Bee Evolution
Bees are insects. Insects make up more than half of all known living species and are the most diverse group of animals on Earth. There are more than one million species of insects, and over 20,000 known species of bees...
Bees are part of the order Hymenoptera, along with wasps and ants. Bees evolved from ancient predatory wasps that lived 120 million years ago. Like bees, these wasps built and defended their nests, and gathered food for their offspring. But while most bees feed on flowers, their wasp ancestors were carnivorous. They stung and paralyzed other insects, bringing them back to feed developing offspring in the nest.
The image below shows some examples of the different types of Bees from around the World...
Bees in the UK
As well as honey Bees there are around 24 species of bumblebee and over 240 species of solitary bee in the UK. The diagram below shows some of the more common types of Bee in the UK:
These species are not spread out across the whole UK, most are mainly found in southern England, with some only found in a few small areas.
The diagrams below show the range of some of these species:-
The Honey Bee (apis mellifera)
The most common Honey Bee in Scotland is the Western Honey Bee. The most common type was originally bred from Italian and Spanish strains of Honey Bees, but the Inner Hebridean Isles still have good numbers of native Scottish Honey Bees , which are nearly all black in colour.
apis mellifera iberiensis
Bee Anatomy (External)
Honey bees are insects and have five characteristics that are common to most insects.
They have a hard outer shell called an exoskeleton.
They have three main body parts: head, thorax, abdomen.
They have a pair of antennae that are attached to their head.
They have three pairs of legs used for walking.
They have two pairs of wings.
The diagram below of the honey bee shows the main parts of a bee's external anatomy:-
External Anatomy of the Head
The diagram below shows the main parts of a Bee's Head:-
The eyes of a Bee
Bee eye color and shape varies among species. All bees have two compound eyes and three small, light-sensing ocelli on the tops of their heads. Some bees have giant eyes that help them see, fly, and forage at night.
Bees have two compound eyes, with thousands of facets that each point in a slightly different direction. Each facet, at the end of a unit called an ommatidium, contributes one part of a larger image. Worker honey bees have up to 6,900 facets per eye.
Bees also have a cluster of three simple eyes called Ocelli on the top of their heads. They act more like light sensors than true eyes. The Bee uses the occelli to decide which way is up when flying, and also allows the Bee to know when to return to the hive at night.
Bees have very different spectral sensitivity from humans. We see from the red to violet range, but bee vision is shifted to slightly shorter wavelengths, including ultraviolet.
Many flowers exploit the UV sensitivity of bees. As as can be seen in the video below, some flowers have striking UV patterns that lead bees and butterflies directly to the nectar source. We don’t see these UV patterns, so these flowers can look completely different to us.
The mouth of a Bee
Bees use their mouthparts to collect food and nesting materials. Some bees have sharp mandibles for slicing leaves. Others harvest nectar from the deepest flowers with incredibly long tongues.
When a bee is ready to extract pollen, nectar, or oils from a flower, its complex set of mouthparts unfold. Bee mouthparts have moving, interlocking pieces evolved specially for hard-to-reach floral rewards.
The video below show how these parts work together to extract nectar from a flower.
Bee Anatomy (Internal)
The diagrams below of the honey bee show the main parts of a bee's internal anatomy:-
Bees, like other insects, have no transport system so gases need to be transported directly to the respiring tissues.
There are tiny holes called spiracles along the side of the insect. These spiracles are openings of small tubes running into the insect's body.
The ends of these tubes, which are in contact with individual cells, contain a small amount of fluid in which the gases are dissolved. The fluid is drawn into the muscle tissue during exercise. This increases the surface area of air in contact with the cells. Gases diffuse in through the spiracles and down the tracheae and tracheoles.
Ventilation movements of the body during exercise may help this diffusion.
The spiracles can be closed by valves and may be surrounded by tiny hairs. These help keep humidity around the opening, ensure there is a lower concentration gradient of water vapour, and so less is lost from the Bee by evaporation.
The diagram below shows a cross-section of a insect's abdomen, showing how the Spiracles are connected to the organs within the abdomen:
Bees and Stinging
The female Bees (Worker Bees and Queens) are the only ones that can sting, drones cannot. This is because the stinger evolved from part of the female Bee's reproductive system, called an Ovipositor.
An ovipositor is a piercing tool used to inject an egg into a host, allowing the egg and larvae to grow inside another insect or animal using that animal as a source of food and protection. Honey Bees have evolved to lay their eggs in complex hives, and so the ovipositor evolved into a defensive weapon, capable of delivering a powerful venom.
The video below shows a wasp using its ovipositor to inject eggs into the larvae of butterflies:-
The stinger consists of a Venom Sac attached to muscles and the stinger itself (which is made up of several moving parts). the Venom is produced in the Venom Gland and is stored in the Venom Sac until it is needed.
When the Bee stings, the muscles contract separately, forcing the blades of the stinger into the skin and pumping Venom into the wound.
The animation below shows this process:-
The Queen and Worker Bees have evolved two different types of stinger, the Queen has a smooth stinger, whereas the workers have stingers covered in barbs.
The reason for the difference is due to the use that the Workers and Queens have for their stingers.
The Queen has a smooth stinger which allows her to use it repeatedly. The Queen uses this stinger to kill any other rival Queens before they hatch.
The workers have a barbed stinger which can only be used once (against a mammal, it can sting other insects repeatedly) before it is torn out of the Bee, killing it. This means that the Worker Bee will sacrifice itself for the greater good of the colony, giving its life to defend it.
The barbs mean that the stinger remains lodged in the skin of the mammal, allowing the stinger to pump more venom into the wound. This obviously increases the pain caused by the venom, driving the mammal away from the colony.
The dying Bee also releases an attack pheromone, causing more Bees to attack its target.
Stinger left behind after a sting
Stinger pulsing after removal
Bee Stings and humans
Through the wearing of correct equipment and good practices when handling Bees, stings can be kept to a minimum, but as a Beekeeper stings are something that will happen.
Honey Bees have been selectively bred to not be aggressive, and will usually only sting when the colony is threatened, or if you crush or hit them.
If you are stung however, the following procedures should be followed:-
Move away from the colony quickly and quietly.
As soon as possible, remove the sting (if still in skin) by scraping with a tool or credit card. Don't pinch it as this will cause more venom to be injected.
Do not return to the colony without safety equipment, as due to attack pheromones, you are very likely to be stung again.
Once you are at a safe distance from the colony, the sting site can be treated. There are lots of ways people think will help a bee sting, but most of these are not really true.
The best recommendation is simply to make sure the site of the sting is clean and apply a cold compress to reduce swelling.
Bee stings are painful because the Venom contains an acidic compound called Melittin, which switches on the pain receptors in mammals. This is felt as an intense itching and burning sensation. Bee stings are seen as one moderately painful type of sting that a person can receive. They rate a level 2 on the Schmidt Pain Scale.
The Schmidt Pain Scale was created by the American entomologist Justin Schmidt. To rate the pain of a sting, Schmidt intentionally stung himself 100s of times with 78 different types of insect. He then ranked them on a rating system of 4 levels of pain (1 least painful and 4 most painful).
The video below shows a brief overview of Schmidt's work:-
The images below shows Schmidt's description of a Honey Bee sting, as well as examples of different insect stings and how painful they are on the Schmidt Pain Scale:-
The Venom also contains Histamines which trigger the mammal's immune system to cause swelling. The Bee have evolved to use Histamines in their Venom as it will make the mammal's own immune system work for the Bees to incapacitate the mammal.
This is even more the case if the mammal experiences a severe allergic reaction (anaphylaxis) to the Venom. This is very dangerous and can result in the death of the mammal.
Anaphylaxis
When most people are stung, there is sharp pain that quickly subsides and a small amount of swelling that goes down after a few days. Some people, however, have an allergic reaction to the Bee Venom and can go in Anaphylactic Shock. This is extremely dangerous, and results in fatalities around the world every year.
Anaphylaxis occurs when the body's immune system overreacting to a trigger, in this case a Bee sting. The whole body is affected, often within minutes of exposure to the trigger which causes the allergic reaction but sometimes after hours. The diagrams below shows some of the effects of anaphylaxis, as well as some statistics of Venom anaphylaxis in the UK:-
If you or someone around you experienced any of the symptoms discussed above, it is vital that you seek medical assistance immediately.
