Tag Archives: pollination

Pollinate Your Plate Part 1: A Nutritious Breakfast

Pollinator Plate Title

Over the next few blog posts, I will share with you a series of posters I created demonstrating what meals might look like if we eliminated all foods that benefit from animal pollination. I’d like to use these posts as an opportunity to explore this topic in greater depth than could be accomplished in the original posters.

The first poster, “A Nutritious Breakfast,” depicts which items of the most important meal come from animal pollinated crops:

The Most Important Meal

The Most Important Meal

While the reasoning behind some of differences between the two meals are obvious (such as the lack of honey holding together those delicious clusters of oats), others are a little more cryptic.

The Bees and the Berries

The Southeastern Blueberry Bee (<i>Habropoda laboriosa</i>) is a native, solitary ground nesting bee. It is a much more efficient blueberry pollinator than the European honey bee. On smaller farms, wild populations of this bee alone can pollinate the entire blueberry crop.

The Southeastern Blueberry Bee (Habropoda laboriosa)

Most berries, such as strawberries, raspberries, blackberries, and blueberries, benefit greatly from bee visitation. One scientific paper estimated that the efforts of a single Southeastern Blueberry Bee (Habropoda laboriosa) resulted in a yield of about $20 worth of blueberries (Cane et al. 1997). I would imagine that, twenty years later, these pollinator services would be worth even more.

Amazing Almonds
By Daniel Schwen (Own work) [CC BY 3.0 (http://creativecommons.org/licenses/by/3.0)], via Wikimedia CommonsAlmonds are another crop dependent on bee visitation. They are one of the main agricultural exports of California (the top almond producer in the world). The Almond Board of California estimated that this crop generates $11 billion/year and 104,000 jobs for the California economy. If you drive through the San Joaquin Valley in late January, you will be surrounded by a sea of white and pink almond flowers- 900,000 acres, to be more exact. At a rate of two colonies per acre, the almond industry is a major driver of the high demand for honey bee hives nationwide.

Osmia lignaria, photo by Kathy Keatley-Garvey.

Osmia lignaria, photo by Kathy Keatley-Garvey.

Blue Orchard Bees, or BOBs, (Osmia lignaria) are alternative pollinators of almonds. So named because of their metallic blue hue, BOBs are desirable almond visitors because they fly at cooler temperatures than many other bees (almond blooms in January or February). In addition, the presence of BOBs can cause honey bees to behave differently, which results in greater fruit yield than just BOBs or honey bees could achieve alone (Brittain et al. 2013). These solitary cavity nesting bees are also sometimes called “mason bees” because they collect mud to build the walls of their nests.
Cross section of a BOB nest

Cross section of a BOB nest

Pollinators and Nutrition
Hopefully I’ve convinced you that without animal-pollinated foods, your breakfast wouldn’t be as delicious. Believe it or not, your breakfast would be less nutritious as well.

Crops that benefit from animal pollination are responsible for 90% of the world’s supply of Vitamin C, and the antioxidants vitamin A flickrβ-cryptoxanthin and β-tocopherol. In addition, the majority of Vitamin A, plant-based lipids, calcium, fluoride, and a large portion of folic acid comes from animal-pollinated crops (Eilers et al. 2011).

Animal pollinators do more than just increase the quantity of nutritious crops. In some cases they increase the nutritional quality of the food as well. For example, in addition to being a good source of vitamin E, almonds are considered a health food because of their high levels of oleic acid. Bee pollination not only increases total almond yield, but also the ratio of oleic acid to linoleic acid in the resulting fruit (Brittain et al. 2014).

To summarize: Without pollinators your breakfast would be less colorful, less delicious, and less nutritious.

But wait! It’s more complex than that…

If we used our magic wand to remove all pollinator contributions from the produce section, some bins might remain the same, while others (such as avocados) would disappear. But most bins would just get smaller.

If we used our magic wand to remove all pollinator contributions from the produce section, some bins might remain the same, while others (such as avocados) would disappear. But most bins would just get smaller.

In these posters I categorized ingredients as either benefiting from animal pollination, or pollinator independent. But in reality there is much more of a gray area in between these two categories. Some foods, such as oats, don’t need pollinators at all. Other foods, such as honey, could not exist without bees. Most plant-based foods exist somewhere on a spectrum between oats and honey. Coffee yields are greatly increased by pollinator visitation, but coffee wouldn’t disappear completely without animal pollination (Klein et al. 2002).

The degree to which bee visits increase citrus fruit yield depends on the variety.

The degree to which bee visits increase citrus fruit yield depends on the variety.

To make things even more complicated, the level to which a particular crop is dependent on animal pollination often depends on which variety being considered. Most oranges used for juice do not need animal pollination, while other citrus varieties, particularly mandarin oranges, do benefit from bee visitation (Sanford 2015). We don’t know a lot about how much citrus benefits from pollinators in large part because orange blossom honey is so desirable that beekeepers will pay citrus growers to put hives in their groves.

Okay, hopefully the length and detail of information in this post haven’t discouraged you from reading this blog altogether! Up next is lunch: an apple, a chocolate chip cookie, and a slice of sausage and pepper pizza. You may have noticed that in the “without pollinators” photo, our granola is looking particularly dry. Stay tuned for an explanation!

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Bad Bees Part I: Sex, Drugs, and Violence

Halictus sweat bee visiting Helminthotheca echioides (prickly ox tongue). (c) 2012 MRS All rights reserved.

Whenever I do education outreach, especially with small children, I like to paint a rosy picture of pollination. The bees and the plants help each other; the bee collects food from flowers, and in return they transfer pollen from the male parts of flowers to the female parts of flowers, which results in the production of seeds. We break out the cute fuzzy bee hand puppet and use velcro yellow balls (simulating pollen), which the kids can transfer from felt flower to felt flower.

When viewed in the visible light spectrum (left), this Mimulus flower looks uniformly yellow. However, when viewed in the UV spectrum (visible to bees- right), a dark arrow-shaped wedge points to the nectaries at the base of the flower.
source: wikipedia.org (Plantsurfer 2009)

When I talk with older audiences, I might portray a slightly racier scenario. After all, what is pollination other than flower sex mediated by a third party? In the photograph above, look at how tenderly the Halictus hooks its hind leg around the seductively curved stigma of the flower, at the profusion of pollen she has so carefully collected on the hairs of her hind legs to carry between flowers. Despite the more adult tack I use, I still tend to emphasize that this is a mutualistic engagement; the flower has evolved nectar and enticing patterns to seduce the bees, and in return the bees transfer pollen between plants. A nice example of this are something called nectar guides, or patterns in the UV spectrum (visible to bees but not to us) that guide bees towards the nectar reward in the flower.

And so the flowers grow. And so we get fruits and nuts and seeds. And so this green planet fluorishes.

As idyllic and parabolic as this picture may be, it brushes over a Machiavellian but more accurate version of how pollination (and evolution, for that matter) really works. In a way, I feel guilty teaching this airbrushed version of pollination because in some ways it may misrepresent how evolution and symbiotic relationships work in real life: as an escalating arms race.

In this darker world, flowers evolve to attract pollinators in order to increase reproductive fitness. In parallel, bees evolve to collect sugar rich nectar and protein rich pollen from flowers. As a byproduct, flowers feed bees and bees pollinate flowers, but this is not the purpose of the plant or bee, merely a byproduct of their concurrent actions.

And thus we enter the dark underbelly of the world of pollination, full of cheats and robbers and generally bad behavior. After all, it takes energy on the plant’s part to produce nectar and nutritious pollen, and pollen that is transfered by bees between plants is pollen that the bee cannot eat. If a bee can find a way to eat without pollinating, or a plant can find a way to be pollinated without feeding the bee, this may give them an edge over their competitors. One basic example of this that we see are bees that fastidiously clean all excess pollen off themselves before leaving a flower. Especially for a small bee, pollen can be quite heavy and make it more difficult to fly. By cleaning itself before takeoff, a bee can travel between flowers more easily but does not pollinate the next plant it visits.

Let’s take a look at the aspects of pollination I leave out of my classroom visits: the sex, the drugs, and the violence.

Sex and Drugs: The Cheating Orchid
The Bee Orchid preys on the sexual urges of male bees and wasps, luring them with drugs called pheromone mimics into a senseless orgy of failed mating. The flower copies in its shape, color, and texture a female bee or wasp. Furthermore, it entices males by releasing an intoxicating perfume: the smell of a female who is ready to mate. Hapless males converge on the flower and fight each other for the chance to attempt to mate. In the process, pollen packets called pollenia attach to the male. The next time it tries to mate with an ersatz bee, the pollenia make contact with the female part of the flower. In this scenario, the cheating orchid reaps all the benefits of pollination while the males get nothing but frustration and lost mating opportunities. For a great video of bee orchids in action (not to mention a rockin’ synthesizer soundtrack), check out this neat excerpt from Wild Orchids of Israel, filmed by Doron Hirschberg:

And Now for some Violence: Big Bad Carpenter Bees
Bees are no strangers to cheating at the pollination game, either. In my Xylocopa post, maybe you noticed that the gargantuan carpenter bees, rather than venturing into the trumpet-shaped structure of the sage flower, clutched onto the outside of the flower. Perhaps you even noticed a dark, drinking straw structure unfurled from the head of the bee and piercing into the flower through the side, rather than the front entrance.

Xylocopa robs the nectar from the an Autumn Sage (Salvia gregii) flower

The sage flower is designed for a pollinator to enter the main opening of the flower in order to reach the nectar. In the constricted petal tube, the bee must crawl past the anthers (pollen bearing structures) to reach the nectar, thus getting covered in pollen. This carpenter bee has other plans, however.

Using its heavily armored mandibles (used to chew through rotting wood to build nests), the carpenter bee rips a hole in the base of the petals, next to the nectar reward. It then sticks its proboscis in through the hole it has ripped, like a kid in a Tropicana orange juice commercial, and drinks the nectar without ever touching the anthers of the flower. The defenseless flower, once ripped open, is now vulnerable to other smaller bees that can use the hole made by the carpenter bee to access nectar directly. This process is called nectar robbing, because the flower is robbed of its nectar but reaps no pollination reward.

So the next time you go out to enjoy a pleasant Spring day, as you watch the industrious bees trundle from flower to flower, take a moment to reflect on the dark designs of both flower and bee. Although salacious and exploitative, I don’t like to think of this interplay in a negative light. To me, the complexity of coevolution makes this relationship more interesting, more beautiful, more strange than the boring stories we tell our children. This intricate biological world we live in operates by its own set of rules separate from Western human morality, and we have much more to gain by learning and appreciating these rules rather than placing value judgments on them.