October 11, 2016

Honey Bee Brain and Nervous System

Honey bees like most insects not only have a brain in their head but several sub brains or ganglia (7 of these) spread throughout their bodies. There are 2 ganglia in the thorax and 5 in the abdomen. Ganglia function independently but can be controlled or over written by instructions from the main brain. They also send feedback to the main brain about the state of the environment in their particular area.

Most locomotion is controlled by the ganglia, not the brain and in fact a beheaded bee can move it’s legs and wings vigorously. A bee will be able to walk and sting for a while when decapitated, but not fly as its balance will be out without a head.

An adult honey bee is one of the most advanced insects and is capable of  a huge range of different complex behaviour. Honey bees are capable of learning and have short-term memory.

The actual main brain of a an adult honey bee is proportionately very large in comparison with its size. In the worker bee the brain consists mainly of the optic lobes, with the central part acting as a coordinating centre and this central part is larger than in most other insects. Nerve fibres connect the brain to the 2 ganglia in the thorax and the 5 in tha abdomen.

Each ganglion has nerve fibres which connect it to sensory receptors on the outside of the body, to bring information back from the outside environment. The antennae are of course the main sites for sensory reception in the bee.

The ganglia also each have fibres which bring information about the condition of the internal organs of the bee and those which send back regulatory information. Fibres also carry information to the muscles to control their actions.

Much is still to be learned about why the bee is capable of displaying such complex behaviour in particular its amazing ability to navigate to and from its hive, remembering and passing on detailed information about the position of  food sources.

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What to Look for When Inspecting a Hive

When inspecting a hive there are several things that you should be looking out for and these are summarised below.

Evidence that the hive is ‘queen right’

Queen right is the term given to describe a colony of honey bees where the queen bee is present and laying eggs. When inspecting your hive  look out for the queen, but if you cannot find her don’t worry. It is not always easy to find the queen especially if the hive has many boxes and large numbers of bees. Ideally you should have your queen marked, which will help you to find her and also to confirm that the queen you have found is your original one and not a replacement.

If you cannot find your queen, look for eggs. If you find eggs you know that your queen was at least in your hive a couple of days ago. If you cannot find your queen and you see no eggs, then you have a problem as either the queen is dead or she has stopped laying or is defective in some way and cannot lay.

As you remove a frame for inspection, be sure to hold it over the hive, in case the queen is on it and falls off. If you are holding it over the hive then she will fall back into the hive. If the queen was to fall onto the ground outside the hive there is no guarantee she will be able to find her way back in.
Presence of all stages of brood
It is important for the colonies survival that there is plenty of brood at all stages of development and in particular plenty capped or sealed brood. You should also as the season progresses see a marked increase in the bee population, which is essential if the bees are to gather enough to produce the honey that you and they need.
Check for any abnormalities
This gets easier with experience and after a while an experienced beekeeper can tell at a quick glance whether there are any real problems or not. You should be looking in particular for any sign of disease (e.g malformed larvae) or pests, such as varroa or wax moth (refer to our pests and diseases section).
Check for sufficient honey and pollen stores
The amount of honey stores will depend upon the time of year, but if you feel that there is insufficient stores then you should feed your bees. The bees will usually store pollen near the brood areas as this is where it is most needed.
Check that there is enough space
Again this depends upon the time of year. In spring and early summer it is important that the queen has plenty space to lay if not you increase the likelihood of losing most of your bees and honey as the colony will swarm. Always add supers in plenty time for the main nectar flow if you are to maximise your honey crop.
You should also  ideally keep a written record of what you have seen in each hive as it is not as easy to remember from inspection to inspection as you might imagine.

Honey Bee Glands

The worker honey bee has several important glands situated in her head, thorax and abdomen. Starting  just inside the bee’s mouth  are the opening points of two very large glands, these are called the hypopharyngeal glands. The  hypopharyngeal glands are crucial to the honey bee and to the survival of the colony.

These glands are made up of a number of secretory cells clustered around a central canal. When the honey bee is young, in the first few weeks of its life, these cells are round and plump and produce brood food, a form of bee milk which is used to feed bee larvae. As the bee gets older and becomes a forager at about three weeks old, these cells become smaller and much reduced in size. The hypopharyngeal glands have now switched from producing brood food to producing invertase, which as the name suggests inverts sugars. However if necessary for the needs of the colony the worker bee can switch back to producing bee food from these glands.

In addition a pair of glands in the mandibles secrete a type of preservative which is mixed with the brood food as it is secreted from the hypopharyngeal glands, this has anti bacterial qualities which prevents the food from deteriorating.

The mandibular glands also produce an alarm scent called heptanone which is used to  alert other bees to danger. This is one of the reasons that beekeepers use a smoker as the smoke masks this scent and reduces the likelihood of the bees orchestrating an attack. The mandibular glands in the queen bee produce a type of fatty acid which is called ‘queen substance’ which is used to ensure the workers are aware of her presence.

Moving down the body there are two salivary glands in the head and thorax, with openings on either side of the bee’s tongue. Their liquid secretion is used to dilute honey and dissolve sugar crystals.

On the upper side of the abdomen of the bee on the last visible segment is the Nasanov gland.  This releases a pheromone which is used to attract members of the colony who might have lost the location of their hive. Often you will notice bees at the entrance of a hive fanning with their wings to propel the airborne scent to the bees flying around, especially when the hive has been disturbed.

Worker bees also have four pairs of wax glands on the underside of the last five segments of their abdomens. Wax is secreted into pockets underneath each gland and quickly solidifies into translucent white blobs which are then removed by mouth and worked on to use to build comb as required (see How and why bees produce wax ).

Finally there are two glands associated with the bee’s stinging mechanism. There is  a long thin venom gland which produces the acidic venom which is contained in the venom sac. The second sting gland produces an alkaline solution which is thought to act as a lubricant for the stinging mechanism.

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Honey Bee Larvae Digestive System – Alimentary Canal

The alimentary canal of a bee larvae is not as complex and developed as that of  a fully grown bee (see Honey Bee Alimentary System ), but still has to function efficiently to ensure nutrients are absorbed quickly to aid the larvae’s rapid growth and ensure that it has sufficient body stores to last it through the sealed pupal stage and onto its emergence as an adult honey bee. Bee larvae have voracious appetites and are fed first larvae royal jelly, then are quickly weaned onto a mixture of honey and pollen (bee bread) by adult worker (nurse) bees. Of course if the larva is to become a  queen, royal jelly will continue to be fed to it.

The bee larva has a very short fore-gut which carries the food from its mouth to its mid-gut, in which the food is digested. Up until the end of its larval period, that is until it has finished feeding and before it is sealed up to pupate, the mid-gut has no exit to the hindgut and digested food residue remains there. This is believed to be to prevent it from fouling its food.

Once the larva is fully fed the hind-gut breaks through into the mid-gut. At the same time the Malpighian tubules which act like kidneys and have being removing nitrogenous waste from the body cavity also break through and discharge their contents, thereby adding uric acid to the feacal matter. This waste is then expelled from the larva and spread over the walls of the brood cell. It is then covered with the silken cocoon that the larva is now spinning.

On emerging from her cell as an adult, one of the first things the bee does even before eating is clean out her birth cell. Ensuring that all her waste matter is removed and the cell is ready to be reused.

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Removing the Queen Cage from a Package of Bees and First Inspections.

Having installed a package of bees for the first time it can often be hard for new beekeepers to resist the temptation of checking what is happening inside their new hive. We are often asked when you should inspect your hive after installing your packaged bees? You must wait at least 5  days any sooner and the bees may not have had a chance to accept the queen and she may be rejected or killed.
After 5 to 7 days, you can open the hive and check to see if the queen has been released from her cage. There will likely be bees on the queen cage and quite possibly they will have started to build comb on the bottom of it. Be very gentle when examining the cage and attached comb as the queen may be on the outside of the cage or on the attached comb. If she is on it gently brush her onto a frame and then shake the remaining bees off, before discarding the queen cage and any attached comb. If the queen has not been released, then you will need to carefully release her. Do not leave the queen cage in the hive longer than is necessary as the bees will cover it with comb and make it difficult to remove without damage to the frame and foundation it is attached to.
If the queen has been released and she is not on the outside of the cage, look for her. By this time, 1 or 2 frames should be drawn and you should be able to see some eggs in the cells. If you don’t find the queen but you do see eggs in the cells, don’t panic, your queen is alive and doing her job. If, however, you cannot find the queen or any eggs in the cells or if you find that your queen is dead within her cage, then you will need to place an order for a new queen, as soon as possible. If the queen is present close the hive and wait another week before inspecting again. Ensuring once again then that the queen is present and laying.
You should continue feeding the colony sugar syrup until you are certain there is a strong nectar flow and the bees are beginning to build up their honey stores.
Note: On the third week you may be concerned to notice a significant reduction in the population of the adult bees. Don’t worry, this is natural as the average life span of a worker bee during the spring and summer months is only 3 weeks and so the newly laid brood has not had a chance to replenish the colony. But as long as your queen is laying properly and you are seeing the cells being filled with brood, you have nothing to be concerned about. You should see the population increasing again within the next 2-3 weeks as the new bees begin to emerge.

Propolis and Bee Hives

Propolis is the sticky resinous substance that bees collect from plants and trees and which gets all over your hands and clothes when inspecting a bee hive.  Propolis is produced by the trees and plants to protect their buds from, bacteria, fungus and most insects. The composition and colour of propolis varies from plant to plant and therefore colony to colony and region to region. Propolis is most commonly an orangey/brown colour.

Bees use propolis to seal up small spaces throughout the hive, bigger spaces are sealed with wax comb . Propolis is sticky above 20 °C (68 °F) and becomes brittle and hard below that temperature. As a result forager bees tend to prefer to collect propolis in warmer temperatures. The bees collect the propolis using their mandibles to scrape the substance from the plants. They then pass the propolis from their mandibles to their forelegs, then to the inner surface of the middle leg or basitarsus. The propolis is then stored for flight in their pollen baskets or corbiculum on their back legs.

On returning to the hive with their load of propolis they go to the part of the hive where it is required. The propolis is removed by other house bees. Just as with pollen, nectar and water the bees will perform a dance to pass on the exact location of the propolis to other bees.

In sealing up small holes and entrances in the hive, the bees are strengthening the structure of their home as well as limiting the possible entrance points for predators and it is believed reducing vibration. In addition, whilst bees will remove any dead bees or small predators from a hive, bigger creatures such as small mice or lizards, which have been attacked and killed but are too heavy to remove will be shrouded in a propolis cocoon. By doing so the bees prevent disease and bacteria spreading from the decaying body.

The bees will also coat the inside of the hive with a thin layer, or varnish of propolis and also coat the inside of a brood cell. This is believed to be a way of using the known anti bacterial, antiviral and antimicrobial properties of propolis to keep the colony clean and healthy and free of disease.

Some strains of bees such as Caucasians use more propolis than others and some beekeepers will not keep them for this reason. Since beekeepers tend to hate having to deal with large amounts of sticky propolis there has been a tendency to favouring and breeding from lower propolis producing colonies in recent decades. Some scientists now suggest that this reduction in propolis use could be interfering with the bees natural weapon against diseases and be contributing to the rise in pests and diseases currently damaging bee colonies worldwide.

Human use of propolis

There is a growing interest in propolis and its natural benefits for humans. Many health stores sell propolis supplements and propolis can now even be found in some toothpaste produced by major toothpaste manufacturers, promoting in particular healthy gums.

Below are some propolis based products you might like to check out

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Bee Blood – Honey Bee Circulatory System

The blood, or haemolymph of a bee carries no oxygen, (that is the job of the tracheal system )  so does not contain the red pigment haemoglobin and as a result is a pale straw or amber colour.  The blood carries nutrients to the tissue and organs of the bee and the waste products from metabolism to the excretion organs, the Malpighian tubules, for elimination. The bee’s blood also contains cells for destroying bacteria, dealing with foreign bodies and other toxic substances and also wound healing.

Unlike larger animals the bee’s blood is not contained within tubes but simply fills all spaces within its body, thereby surrounding all of its organs. This is called an open circulatory system, unlike our own which is a closed circulatory system. Blood circulation in a bee is achieved through a simple heart, which is an elongated organ lying just under the roof of the abdomen. It has muscular walls and has five pairs of openings with one-way valves which allow blood to enter the heart when it dilates. When the heart contracts, the valves close and the blood is forced forwards into the aorta which extends through the thorax and into the head where it ends just behind the brain.

It is worth noting that the only blood vessels to be found in a bee are at the base of each antenna, which force the blood to circulate through them, highlighting the importance of the antennae to a bee.

The bee’s heart  pushes the blood  forward into the brain until pressure increases forcing it back through the body cavity and to all the organs and tissues. On its way from the head, the blood passes back through the thorax, nourishing the flight muscles, then into the abdominal cavity where more nourishment is picked up from the digestive system before it is drawn back into the heart again.

photo courtesy of infovisual.info

Colony Collapse Disorder – Parasitic Fly Could be to Blame

A parasitic fly that hijacks the bees’ bodies and causes them to abandon their hives has been put forward as a possible explanation for Colony Collapse Disorder. Northern California scientists say the fly deposits its eggs into the bee’s abdomen, causing the infected bee to exhibit trance like behaviour, walking around in circles and then leaving the hive at night to die. This is what happens with Colony Collapse Disorder, in which all the adult honey bees in a colony suddenly disappear over night.

This research is another step in the right direction in finding the cause of Colony Collapse Disorder which is having a serious effect on the US bee industry. Research so far points to a combination of factors including pesticide contamination, a lack of the right food sources, mites, fungi, viruses and parasites.

Interaction among the parasite and multiple pathogens could be one possible factor in colony collapse, according to the latest study by researchers at San Francisco State University. It says the phorid fly, or apocephalus borealis, was found in bees from three-quarters of the 31 hives surveyed in the San Francisco Bay area. The combination of a parasite, pathogens and other stressors could cause die-off, lead investigator John Hafernik said. The parasitic fly serves as a reservoir that harbours pathogens ; honey bees from parasite-infected hives tested positive for deformed wing virus and other pathogens, the study found.

“We don’t fully understand the web of interactions,” Hafernik said. “The parasite could be another stressor, enough to push the bee over tipping point. Or it could play a primary role in causing the disease.”

Honey Bee Respiratory System

The respiratory system of the honey bee is made up of a series of tubes called the trachea. In higher species of animals oxygen is carried throughout the body by the blood, in bees and all insects, blood is not used to transport oxygen where needed but instead the trachea are used.

The trachea are made of thickened cuticle and start large but rapidly branch and divide getting smaller until they end in single cells, in such a way as to reach every organ in the bee’s body. The trachea open to the air through holes in the cuticle called spiracles, which have opening and closing mechanisms.

Initially the trachea widen to form air sacs which are used to store air. The trachea arms widen to form air sacs that are large albeit few in number and used to store air. The small branches and tubes emerging from the sacs extend as far as the tissues. Bees can accelerate the passage of air into their bodies by contracting these sacs, which speeds up the oxygenation of the tissues.

Air is drawn into the air sacs by a telescopic movement which lengthens and shortens the abdomen and can clearly be seen when the bee is at rest.

More on the Anatomy and Physiology of the Bee

Honey Bee Exoskeleton

Bees like all insects and unlike vertebrates,  have their skeletons on the outside, exoskeletons , with the muscles attached to the inside. The exoskeleton is made up of two parts, the epidermis and the cuticle.

The epidermis is a single layer of living cells forming a complete sheet over the whole body and covering the internal organs. The epidermis also secretes a non living material which forms the hard, resistant outer covering of the insect which is the cuticle.


Bee’s Cuticle

The structure of the cuticle is built from chitin, into which a protein called sclerotin is injected. The cuticle is covered with a thin coating called the epicuticle, to make it waterproof and scratch resistant.

This dead layer or cuticle means that if an insect wishes to grow the old cuticle needs to be shed or moulted and a new one produced. This process only occurs in a honey bee during the larval and pupal stages.

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