Dear Readers,
Almost every day I read something like this: “One third of all the food we eat is pollinated by bees.” I just read it again today–twice. Some say “every third bite” which sounds like volume; some say “one-third of all crops” which sounds like a species count.
Please tell me about this one third. Is it one-third by weight, volume, calories, dollars, species, or some other measurement I haven’t thought of? I would like to know who came up with this number and how it was calculated. I would also like to know if they really mean bees, or if they mean pollinating insects, or all pollinating animals.
The thing is, it’s hard to defend an argument when you have no clue how the numbers were obtained. I’ve had several readers ask me where the one-third came from and it’s embarrassing not to know. It feels like that circle game where you keep passing on a message, and by the time the last person gets it, it’s totally garbled and nothing like the original.
If anyone can help, I would greatly appreciate hearing from you. There are many other people waiting to hear the answer as well. Remember, we will never be persuasive in our bid to save pollinators, if we are not believable in our statistics. Please help me figure this out!
Rusty
One-third of what?
I’m going to look this up when I get home. I agree with you. My first instinct is to turn to the Xerces Society. this article has a bunch of numbers in it, but i didn’t do the math to see if any of them come out to 1/3, and i dont think there are any sources cited!
I didn’t forget about this, it just took me longer than I expected. Almost everything I can find refers back to the USDA Bee Research Lab, which actually doesn’t cite any sources when they make the “one third” claim on their website, and the other “source” I found was the American Beekeepers Federation, which as far as I know does not conduct actual scientific research, so I can only assume they stole it from the USDA. OK so this actually cites some sources: http://www.nappc.org/pollinatorEn.html
Domestic honeybees pollinate approximately $10 billion worth of crops in the U.S. each year (Watanabe, 1994)
The Myrna Watanabe article was published in Science. I do not have an AAAS or Science membership/subscription so I cannot read it. Not sure if it even addresses the issue, since I have no idea what the value of all crops in the U.S. was in 1994 (was it $30 Billion?), how it was measured, and how well this data holds up in 2010.
Animal pollinators are needed for the reproduction of 90% of flowering plants and one third of human food crops (Buchmann and Nabhan, 1996; Free, 1970 In Tepedino, 1979; and McGregor, 1976 In Tepedino, 1993).
Buchmann and Nabhan, 1996 – The Forgotten Pollinators — if memory serves, this book is not pro-honey bee to say the least, so i can’t see it making that claim.
Free, J. B. 1993. Insect Pollination of Crops. — this is like 600 pages long with 85 pages of references and I can ‘t find the complete text so, I’m not sure about it.
Tepedino, V.J. 1979. — I assume this refers to The importance of bees and other insect pollinators in maintaining floral species composition. Great Basin Naturalist Memoirs 3: p. 139 – 150 (now called Western North American Naturalist). There is nothing remotely similar, so…? Conveniently enough, the Western North American Naturalist has their archives online ( here https://ojs.lib.byu.edu/wnan/index.php/wnan/issue/view/139 ) But there is a twist! There is nothing from Tepedino in 1979 #3. There is also no article by that name published by that journal ever, but Tepedino did write “Spatiotemporal variation in phenology and abundance of floral resources on shortgrass prairie” in Vol. 40 No. 3 in 1980 (so I assume this is the same article — Now, I am now forced into my second assumption about this one resource!?! Scandalous). My conclusion, upon reading this article (finally)? Tependino doesn’t research human food crops.
McGregor, 1976 — I think this is our winner. Check this out : http://www.nap.edu/openbook.php?record_id=11761&page=104 Author writes:
McGregor’s 1976 estimate that one-third of the human diet can be traced directly or indirectly to animal pollination (see Table 4-1)
This article also cites McGregor 1976 as the origin of the “third mouthful” concept. (http://www.lianpinkoh.com/ – Food security not (yet) threatened by declining pollination
Jaboury Ghazoul & Lian Pin Koh — this is published other places but this is the easiest to download for free without subscription) Authors write:
pollination, which is often portrayed as being necessary for every third mouthful we eat (McGregor 1976; and widely repeated since).
This is supposed to be the Insect Pollination Handbook (originally published by McGregor in 1976 via USDA) claims to be continuously updated):
http://www.ars.usda.gov/Services/docs.htm?docid=18054
In Tepedino, 1993 – I did not bother to look this up because I feel like the McGregor 1976 is the source of everyone’s claims so, what’s the point.
I quickly flipped through the most recent version of the Pollination Handbook, and I can’t find anything about one third of human food crops or the third mouthful. I am not sure if it has been revised out and I should find a 1976 version to confirm, or if it is described differently in the original text. Maybe next time I have a little more brain power to spare, I will actually read it.
I am willing to email or call the USDA about this!!! It has been bothering me since you posted this. I do feel pretty confident that I have traced it back to the original source, but I obviously can’t confirm how the number was arrived at and if it is good to use.
have you read Crop pollination by bees by Keith S. Delaplane and D. F. Mayer? On page 2 they discuss the one-third claim, states that it is probably accurate, and refers back to McGregor 1976 again. I really need to see if the library or someone has the original 1976 USDA publication, since it’s out of print and about $42 on amazon.
geez, sorry to leave 500 comments tonight. I keep posting and then reading more, then posting, then reading more. Yes, wild Saturday night. This is from the Pollination Handbook:
Worldwide, more than 3,000 plant species have been used as food, only 300 of which are now widely grown, and only 12 of which furnish nearly 90 percent of the world’s food. These 12 include the grains: rice, wheat, maize (corn), sorghums, millets, rye, and barley, and potatoes, sweet potatoes, cassavas or
maniocs, bananas, and coconuts (Thurston 1969).1 The grains are wind-pollinated or self-pollinated, coconuts are partially wind-pollinated and partially insect pollinated, and the others are propagated asexually or develop parthenocarpically. However, more than two-thirds of the world’s population is in Southeast Asia where the staple diet is rice. Superficially, it appears that insect-pollination has little effect on the world’s food supply – possibly no more than 1 percent.
Within the United States, which accounts for only about 6 percent of the world’s population, about 286 million acres were cultivated in 1969. About 180 million acres were devoted to the wind pollinated or self- pollinated crops, primarily barley, corn, oats, rice, rye, sorghums and wheat, grass hay crops, sugar beets, sugar cane, potatoes, sweet potatoes, and tobacco. About 60 million acres were devoted to crops that may receive some benefit from insect pollination but are largely self-pollinating (beans, cotton, flax, peanuts, peas, and soybeans). About 40 million acres were devoted to hay crops produced from bee-pollinated seeds (alfalfa, clovers, lespedezas). About 6 million acres were devoted to producing fruits, vegetables, and nuts–most of which are dependent upon insect pollination. Table 1 lists the cultivated crop plants, discussed herein, that are dependent upon or benefited by insect pollination. These plants provide about 15 percent of our diet.
The animal products we consume contribute about an equal amount to our diet. These include beef, pork, poultry, lamb, and dairy products–derived one way or another from insect-pollinated legumes such as alfalfa, clover, lespedeza, and trefoil.
More than half of the world’s diet of fats and oils comes from oilseeds–coconuts, cotton, oil palm, olives, peanuts, rape, soybeans, and sunflower (Guidry 1964). Many of these plants are dependent upon or benefited by insect pollination. When these sources, the animal and plant products, are considered, it appears that perhaps one-third of our total diet is dependent, directly or indirectly, upon insect-pollinated plants.
What a prodigious amount of work! I am so impressed!
I thought I had seen the “original research” in Crop Pollination by Bees (Delaplane & Mayer) but I hadn’t gotten around to getting it from the library again. But if it refers back to McGregor, I won’t bother.
Somewhere in my piles of documents I have works by Tedpedino, Watanabe, Buchmann, and Free, but as far as I remember, each of these borrowed the number from someone else as well.
Your last cite seems to have the most detail, but (as you point out) it still doesn’t answer the “percent of what” question.
I can see you are getting just as frustrated as I am about this number. It’s easy to see how rumors spread. Since I published this post a number of people have sent me links to places where it has been used (and abused) even in otherwise believable works.
Thank you so much for this. You have inspired me to resume digging and have saved me a lot of effort as well.
So, after a few hours of sleep, I can understand what “adds up” to one third, but I still can’t puzzle out if it is number of crops or calories or dollars or acres.
15% of “our diet” (US diet) comes from “cultivated crop plants, discussed herein, that are dependent upon or benefited by insect pollination.” this refers to table 1, which is a list of cultivated crops.
We get another 15% (“about an equal amount to our diet”) from “beef, pork, poultry, lamb, and dairy products–derived one way or another from insect-pollinated legumes such as alfalfa, clover, lespedeza, and trefoil.”
the rest of the “one third” comes from “More than half of the world’s diet of fats and oils comes from oilseeds–coconuts, cotton, oil palm, olives, peanuts, rape, soybeans, and sunflower (Guidry 1964). Many of these plants are dependent upon or benefited by insect pollination.” — at this point he switches gears and goes to the “world’s diet,” while the other two numbers are based on US diets. (let’s not even wander down the road of people who don’t partake in animal proteins…)
I really want to believe that if I could just read this correctly, I would understand where it comes from, but McGregor doesn’t cite anything but Guidry 1964, and that’s the smallest part of it.
Hi Jess and Rusty,
thanks for going into this with so much verve!
I was one of the readers asking about the source and the units of the ubiquitous “One Third” back in March. I am working on a bee-film-project and we have been getting quite frustrated in trying to confirm this number, so this information you dug up is really, really helpful! Even when it leaves some questions still unanswered…
I agree with Rusty: “One third” is an important claim – it would be great if there were a way to assess its substance!
I did some more digging and came across this fairly recent Science-paper (Dixon, KW (2009) Pollination and restoration, Science, vol325 (5940) pp571-573) where I found these numbers:
„In agriculture and horticulture, the economic value of pollination is well recognized, with 75% of crop species and 35% of crop value dependent on pollination by animals (1, 2)“
I looked up the references (both available free online):
1: Klein AM at al. (2007) Importance of pollinators in changing landscapes for world crops, Proc. R. Soc. B 274, 303–313, doi:10.1098/rspb.2006.3721
2: C. Kremen, N. M. Williams, R. W. Thorp (2002) Crop pollination from native bees at risk from
agricultural intensification, Proc. Natl. Acad. Sci. U.S.A. 99, 16812
Klein et al. write: „In this review, we expand the previous estimates using novel primary data from 200 countries and found that fruit, vegetable or seed production from 87 of the leading global food crops is dependent upon animal pollination, while 28 crops do not rely upon animal pollination. However, global production volumes give a contrasting perspective, since 60% of global production comes from crops that do not depend on animal pollination, 35% from crops that depend on pollinators, and 5% are unevaluated.“
So, both talk about 35%, but Dixon makes it „35% of crop value“, whereas the original study very clearly speaks of 35% global production volumes. Though obviously related, they need not be the same thing. But it seems – to me, at least – that this study actually settles it: Approximately one third of the global production volume of food crops is depending on animal pollinators.
I do not know if they included crops used as animal feed, though…
Excellent work, Kerstin! Even though the animal production question is not clear, those are the closest things to real numbers I’ve seen. I think we can accept the one-third number without losing too much sleep over it.
I will definitely read the supporting papers. I’ve been a fan of Clare Kremen’s work for quite a while, so I’m surprised I missed the info in that particular paper.
Thank you for your hard work and for making an excellent contribution to this website. Keep me posted on your film so I can let my readers know.
Rusty, I am quite glad to have found some answers, too. It always motivates if you are not the only one with a problem…
I just posted a little blog-entry over at our film-blog MoreThanHoney. You’re in it too
More news about the film you can find both there and on Twitter.
[...] in environmental studies, very nicely discussed these issues in this post in March and again here a few days ago over at Honey Bee Suite and you can see: obtaining these data is not an [...]