Rainy Days Pollination Blues!

 Guest post by David L. Green, retired commercial bee keeper, former editor of small newspaper, teacher. You can visit his website and his blog

Partially pollinated cucumbers. © Dave Green, 2013

With seven inches of rain in five days, bees had very little time to work. They delivered enough pollen grains so that the cucumbers did not abort, but not enough to flesh them out.

The one at left is a total lack of fertilization of the seeds at one end - that meant that the flesh did not grow, and the cuke had a "tail." Three more are slightly better. The one at the bottom has few of the incipient seeds fertilized in the middle, giving a waist to the cuke. These poorly pollinated cukes grow slowly and quickly get tough, sometimes bitter, as well.

If bee populations are normal, this problem should straighten out when the weather is more suited to bee flight. If you get very many like this in good pollination weather, you have a shortage of bees, and may need to work on increasing bee populations or hand pollinate.

My garden is pollinated by a mix of bees, with the bulk of the workload carried by bumblebees and honey bees, but we also have green sweat bees, squash bees, digger (Anthophora) bees, tiny Ceratina bees, and leaf cutter bees doing some of that work.

To make a perfect cucumber, you need to get almost all of the incipient seeds fertilized. That requires two grains of pollen - one for the embryo and one for the seed coat, so each perfectly pollinated cuke represents several hundred grains of pollen delivered to the flower.

A lot of folks think that, if they see a bee in a flower, that pollination is accomplished. But it's not an on/off switch. It's a progressive thing. It takes many bee visits to deliver all the pollen needed for multi-seeded fruits.

Every year, more and more gardeners report the symptoms of lack of pollination in their gardens. The problem seems to be accelerating.

It represents one of our most urgent environmental problems - pollinator decline. Our bees are disappearing. Some of that is due to habitat loss; some due to monoculture and its feast or famine pattern of intense bloom, followed by barrenness; some is from new diseases and parasites; but the worst and most difficult problem to solve is the loss caused by pesticides.

When cotton blooms, bees focus on those nectar-rich blossoms, and drop by the millions when the cotton is sprayed. In July clover is in full bloom in the orchard floor, and more millions of bees die when the fruit is sprayed. Community mosquito sprays are supposed to be applied when bees are not working, but this time limit is very poorly observed, and many more bees are dropped from applications done when they are out. And many gardeners plaster Sevin dust all over their gardens without thought of the bees.

All four of these cases I mentioned are illegal applications, because the label directions forbid them, but label enforcement is rare and usually amounts to a slap on the wrist, if anything.

So, if we do not begin to protect our pollinators - we lose much of the vitamin C (fruits) in our diet. Food costs will rise; only the rich will be able to afford many of the most nutrient-rich foods we have. We are left with grains that do not need bees - but remember that "man shall not live by bread alone."

© Dave Green, 2013
Retired pollination contractor

List of Articles

Beginners Guide to Pollinators and Other Flower Visitors

BUMBLEBEES. Are Some Bumblebees Going the Way of the Dodo?

Who doesn't like a bumblebee? With their plump, fuzzy bodies and striking black and yellow or black and white stripes they easily capture people's hearts, especially when they are seen buzzing around from flower to flower.

What most people don't know is that some species of bumblebees are in decline. We have heard about the plight of its relative, the domestic honey bee; but haven't paid much attention to the situation of this wild cousin. Why should we care? It isn't just because bumblebees are charismatic, but also, and more importantly, because they play key roles in certain ecosystems. So far, we know of only a few species that are showing a reduction in numbers, both in North America and in Europe. It isn't as if all the species of bumblebees were going extinct overnight; fortunately some species are doing well, even in unexpected places such as suburban gardens. But, perhaps we should start paying attention to what is happening now rather than when it is too late. Besides, it is possible that many other species of wild bees are suffering similar declines in their numbers and we have no way to estimate what is happening because we know so little about them.

Here are some of the things that bumblebees do: they pollinate 15% of our food crops, worth about 3 billion dollars; they also pollinate countless wild flowers. Wildflowers are important not just for their beauty, but also for the seeds and berries that they produce. They become food for many species of wildlife, from birds and small rodents to large animals such as bears. Birds don't know what percentage of their food crops are pollinated by bumblebees, but it is possible that for some species is closer to 90% than to 15%. If we are not worried about our own food, we should worry about all the many species of birds and other wildlife that may be suffering because of a reduction on the numbers of wild bumblebees.

Goldfinches and many others owe their food to hard working pollinators such as bumblebees.
List of articles
© Beatriz Moisset. 2010

THE WEB OF LIFE. The Bear, the Waxwing and the Bee

You may be wondering what bears, waxwings and bees have in common. We'll get to that later.

Let us start with a black bear, the formidable resident of forests and broad spaces. An encounter with one of them can be an unforgettable experience. It is surprising to realize that an animal built up with such powerful claws and jaws is seldom a hunter; in fact perhaps only 10 or 15 percent of its diet consists of animal matter and a good part of that is carrion or insects. So, what does a bear eat? With great versatility it finds a wide range of plant food in the course of the year. In early spring, fresh out of hibernation it may find skunk cabbage to its liking as well as sprouts from plants in the pea family, horsetails and sedges. Later in the season it will find the growing cow parsnips and dandelions, as well as flowers of several kinds. It may supplement this vegetarian diet with some animal protein, from caterpillars to the occasional newborn elk; but still about 80 percent of the summer diet is vegetable. In the fall, it is the time to feast on berries; blueberries, raspberries and everything in between. It can devour enormous quantities of this food because it needs to fatten for the long winter ahead. It is hard to believe that such diet can become many pounds of fat in the short period of a couple of months.

And now for cedar waxwings, those attractive birds that are so much fun to watch. They are especially interesting when they are engaging in their peculiar tradition of passing berries from one to another. Cedar waxwings eat an assortment of berries through the year. In summer, when they are raising young, they enrich their diet with insects; but berries are the main staple of their diet.

Finally, let us talk about bees. Let us make it clear that I am not referring to the domestic honeybee but to any of the numerous native bees and bumblebees that feed on pollen and nectar of wild flowers. If we want to be more specific we can choose the blueberry bee. This industrious little bee is very specialized on the pollen it chooses to feed her family. It goes almost exclusively to blueberry flowers. When doing so it carries some pollen from flower to flower and from plant to plant, providing the plant an invaluable service, pollination. Once the flowers are pollinated they can start setting seeds and developing fruits.

Now, you see the link between bees and birds such as the cedar waxwing and larger animals such as the black bear. They feed on the berries that have been pollinated by the bees or, in the case of the bear, on other plant parts that also require pollination to multiply.

Experts on pollination remind us frequently that one third of our food comes to us courtesy of pollinators; most fruits and vegetables require the services of these little go-betweens, most of them bees. What they forget to mention is the large number of other species that also depend on pollinators for a good part of their diet. The bear and the waxwing are just two examples of a very long list that intertwines the little bees with the more visible birds and mammals.

Another twist in this intricate web, the bear and the waxwing digest the berries but not the seeds. So they end up dropping them farther from the mother plant and surrounded with an amount of excellent fertilizer. So, the pollinator, in turn, also depends on the seed dispersers.

But the final, and perhaps most marvelous twist, is that the plants, so dependent on pollinators and seed dispersers are actually making use of them. They are very skilled in attracting their attention and supplying their needs, either with rich pollen and nectar or with juicy, nutritious fruits. At the same time, they make sure that not all the pollen gets eaten and that the seeds can safely go through the intestines of the berry gluttons.
Thus the web is complete: flowering plants need the pollinators and the seed dispersers; bees need the flowers and the seed dispersers and, finally, bears and birds need the plants and the pollinators. When you walk through the woods or the meadows, think about this invisible web and what it is doing to make everything possible.

Bear feeding: BearDiet

Cedar waxwing feeding: Appalachian Mountain Club: Bird of a Feather...

National Pollinator Week

Pollinators are responsible for one third of the food we eat. Most fruits and vegetables have to be pollinated so that they can produce seeds. Also coffee, tea and chocolate need the services of pollinators.

We are so dependent on pollinators that we celebrate them once a year in National Pollinator Week, the last week of June.

© Beatriz Moisset