There is one major persistent myth regarding the olfactory sensitivity of bees versus humans, and multiple spin-off myths.
Knowing full well that bees don't truly have what we would call a sense of smell, and that they don't sniff like dogs, I will freely use of anthropomorphic terms to describe how smell, bees, and olfaction overlap. People talk about sniffer bees, what bees can smell, etc. Starting with the premise that bees are now known to have multiple sensors for odors, that their odor receptors are paired with other sensors such as temperature and wind (e.g, on in their antennae), taste, and their feet may also enter the odor detection sensor suite, I will take the low road and follow the myth that is often posited as What can Bees Smell?
The myth goes like this:
What Can Bees Smell?
The answer:
Bees have a poor smell!Not much better than that of humans!Except for some floral scents! andPheromones!!
If you believe this, which is oft-repeated, don't worry, you are in good company, but you would still be wrong. Frankly, I think the deceit was intentional.
Most beekeepers and many bee researchers believe this conflagration of research articles. You will see this myth repeated in many forms, in reviews, and books by experts, including Mark Winston who is a bee pheromone expert.
As Jose commented to me in some off-line emails, " I sensed that through the process of serial citation things were being interpreted that may not be correct. Democracy is messy, so is science."
If you think I was dismissing older articles, then I failed to be clear. My point is, people don't read the older articles. They read a citation, and they re-cite, with nary a glance at the articles that they are citing - after all, lots of other people also cited those articles
At the crux of this are two figures (actually three). Karl von Frisch, Karl's wife, Margarete (born M. Mohor), and C.R. Ribbands. Now add in a Nobel prize, WWII, and Lysenkoism (i.e., Creative Soviet Darwinism, also known as the Russian (off-with-their heads) version of Lamarckism), and you have the plot of a potential blockbuster for Netflix.
And just as the flat-earthers have re-appeared, as has a re-branded version of Lamarckism/Lysenkoism (minus the Russians chopping offing scientists who didn't agree).
Some day, I plan on writing up the full story.
Muc of this is well laid out in a book by C.R. Ribbands, The Behaviour and Social Life of Honey Bees, 1953.
There you will find that the poor sense of smell came from the 1919 work of von Frisch, using a flawed odor presentation method (in liquid paraffin).The 'not much better than people' was based on the ability of Karl and Margarete to smell scents - they became the stand-in for all humans.The 'except for some floral (or a few) floral scents was based on the floral work of Ribbands, but it was misquoted, and the Pheromones because we all know bees can use and detect pheromones for communications.
To be specific, Karl 1919 measured the threshold of perception by bees for two pure scents dissolved in liquid paraffin. Bees conditioned to bromstyrol readily recognized it at 1:2,000, but typically could not recognize it below 1:20,000 dilution. Methyl heptenone was recognized at 1:2,000, but not at 1:20,000. Then he and Margaret sniffed the samples and concluded that the thresholds of bees and humans were similar.
Two scents, two people - and the myth was born.
Ribbands, being the detail oriented scientist that he was, repeated the von Frisch 1919 trial, using ethylene glycol as the dilutant. He found, for example, that in this fluid, bees' threshold for detection of methyl heptenone was 1:40,000,000 dilution! The most sensitive threshold for the most sensitive 15% of the human population was 1:1,000,000.
Other examples provided by Ribbands for thresholds of detection by honey bees varied from 1:100,000,000 (phenyl ethyl alcohol, benzyl acetate, methyl benzoate; to 1:5,000,000 for linalol. Honey bee thresholds varied from 1/10 to 1/100 of the thresholds for humans, bees were attracted to odorous in concentrations impreceptible by humans, and concluded that "comparison between humans and honeybees was of doubtful value, yet it was certain that honeybee threshold values were substantially lower than those of man."*
* We have used all of the survey methods employed by von Frisch and Ribbands. We added insect antenna electrograms, improved the Proboscis Extension Reflex assay (sPERS), and perfected conditioning systems for free-flying forager bees. Here's our conclusion after nearly three decades of research: (1) antenna electrographs tend to be erratic, since a simple temperature drop or change in air flow speed can produced a false positive, (2) the Proboscis Extension Reflex (PER) is useful for determining whether bees can be conditioned to respond to or search for any given chemical and the threshold limits of detection tend to be low (as described by von Frisch and dramatically improved upon by Ribbands), but (3) perhaps counter-intuitively, the true thresholds of detection can only be determined via conditioning of free-flying bees and applying appropriate statistics such as Receive Operating Characteristic Curves (ROCs). We usually see that the true thresholds of detection are one, two, sometimes even three times lower than those determined using bench top assays like PERs or the 'boxes' and vials of von Frisch.
The comments about bees maybe being better at a 'few' floral scents was based on reports of floral scent trials by Ribbands. However, Ribbands reported this as being true for vrtually every floral scent that he examined. But he was only one man, and he couldn't cover every floral scent available, in the world, even if he lived for several lifetimes. So the 'few' was based on what he had time to examine.
Again, even then, no one questioned the ability of bees to detect pheromones!
Why was the work of Ribbands mostly ignored or forgotten?
As per the Nobel prize, that came later, but von Frisch and Ribbands didn't see eye-to-eye, much as Adrian Wenner and Patrick Wells also disagreed with von Frisch. This is all reported in their book, Anatomy of a Controversy, the Question of a "Language" among bees (1990). Adrian pointed me toward Ribbands many years ago. Frankly, I find the work by Ribbands to be more exacting, careful, and much less inflammatory than Adrian's, but both authors contributed interesting perspectives.
At the time of Ribbands' book in 1953, von Frisch, whose work was put on hold during the War (he couldn't convince the Germans that he wasn't Jewish), was back studying bees. Among other awards, von Firsch had won the Lieben Prize, 1921; Pour le Merite for Arts and Sciences, 1952, Foreign Honorary Member of the American Academy of Arts and Sciences, 1952, and was gaining momentum, along with Nikolaas Tinbergen, and Konrad Lorenz towards their receipt of a Nobel prize.
Unfortunately for Ribbands, not only was he the under-dog in a fight with von Frisch, but he devoted a whole chapter to bee Recruitment to Crops, and he cited field trials and research by Russian scientists. That was during the reign of Trofim Lysenko (1930s-1964), who was termed the Soviet Era's Deadliest Scientist (https://www.theatlantic.com/science/archive/2017/12/trofim-lysenko-soviet-union-russia/548786/) and early part of the Second Cold War with Russia.
Needless to say, given the authoritarian rule of Lysenko and his disastrous and bogus agricultural research, that condemned millions of people to starvation in Russia and then in China, Russian agro-science for that period was not held in great esteem by most of the rest of the world.
I've read extensively about all of this, and it is my opinion that Ribbands work appeared at a time when he was tilting windmills with the hero of the bee dance language, citing work of Russians, who everyone knew couldn't be trusted, and his work got lost in the chatter after von Frisch, Tinbergen, and Lorenz received their Noble prize.
Now remember, I entered into all of this in 1997 when I started working for DARPA and the US Military. I started my path of discovery with Adrian, he pointed me to Ribbands. I and my team then built on their work, and the result is that we've proven bees to be far better than humans for detecting an incredibly wide array of scents, that bees are on par, appear to be as good, possibly better for some scents than dogs - we've no instruments that have the instantaneous recognition and low limit of detection capability of either of these animals, and we have confirmed and improved on the Russian research on honey bee recruitment to crops.
Although much of our military research is under wraps, and much of the crop research that we conducted for seed companies and agricultural research for other countries is unfortunately proprietary, if you want an example proof of just how good bees are at detecting low levels of unusual chemicals (not just floral scents and pheromones), see Alternatives for Landmine Detection, J.MacDonald et al., Rand Science and Technology Policy Institute, 2003, Figure S.1, page 278. The chart shows a Probability of Detection and approximate Receiver Operating Characteristic Curve (ROC) for the probability of a true positive to the probability of a false positive. What we have found, over and over, in double blinded and other trials, is that bee ability to discriminate between blanks and very low (parts per billion, parts per trillion, even parts per quadrillion for some chemicals) scent concentrations tends to be almost perfect (p values less than 0.001). A group of Army Signal Processing experts from Brooks Air Base, after two years of interrogating our bee data, stated that they had never seen such perfect signal detections at such low levels - not by dogs, not by any existing instruments. Bees 'perform as an ideal detector'. I cover some of this work in [PDF]
Bees as Biosensors: Chemosensory Ability, Honey Bee ...
https://www.mdpi.com/2079-6374/5/4/678/pd, talk about the dance language, and cover a bit of the more recent research that was beginning to appear as a resurgence of interest in honey bee odor detection.
If you still think that bees have a poor olfactory sensor system (smell detection), argue that you still see reports and reviews that press this view, and wonder how the work of Ribbands, that stands as the seminal rejection of von Frisch's 1919 experiment, has been and continues to be reported as confirming von Frisch, then all you have to do is to look at our recent election and the debate over whether the election was stolen. Jerry
***********************************************
The BEE-L mailing list is powered by L-Soft's renowned
LISTSERV(R) list management software. For more information, go to:
http://www.lsoft.com/LISTSERV-powered.html
|