Claim: Diesel exhaust stops honey bees from finding flowers they want to forage

This is junk science because…

… the study involved no actual flowers, but chemicals in the laboratory. Given that the claimed phenomenon has not been observed in the real world…

The media release is below.


Diesel exhaust stops honeybees from finding the flowers they want to forage
Exposure to common air pollutants found in diesel exhaust pollution can affect the ability of honeybees to recognise floral odours, new University of Southampton research shows.

Honeybees use floral odours to help locate, identify and recognise the flowers from which they forage.

The Southampton team, led by Dr Tracey Newman and Professor Guy Poppy, found that diesel exhaust fumes change the profile of flora odour. They say that these changes may affect honeybees’ foraging efficiency and, ultimately, could affect pollination and thus global food security.

Published in Scientific Reports (3 October 2013) the study mixed eight chemicals found in the odour of oil rapeseed flowers with clean air and with air containing diesel exhaust. Six of the eight chemicals reduced (in volume) when mixed with the diesel exhaust air and two of them disappeared completely within a minute, meaning the profile of the chemical mix had completely changed. The odour that was mixed with the clean air was unaffected.

Furthermore, when the researchers used the same process with NOx gases (nitric oxide and nitrogen dioxide), which is found in diesel exhaust, they saw the same outcome, suggesting that NOx was a key facilitator in how and why the odour’s profile was altered. The changed chemical mix was then shown to honeybees, which could not recognise it.

Dr Newman, a neuroscientist at the University, comments: “Honeybees have a sensitive sense of smell and an exceptional ability to learn and memorize new odours. NOx gases represent some of the most reactive gases produced from diesel combustion and other fossil fuels, but the emissions limits for nitrogen dioxide are regularly exceeded, especially in urban areas. Our results suggest that that diesel exhaust pollution alters the components of a synthetic floral odour blend, which affects the honeybee’s recognition of the odour. This could have serious detrimental effects on the number of honeybee colonies and pollination activity.”

Professor Poppy, an ecologist at the University, adds: “Honeybee pollination can significantly increase the yield of crops and they are vital to the world’s economy – £430 million a year to the UK alone. However to forage effectively they need to be able to learn and recognize the plants. The results indicate that NOx gases — particularly nitrogen dioxide — may be capable of disrupting the odour recognition process that honeybees rely on for locating floral food resources. Honeybees use the whole range of chemicals found in a floral blend to discriminate between different blends, and the results suggest that some chemicals in a blend may be more important than others.”


8 thoughts on “Claim: Diesel exhaust stops honey bees from finding flowers they want to forage”

  1. Honeybees use floral odours to help locate, identify and recognise the flowers from which they forage. They almost certainly have a different idea of what constitutes an ‘odour’ than the gas chromatographs at the University of Southampton.
    GCs are ‘trained’ to identify odor based on that the operators consider to be an odor. To the trained chemist, CO2 is odorless, but insects (like that mosquito in my bedroom last week) use it to find food.
    Insect olfactory organs clearly work differently.
    Other plant-based chemicals humans consider odorless but insects can detect include isoprene, which is also found in the exhalations of humans.

  2. Kind of reminds me of the core fallacy in global warming theory. What exists wonderfully on paper, may or may not be accurately describing what goes on in the real world. For example, carbon dioxide is a greenhouse gas. Greenhouse gases trap energy and warm the planet. Man produces carbon dioxide, therefore man is warming the planet. Cause and effect plain as day, right? Except that it is only one component to the miriad of factors that determine climate for an area, region, or worldwide at any particular time.

    I’ve had enough engineering to know that computer modeling and lab testing are good places to start, but are not what you build your production model to. A good engineer knows that there is a likely chance that a variable was missed or weighted incorrectly. That’s why they still run wind tunnel tests, still make models, still test prototypes and why products still get recalled and bridges still collapse. They know that all the theory and modeling in the universe won’t guarantee that your product will perform as planned out of the laboratory.

    The natural world still stubbornly defies attempts by theory to tell it what to do.

  3. Deliberately misleading opening statement:
    “Honeybees use floral odours [sic] to help locate, identify and recognise [sic] the flowers from which they forage.”

    While this may be part of the truth, it leaves out the lab tested and empirically observed fact that bees also use colors and patterns. That’s why they often pester people wearing particularly bright, colorful clothing. The study deliberately prevented the bees from using their other senses to help. They mixed the scent chemicals with a high concentration of diesel exhaust not found in the wild, and then with NOx directly. The chemical reaction that occurred was easily predictable and taught the scientists nothing new. Had they used concentrations found in the wild, and at least artificial flowers then the test might actually say something about to what degree diesel exhaust affects bees, but it would still be irrelevant when you compare the routes frequented by diesel engines to the massive open spaces bees prefer.

    Conclusion, either the researchers in question are less intelligent than your average data analyst, or this is just another deliberate scare tactic to drum up interest, and therefore grants, for a subject most people don’t care about.

  4. Their claim should read:
    Unlike biological evolution, he can prove this in laboratory, kind of…

  5. What these people appear to be missing is that these insects don’t rely on a single sensory system. Bees also have a highly developed visual sense. (A bee’s concept of “visible light” is not the same as a humans though.)

  6. My understanding is the prototypes are not used for airliner development.

    Computers and computer modeling are awesome in many applications, but not so good for climate projections.

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