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Friday, May 31, 2013

One Bite out of Three before Columbus


Bumble bee on pumpkin flower © Beatriz Moisset. 2013
Only recently we have opened our eyes to the importance of pollinators in food production. The interest keeps growing almost daily. We often hear it expressed as "we owe one bite out of three to pollinators."

As I mentioned in the previous post, many assume that the honey bee is responsible for all that pollination. Not so! We must remember that the domesticated bee was brought to this continent in the 1600s by European colonists. It was introduced to California even later, in the 1850s. Who did all the pollination before? Was it as necessary then as it is now?

I suspected that the "one bite out of three" was just as valid before the introduction of the honey bee as it is now. I decided to learn about the pollinators that did all the work in pre-Columbian days. First, I searched for information on Native Americans' food plants and then studied how these plants were pollinated. You can immerse yourself on Daniel Moerman's list of 1,500 plants (Native American Ethnobotany Database) or read a shorter list of plants used by peoples of the North East. I will limit myself to painting a picture with an extremely broad brush starting with the most important food sources.

Beans were one of the Three Sisters that Native Americans cultivated © Beatriz Moisset. 2013

In large part of North America the native peoples cultivated the so called Three Sisters: corn, squash and beans. Corn is wind pollinated. But the other two need the help of bees. The squash bee and a variety of solitary bees and bumble bees pollinate the so called vine crops: pumpkins, squash and other gourds. Beans, all varieties of them, also need the help of native bees and bumble bees to produce a crop.
Bumble bee on sunflower © Beatriz Moisset. 2013
Sunflower, another staple of Native Americans, is also bee pollinated and so are blueberries and cranberries and nearly all other berries. Chestnuts, abundant in pre-Columbian times, were a significant part of the diet all along Eastern North America. Unfortunately, the American chestnut has gone almost extinct in the last century, so we don't know much about its pollinators. But the European and the Chinese chestnuts are pollinated by bees. We can be quite confident that it was the same with American chestnuts.
Studying the pollinators of camas lilies in Oregon © Beatriz Moisset. 2013
In the West, the tubers of camas lilies were of great importance to local tribes. Their delicate blue flowers attract a number of insects, many of which serve as pollinators.
Common milkweed was eaten by Native Americans after removing the toxins
© Beatriz Moisset. 2013
Among all the other plants listed on the references given above, I have picked just a few examples of those that require insect pollination: mints, milkweeds, passion flowers, spring beauties and prickly pears.

In South America, all the members of the tomato and potato family are insect pollinated. Figs, cashew nuts, cacao and a number of tropical fruits also require the services of pollinators, not just insects but even hummingbirds and bats.

Of course, Native Americans ate animals in addition to plants. Some of this food also depended indirectly on pollinators. I will limit myself to one example, that iconic bird that represents one of the early interactions between European colonists and natives: the turkey. It feeds, in part, on insect-pollinated berries, crabapples, seeds, roots and nuts.
Wild turkeys © Beatriz Moisset. 2013
Pre-Columbian diets depended on pollinators just as much as present day diets. Native pollinators continued to do a good job when farms and orchards were small. However, in recent times, the Old World domestic bee has become the most important pollinator of American crops because of the development of modern agricultural methods. The role of the native pollinators could be restored by creating the right conditions for them, such as providing nesting sites and reducing pesticides, near crop fields. The Pollination Conservation Resource Center of the Xerces Society and the PollinatorPartnership among other organizations are committed to these goals. You can find valuable resources in their respective websites.

Friday, May 24, 2013

One Bite out of Three


Megachilid or mason bee, often used to pollinate fruit trees.
© Beatriz Moisset

We frequently hear that "one bite out of three comes to you courtesy of pollinators." Other times we hear it expressed as "one bite out of three comes to you courtesy of bees," implying that the bees in question are honey bees. Where did these statements originate? How well documented are they? It all sounds plausible but I hesitate to cite numbers without certainty when I give presentations about pollinators.

Fortunately a group at the University of California at Berkeley decided to get to the bottom of it. I am happy to tell you that they found the first statement to be fundamentally accurate.

Claire Kremen, one of the coauthors of the study and member of the Committee on Status of Pollinators, summarizes the results of their 2006 study as follows: "Out of the 115 crops studied, 87 depend to some degree upon animal pollination, accounting for one-third of crop production globally."

Now, I can relax and go on telling my audiences that pollinators are responsible for one third of our food. I can also face the second claim, "one bite out of three comes to you courtesy of bees." This claim originates from the confusion between pollinators, bees in general and honey bees, and it is not accurate. Some information is in order.

Augochlora pura bees.
© Beatriz Moisset
Honey bees are the most important pollinators of agricultural crops. They excel at pollinating a number of fruit trees such as apples, pears, peaches and almonds. But they are not alone in this task. We owe a lot to all the other carriers of pollen, 20,000 species of bees (4,000 in North America alone) and an assortment of wasps, moths, flies and even bats.
Anthophorini bee. It pollinates several crops.
© Beatriz Moisset
Let us look at crops pollinated mostly or entirely by non-honey-bee pollinators. Alfalfa is the most important one that comes to mind. No, we don't eat alfalfa but cows, sheep, goats and even chickens do. Without alfalfa these animals would be severely malnourished; they may not even survive. Most alfalfa growers use the services of bumble bees, alkali bees and alfalfa bees or a combination of the above plus a few other bees. These insects are well adapted to the structure of alfalfa flowers and handle them efficiently. Honey bees, on the other hand, are not fond of these blossoms and do a poor job. It may take several honey bees to do the job of one alfalfa bee; but they make up in numbers what they lack in finesse. This is why they are used in large alfalfa fields where there is no habitat left for other bees, particularly in California.

When New Zealand ranchers started raising cattle, they also needed to grow clover for cattle feed. They had to purchase seed from abroad every year because the plants failed to set seed for lack of pollinators. European bumble bees were imported to do the job, and in fact they promptly took care of the problem. Notice that it was bumble bees rather than honey bees which were counted for this mission.
Bumble bee buzz-pollinating azalea. © Beatriz Moisset
See video
The flowers of tomatoes, eggplants, peppers and other members of the potato family require special handling by the pollinator, a process called buzz pollination. Bumble bees and other native bees do this efficiently. Honey bees cannot, do not perform this maneuver. For a brief explanation of buzz pollination see: Buzz Pollination by Sue Rosenthal.

Blueberries and cranberries are mostly buzz pollinated. Unfortunately, large fields of these crops provide no habitat for the native bees and bumble bees which are most adept at this task. Under these circumstances, honey bees are used as pollinators despite their poor performance.
Yucca moth, a highly specialized pollinator. © Beatriz Moisset

Figs are pollinated by fig wasps, yucca by yucca moths, and mangoes by bats. A few other specialty crops use the services of specialized insects. Several species of flies are used to pollinate some crops such as onions and cabbage. Honey bees, or even other bees are not involved here, either.

In summary, we must remember to give credit to all pollinators. Let us thank them all. My favorite one is not a honey bee, not even a bee. It is the little fly, or midge, that pollinates the cacao flowers. What would the world be without chocolate?

Thursday, May 9, 2013

Honey Bees, Almond Pollination and Corn Fields


Trucking bees for pollination purposes. © David Green, Wikicommons
I have pondered about the connection between almond crops and honey bees in North America. I found another piece of the puzzle in the Bee Informed website: corn fields play an important role on the problems that honey bees face.

After bees are done pollinating crops, they need to restore the energies and supplies spent on all the traveling and waiting and monoculture feeding to which they have been subjected. Many bee hives used to be taken to the prairies of North Dakota where they used to find abundant wild flowers. But that resource is getting smaller all the time, the reason being that each year a larger area is devoted to corn cultivation.

More and more it seems that the most serious problem honey bees face is the agricultural system. Pesticides play an important role in this matter, but agribusiness also has a lot to do with it. Almond fields are becoming more and more like factories and less like orchards. The practice of using massive numbers of just one species of pollinators is also becoming a factory process.  Are we expecting too much from honey bees? Shouldn't we be changing agricultural practices? Is it time to resort to organic farming? Shouldn't we take advantage of all the many pollinators which would prosper if given adequate habitat near the crops?

Some resources on alternative pollinators:
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© Beatriz Moisset. 2013