Sunday, March 2, 2014

The Importance of Native Pollinators

Bumble bee visiting a sunflower. © 2010 Beatriz Moisset
At the risk of repeating myself, I want to discuss once again the widespread erroneous belief that we depend entirely on honey bees for the pollination of one third of our food and that we would all die if they were to disappear. Honey bees are not the only pollinators. We must value all the others and we should learn to take advantage of them for our crops' pollination.

We must remember that 4,000 species of native bees populate this country; 20,000 the entire world. They vary in size, appearance, season of activity, flower preference. . .  Some live in colonies similar to those of honey bees, but most are solitary and nest in holes in the ground or in hollow tubes inside soft pitted canes or in holes left behind by beetle larvae.

All of them combined are tremendously important, not just for the pollination of wild flowers but also of some crops. In fact, all the crops pollinated by honey bees could be taken care of by one or another of the numerous species of wild bees.

A few examples of the marvelous things native bees do

*Bumble bees and several solitary bees pollinate tomatoes, peppers and eggplants. Only they know how to manage their flowers. Honey bees cannot do it

*The alfalfa bee and the alkali bee pollinate 80% of the alfalfa flowers they visit. Several bumble bees do just as well. The batting average of honey bees is a mere 20%

*A single southern blueberry bee can pollinate $20 worth of blueberries (probably more at current rates). Honey bees don't come even close

Osmia  sp., a mason bee. © 2007 Beatriz Moisset

*An acre of apples can be pollinated by 250 female orchard mason bees. This task would require 1.5 to 2 honey bee hives—approximately 15,000 to 20,000 bees

Squash blossom. © 2014 Beatriz Moisset

*Squash bees are up early in the morning, when squash flowers are at their peak. Later on, when bumble bees and honey bees arrive, most of the pollination has already taken place

*When the weather is bad, too cold or wet, some native pollinators go out anyway. A few work before sunrise or after sunset. The honey bees prefer to stay home under these conditions

An assortment of pollinators provides a degree of insurance. When the population of one species  declines, as it is bound to happen some years, other species take over the slack. This is one of the advantages of diversification. We have depended for too long on just one species.

Despite the advantages of this variety of native pollinators, farmers often resort to honey bees because the wild pollinators are, well, wild, not easily controlled. Honey bees provide a large task force that can be managed and transported where needed. They are perfect for large monocultures, with only one kind of food temporarily available and nothing else the rest of the year.

We shouldn't ignore the contributions of native bees. They can do a superb job at small or medium sized farms. Managing them would require a healthier habitat and less pesticides. A polyculture, the opposite of a monoculture, would also be important.

We are reaching a point in which we cannot rely entirely on just one species of pollinator. The task of changing cultivation practices is huge but it can be done and it needs to be done. The Xerces Society and some universities are committed to developing the ways of putting native pollinators to good use. The results have been highly encouraging.

Long-horned bee on sunflower. © 2007 Beatriz Moisset

 

Additional readings

Farming with Pollinators, the Xerces Society
Wild Pollinators, Agriculture’s Forgotten Partners. WildFarm Alliance
Native Pollinators. Wildlife Habitat Council

List of articles
Beginners Guide to Pollinators and Other Flower Visitors


© Beatriz Moisset. 2014 

Saturday, February 22, 2014

Don't Underestimate the Native Pollinators


Honey bee and several native bees on flowers of fruit trees
© Beatriz Moisset
 The concern for honey bees has exploded in recent years. A day doesn't go by without a new article on the media or comments on numerous nature blogs. Some are agonized cries of help with words such as: Save the bees to save our food supply! Honey bees are going extinct, we are next! Almost completely lost in the shuffle are native pollinators, namely the 4,000 species of bees in the US.

Most of the public is unaware that native pollinators could supply a substantial amount of crop pollination. In many instances one or another native bee or an entire cadre of them results in more efficient pollination than that of honey bees. Here are a few examples:

In an apple orchard, 250 orchard mason bees can do as much as 15,000 to 20,000 honey bees. Squash bees are early risers and are likely to do more pollination of pumpkins and squash than the late arrivals—honey bees and bumble bees. The Southeastern blueberry bee, Habropoda laboriosa, is capable of pollinating $20 worth of blueberries in her lifetime. Many native bees work in wetter or colder weather than honey bees. The alkali bee and the non-native alfalfa leaf cutter bee pollinate a higher percentage of visited flowers than honey bees do. Some small orchards and vegetable fields get most of their pollination done by native bees.

Many native bees practice buzz pollination,
needed by tomatoes and other crops
© Beatriz Moisset
All and all, native bees provide $3 billion worth of pollination to agriculture, while honey bees' contribution is valued at $15-18 billion. If we put native bees to work, we could reverse these proportions. Perhaps the best way out of the so-called honey bee crisis is to find the way to take better advantage of the other bees. How difficult would that be?
A hundred years ago native bees played an important role on crop pollination. As far back as seventy or eighty years, several authors noticed that bumble bee and solitary bee populations were dropping. This loss was most noticeable in larger farms where sometimes fruit or vegetable yield suffered by the absence of pollinators. Nobody seemed terribly concerned as long as the honey bee could be brought into service. Some observers knew that native bees were more efficient in many cases, but felt that the ease with which honey bees can be managed compensated for this drawback.


Some native bees are just as efficient as honey bees
at pollinating fruit trees
© Beatriz Moisset
Intensive farming grew as did the need for pesticides, and beehives started to be transported long distances and in large numbers to do their duty. It was the birth of the pollination industry involving beekeeping practices far removed from what would be considered natural. It shouldn't surprise us that such an unsustainable system is causing troubles for honey bees.

Can we bring native pollinators back after they continued to lose ground for the past century? Are there enough left around to take over the task of pollinating our crops? Even without statistics, we can be sure that only a tiny fraction of the previous populations remains. Perhaps, some species are precariously hanging on the verge of extinction or have already disappeared.


Dead solitary bee © Beatriz Moisset
No species takes the road to extinction willingly. Every creature, large or small, fights tooth and nail, or mandible and tarsal claw as the case may be, to stay alive and procreate. A few years ago, an entomologist found a miner bee's nest in a flower pot in his backyard. Another bee expert encountered a rare species of bee, regarded close to extinction, in the very heart of Washington DC, in a butterfly garden at the Washington Mall. With remarkable tenacity, these little survivors had managed to find just enough resources and shelter to raise their families in the middle of the concrete jungle.
We should not give up hope. Native pollinator populations can be brought back to the levels of yesteryear; perhaps then they can resume pollinating the crops that feed us.

Pollinators. © Beatriz Moisset.

List of articles

Beginners Guide to Pollinators and Other Flower Visitors


© Beatriz Moisset. 2014 


Monday, February 10, 2014

Alfalfa Pollination




What is the most important insect-pollinated crop? Not a fruit or a vegetable but alfalfa. Yes, alfalfa, not because we consume large amounts of their sprouts, but because cattle needs this food. Thus: no alfalfa, no beef or milk.

This crop was first introduced in California during the gold rush. Alfalfa farming grew from there at a steady pace to what it is today, the third largest crop, after corn and soy bean. A few species of bumble bees and solitary bees took a look at this exotic flower, found it to their liking and proceeded to pollinate it. It wasn't a big leap; this plant's blossoms resemble those of other members of the pea or bean family. The native pollinators were familiar with bean flowers and adapted easily to the new arrival.

Alfalfa blossom. H. © Zel. Wikicommons
Peas, beans, alfalfa, clover and several other plants have butterfly-like (papilionaceous) flowers. The lower petals form an enclosure, shaped like the keel of a boat. This structure holds the sexual parts, the anthers and pistil. When an insect lands on the flower, a trigger mechanism makes it snap open or trip the flower. This is how pollination is accomplished.

Honey bees were not present in California when the earliest fields of alfalfa were cultivated. The first beehive arrived in 1853, just one solitary hive; a few others had died in transit. It took many years for the honey bee populations to build up to significant levels. This didn't matter because the wild bees did an excellent job.

New Zealand wasn't so lucky when it started growing alfalfa to feed the recently introduced cattle. The few native pollinators were stumped by the new flower. They lacked the necessary equipment and dismissed the strange blossoms. Year after year, hay grew luxuriantly, but no seeds. Alfalfa growers resorted to importing a few species of bumble bees from Europe to cut down the expenses of having to buy seed every year. Thus, industrious bumble bees saved the day in that country.

Scotch broom, a papilionaceous flower, being tripped. © Beatriz Moisset
 Honey bees detest the rough treatment alfalfa flowers subject them to and soon learn a trick of their own. They enter the flower from the side and help themselves to nectar without tripping its mechanism. Only na├»ve, youthful ones pollinate flowers. Despite the honey bees' poor performance, most alfalfa farmers resort to them because of the convenience in using a managed species.

In addition to the honey bee, two other species of alfalfa pollinators are managed to some extent and used commercially. They are the Japanese alfalfa leafcutter bee and the native alkali bee.

The populations of native bees have been severely reduced in the last one hundred years largely because of intensive agriculture. Restoring their numbers and putting them to work in alfalfa fields would be an arduous task but a worthy one. Some farmers find that, when they include flowering and nesting site places in their fields or orchards, the health of the crop improves and the need for pesticides diminishes. Thus, alfalfa pollination could be done entirely and more efficiently by native bees. This form of agriculture would be more sustainable than the present methods.

List of articles
Bring Back the Native Pollinators
Will We all Die if Honey Bees Disappear?
Growing Insects: Farmers Can Help to Bring Back Pollinators
Organic Farming for Bees


© Beatriz Moisset. 2014

Sunday, January 12, 2014

Beginners Guide to Pollinators




Read the review by Kathy Keatley Garvey at the Bug Squad website, For Beginners, a Guide to Pollinators
So many flowers.  So many pollinators. So many floral visitors.
On every field trip, we see something new and different.
With so much interest in pollinators, it's good to see that biologist Beatriz Moisset has written a downloadable book, "A Beginners Guide to Pollinators and other Flower Visitors." It's meant for young adults and beginners.


Beginners Guide to Pollinators and other Flower Visitors available at:

Friday, December 13, 2013

Roadside Pollinator Gardens and Traffic


Mountain laurel. © Beatriz Moisset
Pollinator gardens are blooming along many highways. Perhaps the idea originated with Lady Bird Johnson and her beautification program. But it goes well beyond that. Planting wildflowers along highways has many advantages besides the esthetic ones. With the growing loss of pollinator habitat, it is a blessing to use the wasteland of roadsides as wildflower gardens to take care of the needs of pollinators.

Butterflies and bumble bees are more abundant where wildflowers bloom than in areas where grasses are dominant and where mowing and pesticide treatments are routine according to many reports. The possible downside is that larger numbers of dead butterflies, and perhaps bumble bees are found along highways with abundant wildflowers. How serious is the problem? Do the benefits outweigh the damages?

Skipper on asters. © Beatriz Moisset
It isn't easy to assess all the aspects of the situation. But the weight of opinion is that the deaths by vehicles are not much higher than those by natural causes. The increase in food supplies and shelter for the pollinators benefits them and contribute to larger populations. So, those who study the matter feel that it is worth to continue creating habitat for pollinators along highways.

Other advantages of such roadside pollinator gardens are a reduction in mowing frequency once the gardens are established and a reduction in pesticide use. Did I mention that the view is also more pleasant to the eye? Perhaps, this improves the mood of the drivers and brings down accident frequency.

Milkweeds. © Beatriz Moisset

References

Pollinators and Roadsides. Xerces Society. 
Manage your Roadsides for Bees & Butterflies. 
Use of Roadside Prairie Plantings by Native Bees. Iowa State University. 
Roadsides as Habitat for Pollinators: Management to Support Bees and Butterflies. Jennifer L. Hopwood.
A Sticky Situation for Pollinators. Minnesota Conservation.

Saturday, December 7, 2013

Globetrotting Skippers


Fiery skipper (Hylephila phyleus). © Beatriz Moisset
 You probably thought I was running out of migratory butterflies after my last two posts. Not quite, there are more. But now I want to turn to skippers and talk about two species that also deserve the name of globetrotters.

Skippers are related to butterflies and often they are called by that name. The clearest difference between the two is that the end of a skipper's antennae ends in a hook, while that of a butterfly ends in a knob. Most are not as colorful as butterflies, they skip along when flying, hence their name.

Butterflies, skippers and moths belong to the order Lepidoptera, which literally means "scaly wings." You can tell them apart from all other insects by this feature. Perhaps, in a future post I will deal with migratory moths. Yes, there are some of those, too. In fact, a few perform amazing trekking feats.

As I mentioned, we know very little about the itineraries and distances covered by migratory butterflies, other than monarchs. We know even less about skippers. The only fact we are certain of about the ones I want to discuss today –the fiery skipper and the long-tailed skipper– is that they travel long distances, not just locally.

Fiery skipper (Hylephila phyleus) is one of the so called grass skippers because its caterpillar feeds on grasses. It has a bright orange color. It lives in temperate and tropical areas and can be found from North America to Brazil and Argentina. Let me clarify that this is its geographic distribution and it doesn't mean that it travels that far. The ones that live in South America are different populations. However, as I said before, it travels north in the spring from the southern states to northern areas. It is thought that many of those migrants don't make it back. Instead, they freeze and die when the weather gets cold.

Long-tailed skipper (Urbanus proteus). © Sean McCann. Bugguide
 The long-tailed skipper (Urbanus proteus) is unusual in two respects, each hind wing has a long projection that gives it its name, and its caterpillar feeds on members of the pea family. This latter characteristic doesn't endear it to farmers. The caterpillar is often called the bean leaf roller because it finds shelter by wrapping itself inside a leaf of this plant. It is just as widespread as the fiery skipper. Once again, it is not known if the ones that travel north or their progeny ever make it back to the South.

Years ago, it was thought that some of the travelers mentioned in previous articles failed to return south when the weather deteriorated perishing at the end of the season. Later on, additional observations showed that painted ladies, red admirals and a few others, do indeed return south in the fall.  I hope that, as we find out more about these two species, we learn that they too are capable of escaping the winter weather by migrating south in the fall.


Globetrotting Butterflies
More Globetrotting Butterflies

Monday, December 2, 2013

More globetrotting butterflies


Monarch butterfly, the most famous traveler. © Beatriz Moisset
In my last post I discussed two butterflies, the red admiral and the painted lady, that rival the monarch in their annual journeys. If you found this information surprising, you would be even more surprised to learn that there are several other butterfly globetrotters. Other insects capable of long range migrations are several species of dragonflies. There may be many others.

Let us look at a few more migratory butterflies.

Cloudless sulphur. © Lynette Schimming. Bugguide.net
Sulphurs are butterflies that range in color from lemony yellow to orange. The name refers to their color. One among them, the cloudless sulphur (Phoebis sennae), travels from Canada to Texas, Florida, and Mexico in the fall. It also lives in South America, as far south as Argentina. We don't know much about the migration of the cloudless sulphur, other than when going south in the fall, they move steadily and purposely, hardly stopping to eat. We know even less about the ones that live in South America, whether they travel much and whether they mix with the North American populations.

Common buckeye. © Beatriz Moisset
Another lovely vagabond is the common buckeye (Junonia coenia), so called for the distinctive spots on its wings. Not content with one pair of eyespots, it has three. Not visible when the wings are folded, they make quite a display when it decides to spread them. It must be a scary sight to a hungry bird, which may induce it to leave the morsel alone.

Common Buckeye. View of the underside. © Beatriz Moisset
When the monarch butterfly shows in large numbers in Cape May, NJ, every October and November, so does the common buckeye. I am just as happy to see one as the other. It lives year round in the southern states, as well as in Central America and Colombia. Apparently, some don't travel much; others get the urge to go north, as far as Canada. Their descendants head south in the fall. Once again, we don't know much more about its movements.


A gaggle of buckeyes takes a rest on their way south
  © Beatriz Moisset
It is curious to me that only one globetrotter, the monarch butterfly, has caught the public imagination, leading to numerous observations. Nowadays, we know quite a bit about its complicated trips north and south. I am just as eager to learn about other tiny organisms' urge to cover large distances that seem to exceed their capabilities. I hope this awakens your appetite for more information on all these adventurous little souls.