POLLINATORS

[mikhurram]

Gold Dusters
They are the Earth’s pollinators. And they come in more than 200,000 shapes and sizes.
http://ngm.nationalgeographic.com/print ... lland-text

By Jennifer S. Holland
March 2011, National Geographic

Row upon row, tomato plants stand in formation inside a greenhouse in Willcox, Arizona. Green stems poke from coconut-fiber blocks, reaching toward the glass-paned sky. Lab-coated technicians on elevated electric carts meticulously prune the crop. Eurofresh Farms harvests 130 million pounds of tomatoes a year from these perfect plants, grown on 311 acres in buildings outfitted with miles of pipe to ferry water and a network of steel wire above to capture the climbing vines. The ripening fruit smells faintly artificial, all sweetness and no soil.

But there is a natural presence here too. It reveals itself as a low hum that settles deep inside the ears: a thousand bumblebees hard at work.

To reproduce, most flowering plants depend on a third party to transfer pollen between their male and female parts. Some require extra encouragement to give up that golden dust. The tomato flower, for example, needs a violent shake, a vibration roughly equivalent to 30 times the pull of Earth's gravity, explains Arizona entomologist Stephen Buchmann, international coordinator of the Pollinator Partnership. "The scale is different," he says, "but consider that fighter pilots usually black out after half a minute at four to six g's."

Growers have tried numerous ways to rattle pollen from tomato blossoms. They've used shaking tables, air blowers, blasts of sound, and vibrators laboriously applied by hand to each bloom cluster. But the tool of choice in today's greenhouses? The humble bumblebee. Give a bee access to a tomato flower, and she'll glom on and quiver fiercely as she feeds, letting loose a cloud of pollen that hits the plant's stigma (the tip of the female anatomy) and also sticks to the bee's fuzzy body. She then ferries those particles to the next blossom. It's called buzz pollination, and it works like a charm.

No surprise that nature's design does the job best. What's astonishing is the array of workers that do it: More than 200,000 individual animal species, by varying strategies, help flowers make more flowers. Flies and beetles are the original pollinators, going back to when flowering plants first appeared 130 million years ago. As for bees, scientists have identified some 20,000 distinct species so far, and about one-fifth of those pollinate flowers in the United States. Hummingbirds, butterflies, moths, wasps, and ants are also up to the task. Snails and slugs smear pollen as they slide over flower clusters. Mosquitoes carry pollen for batches of orchids, and bats, with diverse muzzles and tongues adapted to tap differently shaped blossoms, move pollen for 360 plants in the Americas alone.

Even nonflying mammals do their part: sugar-loving opossums, some rain forest monkeys, and lemurs in Madagascar, all with nimble hands that tear open flower stalks and furry coats to which pollen sticks. Most surprising, some lizards, such as geckos and skinks, lap up nectar and pollen and then transport the stuff on their faces and feet as they forage onward.

Flowering plants—there are more than 240,000 species of them—have evolved in step with their pollinators, using sweet scents and bright colors to lure with the promise of a meal. Flower receptacles, like the animals' transport systems, are wonderfully varied, from tubes and gullets to flaps, brushes, and spurs. Match the right animal and plant parts—long tongue poked into narrow tube, furry face pressed into sticky brush—and pollen is soon on its way.

All that messy diversity, unfortunately, is not well suited to the monocrops and mega-yields of modern commercial farmers. Before farms got so big, says conservation biologist Claire Kremen of the University of California, Berkeley, "we didn't have to manage pollinators. They were all around because of the diverse landscapes. Now you need to bring in an army to get pollination done."

The European honeybee, first imported to the Colonies some 400 years ago, has been the domesticated pollinator workhorse in the U.S. since people began trucking them up and down highways in the 1950s. Now at least a hundred commercial crops in the U.S. rely almost entirely on managed honeybees, which beekeepers raise and rent out to tend to big farms. And although other species of bees—mason bees, for example—are five to ten times more efficient on a per-bee basis at pollinating certain fruits, honeybees have bigger colonies (30,000 or more bees per hive), forage over longer distances, and tolerate management and movement better than most insects. They're not picky—they'll spend their time on almost any crop. It's tricky to calculate what their work is truly worth; some economists put it at more than $200 billion globally a year.

Industrial-scale farming, however, may be wearing down the system. Honeybees have suffered diseases and parasite infestations for as long as they've been managed, but in 2006 came an extreme blow. In the U.S. and other countries, bees in massive numbers began to disappear over the winter. Beekeepers would lift the lid of a hive to find only the queen and a few stragglers, the worker bees gone. In the U.S. a third to half of all hives crashed; some beekeepers reported colony losses near 90 percent. The mysterious culprit was named colony collapse disorder (CCD), and it remains an annual menace—and an enigma.

When CCD first hit, many people, from agronomists to the public, assumed that our slathering of chemicals on agricultural fields was to blame. Indeed, says Jeff Pettis of the USDA Bee Research Laboratory, "we do find more disease in bees that have been exposed to pesticides, even at low levels." But CCD likely involves multiple stressors. Poor nutrition and chemical exposure, for instance, might pummel a bee's immunities before a virus finishes the insect off.

It's hard to tease apart factors and outcomes, Pettis says. New studies reveal that fungicides—not previously thought toxic to bees—can interfere with microbes that break down pollen in the insects' guts, affecting nutrient absorption and thus long-term health and longevity. Some findings pointed to viral and fungal pathogens working together. "I only wish we had a single agent causing all the declines," Pettis says. "That would make our work much easier."

As managed bees take a hit, so too do wild pollinators, whose work pollinating U.S. crops is worth about three billion dollars annually. Some notable bumblebee species are rarely seen anymore, with others becoming increasingly scarce. But few of the scores of native pollinators, less visible and less valued than the big-money honeybees, have been monitored long term.

What to do? Give pollinators more of what they need and less of what they don't, and ease the burden on managed bees by letting native animals do their part, say scientists. Reduced reliance on chemicals in agriculture is part of the solution, says Buchmann, since all animals need their immune systems in top shape to combat pathogens in their environment.

Meanwhile, habitat loss and alteration, he says, are even more of a menace to pollinators than pathogens. Claire Kremen encourages farmers to cultivate the flora surrounding farmland to help solve habitat problems. "You can't move the farm," she says, "but you can diversify what grows in its vicinity: along roads, even in tractor yards." Planting hedgerows and patches of native flowers that bloom at different times and seeding fields with multiple plant species rather than monocrops "not only is better for native pollinators, but it's just better agriculture," she says.

Pesticide-free wildflower havens, adds Buchmann, would also bolster populations of useful insects such as blue orchard bees—an extremely effective pollinator of almonds in California. Native bumblebees in Wisconsin aren't as finicky about cold, wet weather as honeybees, so managing the landscape for their benefit would mean more buzz in the orchards in early spring.

Even in the busiest cities, pollinators can be coddled with a little creativity. Recent studies show that bees off the farm have a healthier and more varied diet than those making the commercial-crop rounds. Rooftop beehives in New York City help urban gardens and Central Park foliage flourish. And ecologists are now transforming part of what was once a 2,200-acre landfill on Staten Island into a flowering meadow to give native pollinators a sugar boost. It's a fairly simple calculation. If there's habitat, they will come.

Fortunately too, "there are far more generalist plants than specialist plants, so there's a lot of redundancy in pollination," Buchmann says. "Even if one pollinator winks out, there are often pretty good surrogates left to do the job." The key to keeping our gardens growing strong, he says, is letting that diversity thrive.

Take away that variety, and we'll lose more than honey. Many flowering plants would disappear, and with them apples, peaches, pears, and a host of other crops. Without pollinators there'd be no raspberries, blueberries, or even milk on your cereal (cows feed on bee-pollinated alfalfa and clover). No coffee or chocolate. No canola, a biofuel crop. No more summer watermelon or Halloween pumpkins. U.S. almond growers, who provide 80 percent of the world's crop, employ a third or more of the country's commercial beehives during the growing season—a bee extravaganza that's been called the largest pollination event on the planet. That too would fizzle.

"We wouldn't starve," says Kremen. But without the birds and the bees (and the bats and the butterflies), what we eat, and even what we wear—pollinators, after all, give us some of our cotton and flax—would be limited to crops whose pollen travels by other means. "In a sense," she says, "our lives would be dictated by the wind."

[KBW]

When we spray pesticides, many of these insects die down. Effect, seed formulation will be very weak. Remedy, buy seed from seed sellers, what are they meant for afterall. But what about the insects? What insects?

[mikhurram]

An entomologist at U.C. Berkely carried out a survey of 1000 different plants (50 native and 950 non native) in U.S.A. The findings were that 50-80 % of the 50 native plants drew the pollinators and merely 10% of the of the 950 plants attracted pollinators.

[Farhan Ahmed]

There is a reason behind it.......All don't buy starbucks when it opens first

[mikhurram]

Basically each and every specie of flowering plant has its own unique flowering evolutionary story that is closely coupled with the animals that pollinate it e.g. Jade wine is pollinated by bats and it is implied is the reason why its flowers hang upside down to facilitate pollination by bats and its unusual jade green colours stands out at night enticing bats.

Likewise in the case of orchids the lower lips of the flower is controlled by a specific set of genes which means it can evolve and change its shape and colour while the rest of the petals remain the same. Some of the orchids mimic the shape of female bee to attract male bees to mate it for pollination. The Mediterranean Ophry's orchid (image below) resembles a female wasp and emits a similar odour to attract the male wasp. In his attempt to mate with the flower, the male wasp picks up pollinea-pollen masses which eventually brush off another flower enabling pollination.

Mediterranean Ophry's Orchid bearing resemblance to female wasp

To gather nectar insects too have perfected their adaptation. Mouth parts have developed into straw like proboscises, often longer than the insect bodies that penetrate deep into the flowers evident in the case of the white Christmas Star orchid (Angraecum Sesuipedale) found in Madagascar, has an exceedingly long spur, or nectary, hanging down from the flower lip. (see image below). The spur is about a foot long, but the nectar fills only an inch and a half at the extreme end. Charles Darwin speculated about the existence of a moth with a long proboscis. Entomologists ridiculed his prediction, but 40 years later Xanthopan Morgani Praedicta, a night flying moth with a 12 inch tonque was discovered in Madagascar.

Christmas Star Orchid

The mutual adaptation has become so interwoven that some plants cater only to certain insects, whose lives in turn hinge exclusively on that plant .One of nature’s delicacies the fig tree grown in California known as Calimyrnas (female fig plant) unlike the other fig varieties cannot mature without pollination a feat only done by fig wasps since prehistoric ages. Technically figs are inverted flowers that store their pollen inside the fruits. Introduced to California from Turkey in the 19th century growers tried to solve this problem by hand pollinating the female fruit which required too much labour. Then they got the answer that the pollination job in Turkey from where the fig originated was done by fig wasps.

The fig wasps begin their work inside the fruit of the male fig tree, called the Capri fig which actually consists of a case enclosing fruit pulp and at the center two kinds of flowers, one male (stamen) and one female (pistel). The male fig flower of Capri fig is the only flower where the female can lay its eggs at the base of the flower. Then the flowers grow a protective covering known as gall. One gall can become the haven for as many as 600 eggs.

The baby wasps which mature into blind wingless male wasps have sharp teeth which they use in chewing a hole in the top of a globular gall and then drop down on the females fertilizing them by inserting their specially adapted abdomen and then die (within a day from their birth). Female wasps then use this hole as an escape route to go to the outside world. The female passes through a thicket of pollen producing flowers through which she must pass to reach the outside world. On the way out she becomes loaded with white pollen which tries to shed but cannot and flies off in search of male figs (Capri figs) to deposit their eggs in and the cycle begins again.

If a female fig wasp enters an edible female fig (Calimyrna), she tries to deposit an egg at the base of a flower part called style by thrusting her short ovipositor (Ovary depositor) at the base in the female fig’s flower which hinders her attempts to lay her eggs as the style is too long. The female wasp again and again she tries to brush off the male pollen loaded on her body against the female flowers. Frustrated the female dies in her unsuccessfull quest to lay eggs but succeeds in pollinating the female flowers. Only in the male figs (Capri) flowers can she successfully laying her eggs. Pollination ensures that the female flower of Calimyrna ripens into an edible fig fruit consumed by us. Long before this edible fig matures, its enzyme completely assimilate the female wasp by breaking its carcass into protein. The male and female wasp life span is merely a day but complete their role assigned by nature. It’s a win win situation for the grower who ends up with either Capri figs full of wasp eggs or edible figs full of seeds.

Fig growers trick female wasps in finding another male fig (Capri fig) by stapling bags of wasp filled Capri figs in the female fig trees (Calimyrana). The merging wasps instinctively try to lay their eggs in the most convenient fig and the relocation assures that they will fly to commercially valuable Calimyrana rather then to a distant male Capri fig.

[mikhurram]

Clarification: The first image is of a male wasp pollinating Ophry's Orchids whom the male wasp perceives to be a female wasp.

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