How big is a bee’s brain? Clearly much smaller than my ‘pea-brained’ derogatory insult sometimes hurled at siblings in the battles of teenage youth. Although it seems from quite recent archaeological discoveries that one of our ancestor primates (Aegyptopithecus zeuxis) from 29 million years ago, whilst possessing the larger eye sockets, and developing visual cortex indicative of a move to vision becoming the dominant sense, had a brain little bigger than a pea, inside a cat sized body. From which the paleontologists deduce that the much bigger brains typical of all higher apes developed much later on in evolutionary terms, than was previously thought. Click here for more. ( I have few relevant images to accompany much of the text, so please bear with photos from the garden over the last 2 weeks to break up the tedium, and stop you seeing lots of white bands…)
But where has this move to the dominance of visual acuity got us as a species? And what about the bee’s brain? I started to think about this with the annual morning buzz which filled the air outside the front door, very suddenly, on the first day that the tiny Cotoneaster horizontalis flowers began to open. All it needed was a little warmth, and within 15 minutes, the flowers were covered in wasps, bumble and honey bees, probing tongues desperate to find a way into the tiny, still tightly furled flowers… But none of these insignificant flowers had any obvious scent as far as I could detect. And none of these insects would ever have experienced any of these flowers before in their short lives. So what was going on?
It turns out that the attraction trigger for most flowers is not the nectar ( as I’d assumed), but rather distinct volatile organic floral scents released by specialised cells often closely located near the flower’s nectaries. (If you want a more complete explanation of what I’ll now try to precis, then do click here for a brilliant in depth, scientific, though thoroughly readable chapter by Judith Reinhard and Mandyam V. Srinivasan, titled “The Role of Scents in Honey Bee Foraging and Recruitment”.)
The majority of floral odorants are chemicals called terpenoids, but there are also large numbers of alcohols, aldehydes, ketones, and esters. Among theses are twelve odorants that occur in over 50% of all floral bouquets analyzed and are hence regarded as typical floral odorants. Different flower species obviously have different scents. The difference in fragrance can be due to a difference in the mix of these floral chemical constituents, but also in their intensity. A floral bouquet can also vary within a species, depending on the environmental conditions, such as the location of an individual flower, time of day, pollination status, nectar content, and age of the flower.
Honey bees are also exposed to numerous scents within the hive – both complex pheromones produced by the bees within the hive, but also exposure to the scents of pollen, nectar and those lingering on the bodies of the bees returning from foraging. It’s obviously pretty dark within a hive, so these scents are critical cues for much bee behaviour, including the amazing progression of roles that the typical honey bee has in its short 6 weeks or so existence.
Did you know that they can move through a range of tasks before they ever make it outside? I didn’t. Cell cleaning, nurse bee, wax production, honey sealing, drone feeding, Queen attendants, honeycomb building, pollen packing, propolizing, mortuary bees ( a critical role in removing dead bees or larvae well away from the hive), fanning bees ( to regulate the hive’s internal temperature in hot weather), water carrying bees (partly to help cool the fanning bees using a specialised water carrying stomach), guard bees…
And then. Phew! For the last 3 weeks or so of their short lives, actually foraging for food – nectar and pollen. (Click here for more on worker bee tasks).
How they actually detect scents led me to the answer to the question I posed at the beginning. A honeybee brain is a mere 1mm cube size. Yet this, together with the neurological system for scent detection, places it as one of the most accomplished of scent detectors in the animal kingdom, being able to pick up traces of chemical down to one part in a trillion – equivalent to a grain of salt in an Olympic sized swimming pool. And their ability to track a scent plume down by flying upwind and in and out of the plume’s edge in a defined pattern means that they can quickly and easily track miniscule quantities of scent down to an origin source well over a distance of a hundred metres or more.
Moreover their bee brains, and detection systems are very ‘plastic’ and intuitive, and a new scent can be learned within as little as 5 minutes, and then retained for their lifetime. This has led to some interest in their role as potential detectors of drugs, explosives or even in medical work, since they seem capable of being trained to detect scent cues released in people’s breath linked to certain types of cancer, diabetes and tuberculosis. Click here for pictures of an interesting glass chamber developed by a Portugese scientist, Susana Soares which utilises the bees’ sniffer skills. They are also very sensitive to the smells released from animal’s apocrine or sweat glands.
The medical bee training process is typically Pavlovian. Expose them to a new scent, and when they respond to it reward them with a drop of sugar solution. Within 5 minutes, they will have ‘learned’ the new scent and will stick out their tongue whenever they experience the scent in future, expecting their treat.
Their superb olfactory acuity is determined by their scent processing anatomy. Their antennae are covered with specialised sensory pore plates linked to 48,000 olfactory nerve cells. Within the pore plates are about 160 different ‘receptor’ proteins, which will bind to a scent molecule which drifts in through the open pore. As a result of this ‘binding’, a chemical/ionic reaction triggers the linking sensory nerves to fire off impulses, through a system of processing centres – all the different nerve fibres processing a particular receptor protein pore’s reactions, converge on a single centre or ganglion, and eventually to the olfactory centres within that tiny bee brain. Some receptors are specific to single individual bee pheromone chemicals, whereas with floral scents, the sensor receptors are more generalised.
But it now became a little clearer to me that the Cotoneaster flowers, whilst having their own mix of chemical attractant cues, will no doubt be using a blend of chemicals which the bees will already have ‘learned’ from their earlier few days of spring flower foraging, as indicating a good food source.
It seems that with the exception of the occasional individual like Roja Dove, (who I only discovered this week, Click here for more, a British parfumier who claims to be able to detect 800 scents blindfold – and then blends them into perfumes starting at £275 a bottle), our particular line of higher apes have really regressed when it comes to olfactory perception over the humble honey bee, with its miniscule brain.
And I haven’t even ventured into the role of olfactory cues released by plants in their battle against herbivores, which some think floods the world with a range of chemical scent cues which vastly outnumber even those produced by plants in their quest to attract pollinators …(click here for an interesting insight)…
As a ‘higher’ species, how is it that we’re now so divorced from all these olfactory stimuli which are hugely influential in how the natural world that surrounds us goes about it’s daily life?
Do smells really only have a value to us when bought in a crystal encrusted bottle?
Is this evolutionary loss of olfactory appreciation now beginning to come home to roost, with a more general disconnect of our species from our place within the vastly complex ecosystems on our planet?
But all this revelation for me in the role of olfactory cues, came after the event of having to ask our bee keeper to come and remove his hive of honey bees from one corner of our hay meadow. Why?
Well I’d begun to notice that later on in the day of Andy’s roughly weekly visit, clad in protective gear, to check the single hive, I was being charged by guard bees.
Even some distance from the hive.
2 days later whilst filming bumblebees on the flowers in the high meadow I had to abandon the Camcorder after being ‘buzzed’. It’s difficult to describe just how unsettling it is to have a guard, or should it be ‘attack’ bee, approach like this. It’s fast, sounds really angry, and often hits you in the face, in an instant, at speed. Bang. Or BZZZZZZZZ.
No facial hit.
In the end, whether the bees were really a ‘cranky’ hive, or not ( it seems that ‘cranky’ is a favoured term amongst bee keepers to describe such aggressive bees), I felt that they had to go. We still have visiting honeybees in the garden, but I can relax, when outside. I really don’t blame the bees. It was yet another demonstration of their supreme abilities – in this case warding off a much bigger potential predator, from proximity to the hive extremely effectively.
I now realise that such impressive hive defence almost certainly came down to olfactory cues (from my sweat, or possibly a leather hat) that placed me in the same category of Andy with his leather gloves on, who on his weekly visits would regularly end up, with the best will, squashing a few bees during his inspections, and coming away with a few stings in his suit…and consequently all those ‘ATTACK’ pheromones being released by the dying bees. What perhaps made it worse was that he always visited us after first checking out his other hives elsewhere, so his suit was probably really suffused with anger inducing chemicals by the time he got to our hive!
Bee keepers recognise that hives are unsettled for several hours after being opened, and with regular garden work, and hay making shortly, there were genuine safety concerns for me and other garden visitors. So very sadly, and with great irony for someone who has worked for years to create a garden full of insect friendly flowers, it was bye bye bees.
Actually, the garden still has numerous worker honeybees in it, flying in from further afield. Perhaps in time I might feel inclined to put out a bait hive, to try to attract a colony so that we have honeybees around early in the spring, when it’s just too cold for them to reach the garden from a distance. (Click here for a fascinating insight from Amelia on “A French Garden” on how this process of attracting in a swarm can work in practice.)
May 2015 will be remembered here mainly as the month of Cuckoos and Camassias. We’re still lucky in always hearing cuckoos, but this year (after a poor year in 2014), has seen several sightings, but more particularly hearing the male’s territory call on 5 or 6 occasions nearly every day throughout the month, moving in a progression around the fields surrounding us, or flying directly overhead. This is particularly exciting since our work clearing rushes from the lower wet meadows in previous years was, I’m sure, just a temporary disruption for them.
Apparently it’s the rarely seen female bird who actually chooses the territory, but we now realise with their dramatic decline in numbers throughout the UK just how fortunate we are, for now, to hear them so much – in part because the unspoiled terrain roundabout supports sufficient insects and caterpillars to feed the adults, during their brief stay in the UK. Thanks to my brother Mark, who is based in the same college, I was sent a link to the pioneering work of Professor Nick Davies at Cambridge University in establishing much of what is now known about Cuckoo ecology. Click here for a radio discussion about Cuckoos ( starts about 13 minutes into the programme), or here for a link to his recently published book, “Cuckoo, Cheating by Nature” which is now added to my wish list.
The Camassia quamash bulbs planted in the multicultural magic terrace garden last autumn have been a huge delight throughout May. Attracting bees of all sorts, blending in perfectly at the same flowering time as the mossy Saxifrage and Purple Ajuga’s blue flowers, and being just the right height in proportion to this ground cover. They’ve also added interest for that critical period between the end of the tulips, and the opening of the drooping flowers of the Nectaroscordum from their papery sheaths. More are planned for next year to cover the whole central space. But what to do with all the viable seed being produced?
I’m toying with the idea of scattering some in our top meadow, since they’re such a brilliant early insect friendly flower, clearly have huge floral impact and also, unlike many bulbs, aren’t toxic. Indeed the bulbs were considered a delicacy by several Native North American Indian tribes – Blackfoot, Cree, Nez Pierce – and after slow cooking in a heated boulder filled pit for 2 days, they apparently develop a sweet chestnut like flavour as prolonged slow cooking turns the indigestible inulin that the bulbs contain, into fructose. ( Perhaps such slow cooking would also work with Jerusalem artichokes, which contain 76% inulin) Click here, and here for more. Is such a seed scattering a crazy idea? Or might slow roasted Camassias appear at the Lampeter Food festival in years to come …
A simple protective cloche like structure to aid growing Squash and Courgettes outside. Placed over the part manure filled big bags, they should provide a bit of much needed added warmth for these plants which otherwise struggle in this open and sunny, though often windy, location. The challenge has been working out how to prevent the sheets being blown away, whilst being fairly simple to slide off for occasional access. I hope I’ve nearly resolved this. Plenty of water filled bottles internally add an additional heat store. It looks like we’ll have our first courgettes in a couple of days – weeks ahead of what I normally manage.And this in such a cold May that many of our Ash trees are only just beginning to come into leaf, and hail has been falling…Whether there will be quite enough room for them remains to be seen, since I’ve even squeezed in a couple of Pumpkins, in an attempt to save my own seed for bread baking. I was interested to see that my locally sourced health food shop dried pumpkin seed, seems to have zero viability. Why? The same goes for Poppy seed with minimal viability for bought seed, compared with my home saved seed, which has germinated fantastically, between ageing daffodil foliage… Is the bought seed old? Has it been treated in some way? Whatever, I feel that if I can grow my own, at least one will know the provenance and history of what you end up eating.
Finally much effort over the last fortnight has seen me working to set up a fledgling blog/website for the Carmarthenshire Meadows Group. A huge thanks should be recorded for Isabel Macho who, as the county’s Biodiversity Officer, had the initiative to try to get a group formed, and provided me with most of the copy. And translations! The site has just gone ‘live’, so anyone interested could click here. Just as our first Yellow rattle flowers are adding more colour to the interesting mix of plants already flowering in our own meadow. (Speedwell and Lousewort, below)…
Thanks for reading.