin laying eggs and will build up her own colony.
The workers are most likely the bees that you see if you ever spot a bee. The workers feed the queen and larva, forage for food, build the hive, and even act as air conditioning. Using their wings workers can cool down or heat up the hive depending on the temperature needed. In colder climates during the winter the workers huddle around the queen and the eggs to keep them warm. Younger bees secrete a substance made of fats and acids that become wax which they use to build the amazing hexagonal cells that make up the hive. The cells are used to house the larvae and as storage with bees even using wax to seal honey in order to preserve it. As the workers grow their wings become larger and they develop a pollen basket, corbicula, on the tibia to carry as much pollen as they can do. Active during the day the bees will fly to various flowers collecting pollen which they return to the hive. Infamously worker bees have a stinger which they use for defence but it comes at a cost. The stinger is attached to the digestive system and major muscles so if a bee stings something the only way the bee can escape is to fly off with the stinger, and its organs, still attached to the enemy. However, not all stings are fatal. When fighting other insects bees can sting without the stinger being stuck in the opposing animals meaning they can survive the sting.
Communication
Bees have developed pheromones as a way to communicate with one another. The queen has specific pheromones which help bees in a hive identify one another, and identify bees that have gone into the wrong hive. It can also help the queen keep her control over the hive as the pheromones alienate any larvae not hatched by the queen, so that way workers only care for her larvae. Similarly, bees emit pheromones when they sting other animals which attract other members of the hive as it gives the indication that the hive is under attack. This is how the Africanised honey bee got its reputation – being more aggressive it is more likely to sting, which attracts more bees who will, in turn, sting more. Honey bees are also famous for their ‘dancing’. When a forager finds an abundant supply of food they do certain dances, normally in a figure of 8 formation, to indicate where the food is, including dances for how far away the food is.
Distribution and Habitat
Western honey bees are naturally found across continental Europe, Asia, and Africa making them one of the widest spread insects in the world. Through human efforts the western honey bee is now found worldwide, everywhere except Antarctica. They were first introduced to Britain by the Romans, and Europeans would introduce bees to North America in the 1600s. European colonisation would see the western honey bee, mostly the European dark bee and East African lowland honey bee, spread to South America, Australia, New Zealand, and even east Asia where it is now found alongside the eastern honey bee. As long as there are flowering plants, water, and cavities to build hives in honey bees can call it home. As a result, they are found in woods, grasslands, shrubs, wetlands, and even deserts can all provide homes for western honey bees.
Diet and Predators
Honey bees have a varied diet based on what role they have in the hive. Primarily, bees eat nectar, pollen, honey, and secretions that the other bees produce. Workers will fly to flowers where they use a long tongue to drink up nectar, and at the same time pollen sticks to the bee. Workers may lick up some of the pollen which, with the nectar, is stored in the gut. When returning to the hive the worker can regurgitate the pollen and nectar as a crop which is fed to another bee, or is processed into honey. Bees can also secrete a substance called ‘worker jelly’ or ‘queen jelly’ depending on whether the larvae is to become a worker or queen. Western honey bees are generalists and do not have preference for what plants they visit which has made them some of the greatest pollinators among animals, with many flowers evolving to better attract honey bees.
Bees are on the menu for a lot of animals. A type of wasp, bee wolves, and bird, bee-eaters, are so named because bees are such a significant part of their diet. Wasps, spiders, other bees, and some beetles can all hunt bees, with a group of social wasps, called Vespids, being prolific bee hunters. These wasps can attack honey bee hives in a swarm and have been known to completely overwhelm bee hives destroying them. Vertebrates do also hunt bees, most of them being among the birds. Lizards, toads, frogs, rats, mice, honey badgers, skunks, armadillos, and bears all will eat bees or raid their hives for honey and the larvae. Of course, there is also humanity. Due to their often tranquil nature western honey bees have been independently domesticated western honey bees for millennia. Cave paintings from the Spanish Cuevas de la Arana dating to around 7,000 BCE depicted people taking honey from bee hives, although actual domestication would come later. The earliest known instance of domestication comes from ancient Egypt, by around 2,600 BCE, meaning that humans have been harvesting bees for over 4,000 years. Just as today, bees have been farmed for their honey, beeswax, and also their pollination.
Conservation and Threats
We have a bit of an issue with the western honey bee as the IUCN lists them as being ‘Data Deficient’, meaning that there is not enough data to determine if the western honey bee is endangered or not. A big part of this lies with the difficulty in determining whether certain bee populations are actually domesticated or not. Western honey bees are indeed invasive species and openly compete, often successfully, with native bee species. Being generalists western honey bees will visit as many plants as they can and plants evolved alongside them as a result, but in areas they were introduced in the local plants have not adapted to this. Consequently, plants in the Americas and Australasia have faced issues with pollination as the western bees outcompete the local ones and don’t as readily pollinate the plants. Milkweeds have even been known to kill western honey bees when they try and pollinate them.
Despite this, western honey bee numbers are dropping, alongside with the numbers of many other bee species. Unsurprisingly, human activity is behind it. The use of pesticides and insecticides in farming have been devastating upon bee populations by either killing bees or making them lose contact with their hives meaning they get lost until they die. The globalised economy has also allowed viruses and mites to spread to hives across the world which can wipe out entire bee colonies. Finally, global warming is also wiping out bees. Changes in the climate causes plants to grow and bud at uneven times which impacts the rhythms that bees need to survive. Air pollution further poisons bees, and rising temperatures makes it harder for bees to maintain the conditions in their hives. While we do not know exactly how much bee numbers have dropped by, but they have certainly dropped by a large number. This not only devastates bees, but so many other forms of life – from plants needing them for pollination to fungi who use their hives for safety to us. If the bees go, so will a lot of life.
Bibliography:
- George Hammond and Madison Blankenship, ‘Honey bee’, Animal Diversity Web, (2009), [Accessed 30/04/2023]
- Animalogic, ‘The Amazing World of Bees’, YouTube, (03/01/2017), [Accessed 30/04/2023]
- Vivian M. Butz Huryn, ‘Ecological Impacts of Introduced Honey Bees’, The Quarterly Review of Biology, 72:3, (1997), 275-297
- Mary Percival, ‘Pollen Collection by Apis mellifera‘, 46:1, (1947), 142-173
- May Berenbaum, ‘Bees in Crisis: Colony Collapse, Honey Laundering, and Other Problems Bee-Setting American Apiculture’, Proceedings of the American Philosophical Society, 158:3, (2014), 229-247
- Carissa Wong, ‘World’s Most Common bee originated 7 million years ago in Asia’, New Scientist, (03/12/2021), [Accessed 30/04/2023]
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