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Saturday, August 27, 2011

Bees and Vitamins

We need the vitamins provided by fruits
It is said that bees and other pollinators are responsible for one third of all our food. Whether this is exactly right I do not know; but a trip to the grocery store confirms that a substantial part of our food comes from plants that have been pollinated by insects rather than by the wind: most vegetables and fruits, drinks such as coffee and tea. We even have to include in this list beef, poultry and dairy products because farm animals feed partly on alfalfa or clover which have been pollinated by insects. Without pollinators we would be reduced to eating grains or cereals, potatoes, sea food and fish and very little else (and undernourished beef and poultry).

Tomato flowers
What is never mentioned but I find perhaps even more important than food quantity is quality. Many of our essential vitamins and antioxidants come to us courtesy of pollinators. Vegetables and fruits are loaded with vitamins such as beta carotene, vitamin C and a few others.

So, in summary, if it wasn’t for pollinators we wouldn’t be one third hungrier. Instead we would be one hundred per cent dead.

Vegetables are indispensable because of their vitamins


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© Beatriz Moisset. 2012

Wednesday, August 10, 2011

Sunnyside Dru: Bee Barracks update

Sunnyside Dru: Bee Barracks update: "Earlier this year we posted a picture of this bee block. There are many variations to this all over the farm..small, not really noticeable, ..."

Sunday, July 3, 2011

Mountain laurels instead of rose bushes?

Last year I was traveling along the Blue Ridge in May and was pleasantly surprised by the beauty of the blooming mountain laurels. I had to look again and again to convince myself that what I was looking at wasn’t a rose garden but just a natural grove of mountain laurels.

I want that look in my garden. I have two rose bushes which I inherited from the previous owner of the property and I want to replace them. The advantages are obvious to me. Roses are not native; they provide no food for pollinators. Mountain laurel, on the other hand, is pollinated primarily by native bumble bees.
It has a peculiar system of pollination. The unopened blossoms present little knobs which give them a funny look. When the flowers open, the function of these little knobs become apparent. They are pockets that hold the anthers (the pollen carrying part of the flower) trapped. It still doesn’t explain why this is so; in most flowers the anthers are free and exposed, better to spread their pollen at the slightest touch of a flower visitor.

The mountain laurel has a different strategy. The pollen is well protected against rain and wind; but when a pollinator lands on the flower searching for nectar, the weight acts as a trigger, causing the taut stem of the anther to spring. The anther hits the pollinator gently on the back and gives it a dusting of pollen.
Mountain laurel flowers produce a moderate amount of pollen; but most of it ends up where it is intended, on the body of a pollinator, rather than being wasted in other ways. It seems like a highly economic method to spread the pollen.

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Wednesday, June 15, 2011

Rain and Pollinators

Where do pollinators go when it rains? You certainly don't see many of them around when it is pouring. They may be sturdy little fellows but they have some limitations. Wind or rain (or even cloudiness) can be too much for most of them. Cold weather also makes them think twice before going outside.
Gathering of male Andrena bees early in the morning

There are many different kinds of pollinators: bees, flies, butterflies, moths, and a few other insects; not to mention a few non insect ones such as many kinds of birds, bats and even a few other mammals. Let us look at one group in particular, bees. Bees probably do about 90% of all pollination so they deserve our attention. Bad weather is too much for most of them, but some fare better than others. A few bumblebees tolerate the cold of the Arctic Circle. Some bees fly at dawn or dusk or in the very early spring, although the majority prefers the daytime, sunny weather and warm temperatures. Wind is harder to overcome than chilly weather. There are physical limitations to flight, so when the wind reaches certain speed all flying insects find themselves grounded. That is why a steady breeze brings welcome relief from mosquitoes and gnats.

Rain is a serious problem to insects; a mere drop of rain is the equivalent of a big bucket to us; it would knock them down harshly. The weight of the moisture clinging to their bodies proportional to their own body weight would also be a major problem.

Insects are sensible enough to lay low when conditions are severe. Females return to their nests and stay there. Males, on the other hand, do not have nests to return to; they are not homemakers and know nothing about nests so they resort to a different kind of shelter. The males of many species seek each other company. They may stay in groups on flowers or leaves, or hanging from twigs. They clamp their strong jaws onto a twig and go to sleep this way. There are times in the early morning in which you can find one of these roosts. The insects may be dew covered and very sluggish and will need some sunshine before they can start moving around. Others cluster inside large flowers such as squash. These places offer some protection from the weather.
Carpenter bees spending the night clinging to a Passionaria flower

Probably these roosting places are not as secure as the nests where the females stay and this may very well be one of the reasons why male lives are shorter than female's. Males only mission in life is to mate; after that they are dispensable. Females, on the other hand, need to live a little longer in order to build nests, gather food, lay eggs and seal the entrance to their nests.

Sometimes, after a particularly rainy spring, trees produce very little fruit and one wonders about the connection between the abundant rain and poor crop. What happens is that the pollinators didn’t have enough opportunity to visit flowers because of the weather.

It is interesting that many native bees can face these hardships better than honey bees and turn out to be better pollinators under certain circumstances. Honey bees are very quick to return to their hives when weather conditions are poor. They also work shorter hours, starting later in the morning and quitting earlier in the afternoon. Some bee specialists say that native bees and bumblebees are not unionized and find themselves forced to work longer hours and under poorer conditions.

Roosting male bees

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Monday, June 13, 2011

Magnolias and Beetle Pollination


Magnolias were among the earliest flowering plants, which evolved many million years ago, long before there were any bees. Butterflies and moths were also absent in those days. The only pollinators available were probably beetles and flies, the so-called “dumb pollinators”. This term refers to the fact that the late-comers to the world of pollination, particularly bees, can perform remarkable feats of memory and skillful manipulation of flowers.

When bees entered the scene, perhaps twenty or thirty million years later (give or take a handful of millions), they took to the pollinating job with gusto. They became real pros which adapted to the ever growing variety of flowers and developed skills par with the complexity of these newly evolved plants. The same can be said of many butterflies and moths and also some wasps. That is how they earned the name of "smart pollinators".

Neither magnolias nor beetles are very specialized to pollination by insects. The flowers, though lovely have a very simple structure; for instance, there is no distinction between petals and sepals as in most other flowers. In turn their pollinators, beetles, are very clumsy at their task; sometimes they get carried away and eat parts of the flowers along with the pollen they find there. Their mouth parts are made for chewing, rather than for gathering nectar and pollen, so they can’t be blamed for their sloppiness. The flowers, in turn, are adapted to this rough treatment; that is why magnolia petals tend to be rather leathery; and, most importantly, the seeds are well protected.


You develop a new respect for the pollinating responsibility of beetles when you take a look at the many families of these insects that visit magnolia flowers: sap-feeding beetles, tumbling flower beetles, leaf beetles and weevils, among others (or if you prefer their technical names: Nitidulidae, Mordellidae, Chrysomelidae and Curculionidae).



Bees, bumblebees, flower flies, a few types of stink bugs, leafhoppers and several other types of insects are also found visiting magnolia flowers attracted by their nutritious pollen and nectar.

But most of them arrive at the flowers too late, after the blooms are past their prime and are not receptive for pollination. So it is the beetles that carry the lion's share of the responsibility for perpetuating these plants.



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© Beatriz Moisset. 2012

Sunday, May 29, 2011

Nectar: Drink with a Zing?


We saw that floral nectars aren’t just empty calories (Nectar: Breakfast of Champions); they supply pollinators with valuable nourishment. The singular properties of nectar don’t end up there. When chemists continued analyzing the nectar of diverse flowers they found a few surprises.

In some instances caffeine or nicotine are added to the menu. Who would have thought! Then again, if bees love spilled Coca-Cola, it is perhaps for more than the sweetness. Do the clients of floral restaurants seek these stimulants? Do flowers find it important to indulge such demands? One thing is clear: some special ingredients in nectar must be important, both for the pollinator and the flower.

There are cases in which the sugar in nectar ferments into alcohol to the point that it may intoxicate thirsty flower visitors. Bumble bees visiting such flowers behave like drunken sailors, bumping clumsily into flower parts, shaking loose the pollen from the anthers and thus getting an extra dose of pollen dusting. Moreover, they neglect their fastidious grooming and remain rather dusty all over for some time. Perhaps this is beneficial to the flower which may end up getting more pollination under these circumstances. Nobody knows for sure but it is an interesting theory. I wonder whether the little gourmets develop a taste for certain vintages and visit more frequently the restaurants that deliver the desired beverage.

The flowers of a palm tree in Malaysia produce alcohol that can reach a concentration of 3.8%, comparable to some beers. And the tree smells like it! There is a little tree shrew, a fairly unusual pollinator, which visits these flowers assiduously. Up and down the trunk it runs visiting thousands of flowers. It is capable of drinking the equivalent of nine glasses of wine, day after day during the blooming season. Those who have studied this behavior claim that the animals show no sign of loss of coordination or similar consequences of heavy drinking.

Pollinators do a lot of traveling in their quest for nectar and pollen. They carry more than what is intended from flower to flower. Like tiny typhoid-Maries they are likely to pick up and spread pathogens along with their legitimate cargo of pollen. Nectar is the perfect culture broth for many bacteria and fungi. Flowers can become quite sick so they need to protect their precious reproductive organs against infections. It should come as no surprise that they can produce an assortment of antiseptics. There are substances in nectar that produce peroxide, the same disinfectant your mother used to apply to your scraped knees.


Perhaps the most mysterious thing is that some nectars carry bitter tasting substances and even toxins. What would be the purpose of that? Some of the bad tasting ones deter only some flower visitors, while they don’t bother others. Perhaps the plant is being selective, inviting only the most efficient pollinators and keeping others away. It is also possible that some pollinators can only tolerate a small amount of the bitter nectar, thus, abandoning the flower sooner and performing more pollination with less consumption of nectar. Let us remember that nectar production is an expensive investment for the plant.

Most plants produce toxins to protect leaves, stems, etc. against the hordes of herbivores. In other words, plants synthesize organic pesticides. Ordinarily they filter out these toxins from the nectar. But some accomplish this only partially. It seems like an unfortunate side effect, an instance of unintended contamination. Perhaps we are not the first ones to run into such a problem, plants made that blunder millions of years ago.



Nectar chemistry
Nectar, the first soft drink
Tiny treeshrews chug alcoholic nectar without getting drunk
Nectar, breakfast of champions

List of articles

© Beatriz Moisset. 2012

Saturday, May 21, 2011

Nectar: Breakfast of Champions


I used to believe that flower nectar was sugary water and not much else. That simple drink should be adequate for many of the insects that visit flowers. Sugar provides the fuel to power their flight, thus taking care of a fundamental need. Many insects have a very short adult life. They have already accumulated, during their larval life, most of the nourishment that they need as adults. In fact there are even some insects, such as the Luna moth, that do not feed at all as adults. Moreover, nectar drinkers often have other foods in their menu. For instance, bees collect pollen, as well as nectar, from flowers; wasps hunt insects. So it wouldn’t be surprising if nectar provided nothing more than sugar as a reward to pollinators.

I was wrong, but I wasn’t alone in my ignorance. Only recently, scientists have been able to study the chemistry of nectar, given the tiny amounts available for study. What they have learned in recent years surprised everybody. Nectar is a true cocktail including an assortment of substances, from nutritious to intoxicating, not to mention scented, colored or with preservatives. Flowers are known for the complexity and diversity of their shapes and colors. Now we know that their nectar can be just as rich in complexity and variety. Nectar drinkers seem to be connoisseurs of the restaurants they visit and flowers must have good reasons for developing such a complex menu to satisfy the demands of their clientele.

First of all the concentrations of sugars vary depending on a number of factors. Perhaps, the most important one is the most frequent visitors of a particular species. Butterflies and moths and some bees have very long tongues which they use like drinking straws. They visit flowers that provide a rather watery drink not likely to clog these very thin pipes. On the other hand, other insects, with shorter tongues, merely lap or slurp fluids and can take advantage of thicker nectar, richer in sugar.


In addition to sugar there are other substances in nectar. Like the power drinks used by athletes some contain ion supplements, such as potassium and sodium. Other common supplements of nectar are aminoacids, the building blocks of proteins. Let us remember that adult butterflies and moths cannot eat any solids. They have no chewing parts, only a long, thin tongue good enough for fluids and maybe the occasional pollen grain. As I mentioned before, most insects are short lived and may do fine without proteins in their diet, but the beloved monarch butterflies live for several months and have to make an arduous journey. They certainly need a well balanced diet; sugar alone would not suffice them.

There are other ingredients in nectar which I will discuss in future posts. I only want to mention here that in addition to nutrition, these substances may add flavor to this food making it more attractive to the pollinators and other flower visitors.

It is rather amazing to realize that we didn’t invent energy drinks; flowers did it millions of years ago. It gives me pause when I prepare to refill the hummingbird feeder. Are we turning our loved birds into soft drink junkies? Would they be better off without our help? I don’t feel too guilty because I know that they also feed on insects so they must be getting a balanced diet despite the empty calories at the hummingbird feeder. But, just in case, I will start growing plants for hummingbirds in my garden and cutting down on the junk food.


I can think of a few (natives only): butterfly weed, lobelia, beebalm, columbines, trumpet honeysuckle, penstemon, zinnia, nicotiana. Any suggestions?

Here is a list of “Top Ten” native hummingbird plants of the Operation Rubythroat web site.

Nectar, a drink with a zing
Nectar chemistry
Nectar, the first soft drink
Tiny treeshrews chug alcoholic nectar without getting drunk

List of articles

© Beatriz Moisset. 2012