Pollinators and the food we eat

I wrote and published this post for the GROBigRed blog on 6/21/17.  Check out that blog for great gardening information from all of my Nebraska Extension colleagues in Omaha.

Pollinators and the food we eat – GRO Big Red

It has been well-established and well-discussed that pollinators are responsible for the production (and reproduction) of about 35 percent of the crops that we grow for consumption.  While most of the staple crops like corn and wheat are wind pollinated and don’t require a pollinator, our diet is much more varied and interesting thanks to the pollination services offered primarily by bees.

Notice that I said bees, not specifically honeybees.  While honeybees are what come to mind for most people, there are a whole host of native bee species that are responsible for pollinating our crops.  Many people don’t realize that honeybees are not native to the United States – early settlers brought them over from Europe.  In most areas of the country, honeybees aren’t capable or surviving in the wild, succumbing to weather and parasites if they try to make a go of it outside of a hive maintained by a beekeeper.  Honeybees are an introduced species.

Thanks to a growing interest in beekeeping and greater awareness of pollinators issues, this year’s USDA statistics show that the number of honeybee hives maintained by beekeepers is at a 2 decade high.  Numbers of wild native bees are harder to quantify, and there are several things that are a threat to native bees including habitat loss, climate change (flowers become out of sync with pollinators), pesticide misuse, and more.  But greater awareness, more gardeners consciously planting forage for bees, and the fact that they suffer from fewer diseases and pests than honeybees means good things for native bees.

Who pollinates what?

Bumble bees, solitary bees, and even the annoying sweat bees are great pollinators and for some crops may be more important than honeybees.  Other crops don’t require pollination assistance at all and are either self-pollinated or wind pollinated.  Crops in the grass family, like wheat, rye, and corn, are all wind pollinated.  If you take a look at a

Tomato_flower_blossom
The form of a tomato flower excludes bees from accessing reproductive structures.

tomato flower, you’ll notice that the stamens and the pistil are enclosed within the flower where bees can’t access them.  Tomatoes are self-fertile, relying on wind to knock the pollen around inside the flower.  Bumblebees may stop by trying to get a meal, but they may only end up with a little pollen that falls out of the flower.  The vibrations caused by the bee can assist with this pollination, though.  In this case, bees would be considered a negligible pollinator since wind movement, and not bee vibrations, are the major contributor to tomato self-pollination.  The process is sometimes referred to as “buzz pollination“.

Whether a crop is bee pollinated or not can have big consequences for gardeners and farmers alike.  Bee pollinated crops like squashes, cucumbers, and melons require (you guessed it!) a pollinator.  If the pollinators aren’t around to pollinate or if they can’t access the flowers, you’ll get poor pollination.  Reasons for lack of pollinators/poor pollination can vary from lack of sufficient forage nearby, improper use of pesticides, and even extended periods of rain when the crop flowers are in bloom.

Another consequence of pollination method comes for gardeners and farmers who like to save their own seeds.  If you’re trying to save seeds from your grandmothers favorite pumpkin, cross-pollination from bees could mean that pollen from another variety could totally change the offspring from the seeds you save.  The effects can be drastic considering that, despite their different appearances, pumpkins and zucchini are the same species.  See a previous article about the results of a zucchini/pumpkin cross that I call a “puccini”.   If you’re wanting to save that prized pumpkin, you’ll need to do some hand pollination (and protect the flowers with bags) or make sure there aren’t any other pumpkin varieties (or zucchinis) within a 2-3 mile radius of your plant, which is the average distance a bee can travel.

This is why the majority of “heirloom” crops are things like tomatoes and beans, both of which are self-fertile and have little cross pollination.  You can plant tomatoes within a few feet of each other and they won’t cross.

What needs a pollinator?

I found some great crop pollination lists that I’ll share below.  For now, here’s the gist of what needs a pollinator and what doesn’t (from the first link below):

Requires a Pollinator

• Cucumbers
• Melons and watermelons
• Berries
• Tree fruits

Doesn’t need a bee/insect pollinator:

• All leafy greens
• Brassicas: broccoli, cauliflower, cabbage and kohlrabi
• Below ground root veggies and tubers such as carrots, parsnips, salsify, potatoes, sweet potatoes, horseradish
• Ground level root veggies such as beets, turnips, rutabagas
• Most legumes including peas and beans
• Corn—like other wind pollinated veggies, giving them a little shake helps distribute the pollen.
• Herbs, like the lemon balm pictured
• Celery
• Onions and leeks

Vegetable Crops that Don’t Need Pollinators

Lists of crops that don’t need honeybees

So, without bees you’d still have bread, and corn, and tomatoes, and celery, but you wouldn’t have a crisp apple, a juicy peach, a cold slice of summer watermelon, or a luscious strawberry.  Our diet would indeed be less enjoyable without our friends, the bees!

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