Sunday, 2 December 2012

Bumblebees and Honeybees

The bees that most people can easily recognise and identify are bumblebees and honey bees.






Bumblebees


Bumblebees [Bombus terrestris] are related to honeybees [Apis].

Bumblebees, which we think of as very furry black and yellow striped creatures with pollen sacks on their legs, also live in colonies, feed on nectar and gather pollen to feed their young.  They also produce small amounts of honey.

They are mostly found in higher latitudes and / or high altitudes and there are around 250 known species in the Bombus genus.

They form colonies, although these are much smaller than honey bees, and are usually underground or in mounds of grasses.  They don’t usually keep the colony from one season to the next and it is a queen that has overwintered that will start the construction of a new nest in the Spring.

Bumblebees will visit patches of flowers up to 1-2 kilometres away from their colony and will continue to visit for a long as they continue to find both nectar and pollen.  Some species can leave a scent mark on a flower which deters other bumblebees from visiting whilst the scent marks lasts.  Apparently they also differentiate between rewarding and unrewarding flowers !

Bumble bees are important pollinators of both crops and wildflowers.  People are increasingly using bumblebees as pollinators, especially for plant species that others cannot pollinate, using a technique known as ‘buzz pollination’

Certain plants hang on to their pollen more firmly in their anthers, which are typically tubular with an opening at only one end and the pollen inside is smooth and firmly attached.

Some species of solitary bees and bumblebees use this method – also called sonication – where the bee grabs onto the flower and moves its flight muscles rapidly, which causes the flower and anthers to vibrate, dislodging the pollen.  8% of flowers in the world are primarily pollinated by buzz pollination and the following are those that are more efficiently pollinated :
  • Many members of the Solanaceae family, including many species of the genus Solanum
  • tomatoes
  • potatoes
  • aubergines or eggplants
  • Some members of the genus Vaccinium
  • cranberries & blueberries
  • Senna
Other plants are
  • Arctostaphylos – manzanitas
  • Dianella – Flax lily
  • all Dodecatheon – shooting stars
  • Heliamphora
  • Hibbertia


So, the reason for engaging the use of bumblebees is to pollinate, particularly, greenhouse-grown tomatoes and aubergines, which require pollinating to produce any fruit.  Apparently, pollination used to take place by using electric vibrators (!) – one brand name was ‘Electric Bee’ – but using bumblebees was found to be far more cost effective than human labour and cut out the inevitable breakages of plants within the confined space of the greenhouse.

In Australia there are no native bumblebees and they have suffered a number of widely publicised environmental disasters, caused by introduced species that have escaped.  Research is being carried out to see whether the native Blue Banded Bees can be used for the task, but this is meeting lobbying by bumble bee importers who seem to prefer to disregard this risk and any ‘home-grown’ solution !

The agricultural use for bumblebees is, however, limited to pollination as bumblebees do not overwinter the entire colony and so are not obliged to stockpile honey for food.  So they are not useful as honey producers.


Honeybees


Honey bees, of which there are seven recognised species, but with a total of 44 subspecies in the Apis genus, would appear to have a centre of origin in South and South East Asia.

The European or Western honeybee [Apis mellifera], which seems to have originated in eastern tropical Africa and spread to northern Europe and Asia, is the most commonly domesticated species and has the distinction of being the third insect to have its genome mapped – 28 October 2006.

The name was given to them by Carl Linnaeus in 1758 and the mellifera part comes from the Latin : melli meaning ‘honey’ and ferre meaning ‘to bear’ – so, ‘honey-bearing bee’.  However, he realised that they do not bear honey, but nectar and later tried to correct this to Apis mellifica [‘honey-making bee’] in a later publication.  According to the rules of synonymy – which is the scientific nomenclature or name – the older name has precedence.

Apis mellifera is not a native to the Americas and were taken there by colonists, although there were other native species that were kept and traded by the indigenous peoples.  The colonists also introduced the dark bee [Apis mellifera mellifera] and later the Italian bee [Apis mellifera ligustica] and others.  Many of the crops that depend on honeybees for pollination have also been imported since colonial times.

Again, to anyone reading this who has a greater in-depth knowledge of bees, this is only meant to give an outline of how bees work and how a hive functions – there is so much fascinating detail that I have been obliged to leave out, otherwise I would be producing an Encylopaedia-Britannica-length post !

Honey bees live in very organised colonies averaging between 40 000 to 80 000 bees in a healthy hive in mid-Summer.

There is one Queen to the colony – she is the only fertile female and lays the eggs from which all the other bees are produced.  She mates with the Drones.

The Drones are male bees, which represent approximately 10% of the hive colony.  Their principal function is to mate with the Queen, after which they die.  They have very strong wings and in some species they use these to regulate the temperature of the hive.  At the beginning of the Winter, when they have outlived their usefulness, the Workers bite their wings off and kick them out of the hive to die of cold and starvation, since they are unable to forage, produce honey or take care or themselves (!)  They have no stinger or ovipositor.

Worker bees are infertile females.  They clean and maintain the hive, raise the young and feed them on royal jelly, guard the hive, forage for nectar and pollen and produce the wax, from special glands, that is used to make the comb and seal the cells.

There are four distinct stages in the life cycle of a honey bee.

The queen, once mated with the drones starts to lay eggs from mid Winter onwards, in temperate climates.

After three days, the egg hatches into a larva and is fed ‘bee milk’ and ‘bee bread’ by the worker bees.  Then it spins a cocoon during days 4 to 9.

In the cocoon, the larva develops into a pupa with eyes, wings and legs.  This developments takes anywhere from 10 to 23 days.

The adult finally emerges from the cell in the comb by chewing its way out.  It metamorphoses into a fully grown bee from days 16 to 24, depending on the caste of bee.

The worker bees, that forage for nectar, have ultraviolet vision which allows her to see patterns on flower petals that draw them in.  The nectar is stored in her honey stomach until she reaches the hive where it is passed to others to store in the comb.  They also use their wings to fan the cells that contain nectar as this is 80% water and by fanning they help to evaporate the water, which means the honey remains in the cells.

They communicate through ‘dances’, but it is believed that they also rely on their olfactory senses once the foragers have been given directions from the waggle dances.

Worker bees have to forage approximately 5.5 million flowers to produce approximately a kilogramme of honey.

Worker bees’ stings are barbed but do not always detach on stinging and bumblebees do not have a barbed sting.  Even if honeybees do lose their sting, they do not necessarily die afterwards.  Most bees are non-aggressive and only sting to protect themselves or the hive, which is why bee keepers use puffs of smoke to calm the bees.

The buzzing sound a bee makes is not caused by the beating of their wings but it is a result of the bee vibrating its flight muscles.  Bumblebees have an especially pronounced buzz as they have to warm up their bodies before they fly when temperatures are low.


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