6th Honeybee behaviour revision post: honey bee foraging

Posted on March 17, 2011 by Emily Scott

This might be my last revision post for my BBKA Module 6 Honeybee Behaviour exam on Saturday! And I’ve only got half way through the syllabus.

Section 6.7: the behaviour of the foraging bee and its work methods in the field including orientation;

Which honey bees forage?

It is the oldest female workers in the hive, aged between 3-6 weeks of age, which forage for the colony. They literally work themselves to death doing so. The lifespan of a worker bee is dependent not so much on chronological age as the amount of work she does. Workers have glycogen reserves in their flight muscles which last for approximately 800km of flight; after these are exhausted the bee is unable to create more and will collapse and die.

During the foraging seasons around 25-30% of the colony’s population is potentially a forager bee, depending on the availability of flowers and the needs of the colony. Once bees are old enough to forage they will remain doing this task for seven to eight days on average before they die. So the bees you see returning to the hive laden with pollen are likely to be reaching the end of their days.

Albanian honeybee on a poppy

Albanian honey bees on poppies.

What do honey bees forage for?

They leave their home to collect four essential products: pollen, nectar, water and propolis. What they collect is dependent on time of year and temperature, for example nectar is generally collected at minimum temperatures of 12-14°C or above and propolis is too hard to collect at under 5°C. A study by Ribbands (1949) found that around 58% of bees collect nectar only, 25% pollen only and 17% both nectar and pollen.

Bee on blue flower 2

Honey bee foraging at Osterley Park, West London

 

How far do they go?

Honey bees generally forage within a 1km radius from the hive, but in extreme cases go up to 13km for particularly rewarding sources. A study has found that they forage for nectar up to 13km, for pollen up to 6km and for water up to 2-3km (‘The Foraging Honey Bee’, JJM van der Steen, BBKA News February 2015). Pollen is a lighter load, but nectar gives them a higher energy return relative to effort (8:1 gain pollen, 10:1 gain nectar if a 40% sugar nectar). Foraging trips usually take ten minutes for nectar and thirty to eighty minutes for pollen – perhaps pollen is more time consuming to collect because it needs to be brushed and packed into the bees’ pollen baskets.

How much do they collect?

On average loads of 30-50mg of nectar, 16mg (8mg x 2 pollen baskets) or 25mg of water are collected – impressive considering a honey bee only weighs about 100mg. The amount collected depends on the distance flown to find the nectar source and on the nectar sugar concentration, with bees collecting less of a nectar if it is low in sugar. Both nectar and pollen collectors need to visit anywhere from 1-500 flowers to collect a full load and will go on an average of 10-15 trips a day.

It takes four pounds of nectar evaporated down to produce one pound of honey; it takes about a dozen bees to gather enough nectar to make just one teaspoon of honey, and each of those dozen bees needs to visit more than 2,600 flowers. The amount of flowers available place a limit on how much honey a colony can produce to meet its needs – no location supports an infinite amount of colonies.

Annually, an average colony requires 60-80kg of honey, which requires a minimum of 125kg nectar to be collected and then evaporated down to create honey. This will take the colony around 4,000,000 foraging trips. The numbers are staggering and really make you appreciate the colossal effort the bees go to in order to produce their golden prize. Large amounts of protein in the form of pollen is required too – 15-30kg pollen annually, depending on the amount of brood in the colony.

Albanian honeybee on clover

White clover is a honey bee favourite

 

Finding the flowers…

Workers watch the round, transition and waggle dances given by their fellow foragers and judge from the sugariness of nectar samples offered, the number of dancers for a particular crop and the enthusiasm of the dancers in terms of waggle intensity which flowers are best to visit. To help themselves orientate and successfully follow the dance instructions they rely on the direction of the sun, polarised light patterns if it is a cloudy day, the smell of flowers and the earth’s magnetic fields (workers have cells with iron containing granules in their abdomen). Younger bees rely more on wagtail dances to find forage, older bees tend to remember the location of flowers.

New discoveries are happening all the time into the ways flowers attract bees and how bees detect the most promising flowers. In February 2013 the journal Science published a paper on ‘Detection and Learning of Floral Electric Fields by Bumblebees‘, by Dominic Clarke, Heather Whitney, Gregory Sutton and Daniel Robert.

Bumble on blackberry bramble

Scientists have known for a long time that bumblebees build up a positive electrical charge as they rapidly flap their wings in flight; when they land on flowers, this charge helps pull pollen towards their hairs. Now Daniel Robert and a team at the University of Bristol have found evidence that bumble bees are aware of these electric fields and use them to guide their activities, to see if flowers have been recently plundered by other bumblebees or not. These findings may well apply to honey bees too. See the Nature.com article ‘Bumblebees sense electric fields in flowers‘ for more information on this discovery.

Coffea flowers

Another major finding reported during 2013, again in Science, is that some plants, for example the coffee plant (Coffea), use caffeine to manipulate the memory of bees and tempt them back. Their nectar contains low levels of caffeine, which appears to enhance the long-term memory of bees for where those particular flowers are located. The plants benefit from repeat bee pollination by producing more fruits and seeds. Read more about this on the National Geographic website – ‘Bees Buzzing on Caffeine‘.

Their work methods…

To collect nectar bees land on the flower, insert their proboscis inside, and pump nectar up into their mouths. Sometimes the bees can cheat the flowers by gaining their nectar reward without picking up any pollen, for example bumble bees occasionally chew holes in the side of blueberry flowers to get at the nectar and honeybees take advantage of these holes afterwards.

There are many different ways of pollen collection:

  • Open flowers – petals are arranged in a broad, open cup around the flower’s pollen organs. the bee bites the anthers, which produce the pollen (male reproductive cells) with her mandibles and uses her forelegs to pull the anthers towards her body. Examples of this are orchard flowers like apple, cherry, pear, plum.
  • Tubular flowers – bees insert their proboscis into the flower’s central nectariferous areas searching for nectar; as they do this pollen gets stuck to their mouthparts and legs.
  • Closed flowers – bees force the petals apart with their forelegs and gather pollen on their mouthparts and legs.
  • Spike or catkin flowers – bees run along the spikes or catkins picking up pollen on their body hairs.
  • Presentation flowers – bees press their abdomen against infloresence marks, causing a pollen mass to be pushed out of the flowers.

Honey bees are particularly efficient pollinators because they tend to return to the same flowers each day as long as there is a good nectar flow. They will visit their crop of choice at the same time each day, as flowers tend to release nectar at a particular time, for example chestnut trees produce morning nectar.

Below is a bee on an apple flower…unfortunately apple nectar is  low in sugar for a spring blossom and not very attractive to bees. However, the pollen, which is a greenish to pale yellow colour, is useful.

References:

  • ‘The Foraging Honey Bee’, JJM van der Steen, BBKA News, February 2015, p.43-46
  • The Honey bee Around & About, Celia F. Davis (Bee Craft Ltd, 2009)
  • Plants and Honey bees: Their relationships, David Aston and Sally Bucknall (Northern Bees Books, 2009)

More revision/Module 6 themed posts:

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5th Honeybee behaviour revision post: bee communication

Posted on March 15, 2011 by Emily Scott

Another revision post for my BBKA Module 6 Honeybee Behaviour exam on Saturday.

Section 6.5: the methods of communication used by the honeybee including food sharing (trophallaxis), dancing, scenting and vibration;

Of all the ways human beings communicate, probably the only one we have in common with honeybees is dancing. We don’t generally regurgitate food into each other’s mouths or waggle our bum in the air to release pheromone messages, for which we can all be grateful.

In bee world, the main communication methods between one bee and another are:

  • Trophallaxis (fancy word for food sharing)
  • Pheromones
  • Dancing
  • Vibrations

Many of these can occur simultaneously, for example during the waggle dance foragers will offer other bees a taste of the nectar source.

The world of bees: the colony is in constant communication

Trophallaxis

A Greek commenter below has kindly explained that ‘trophallaxis’ is an ancient Greek word over 5,000 years old, from the words trophi (food) and allaxis (exchange). Thanks Alex!

One of the ways a guard bee patrolling the hive entrance recognises fellow colony members is the colony’s common smell. Experiments using coloured nectar have found that within 24 hours of nectar being brought back by just ten foragers 50% of the colony had the nectar within their honey stomach. If several colonies are close by and sharing large areas of a single crop such as rape, they will often become irritable because lots of drifting occurs and they cannot tell each other apart.

Trophallaxis more often takes place by an older worker giving to a younger worker rather than vice versa. One bee will beg from another by pushing its tongue towards their mouth parts. The giver bee will respond by opening her mandibles, regurgitating a drop of nectar and pushing it forward on her tongue.

During trophallaxis the antennae of the two bees will touch, allowing them to pass on scent messages such as queen substance.

Pheromones

Smell is as useful to bees as sight is to humans. They live in a world of scent which we unfortunately have reduced and polluted by introducing cars and concrete where flowers once wafted their heavy perfume into the breeze.

Pheromones were only discovered in the 1950s and are substances which are secreted to the outside by an individual and received by a second individual of the same species, in which they release a specific reaction which may be behavioural, developmental or physiological. Some important honeybee pheromones:

Pheromones which are attractive to bees…

  • Queen substance, mainly made up of the queen’s mandibular 9-oxodec-2-enoic acid (9-ODA) secretion, which attracts drones on mating flights, keeps the colony calm and inhibits workers laying.
  • Open-brood pheromone – really two pheromones, brood ester pheromone (BEP) and E-β-Ocimene – is a pheromone given off by uncapped brood. It is attractive to workers and they are loath to leave uncapped brood, so can be used as a way to encourage a newly captured swarm to stay. It also has the effect of suppressing workers’ ovaries, preventing laying workers. Read more about this on Rusty at Honey Bee Suite’s blog post ‘What is open-brood pheromone?‘
  • Nasonov pheromone, a lemony aroma which is released by workers raising their abdomens in the air to reveal their Nasonov glands and fanning their wings to disperse the scent. It is used to mark scentless locations such as water or a new colony location. I have seen my bees do it when their hive was moved a couple of feet, presumably to help returning foragers find their way home. Similarly, when a virgin queen leaves the hive to mate, workers will mark the entrance with Nasonov pheromone to guide her back.A chemical called Geraniol is part of the scent produced by the Nasonov gland. It is so alluring to bees that they can be side-tracked while flying even by something as visually unappealing as a fishing line which has had its end dipped in geraniol (BBKA News, April 2018, p.117). Its seductive smell is also used by waggle-dancers to mark their flight trails and the flowers they lead recruits to.
The Nasonov gland being revealed at the tip of this bee’s abdomen
Nasonov gland scenting

 

Pheromones which are unattractive warning signals…

  • Isopentyl acetate, the primary alarm pheromone from the honeybee’s sting gland, a strong banana like aroma which attracts all the other bees to come and sting you. Queens and young worker bees up to three days old do not produce it.



Pheromones which are defence mechanisms…

  • 2-heptanone is a pheromone produced from the worker mandibular glands. Until as recently as 2011, it was thought to be an alarm pheromone used by guard bees to ward off robbers or used by foragers to scent-mark recently visited and depleted flowers.

However, 2012 research by a team of researchers from Greek and French organisations in collaboration with Vita (Europe) Ltd, the UK-based honey bee health specialist, has contradicted these theories. Their work uncovered for the first time that the compound has local anaesthetic properties. Independent tests have verified these findings.

Astoundingly, honey bees can use their mandibles to bite smaller parasites like varroa mites and wax moth larvae, in the process secreting 2-heptanone into the bite wound. The compound’s paralysing effect works for up to nine minutes, giving the time bee to eject the enemy from the hive – a particularly effective defence against pests which are too small to sting.

The ‘grooming’ behaviour which some beekeepers believe helps ‘hygienic’ honey bees to control varroa populations may reveal itself to be biting behaviour.

For more on this fascinating discovery:

Dancing/vibrations

The waggle dance is the famous one, but there are many different types of bee dances: round, transition, buzzing runs and the DVAV (dorsoventral abdominal vibrating dance).

The most amazing thing is that these dances are done in the dark of the hive. The bees rely not on watching the waggle dance but on feeling its vibrations to understand the complex information contained. Their Johnston’s organs at the base of their antennae pick up movement and vibrations and are most sensitive in the range of 200-350Hz. There are other similar vibration sensors in many of their joints, particularly in their legs. Whilst walking around on comb, bees are constantly experiencing the vibrations produced by the colony.

One of the simplest dances is the round dance, used to tell other foragers that there is high sugar content food somewhere within 15m of the hive, and to go out and find it. No indication of direction is given. It’s the dance that encourages robbing if a silly beekeeper leaves some honey out in the apiary.

The transition dance is usually given if food is between 15 and 100m away. It’s half way between a round dance and a waggle dance. Some species have a slower transition dance, others more direct.

The well-known waggle dance tells bees where food sources over 100m are located. It’s a figure of eight shape with the waggle in the middle. The dancer will stop to exchange the nectar she’s collected with watching workers so they know what they’re looking for.

The direction of the dance relative to the vertical face of the comb indicates the direction of the nectar or pollen in relation to the sun. As honeybees can perceive polarized light, the sun does not have to be shining for the dance to be successful. The nearer and more high quality the forage, the faster the dance and the more waggles in the middle.

Waggle dance diagram:

The DVAV (dorsoventral abdominal vibrating dance) is believed to be ‘get a move on’ message. A worker will mount or grab another bee and vibrate their abdomen on top of her. It’s used to recruit more foragers during a nectar flow and also on queens just before a swarm exits the nest.

The buzzing run seems to be an excited dance. The worker runs through the colony buzzing her wings. Other workers she runs into will pick up her movement and start running around buzzing too. It’s used as a signal for a swarm to exit the hive or take off once a new home has been found.

The shaking dance is thought to be a grooming request. A worker will stand on the spot shaking her body from side to side until another worker runs over and nibbles the difficult-to-reach spot between the thorax and abdomen.

References:

  • ‘Fragrant clues: Geraniol points the way’, Jurgen Tautz, BBKA News April 2018, p.117
  • ‘Honey factory‘ – this post on ‘The Prospects of Bees’ blog has some interesting notes on honey bee dances, taken from a 2013 lecture by Dr. Thomas Seeley, a Professor in the Department of Neurobiology and Behavior at Cornell University and renowned bee genius.
  • ‘Honey bee pheromones: common scents’ by Rusty Burlew, Honeybeesuite.com, February 2016 – explanations of honey bee pheromones, in alphabetical order by common name.
  • Why do bees buzz’, Dan Basterfield, BBKA News October 2013, p.13

More revision/Module 6 themed posts:

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4th Honeybee behaviour revision post: social organisation of the colony

Posted on March 14, 2011 by Emily Scott

Another revision post for my BBKA Module 6 Honeybee Behaviour exam on Saturday.

Section 6.5: the social organisation of the honeybee colony including worker policing

Honeybee colonies rely on large numbers of more or less sterile individuals working together to raise young and look after the colony’s needs on behalf of a few reproductives, the queen and the drones. The colony system is based on individuals belonging to one of three castes, with labour divided up accordingly…

The Queen:

The star of the show, the colony’s egg laying machine.  The diploid (two sets of chromosomes) queen lays day and night during the spring and summer, with only short breaks to feed and rest.

Queen Lavender perched on Emma's finger

The queen has certain weapons to keep the egg laying to herself. 9-ODA (9-oxodec-2-enoic acid) is the main component of her ‘queen substance’ pheromone mix which inhibits the workers building queen cells and worker ovary development. The system usually works well, with a queen-right colony having on average only 0.1% of the workers producing adult males and only 0.01% of the workers having full-sized eggs in their ovaries.

Should the colony lose its queen, the absence of queen substance and a lack of pheromone given off by growing brood will cause the workers to raise a final set of drone sons. Eggs laid by workers can be spotted because their abdomens are too short to reach the bottom of the cell, so the eggs will be stuck to the side. More than one egg may be laid in a cell and they are laid in a haphazard, spotty manner rather than the methodical, neat laying pattern of the queen’s rows of eggs. In a queen-right colony workers will police the eggs, removing and eating eggs laid by their worker sisters because they will not smell of the queen’s pheromones.

A queen’s pheromones also stimulate comb construction and foraging in general, particularly for pollen. The minimum number of worker bees required to be together before comb building begins is lowest (50 bees) in the presence of a laying queen and progressively increases in the presence of a virgin queen (75 bees) and a dead queen (200-300). Queenless bees build no new comb no matter how big the colony is.

A honeybee queen and her court. The workers take it in turns to feed, lick and groom the queen, picking up some of her pheromones as they do so. They will then go on to touch other worker bees, helping to distribute queen substance around the colony.

The Worker:

Also diploid, workers live for about 40 days in the summer, taking on jobs in a sequence moving gradually out from the brood nest into the outside world. Winter worker bees can live for several months as they spend most of their time clustering in the hive, conserving their energy so they can survive to spring.

Bee on blue flower 2

The Drone:

The laziest colony members, drones are male and haploid, possessing only one set of chromosomes from an unfertilised egg. They have no father, only a grandfather. Although drones make little contribution to everyday colony life, their only purpose being to mate with a young queen, some beekeepers feel the workers like having drones around and handle differently if drones are removed. There is also some evidence that their large bodies can help keep brood warm in cold weather. 

To help them fulfil their role as mating machines, drones are big with strong abdominal and flight muscles. They have larger antennae carrying ten times as many sense organs as those of a worker, helping them detect the wafting pheromone of a young queen up in the sky. Having found a queen by scent, the drone’s enormous eyes come into play, helping him keep her in sight as he flies up behind her for mating.

Drones will often pay visits to neighbouring hives, perhaps in the hope that they may find a virgin queen to get a head start on the chase once she leaves.

A handsome drone in prime mating condition, his chunky thorax almost looking like a lion’s mane. Was he successful? We’ll never know.

Drone face

More revision/Module 6 themed posts:

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More revision & shook-swarm notes

Posted on March 13, 2011 by Emily Scott

One of the Ealing beekeepers, Andy Pedley, kindly gave me a lift to a BBKA module exam revision session held in Harrow yesterday – the exam is next week, eek! The lady running it, Jo Telfer, was really nice and went through some of the Module 6 past questions with me. She got us all to sit and try writing our answers to one of the essay style questions for half an hour, which was very helpful. She pointed out that timing is very important and we mustn’t be distracted by spending too long on questions not worth many points. Also writing essay plans in the margins is a good idea so examiners can see what you would have written about if you run out of time.

Went down the Perivale apiary afterwards to check on my bees. They were as busy as ever, the fondant Pat gave them three weeks ago was nearly completely finished and the foragers returning to the hive had all sorts of different colours in their pollen baskets. Here’s some pics…

Close up top view

If you look carefully at the bees below you can see the different pollen colours, from bright yellow on the mouseguard to oranges and browns on the bees higher up. Also the difference in the colour of individual bees, the madam flying in on the far left has quite a amber upper abdomen whereas many of the others are much darker, which suggests they probably had different drone fathers.

 

12th March 2011

After taking this photo I removed the mouseguard, as Jo told me she’s just taken hers off as it’s safe to do so now and it brushes some of the pollen off the bees as they come back in.

As if that wasn’t enough beekeeping activity for the day, I then went on to the monthly training session which the Ealing beekeepers have. We were mainly talking about the shook swarm we’re doing at the apiary next week, after which Pat gave us a talk on queen rearing.

Shook swarm notes

  • The Beebase website has a free downloadable shook-swarm factsheet which is worth bringing with us and following step-by-step
  • Bees on new comb do better than bees on old comb, which is why we do a shook swarm or Bailey comb exchange at the apiary every spring
  • We need to shake each colony into a hive we have prepared with a open mesh floor, a queen excluder on top of the floor, a brood box with eleven new frames (if a National hive) and a dummy board, a crown board and a roof
  • Also need 2-1 spring strength sugar syrup ready, made from white granulated cane sugar
  • After finding the queen and shaking bees into their new hive need to keep coming back to replace the sugar syrup, which they will sometimes consume in a day
  • Do on a nice warm day, preferably 15C but 12C upwards would do
  • Can cut out any honey stores in brood before burning the frames if you want to make mead or honey marmalade
  • The queen should be laying again within a week, after which you can take the queen excluder away
  • Can remove first 1-2 frames of brood the queen produces if you want to destroy as much varroa as possible, but this will delay your colony’s development

So next Saturday will be busy – Module 6 Honeybee Behaviour exam in the morning, followed by a Shook swarm with an unmarked queen in the afternoon if the weather’s warm enough. Don’t know which I’m more nervous about!

See also:

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Fondant munchers

Posted on March 5, 2011 by Emily Scott

Mixed emotions at the apiary today. Happiness because my bees are doing well, sadness because we looked at more dead hives today.

Bear in mind that the last lot of fondant I put on took two months for my bees to eat, and now look what they did to the new fondant block in just two weeks:

fondant

They’re really going for it! And bringing lots of a light brown/grey biscuity pollen back:

Anyone know what this pollen might be?

Wikipedia has a pollen colour chart, check out this blue Siberian squill pollen:

Sadly one of the apiary beekeepers, Stan, discovered today that one of his two colonies had died. I never know what to say when someone loses their bees, it must be so disheartening after the hard work put in during the year. There was a lot of dysentery so nosema may be to blame. A beekeeper with a microscope at home took one of the pooey frames with him to analyse. There were plenty of stores and it was a big colony so it wasn’t starvation or cold that was to blame. Another beekeeper’s nucleus had been invaded by mice which had eaten the honey out of the frames, even though the entrance hole was tiny.

We’re going to be shook-swarming at the apiary next week if the weather’s warm enough, but it’s been so cold lately we may have to wait another week.

A final link: http://www.beesinfrance.com/2011/black-white-bees/ – these photos of a black & white French Ashy Mining Bee are stunning, I’ve never seen anything like her. We need to look after our solitary bees too!

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Honeybee & Bumblebee talk notes

Posted on February 27, 2011 by Emily Scott

On Saturday I helped out with the food at a seminar held by the Ealing & Harrow beekeeping associations. Baklava went down very well with the beekeepers, even though I cheated and used Cornish honey rather than Greek. Here’s a few notes I took from one of the talks by the brilliant Dr Juliet Osborne…

Dr Juliet Osborne, Dept of Plant & Invertebrate Ecology, Rothamstead Research Institute. ‘Honeybees & Bumblebees – what is happening to them?’

Pollination value

87 of the world’s crop species require bee pollination to some extent – 35% of global food production (Klein et al, 2007). These species include most fruit crops (especially orchard fruits), salad crops (e.g. courgettes, peppers, tomatoes etc), seed & oil crops (sunflower, rape, beans) and some crops which may surprise people (coffee, cocoa). It’s hard to estimate the value of bee & insect pollination to the UK crop market, but estimates vary from between £200m-430m.

Are bees dying out?

Because there have been many stories on Colony Collapse Disorder and disappearing bees in the media over the last couple of years, many people have the impression that honey bees are dying out or at least reducing in number. In fact the situation is more complicated that that. A recent study by Aizen & Harder (2009) found that globally, honey bee stocks are actually increasing (see abstract: http://www.cell.com/current-biol…. However they also found that we’re becoming more dependent on crops that depend on animal pollination, which may cause problems with global pollination capacity.

In some places honey bees have indeed declined – the UK, USA, USSR, Germany. But in others stocks have risen – China, Argentina, Spain. There have been no reports of high colony losses in the Southern hemisphere – South America, Africa, Australia – which are areas with either no or lower varroa levels. There is some evidence that high losses are perhaps associated with varroa & its associated viruses. Promising anti-varroa discoveries have been made recently, so hopefully in the future we might be able to better control it.

Dr Osborne’s work…

Bees have a variety of stresses in their lives, both inside the hive (e.g. beekeeper’s interventions, varroa mites, disease) and outside (e.g. pesticides, bad weather, lack of available forage). Dr Osborne and her team are currently carrying out a three year project looking at how these inside and outside factors combine to affect bees. They track foraging bees using tiny 16mm aerials which only weigh 3mg. When the forager arrives back at the hive they remove the aerial so she doesn’t get stuck inside!

The team are only into the first year of their project but have already made some interesting discoveries from their radar data. Having radar tracked the first orientation flights of young bees, they found that bumblebees start by doing complex loops and only do 1-3 practice flights before starting foraging. In contrast, honey bees do very simple loops and take up to 18 practice flights before foraging. It may be that honey bees follow waggle dances even in their first flights, explaining the ‘there and back’ simple loops.

Bumblebees are important too…

Sadly, in the UK most bumblebee species have decreased in range and one may be extinct. Many species are now only present in the West country, South East and Norfolk. There are about 23 species of bumblebees in the UK, six of which are common. Bumblebees don’t store honey, so they are very vulnerable in spring to changes in the weather, although they can forage in cooler temperatures than honey bees. They need plenty of food and undisturbed nesting sites, having a particular preference for vacated small animal nests. Some nest underground in shortish turf; the most vulnerable are the surface nesters, whose nest will be destroyed by any management of the turf.

We have one newcomer here, the handsome ‘tree bumblebee’, Bombus hypnorum. It was first seen in 2001 near Southampton and has since spread rapidly northwards. It loves living in bird nest boxes and can unfortunately be quite aggressive compared with our native species, sometimes stinging without provocation. A pic of Bombus Hypnorum (see more on the BWARS Bees, Wasps & Ants Recording Society website):

Dr Osbourne reminded us that gardens are good habitats for bumbles. They like undisturbed, un-mown areas best, in tussocky grass. Old bird boxes and compost heaps are also good. In her opinion, the bumblebee bee boxes you can buy from garden centres just don’t work! So those of us with gardens should be letting them grow as wild and messy as possible if we want to encourage bees and other wildlife. As beekeepers we should be encouraging the public to keep any unwanted bumblebee nests in their gardens, and if they cannot be persuaded, try to move the nest to somewhere suitable. This is best done at night when most of the bumbles will have returned home.

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3rd Honeybee behaviour revision posts: the queen’s egg laying behaviour & seasonal variations in the size of a colony

Posted on February 20, 2011 by Emily Scott

On with the revision posts for my BBKA Module 6 Honeybee Behaviour exam. I’m trying to work my way through the 21 sections on the syllabus, but the exam date is March 19th, so I’d better start doing more than one of these a week!

So, section 6.3: the queen honeybee’s egg laying behaviour and its relationship to changing circumstances in the hive and external factors relating to climate and season;

and, since it’s related…

6.4: the seasonal variations in the population size of a honeybee colony and an explanation of such variations;

Queens can mate up to 4 weeks after they emerge; after this time it is too late for a queen to mate and she becomes a drone layer. Given good weather, queens generally mate in the first 2 weeks of their adult life. 

Once the queen has mated, she soon begins laying eggs, usually within the space of a week after mating. So a good young queen should be mated and laying eggs by 21 days after emerging; but allow an extra week if the weather has been poor. 

Queen Rose

One of our 2011 queens, Queen Rose

Her two ovaries are enormous compared to a worker bee’s, with each of the ovaries consisting of 150-180 egg producing ovarioles, compared to 2-12 in a worker ovary. Her spermatheca can hold up to seven million sperm, and it usually takes 2-4 years after mating before all the sperm are used up.

She inspects each cell carefully before backing into it and producing first a sticky substance for the egg to stick to and then the pearly white cylindrical egg, laid at the bottom centre of the cell in a standing position (a laying worker’s abdomen will not reach the bottom of the cell, only the cell sides). Think of her as a bee version of Kim & Aggie from the Channel 4 show ‘How Clean is Your House’, as she is extremely picky about how well the worker bees have cleaned the cells and will not lay into one which has not been cleaned to her satisfaction.

She uses her forelegs to judge the size of the cells built by the worker bees – worker cells are smaller, drone larger. If the cell size is that of a worker, she will release a sperm on top of the egg she lays. If no sperm is attached to the egg, it will develop into a drone. After each egg is laid she moves onto the next cell and repeats the process. It must be an extremely monotonous life after the excitement of flying high in the sky for her triumphant mating flights.

Seasonal differences

A young, well-mated queen’s laying rate depends on a few factors:

  • supply of food, particularly pollen
  • seasonal factors, such as temperature
  • if the colony is going to swarm soon

Winter – spring

The colony huddles together in a ball shape during winter, keeping the queen warm in the centre. The colony’s population will drop to around 10-15,000 and the queen will be laying very few eggs, because only at the centre of the cluster will the colony be able to keep brood warm enough.  In the UK there is likely to be a broodless period during December and possibly longer, during which time the bees can drop the cluster temperature to 21-24°C.

Even within the depths of the cluster, the worker bees can sense the minutes of daily sunlight beginning to increase following the shortest day of the year, the winter solstice on 22nd December. Within a few days of the solstice, they will slowly begin to raise the cluster to a warmer brood-rearing temperature of 34-35°C. This increase in warmth triggers the queen to begin to lay a small number of eggs.

As plants begin to flower in early spring, and workers return laden with the first spring pollen, the queen’s lay rate increases. This increase will only be interrupted by periods of poor weather. A colony trying to raise brood in the winter, before the first flowering plants appear, will need to rely on good supplies of pollen collected during the previous season.

Another of our 2011 queens, Queen Lavender

Another of our 2011 queens, Queen Lavender

Spring – summer

In the UK the main nectar flow is often over a short three-week period in May-June. As long as enough pollen is being brought in to produce brood food, at the height of the season the queen may lay more than 1,500-3,000 eggs a day, depending upon her race and strain – more than her own body weight in eggs. Apart from short rest periods of 5-10 minutes, she will do this round the clock. Laying such a huge amount of eggs takes a great deal of energy, so a ‘court’ of workers follow her around supplying her with food. The colony should soon have between at least 30,000-60,000 bees, causing a high-risk of swarming, which will reduce the colony population by up to 50% or more if there are after swarms.

Summer – autumn

After peaking in May-June the queen’s lay rate will start to drop off from July onwards, as the colony switches to concentrating on building up stores to survive the coming winter. As less brood is being laid, and workers live for about 40 days, by mid August there is a rapid reduction in worker population. There will be less available forage and the temperature will cool as winter arrives. Over the winter she will either lay very few eggs or stop laying completely.

Swarming

It is the worker bees who make the decision to swarm, usually as colony population peaks. In the week before swarming they starve the queen to reduce her size and get her light enough to be able to fly. They also act as particularly vicious personal trainers, chasing her around the frames and shaking, pushing and biting her to force her to keep moving. The reduction in food and weight loss causes her egg laying rate to fall before she leaves with the rest of the swarm.

References:

  • Celia Davis, 3,6,12 and Counting, BBKA News, April 2013, p9-10. 
  • Dan Basterfield, Very Simple Queen Rearing, BBKA News, April 2013, p19-20

More revision/Module 6 themed posts:

Posted in Bee behaviour, Bee biology, Exams, Queens | Tagged , | 7 Comments

Dead bee inspecting, shook-swarming and bees in Oman

Posted on February 12, 2011 by Emily Scott

Last week it was cold and wet and no bees were to be seen. Today was surprisingly warm, and taking a look at the floods of bees zooming into hives around the apiary I decided to put my bee suit on.

crocuses

There were loads of my lot hob-nobbing on their front porch, smeared with a bright yellow pollen – possibly from the snowdrops or purple crocuses which have sprung up around the apiary? To my horror, I found when I popped my head in the hive that they had completely finished off their fondant. Luckily Pat, one of the many nice Ealing beekeepers, has some at home which he sold me; he’s going to pop it in my hive when he goes down to the apiary on Tuesday.

pollen covered bees

bee close up

Went on to the monthly meeting the Ealing Association has in a local scout hut, every second weekend in the month. This week John Chapple (the Queen’s beekeeper!) brought in a hive from his garden, which had sadly died (a living, or not-so-living example, as he put it!). He wanted us to try and guess what had killed them off. A lot of dead bees had fallen through to the floor, where something had eaten off their heads. Some earwigs spilled out of the hive still wiggling away, but the gardeners amongst us pointed out that earwigs are vegetarian, so spiders got the blame for the beheadings. John eventually gave us his opinion that the cluster had got split into two, causing them to die of cold. There were plenty of stores but not enough bees to form enough of a cluster. John pointed out that with most of his hives he punches a hole through the centre of each frame to allow bees easy access through, which he hadn’t done with this one.

Next we were given a reminder about how to do the ‘shook swarm’ procedure which we need to carry out at the apiary sometime in March. The National Bee Unit have on their website a free step-by-step pdf factsheet on how to do this. Very basically it involves shaking your bees into a new hive with new frames of foundation and burning all your old frames, in order to help prevent disease. Since everyone at the apiary started shook swarming about four years ago there hasn’t been a case of European Foul Brood, whereas before it used to reoccur almost annually. I’m a bit nervous about doing it, both because the bees aren’t necessarily grateful for being shaken into a new home and because my queen is unmarked, so I hope I can find her. If you shake a queen in you risk damaging or losing her, so you’re supposed to find her first and keep her safely in a queen cage in your pocket.

Finally John gave us a fascinating talk about his travels to see bees in Oman. There are not enough bees to pollinate the palm trees there at the moment, so the palm trees are being pollinated by hand by cheap labour. The government is therefore keen to encourage beekeepers, and providing someone has passed an exam will supply them with free queen cells. Bees are also valued for their honey, which fetches a great price over there. This is partly because Omani bees are smaller and produce much less honey than western Apis Mellifera honey bees – about a frame and a half of honey per hive a year. The bees are usually kept in a single box with no supers as they do not need extra space for stores. John said the Omani government are extremely well-informed about bees, as they recognise that their oil will eventually run out and they may need to fall back on their previous top exports, dates and limes.

Bees in Oman face several difficulties ours do not here, from the danger of the heat rising to levels at which their wax melts to persistent predators such as giant hornets and ants. Omani hives have hornet traps and their legs stand in pools in oil to prevent ants climbing up. The traditional way of keeping bees is in hollowed out palm trees, but nowadays most beekeepers use Langstroth style hives. John has taken lots of photos and the plan is to have a little slide show, so I will look forward to seeing those.

This isn’t related to anything above, but I found this great photo on the internet of a man far braver than me:

Posted in Colony management, Disease prevention | Tagged , , , | 5 Comments

2nd Honeybee behaviour revision post: honey bee mating

Posted on February 6, 2011 by Emily Scott

Revision post for this week: section 6.2 of the BBKA’s Module 6 syllabus –
the mating behaviour of the honey bee queen and drone including an account of the pheromones involved and the concept of drone congregational areas

Virgin queens are sexually mature and ready to mate within 5-6 days of emerging from their queen cell as an adult bee. They then have four weeks to find some suitors; after that period they are no longer able to mate. As long as the weather is warm enough (preferably between 21 to 27°C and little cloud cover) the queen will go on one or more mating flights. She is encouraged out by the workers, who may treat her roughly by vibrating her up to 1200 times an hour or pulling at her wings. She is no one-man romantic; quite the opposite, she likes to have liaisons with as many drones as possible, mating with an average of around 13 in total.

Flight timings

Drones from several hives, up to 6km away, will fly up on a sunny summer day to await their fate in drone congregation areas (DCAs) 10-40 metres above the ground, much higher than foraging worker bees fly. There can be as many as 10,000 drones in a single DCA and there are usually several DCAs for a Queen to choose from within flying distances of apiaries.

Drone flights take place in the afternoon, generally beginning about one hour before virgin queens take their nuptial flights (Ruttner 1966). When drones reach the congregation areas, they remain flying in wide loops until they are depleted of energy stores and need to return home to feed. Only queens within the areas attract their attention; outside of the areas, virgins are ignored (Ruttner and Ruttner 1965a, 1966). For a rare film of drones whirling in the air after the queen, see this Russian YouTube video: www.youtube.com/watch?v=hAzZHdX0k2E.

The drone: big, butch & beady eyed

Drone face

DCA locations

There are still many unanswered questions as to how the drones decide on the DCAs, but each generation of drones certainly seem to choose the same spot year after year. There is a DCA over Selborne Common in Hampshire (south England) that was first described by the well-known naturalist Reverend Gilbert White in the 1700s. It still reappears in the same place each year and can easily be heard on a fine summer’s day (A Practical Manual of Beekeeping, David Cramp, 2008).

How do the drones find the DCAs? Older boys cannot be showing them the way, as any drones still alive and unmated at the end of  the mating season in autumn are turfed out of the hive by the workers, to die of exposure and starvation. The DCAs tend to be over open ground and sheltered from the wind, but some are not. Following experiments with a queen pheromone lure on an extra-long fishing rod in 2015, beekeeper blogger Turlough concluded that “A local rise in the land, no vertical obstructions and the presence of a breeze” were common features of the DCAs he discovered (In search of drone congregation areas’, Turlough, Beecraft magazine, December 2015).

It’s even possible that the earth’s magnetic field is important, as drones develop large quantities of magnetite in their abdomens (magnetite is a naturally magnetic iron oxide which can respond to magnetic fields). It is an area of bee behaviour which could do with further research.

The great chase

The congregating suitors are attracted from several metres away by a virgin Queen’s pheromones (from her mandibular glands within 100m & tergite glands within 30cm), forming a black drone ‘comet tail’ behind her as they chase her though the congregation area. Drones also have huge bulging compound eyes which help them spot as well as smell the Queen.

Then comes the exciting bit – when within sight of the Queen’s behind, a drone will approach from below to catch the queen with his legs, impregnate her and then flip back, breaking his endophallus which explodes spectacularly, releasing his sperm into the Queen’s sting chamber. How a drone looks post mating….

It’s all over for the drone within seconds, and he falls to the ground dying. I can’t help wondering – does the drone anticipate his fate? Or does it come as a bit of a shock? Amazingly, the drone’s left behind endophallus in the queen’s sting chamber glows, emitting ultraviolet (UV) light which attracts other drones to come and get her. See Chris Slade’s Bee Blog for a spectacular sonnet on the life and unfortunate death of the drone (I’m nearest, what is there to lose?/Got her! I’ll mate with all my might/WOW!!!/OWWW!!!!).

The queen’s prize

Immediately after mating, the oviducts of a queen contain an average of 87 million sperm and a maximum of up to 200 million, although when full her spermatheca contains only 5.3 to 5.7 million sperm, which represents contributions from all the drones which have mated with her. Intriguingly, research has shown that worker bees back in the colony will pay more attention to a queen that has mated with a large number of drones than to one which has mated with fewer, and that they will more readily accept her – there are pheromonal differences which they can detect. The queen will lay between 175,000 and 200,000 eggs annually, so as long as she is well mated the sperm she receives as a young Queen lasts long enough to fertilise worker eggs for the rest of her average lifespan of less than four years.

Director Markus Imhoof has successfully managed to capture a remarkable 36 seconds of footage showing a queen bee mating high up in the air: Queen bee wedding flight video. The drone grasps the queen and strains to bend his abdomen forward to reach hers…

The queen bee grows fat on royal jelly
So she can grow eggs in her belly.
Her suitors she’ll goad
Till their testes explode.
What else could she do, without telly?

(Extract from a limerick by Elissa Malcohn, for Bug Girl’s Ribald Limerick Contest 2011: http://membracid.wordpress.com/2011/11/14/ribald-tales-of-entomology-limerick-contest-1st-runner-up.)

References:

  • A Practical Manual of Beekeeping, David Cramp (2008)
  • ‘In search of drone congregation areas’, Guest Beekeeper Blogger Turlough (Beecraft magazine, December 2015, p.7-9)
  • Mating Biology of Honey Bees, Gudrun Koeniger (2015)
  • ‘Rediscovering the first drone congregation area‘, Turlough (vita-europe.com, August 2015 blog post) – includes a nice recording of the sound of the drones and links to other posts in the series.

More revision/Module 6 themed posts:

Posted in Bee biology, Exams, Queens | Tagged , , , | 4 Comments

1st Honeybee behaviour revision post: bee jobs

Posted on January 28, 2011 by Emily Scott

This is a revision post for the BBKA Module 6 Honeybee Behaviour exam. I’m trying to work my way through the syllabus, one section at a time. Starting at the beginning:

6.1 The candidate shall be able to give a detailed account of: the function and behaviour of the worker honeybee throughout its life including the types of work done, duration of work periods under normal circumstances and the variations in behaviour due to seasonal changes in the size of the colony.

First days

When a worker bee emerges, all soft and fuzzy, one of her main priorities will be eating pollen from nearby cells. The protein in pollen is important for developing her hypopharyngeal (they don’t make these names easy) & mandibular glands, which will produce brood food and royal jelly, as well as her wax glands. Between pollen eating she will help out the colony by beginning in days 1-3 with the simple tasks of cleaning the cell she emerged from and those around it (which takes hive-proud bees longer than you might imagine – about 41 minutes a cell, with about 15-30 worker bees helping out) and, if necessary, brood incubation by sitting on top of capped brood cells.

Bees hanging out on a comb.

Wave your bum in the air like you just don't care

Moving outwards

About days 4- 6 she will progress to becoming a Nurse bee, feeding young larvae with the brood food secreted from her glands and older larvae with additional honey & pollen. If it is swarm season, or the bees decide to supersede the existing queen, she may be helping raise queen larvae, which will receive large amounts of protein-rich royal jelly.

By around 10-12 days old her wax glands will have developed and she can begin wax making, along with processing honey into nectar, pollen packing and temperature control duties such as fanning in hot weather. She may also be an undertaker bee, removing dead bees and other debris from the hive. By days 16-20 her hypopharyngeal gland decreases in size and begins producing invertaze and glucose oxidase, enzymes required for honey production. Her body is getting ready to forage.

Bees on a frame of pollen.

Out and about

Our bee has progressed from spending most of her time in the centre of the brood nest to moving further out on the comb for wax building and food handling duties. She will spend days 19-21 on the edge of the nest, fanning or guarding the entrance and making longer orientation flights than previously – she has become an outside bee. Her body is now able to produce the alarm (2-heptanone) & sting (isopentyl acetate) pheromones, along with venom.

She will spend the rest of her life – about another 20 days – foraging for nectar, pollen, water and propolis. The flight distance she accumulates rather than her chronological age seems to do her in, since workers tend to die after flying a total of about 800 km, whether that distance was flown in 5 days or 30. This appears to be caused by exhaustion of the necessary glycogen reserves which accumulate in the flight muscles of young workers; older foragers are unable to produce more glycogen and die of exhaustion.

Bee on blue flower

But bees are very flexible…

Despite the rough time frames given above, the activities a bee carries out are extremely variable and flexible depending on factors such as colony population or the time of year, for example in spring as the colony expands foraged food is mainly eaten by the brood and little honey is stored. If a lot of nectar is being foraged by outside bees, house bees will be encouraged to become receivers and honey makers earlier. However, certain duties such as wax making and entrance guarding are dependent on gland development.

Despite their reputation for being ‘busy bees’ workers often spend a lot of the time resting or walking around the colony, allowing them to react quickly to emergencies or an increase in nectar/pollen flow. Resting or alternating tasks also allows their body time to recover, for example for the wax glands to produce more wax before a bee returns to comb building or for the hypopharyngeal glands and mandibular glands to produce more brood food.

Winter bees

The tasks described above are the life of a spring/summer worker bee. Autumn bees that do not raise young live longer, as the pollen they eat is not used for brood food production but instead increases their body’s fat content, which helps them to live longer as they over-winter. When the temperature falls to about 18C they begin to cluster around the Queen with their heads inwards, contracting the cluster as the temperature drops. They consume honey and shiver their flight muscles in the thorax to generate heat. Once the weather warms and the queen starts to lay eggs again they will begin nursing brood and foraging.

More revision/Module 6 themed posts:

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