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May 6, 2008 — The quality of pollen a plant produces is closely tied to its sexual habits, ecologists have discovered. As well as helping explain the evolution of such intimate relationships between plants and pollinators, the study — one of the first of its kind and published online in the British Ecological Society’s journal Functional Ecology — also helps explain the recent dramatic decline in certain bumblebee species found in the shrinking areas of species-rich chalk grasslands and hay meadows across Northern Europe.

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Loss of biodiversity in pollination networks may threaten the persistence of plant communities.

Relationships between plants and pollinators have fascinated ecologists since Darwin’s day. While ecologists have long known that pollinators such as honeybees and bumblebees are often faithful to certain flowers, and have done much work on the role of nectar as a food source, very little is known about how pollen quality affects these relationships.

Working on Salisbury Plain, the largest area of unimproved chalk grassland in north west Europe, ecologists from the universities of Plymouth, Stirling and Poitiers in France collected pollen from 23 different flowering plant species, 13 of which are only pollinated by insects while the other 10 species can either pollinate themselves or be insect pollinated. They analyzed the pollen for protein content and, in the second part of the study, recorded bumblebee foraging behavior.

They found that without exception, plants that rely solely on insects for pollination produce the highest quality pollen, packing 65% more protein into their pollen than plant species that do not have to rely on insect pollinators. They also discovered that bumblebees prefer to visit plants with the most protein-rich pollen. According to the lead author of the study, Dr Mick Hanley of the University of Plymouth: “Bumblebees appear to fine-tune their foraging behavior to select plants offering the most rewarding pollen. Although there is some debate about how they can tell the difference, it is possible they are using volatile compounds.”

By helping understand the advantages and disadvantages of plant-pollinator relationships where particular plants rely on particular insects to reproduce, and those insects rely on the same plants for food, the results could help ecologists conserve certain bumblebee species and the species-rich chalk grassland and hay meadow communities in which they live, all of which are becoming increasingly rare.

“For the plant, relying on a small group of insects such as bumblebees as pollinators is very beneficial because it ensures efficient pollen transfer. Bumblebees quickly learn to visit the most rewarding flowers, so providing protein-rich pollen is one way plants can encourage bumblebees to be faithful. But this close relationship has many potential pitfalls, because if the pollinators are lost, the flowers may not be able to reproduce, and this may be what we are seeing in the hay meadows, chalk grasslands and bumblebees species throughout Northern Europe,” Hanley says.

Journal reference: Michael Hanley et al (2008). Breeding system, pollinator choice and variation in pollen quality in British herbaceous plants, Functional Ecology, doi: 10.1111/j.1365-2435.2008.01415.x, is published online on 6 May 2008. Retrieved May 7, 2008, from http://www.sciencedaily.com /releases/2008/05/080505211806.htm

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ScienceDaily (Apr. 9, 2008) — Just like people who are looking for a perfect place to live, some female bees search for the ideal place to build their nests.

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Studies of the blue orchard bee–shown here visiting an apple blossom–may reveal new ways to lure these proficient pollinators to live and work in orchards and fields. (Credit: Image courtesy T. L. Pitts-Singer)

Agricultural Research Service (ARS) entomologist Theresa L. Pitts-Singer is discovering more about the “nesting cues” that influence wild bees’ house-hunting decisions. It’s information that may help entice more of the hardworking pollinators to take up residence in new, ready-to-occupy nesting structures that growers and beekeepers provide.

Some bees like living in snug, dark recesses called “nesting cavities.” These range from deep holes drilled into wooden boards, to bundles of cardboard tubes or hollow reeds. Growers and beekeepers place bee housing in orchards and fields where they need the bees to live and work.

Wild bees augment the work of the European honey bee, currently plagued by a puzzling problem known as colony collapse disorder. That’s according to Pitts-Singer, with the ARS Pollinating Insect Biology, Management and Systematics Research Unit in Logan, Utah.

Scientists already know that female blue orchard bees (Osmia lignaria) and certain other wild bees prefer to nest in cavities that other females of their species once occupied. That’s problematical because old nests may be contaminated with disease-causing spores.

To find out what’s making old nests alluring, Pitts-Singer is investigating components from the old homes, including old pollen, leaves, mud, and a fluid bees apply to cavity walls.

In one test, Pitts-Singer and colleagues used glass tubes to approximate drilled nesting holes, then collected the now-dry fluid that bees had left on walls. The scientists are using sophisticated laboratory instruments to glean some of the first-ever information about the chemical composition of the fluid.

Perhaps secreted by bees to differentiate one home from another, the fluid may also add to the overall appeal of a previously occupied nesting site. If that’s the case, Pitts-Singer’s investigations might lead to using synthetic versions of the fluid to make tomorrow’s new nesting structures more inviting.

Adapted from materials provided by US Department of Agriculture.

US Department of Agriculture (2008, April 9). Creating Homes That Please America’s Wild Bees. Retrieved May 7, 2008, from http://www.sciencedaily.com /releases/2008/04/080405092526.htm

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Bumblebee in flight. (Image Credit: Christian Stamm / via German Wikipedia)

Cambridge University – Bumblebees prefer warmer flowers and can learn to use color to predict floral temperature before landing, a new study reports.
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Colonies which learn colours quickly are more successful. (Credit: Image courtesy of Queen Mary, University Of London)

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A bee’s favorite color can help it to find more food from the flowers in their environment, according to new research from Queen Mary, University of London.

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This photo was published in the April issue of Science (296: 636), 2002. Credit was missing but appeared on 296:2336, 2002.
All the following photos were taken April 2001, in the Peony Garden, Beijing Botanical Garden, China.
Bees: Apis mellifera
Plants: Paeonia spp, Paeoniaceae.

Flower color is traditionally viewed as a method by which a plant advertises its nectar, a sweet reward for ensuring pollination, to hungry insects. However, a recent collaborative study by the University of Cambridge and Queen Mary University London has revealed that bees will choose flowers of a certain color if they have learned that it indicates warmth as well.

Dr Heather Whitney, Miss Sarah Arnold, Dr Adrian Dyer and Dr Beverley Glover, Department of Plant Sciences, University of Cambridge, and Professor Lars Chittka, Queen Mary University London, published their findings in this week’s issue of Nature.

Dr Whitney stated, “It has been observed that flowers with warming structures attract basking insects, and previous work has shown that insects can obtain a metabolic reward from warmer flowers. However, this is the first time it has been shown that insects can use other cues, such as color, to preferentially seek out warmer flowers.”

These findings indicate that varying temperatures of plants may be an adaptation to encourage pollinators to visit flowers. As flower temperature varies widely, it is believed that the heat may influence which plant the pollinator chooses to visit (depending on the insect’s temperature preference).

Like many other insect pollinators, bumblebees invest energy in keeping their body temperature above the ambient level. On cold days, they must warm themselves up before they can fly far. Researchers discovered that, in an effort to conserve energy, bees will select warmer flowers identified by their color to stay cozy. When tested, bumblebees consistently chose warmer flowers over cooler flowers containing the same nectar reward.

Dr Glover stated, “We’re very excited by this result as it suggests that a whole range of structures act as potential pollinator attractants. We can now re-evaluate the roles of lens-shaped petal cells, sun-tracking by flowers, light and heat absorbing pigments and specialized surface structures, all of which may be part of a plant’s bag of tricks for attracting pollinators.”

The scientists hope that this study will shed some light on why specific floral structures have evolved, as well as on the connection between floral sensory cues, floral temperature and pollinator behavior.

Adapted from materials provided by University of Cambridge. Retrieved May 7, 2008, from http://www.sciencedaily.com /releases/2006/08/060803082644.htm

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A bee on canola.

Dr Nigel Raine and Professor Lars Chittka from Queen Mary’s School of Biological and Chemical Sciences studied nine bumblebee (Bombus terrestris) colonies from southern Germany, and found that the colonies which favoured purple blooms were more successful foragers.

Dr Raine explains: “In the area we studied, violet flowers produced the most nectar – far more than the next most rewarding flower colour (blue). Inexperienced bees are known to have strong colour preferences, so we investigated whether the bumblebee colonies with a stronger preference for violet flowers foraged more successfully in their local flora.”

The team first observed the colour preferences of naïve bees (those which had never before seen flowers) using violet (bee UV-blue) and blue (bee blue) artificial flowers in the laboratory. They then observed the rate at which bees from the same colonies collected nectar from real flowers in the wild.

The results showed that the colonies who preferred violet to blue flowers in the laboratory, harvested more nectar from real flowers under field conditions. In fact the colony with the strongest preference for violet (over blue) brought in 41 per cent more nectar than the colony with the least strong bias.

The team’s findings suggest that bumblebees have developed their favourite colour over time, to coincide with the most profitable, nectar-rich flowers available.

It has been long accepted that animals show innate preferences when selecting a mate, but little research has been carried out on how such sensory biases affect foraging habits. The researchers believe their work could have implications for other species.

“A straw poll of friends always reveals many personal differences in ‘favourite colour’. Some human societies also have very different colour preferences,” explains Raine. “In our work on bees we actually show there is some useful purpose to having such favourite colours. These innate sensory biases seem to play an important role in helping naïve animals to find food.”

Reference: Raine NE, Chittka L (2007) The Adaptive Significance of Sensory Bias in a Foraging Context: Floral Colour Preferences in the Bumblebee Bombus terrestris. PLoS ONE 2(6): e556. doi:10.1371/journal.pone.0000556 (http://www.plosone.org/doi/pone.0000556) Funded by Natural Environment Research Council (NERC) and the German Research Foundation (Deutsche Forschungsgemeinschaft).

Adapted from materials provided by Public Library Of Science, via AlphaGalileo.

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A honey bee (most likely Africanized, Apis mellifera scutellata) foraing on a bottle-brush (Callistemon spp, Myrtaceae). Bees sometimes become traped there because the filaments are so long. April 12, 2000. Tucson, AZ.
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A decline in bee diversity and abundance linked to habitat loss and disease in Europe together with a 50% drop in the number of managed honeybee colonies throughout North America are part of a global phenomenon known as the ‘pollination crisis’.

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A decline in bee diversity and abundance around the globe has been deemed a ‘pollination crisis’. (Credit: Scott Bauer, USDA/ARS (Agricultural Research Services))

Over 80% of crops in Europe are pollinated by insects and the contribution of bumblebees to Irish agriculture is often underestimated. Bees are responsible for most crop pollination and are often actively introduced by farmers into crops to improve production. Each year, Irish growers import hundreds of commercial bumblebee colonies from mainland Europe to improve fruit quality and yield. However, without proper management, this could lead to the introduction of new diseases in native bumblebee populations. The nature of the bee pollination service in Ireland has changed quite dramatically over the last ten years.

Crops such as apples, pears and berries are entirely dependent on pollinators for fruit production, while in crops like oilseed rape, sunflowers, peppers and tomatoes, visits by pollinating insects like bees improve the quality and quantity of fruit and seeds produced. Recent intensification of agriculture in the United States has necessitated the direct and large-scale importation of honeybees to pollinate crops such as alfalfa and almonds.

Researchers at Teagasc Oak Park are working on the management of diseases in honeybees and the protection of native bumblebees through the proper management and containment of imported species. This research is featured in the latest issue of TResearch, Teagasc’s research and innovation magazine, and is particularly relevant considering the emergence of ‘Colony Collapse Disorder’, which is devastating US bee populations.

The Varroa mite (Varroa destructor) was accidentally introduced into Ireland and was first detected in Sligo in 1998. Early attempts at containment failed and it has now spread to most parts of the country. Teagasc has conducted research on Varroa since the mite was first found in Ireland. Varroa infestation has also been associated with an increased incidence of viral diseases in bees. Research at Teagasc is developing alternative Varroa management strategies that are suitable for Irish climatic conditions.

“By improving Varroa management and understanding the dynamics of bee diseases, Teagasc research aims to contribute to increased honeybee densities in the Irish countryside,” explains Dr Finbarr Horgan, Teagasc Oak Park Crop Research Centre.

“The effective management of Varroa and associated diseases in honeybees, as well as the protection of native bumblebees through the proper management and containment of imported species, is expected to improve pollination efficiency and contribute to sustained increases in crop productivity.”

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The Target Health Blog wishes to thank the extremely talented, Dr. Zachary Huang, for most of the extraordinarily beautiful nature photographs, used on the BLOG today, [and yesterday] to illustrate some glorious aspects of the planet, that we humans have inherited. This shared habitat needs more care, from the humans who inhabit it. We’re a part of nature and not above it.
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Zachary Huang “Zach”
Assistant Professor
Apiculture

243 Natural Science
Phone: (517) 353-8136
email: bees@msu.edu
Fax: (517) 353-4354

Education:
B.Sc. (Hons) Plant Protection, Hunan Agricultural University
Ph.D. Honey Bee Behavior & Physiology, University of Guelph

Appointment:
21% Research, 53% Extension, 26% Teaching

Research-extension program:
Huang’s main research interest is in honey bee biology. He uses computational, behavioral, physiological, and biochemical methods to understand the social organization of a bee colony. One of his goals is to combine basic and applied research to develop a program that would benefit the beekeeping industry. His current research focuses on impact of parasites (Nosema apis, Varroa jacobsoni) on physiology and foraging behavior of worker bees. He maintains a web page for extension purpose and is working closely with Michigan beekeepers to find better strategies for pest and disease management in honey bees. He teaches a course in apiculture and co-teaches Insect Physiology with Alex Raikhel.