, Sep 15, 2009  —  Master gene that switches on disease-fighting cells identified by scientistsThe master gene that causes blood stem cells to turn into disease-fighting ‘Natural Killer’ (NK) immune cells has been identified by scientists, in a study published in Nature Immunology, yesterday. The discovery could one day help scientists boost the body’s production of these frontline tumor-killing cells, creating new ways to treat cancer.


The researchers have ‘knocked out’ the gene in question, known as E4bp4, in a mouse model, creating the world’s first animal model entirely lacking NK cells, but with all other blood cells and immune cells intact. This breakthrough model should help solve the mystery of the role that Natural Killer cells play in autoimmune diseases, such as diabetes and multiple sclerosis. Some scientists think that these diseases are caused by malfunctioning NK cells that turn on the body and attack healthy cells, causing disease instead of fighting it. Clarifying NK cells’ role could lead to new ways of treating these conditions.

A Natural Killer cell (red) recognizing and embracing a target cancer cell (blue) prior to destroying it (courtesy of Dan Davis’ lab, Imperial College London)

The study was carried out by researchers at Imperial College London, UCL and the Medical Research Council’s National Institute for Medical Research.

Natural Killer cells – a type of white blood cell – are a major component of the human body’s innate, quick- response immune system. They provide a fast frontline defense against tumors, viruses and bacterial infections, by scanning the human body for cells that are cancerous or infected with a virus or a bacterial pathogen, and killing them.

NK cells – along with all other types of blood cell, both white and red – are continuously generated from blood stem cells in the bone marrow over the course of a person’s lifetime. The gene E4bp4 identified in today’s study is the ‘master gene’ for NK cell production, which means it is the primary driver that causes blood stem cells to differentiate into NK cells.

The researchers behind today’s study, led by Dr Hugh Brady from Imperial College London’s Department of Life Sciences, are hoping to progress with a drug treatment for cancer patients which reacts with the protein expressed by their E4bp4 gene, causing their bodies to produce a higher number of NK cells than normal, to increase the chances of successfully destroying tumors.

Currently, NK cells isolated from donated blood are sometimes used to treat cancer patients, but the effectiveness of donated cells is limited because NK cells can be slightly different from person to person.

Dr Brady explains: “If increased numbers of the patient’s own blood stem cells could be coerced into differentiating into NK cells, via drug treatment, we would be able to bolster the body’s cancer-fighting force, without having to deal with the problems of donor incompatibility.”

Dr Brady and his colleagues at the MRC National Institute for Medical Research proved the pivotal role E4bp4 plays in NK production when they knocked the gene out in a mouse model. Without E4bp4 the mouse produced no NK cells whatsoever but other types of blood cell were unaffected. As well as proving their hypothesis about the function of the E4bp4 gene, this animal model will allow medical researchers, for the first time, to discover if NK cell malfunction is behind a wide range of medical conditions, including autoimmune disorders, inflammatory conditions, persistent viral infections, female infertility and graft rejection.

Dr Brady explains: “Since shortly after they were discovered in the 1970s some scientists have suspected that the vital disease-fighting NK cells could themselves be behind a number of serious medical conditions, when they malfunction. Now finally, with our discovery of the NK cell master gene and subsequent creation of our mouse model, we will be able to find out if the progression of these diseases is impeded or aided by the removal of NK cells from the equation. This will solve the often-debated question of whether NK cells are always the ‘good guys’, or if in certain circumstances they cause more harm than good.”

The researchers were initially studying the effect of E4bp4 in a very rare but fatal form of childhood leukemia when they discovered its importance for NK cells.

The study was funded by the charities CHILDREN with LEUKAEMIA and Leukemia Research.

NexBio(R) Presents DAS181 (Fludase(R)*) Potently Inhibits Novel Swine-Origin A(H1N1) and NAI-Resistant Influenza Viruses, at ICAAC 2009

SAN DIEGO, Sept. 15 /PRNewswire/ — NexBio, Inc. announced today the
presentation of two studies of DAS181 activity against H1N1 influenza and
NAI-resistant influenza at the 2009 Interscience Conference on Antimicrobial
Agents and Chemotherapy (ICAAC) meeting on Sunday, September 13, 2009, in San
Francisco, CA.  The work was performed in collaboration with researchers at
the Centers for Disease Control and Prevention (CDC), University of Hong Kong,
and Saint Louis University.

DAS181 (Fludase(R)) is an investigational broad spectrum drug candidate being
evaluated in human clinical development for treatment and prevention of
Influenza-Like Illness caused by all strains of influenza and parainfluenza.
Unlike neuraminidase inhibitors (NAI), e.g. Tamiflu(R), which directly target
the influenza virus (“pathogen target”), DAS181 works by inactivating the
human receptor (“host target”) for these viruses; thus, it may be less likely
to encounter acquired resistance compared with currently-available antiviral
drugs. Extensive, prolonged nonclinical influenza studies have not shown the
development of any meaningful resistance. This approach may have advantages
over mono-therapy or combination therapy which directly target the pathogen.
Previously announced preclinical studies conducted in collaboration with the
CDC and others have shown DAS181 to have significant therapeutic and
prophylactic activity in in vivo animal models and in human ex vivo lung
tissue for a highly virulent H5N1 (A/VN/1203/04) strain of influenza.

A “Late Breaker” presentation, entitled “Novel Swine-Origin A (H1N1) Influenza
Viruses are Potently Inhibited by DAS181, a Sialidase Fusion Protein” examined
in vitro, ex vivo, and in vivo models to evaluate the activity of DAS181
against multiple human novel 2009 influenza A/H1N1 viruses (Novel H1N1 or
“Swine Flu”).  The data presented at the meeting suggested that DAS181
exhibited potent inhibitory activity against these Novel H1N1 viruses in these
different models. 

The related presentation, entitled “In Vivo and In Vitro Activity of DAS181
Against NAI-Resistant Influenza Virus” examined the in vivo and in vitro
activity of DAS181 against patient isolates of community-acquired seasonal
influenza from the 2008-2009 influenza season.  All isolates had the H274Y
mutation associated with resistance to Tamiflu.  DAS181 in vitro was an
effective inhibitor of Tamiflu-resistant influenza virus.  In addition, in
vivo mouse challenge studies with another NAI-resistant strain demonstrated
strong sensitivity to DAS181 treatment.

Both studies are presented by Ronald Moss M.D., Executive Vice President,
Clinical Development and Medical Affairs.  “Based on these encouraging data we
are moving forward with our ongoing clinical development of DAS181, and we
will continue to work closely with FDA, CDC, and NIH on this clinical program
during the current pandemic,” stated Dr. Moss. “Because of viral evolution,
alternatives to current treatment strategies are needed to deal with potential
drug resistance. DAS181 may play an important role for public health
preparedness during influenza pandemics.”


NexBio, Inc. is a privately held clinical-stage biopharmaceutical company
located in San Diego. NexBio’s mission is to save lives and to improve the
quality of life by creating and commercializing novel, broad-spectrum
biopharmaceuticals to prevent and treat current and emerging life-threatening
diseases. DAS181 (Fludase(R)), a recombinant fusion protein, inactivates viral
receptors on the cells of the human respiratory tract, thereby preventing and
treating infection by influenza, including potential pandemic strains, and by
parainfluenza viruses (which may cause serious respiratory illness similar to
influenza and for which there is no approved vaccine or therapeutic).  The
DAS181 development program is funded by the National Institute of Allergy and
Infectious Diseases (NIAID), part of the National Institutes of Health, under
BAA Contract HHSN266200600015C and grant U01-AI070281. ViradinTM, invented and
developed by NexBio, is a parenteral protein under development, currently at
lead optimization stage, directed to the treatment of viral hemorrhagic fevers
and bacterial biothreat sepsis.  TOSAPTM is a technology invented and
developed by NexBio and is used to formulate DAS181 for inhalation, as well as
to make nano/microparticles from virtually any type of molecule.  TOSAPTM is
offered for the formulation of compounds of partners, under license.

For more information about NexBio, Inc., please visit

* FDA has yet to approve the name Fludase.

This release contains forward-looking information about the research and
development program of NexBio and the potential efficacy of product candidates
that might result from programs that involve substantial risks and
uncertainties. Such risks and uncertainties include, among other things, the
uncertainties inherent in research and development activities; decisions by
regulatory authorities regarding whether and when to permit the clinical
investigation of or approve any drug applications that may result from the
programs as well as their decisions regarding labeling and other matters that
could affect the commercial potential of product candidates that may result
from the program; and competitive developments, September 15, 2009, By RON WINSLOW The drug metformin, a mainstay of diabetes care for 15 years, may have a new life as a cancer treatment, researchers said.

In a study in mice, low doses of the drug, combined with a widely used chemotherapy called doxorubicin, shrank breast-cancer tumors and prevented their recurrence more effectively than chemotherapy alone.

The findings add to a growing body of evidence that metformin, marketed as Glugophase by Bristol-Myers Squibb Co. and available in generic versions, could be a potent antitumor medicine.

They also lend support to an emerging theory that cancer’s ability to survive and resist therapy is regulated by cancer stem cells that drive a tumor’s growth and survival.

Chemotherapy is effective against many tumors, said Kevin Struhl, a Harvard Medical School researcher and principal investigator of the study. “The problem is cancer stem cells acquire resistance” to treatment, he said. “They are able to regenerate the tumor and as a result you end up with a relapse.”

About 5% to 10% of a tumor’s cells are believed to be cancer stem cells, he said.

In the report, being published in the Oct. 1 edition of Cancer Research, a journal of the American Association for Cancer Research, researchers said the combination of metformin and doxorubicin killed both regular cancer cells and cancer stem cells.

In contrast, doxorubicin alone had limited effect on the stem cells.

Mice that grew tumors generated from human breast-cancer cells have remained tumor-free for nearly three months on the combined treatment, while tumors have recurred in those not given the diabetes remedy.

Researchers said the results have potentially broad implications for cancer treatment.

“If we could get some magic bullet to hit that stem-cell population, the thought is we could have more effective treatments,” said Raymond DuBois, provost and executive vice president, University of Texas M.D. Anderson Cancer Center.

It is too early to tell whether and how metformin might be used to treat cancer patients.

A clinical trial testing metformin alone in early-stage breast-cancer patients, after they have had surgery and chemotherapy to treat their tumors, is being sponsored by the National Cancer Institute of Canada and could begin enrolling patients next year, said Jennifer Ligibel, a breast-cancer doctor at Dana-Farber Cancer Institute, Boston. The idea is to see if metformin is effective in preventing the cancer from recurring. U.S. cancer researchers are participating.

The new findings, she said, suggest that additional trials should evaluate metformin in combination with chemotherapy. She wasn’t involved in the current research.

Metformin, which was approved in 1994 to lower blood sugar in people with Type 2 diabetes, achieved peak sales of $2.3 billion in 2001 before patent expirations opened the market to generic competition.

Several recent studies have observed the drug’s potential effects against cancer.

One study from M.D. Anderson Cancer Center, for instance, found that diabetic patients treated with metformin were less likely to develop pancreatic cancer than those who weren’t taking the drug for blood sugar.

How metformin affects cancer isn’t certain, but one possibility is that it deprives tumor cells of sugar.

“Cancer cells are gluttons for glucose,” said George Prendergast, president and chief executive officer of Lankenau Institute for Medical Research, Wynnewood, Pa. “It is likely that metformin is taking advantage of this gluttony of the cancer cell in order to attack it.”

Another possibility is that the drug affects the immune system and helps stave off a tumor’s recurrence, Dr. Struhl said.

The study was sponsored by the National Institutes of Health and the American Cancer Society.

Dr. Struhl and Harvard Medical School have applied for a patent that would cover a combination of metformin and a lower dose of chemotherapy to treat cancer.

Write to Ron Winslow at


ScienceInSociety.Northwestern,edu, September 15, 2009, by Victoria Gunderson, Michael Wasielewski PhD  —  The sun-our lives literally revolve around it. Now, researchers are working to harness its power as the ultimate renewable energy source, making it an unlikely ally in the fight against climate change.

You might be thinking, “Aren’t we already using solar energy for power?” We are. From small solar-powered calculators to the larger solar-powered highway traffic signs, limited applications of solar energy can be found in our everyday lives. However, the current technology used to capture and convert the sun’s energy is very expensive to produce, preventing solar power from becoming a widespread solution to our world’s dependence on carbon-emitting fossil fuels.

One strategy is to develop solar cells that are easier and cheaper to manufacture. Current solar cells are made of silicon, which is derived from sand and formed into crystals through an energy-intensive, expensive process. “Organic photovoltaics,” a promising alternative, are solar cells made primarily of organic molecules-molecules that contain carbon. The atoms that compose these molecules are linked in ways that make them very flexible. By contrast, silicon atoms are arranged in tightly packed units, making silicon products very rigid.

Because of their inherent flexibility, organic photovoltaics may be manufactured in large rolls, or even as inks or paints, which could easily be spread over large surfaces. While organic photovoltaics will not be nearly as efficient as silicon-based solar cells, they may eventually be produced at just a fraction of the cost.

Applications of solar energy encompass more than just advancements in organic photovoltaics. For example, at night, solar cells can no longer receive energy from the sun. Therefore, it is important to be able to store the energy acquired during the daylight hours and use it at night. Photochemical fuel cells do this. They utilize similar strategies found in organic solar cells to collect light, but couple it to methods that produce usable fuels, such as hydrogen. These fuels can then later be used to power your home or workplace, or the electricity generated from the solar fuels can even be shipped to a new location where sunlight is not as abundant.

To design these solar-powered devices, we look to nature’s model for converting sunlight into usable energy-photosynthesis. For eons, photosynthesis has been sustaining life on our planet, and the evidence is not difficult to find. From the food we eat to the air we breathe, it is an evolved, complex, and finely tuned process that supplies the inspiration for a variety of applications.

Of particular interest is photosynthesis’ initial steps, in which sunlight is collected by a plant’s light-absorbing molecules. That energy is transferred to a place where it strips an electron from a special pair of molecules. This free, high-energy electron is then transferred from molecule to molecule within the plant cell until it is far enough away from its source to be stable. This process then provides the energy to convert carbon dioxide into usable products such as carbohydrates (sugars).

We are now working to apply these fundamental principles to develop new solar energy conversion technologies, known as “artificial photosynthesis.” Our goal is to capture and transfer energy as nature does, but to also generate fuel we can use. The diverse talents of many scientists from many different fields- chemistry, biology, physics, and engineering, to name a few-will be required to recreate this entire process. But first, to fully understand photosynthesis as a whole, each step must be carefully studied and replicated.

Our lab focuses on the basics of energy and electron transfer processes. How is light harvested and transferred? How quickly are electrons moved from one molecule to another? And how do we finally take those electrons and couple them to systems that can split water into oxygen and hydrogen to use as fuels?

First, we can monitor an electron’s travels by observing how the molecules through which the electron is moving absorb light. Visible light, or white light, is actually comprised of seven different colors-red, orange, yellow, green, blue, indigo, and violet. Objects absorb certain colors of light and reflect the others-for example, if your shirt is green, it is reflecting the green light and absorbing all the others.

When a molecule loses an electron, its structure changes slightly, causing it to absorb different colors of light than it would if the electron was still present. Likewise, when the electron returns, the molecule’s light absorption pattern changes back to its original form. Observing these patterns allow us to infer where the electron is traveling and how quickly. With advanced instrumentation, we can detect changes that occur within a picosecond, or a millionth of a millionth of a second (10-12 second)!

Our goal is to create a series of molecules, or building blocks, through which electrons will travel, like a circuit, to eventually power a light bulb or generate fuel. We want these molecules to give up electrons quickly, take them back slowly and travel long distances efficiently, allowing the electrons to effectively reach their final destination where they can be used appropriately.

These building blocks must be easy to produce and be able to self-assemble. “Self-assembly” refers to the process of disorganized molecules in solution arranging themselves into a specific pattern spontaneously, forming a larger structure. This property is crucial to producing solar cells from liquids, like a paint or ink, rather than solids.

We have recently made exciting progress in developing these self-assembling structures with photosynthetic capabilities. Molecules we’ve designed arrange themselves in solution into distinct horizontal units that stack vertically. Shining light on them results in electron transfer both within each building block, or horizontal units, and also between their self-assembled neighbors, or vertical units. This means that the electrons can potentially travel far enough away from their source to be utilized in a circuit.

Although this is an important step forward, many more will be necessary before a complete, artificial photosynthetic system can be created. For example, while the building blocks that we’ve created do self-assemble, they stack together in a helical formation (each level is rotated slightly relative to the previous), rather than directly on top of one another. This makes it difficult for the electrons to travel between all subunits. We are now working on a different arrangement of these building blocks so that electrons can travel more freely and efficiently.

  • Even when this is achieved, the transition from basic research findings to prototypes to final mass production will not occur overnight. The challenge facing scientists today is converting the principles of basic research discoveries into new technologies. Our hope is that someday, by understanding the most basic principles of photosynthesis, we can develop efficient, economical methods for solar energy conversion, providing one answer to the multi-faceted energy problem facing society today.

200909016-8, September 15, 2009, by Josh Vura-Weis, Michael Wasielewski PhD  —  Carbon-neutral energy sources, especially the “Big 3”-solar, wind, and nuclear power-have the potential to relieve our dependence on fossil fuels and lessen our impact on global warming. However, for any of these possibilities to surpass fossil fuels as a real, widespread solution, the price must be right.

Nuclear power has great promise, but it comes with significant roadblocks. To accommodate our world’s estimated energy needs by the year 2050 through nuclear power alone, 10,000 new nuclear power plants would have to be constructed. To put this in perspective, only 436 plants exist worldwide, less than one-fourth of which are in the US. Considering the generally negative feelings in our country toward nuclear power, and the cost associated with constructing the plants, this kind of expansion is unlikely.

When it comes to wind power, the problem lies not in safety or price but in volume. There is a finite amount of appropriate land on which to construct windmills, and only so much wind to turn them. Even if all of this land were used optimally, experts estimate the energy produced could only provide, at most, 10% of our world’s total needs.

With all of these restrictions in mind, solar energy stands out as our best bet. Without a doubt, the sun’s rays can provide more than enough energy-it’s just up to us to harvest it. This presents two key problems. First, to accommodate our national energy needs, we would need 60,000 square miles worth of solar cells-this is equivalent to the entire highway and road system in the United States. To put this in perspective, the US only produces 700 square miles of carpet per year. So, these solar cells must be very easy to manufacture.


The other problem, of course, is cost. Current solar energy technology is expensive. Traditional solar cells are made of silicon, which is derived from common sand. While sand is cheap, the manufacturing process is not, requiring temperatures of more than 3000ºF. Then, the silicon must be formed into large, highly pure crystals. This whole process, aside from being expensive, also requires a lot of energy. In fact, it can take up to 4 years before the cells produce as much energy from the sun as it took to make them in the first place.

Researchers are now working on several alternative forms of solar cells with cost and scalability in mind. One option is to use a less pure version of silicon-multicrystalline silicon-which is cheaper and less energy-intensive to manufacture. Traditionally, it has also been less efficient, converting only 15% of the energy it absorbs from the sun into usable power, versus the 20% efficiency of the more expensive version. However, researchers are now testing new versions of cells using multicrystalline silicon, and have nearly hit the 20% mark.

Other metals under investigation include thin sheets of cadmium telluride and nanocrystals of copper indium gallium diselenide. Both have been made into solar cells that are about 10% efficient, which is the minimum for commercialization. While this is much lower than silicon cells, the benefit lies in price. Two companies that produce these cells, First Solar and Nanosolar, claim to manufacture them at a cost of only $1 per watt, a unit of energy, which is about 20% the cost of traditional silicon cells.

Our research group works on another exciting alternative, known as organic photovoltaics. In chemistry, “organic” means that something contains only lightweight atoms such as carbon, nitrogen, oxygen, and hydrogen. These atoms link together in long chains known as polymers, making their products very flexible.

Because of this flexibility, organic solar cells can be constructed using a roll-to-roll processing method (think of the large machines that assemble newspapers or magazines). They can also be created by dissolving the polymer to form an “ink,” which is then inkjet-printed onto a flexible metal film. This could enable the mass production necessary to meet our nation’s energy needs.

Organic solar cells also have the potential to become a true mainstream solution for the everyday consumer, in that an expensive, specialized expert may not be needed to install the technology. For example, cells could be incorporated into building materials such as wall siding or shingles. Some scientists have even proposed “solar paint,” which could be applied to almost any surface to harvest the sun’s rays. Imagine picking that up at your local hardware store!

It is this versatility that stands to make organic photovoltaics truly revolutionary. Much like other solar cell alternatives, their efficiency may never match silicon. Current versions are about 5% efficient, and we expect this to reach 10%. However, organic solar cells require much less energy to produce, lowering their costs. We estimate they’ll eventually be produced more cheaply than even the cadmium telluride and copper indium gallium diselenide versions.

It is important to remember that commercially competitive organic photovoltaics are still 5-10 years in the future, and that there are other obstacles in place. Even with solar cell shingles on homes and businesses, a great expanse of solar cell “power plants” will be needed to power the entire country. In fact, researchers estimate they’ll need land equivalent to the size of the state of Oklahoma. Which states will contribute this land? And, when these plants are built, efficient ways of channeling the power back to cities across the country will need to be constructed.

While these obstacles are significant, they are not insurmountable. With the right buy-in from consumers, business owners, and our nation’s leaders, a carbon-neutral energy solution just might be on the horizon.


A bumblebee (or bumble bee) is any member of the bee genus Bombus, in the family Apidae. There are over 250 known species, existing primarily in the Northern Hemisphere.

Bumblebees are social insects that are characterized by black and yellow body hairs, often in bands. However, some species have orange or red on their bodies, or may be entirely black. Another obvious (but not unique) characteristic is the soft nature of the hair (long, branched setae), called pile, that covers their entire body, making them appear and feel fuzzy. They are best distinguished from similarly large, fuzzy bees by the form of the female hind leg, which is modified to form a corbicula; a shiny concave surface that is bare, but surrounded by a fringe of hairs used to transport pollen (in similar bees, the hind leg is completely hairy, and pollen grains are wedged into the hairs for transport).

Like their relatives the honey bees, bumblebees feed on nectar and gather pollen to feed their young.

The blood or hemolymph, as in other arthropods, is carried in an open circulatory system. The body organs, “heart” (dorsal aorta), muscles, etc. are surrounded in a reservoir of blood. The dorsal aorta does pulse blood through its long tube, though, so there is a circulation of sorts.

In fertilized queens the ovaries are activated when the queen lays her egg. It passes along the oviduct to the vagina. In the vagina there is a container called the spermatheca. This is where the queen stores sperm from her mating. Before she lays the egg, she will decide whether to use sperm from the spermatheca to fertilize it or not. Non-fertilized eggs grow into males, and only fertilized eggs grow into females and queens.

As in all animals, hormones play a big role in the growth and development of the bumblebee. The hormones that stimulate the development of the ovaries are suppressed in the other female worker bees while the queen remains dominant. Salivary glands in the head secrete saliva which is mixed with the nectar and pollen. Saliva is also mixed into the nest materials to soften them. The fat body is a nutritional store; before hibernation, queens eat as much as they can to enlarge their fat body, and the fat in the cells is used up during hibernation.

Like all bee tongues, the bumblebee tongue (the proboscis) is composed of many different mouthparts acting as a unit, specialized to suck up nectar via capillary action. When at rest or flying, the proboscis is kept folded under the head. The abdomen is divided into dorsal tergites and ventral sternites. Wax is secreted from glands on the sternites.

The brightly-colored pile of the bumble bee is a form of aposematic signal. Depending on the species and morph, these colors can range from entirely black, to bright yellow, red, orange, white, and pink. Thick pile can also act as insulation to keep the bee warm in cold weather. Further, when flying a bee builds up an electrostatic charge, and as flowers are usually well grounded, pollen is attracted to the bee’s pile when it lands. When a pollen covered bee enters a flower, the charged pollen is preferentially attracted to the stigma because it is better grounded than the other parts of the flower.

A bumblebee does not have ears, and it is not known whether, or how, a bumblebee could hear sound waves passing through the air; however, they can feel the vibrations of sounds through wood and other materials.

Bumblebees are typically found in higher latitudes and/or high altitudes, though exceptions exist (there are a few lowland tropical species). A few species (Bombus polaris and B. alpinus) range into very cold climates where other bees might not be found; B. polaris can be found in northern Ellesmere Island – the northernmost occurrence of any eusocial insect – along with its parasite, B. hyperboreus. One reason for this is that bumblebees can regulate their body temperature, via solar radiation, internal mechanisms of “shivering” and radiative cooling from the abdomen (called heterothermy). Other bees have similar physiology, but the mechanisms have been best studied in bumblebees.

Bumblebees form colonies. These colonies are usually much less extensive than those of honey bees. This is due to a number of factors including: the small physical size of the nest cavity, a single female is responsible for the initial construction and reproduction that happens within the nest, and the restriction of the colony to a single season (in most species). Often, mature bumblebee nests will hold fewer than 50 individuals. Bumblebee nests may be found within tunnels in the ground made by other animals, or in tussock grass. Bumblebees sometimes construct a wax canopy (“involucrum”) over the top of their nest for protection and insulation. Bumblebees do not often preserve their nests through the winter, though some tropical species live in their nests for several years (and their colonies can grow quite large, depending on the size of the nest cavity). In temperate species, the last generation of summer includes a number of queens who overwinter separately in protected spots. The queens can live up to one year, possibly longer in tropical species.

Bumblebee nests are first constructed by over-wintered queens in the spring (in temperate areas). Upon emerging from hibernation, the queen collects pollen and nectar from flowers and searches for a suitable nest site. The characteristics of the nest site vary among bumblebee species, with some species preferring to nest in underground holes and others in tussock grass or directly on the ground. Once the queen has found a site, she prepares wax pots to store food and wax cells into which eggs are laid. These eggs then hatch into larvae, which cause the wax cells to expand isometrically into a clump of brood cells.

These larvae need to be fed both nectar for carbohydrates and pollen for protein in order to develop. Bumblebees feed nectar to the larvae by chewing a small hole in the brood cell into which nectar is regurgitated. Larvae are fed pollen in one of two ways, depending on the bumblebee species. So called “pocket-maker” bumblebees create pockets of pollen at the base of the brood cell clump from which the larvae can feed themselves. Conversely, “pollen-storers” store pollen in separate wax pots and feed it to the larvae in the same fashion as nectar. Bumble bees are incapable of trophallaxis (direct transfer of food from one bee to another).

With proper care, the larvae progress through four instars, becoming successively larger with each molt. At the end of the fourth instar the larvae spin silk cocoons under the wax covering the brood cells, changing them into pupal cells. The larvae then undergo an intense period of cellular growth and differentiation and become pupae. These pupae then develop into adult bees, and chew their way out of the silk cocoon. When adult bumblebees first emerge from their cocoons, the hairs on their body are not yet fully pigmented and are a greyish-white color. The bees are referred to as “callow” during this time, and they will not leave the colony for at least 24 hours. The entire process from egg to adult bee can take as long as five weeks, depending on the species and the environmental conditions.

After the emergence of the first or second group of workers, workers take over the task of foraging and the queen spends most of her time laying eggs and caring for larvae. The colony grows progressively larger and at some point will begin to produce males and new queens. The point at which this occurs varies among species and is heavily dependent on resource availability and environmental factors. Unlike the workers of more advanced social insects, bumblebee workers are not physically reproductively sterile and are able to lay haploid eggs that develop into viable male bumble bees. Only fertilized queens can lay diploid eggs that mature into workers and new queens.

Early in the colony cycle, the queen bumblebee compensates for potential reproductive competition from workers by suppressing their egg-laying by way of physical aggression and pheromonal signals. Thus, the queen will usually be the mother of all of the first males laid. Workers eventually begin to lay males later in the season when the queen’s ability to suppress their reproduction diminishes. The reproductive competition between workers and the queen is one reason that bumble bees are considered “primitively eusocial“.

New queens and males leave the colony after maturation. Males in particular are forcibly driven out by the workers. Away from the colony, the new queens and males live off nectar and pollen and spend the night on flowers or in holes. The queens are eventually mated (often more than once) and search for a suitable location for diapause (dormancy) .



Bumblebees generally visit flowers exhibiting the bee pollination syndrome. They can visit patches of flowers up to 1-2 kilometres from their colony. Bumblebees will also tend to visit the same patches of flowers every day, as long as nectar and pollen continue to be available. While foraging, bumblebees can reach ground speeds of up to 15 m/s (54 km/h).

When bumblebees arrive at a flower, they extract nectar using their long tongue (“glossa“) and store it in their crop. Many species of bumblebee also exhibit what is known as “nectar robbing”: instead of inserting the mouthparts into the flower normally, these bees bite directly through the base of the corolla to extract nectar, avoiding pollen transfer.[11] These bees obtain pollen from other species of flowers that they “legitimately” visit.

Pollen is removed from flowers deliberately or incidentally by bumblebees. Incidental removal occurs when bumblebees come in contact with the anthers of a flower while collecting nectar. The bumblebee’s body hairs receive a dusting of pollen from the anthers which is then groomed into the corbiculae (“pollen baskets”). Bumblebees are also capable of buzz pollination.

In at least a few species, once a bumblebee has visited a flower, it leaves a scent mark on the flower. This scent mark deters visitation of the flower by other bumblebees until the scent degrades. It has been shown that this scent mark is a general chemical bouquet that bumblebees leave behind in different locations (e.g. nest, neutral, and food sites), and they learn to use this bouquet to identify both rewarding and unrewarding flowers. In addition, bumblebees rely on this chemical bouquet more when the flower has a high handling time (i.e. it takes a longer time for the bee to find the nectar).

Once they have collected nectar and pollen, bumblebees return to the nest and deposit the harvested nectar and pollen into brood cells, or into wax cells for storage. Unlike honey bees, bumblebees only store a few days’ worth of food and so are much more vulnerable to food shortages. However, because bumblebees are much more opportunistic feeders than honey bees, these shortages may have less profound effects. Nectar is stored essentially in the form it was collected, rather than being processed into honey as is done by honey bees; it is therefore very dilute and watery, and is rarely consumed by humans.

“Cuckoo” bumblebees

Bumblebees of the subgenus Psithyrus (known as cuckoo bumblebees, and formerly considered a separate genus) are a lineage which live parasitically in the colonies of other bumblebees and have lost the ability to collect pollen. Before finding and invading a host colony, a Psithyrus female (there is no caste system in these species) will feed directly from flowers. Once she has infiltrated a host colony, the Psithyrus female will kill or subdue the queen of that colony and forcibly (using pheromones and/or physical attacks) “enslave” the workers of that colony to feed her and her young.[17] The female Psithyrus also has a number of morphological adaptations, such as larger mandibles and a larger venom sac that increase her chances of taking over a nest.[18] Upon hatching, the male and female Psithyrus disperse and mate. Like non-parasitic bumblebee queens, female Psithyrus find suitable locations to spend the winter and enter diapause upon being mated.

In temperate zone species, in the autumn, young queens (“gynes“) mate with males (drones) and diapause during the winter in a sheltered area, whether in the ground or in a man-made structure. In the early spring, the queen comes out of diapause and finds a suitable place to create her colony, and then builds wax cells in which to lay her fertilized eggs from the previous winter. The eggs that hatch develop into female workers, and in time the queen populates the colony, with workers feeding the young and performing other duties similar to honey bee workers. New reproductives are produced in autumn, and the queen and workers die, as do the males.

Queen and worker bumblebees can sting, but unlike a honey bee‘s, a bumblebee’s stinger lacks barbs — so they can sting more than once. Bumblebee species are normally non-aggressive, but will sting in defense of their nest, or if harmed. Female cuckoo bumblebees will aggressively attack host colony members, and sting the host queen, but will ignore other animals (including humans) unless disturbed.

Bumblebees and people


Bumblebees are increasingly cultured for agricultural use as pollinators because they can pollinate plant species that other pollinators cannot by using a technique known as buzz pollination. For example, bumblebee colonies are often emplaced in greenhouse tomato production, because the frequency of buzzing that a bumblebee exhibits effectively releases tomato pollen.

The agricultural use of bumblebees is limited to pollination. Because bumblebees do not overwinter the entire colony, they are not obliged to stockpile honey, and are therefore not useful as honey producers.

Endangered status


Bumblebees are in danger in many developed countries due to habitat destruction and collateral pesticide damage. In Britain, until relatively recently, 19 species of native true bumblebee were recognized along with six species of cuckoo bumblebees. Of these, three have already become extinct, eight are in serious decline, and only six remain widespread. A decline in bumblebee numbers could cause large-scale sweeping changes to the countryside, leading to inadequate pollination of certain plants.

The world’s first bumblebee sanctuary was established at Vane Farm in the Loch Leven National Nature Reserve in Scotland in 2008.


According to 20th century folklore, the laws of aerodynamics prove that the bumblebee should be incapable of flight, as it does not have the capacity (in terms of wing size or beats per second) to achieve flight with the degree of wing loading necessary. Not being aware of scientists ‘proving’ it cannot fly, the bumblebee succeeds under “the power of its own ignorance”.The origin of this myth has been difficult to pin down with any certainty. John McMasters recounted an anecdote about an unnamed Swiss aerodynamicist at a dinner party who performed some rough calculations and concluded, presumably in jest, that according to the equations, bumblebees cannot fly. In later years McMasters has backed away from this origin, suggesting that there could be multiple sources, and that the earliest he has found was a reference in the 1934 French book Le vol des insectes; they had applied the equations of air resistance to insects and found that their flight was impossible, but that “One shouldn’t be surprised that the results of the calculations don’t square with reality”.

Some credit physicist Ludwig Prandtl (1875-1953) of the University of Göttingen in Germany with popularizing the myth. Others say it was Swiss gas dynamicist Jacob Ackeret (1898-1981) who did the calculations.

In 1934, French entomologist Antoine Magnan included the following passage in the introduction to his book Le Vol des Insectes:

Tout d’abord poussé par ce qui fait en aviation, j’ai appliqué aux insectes les lois de la résistance de l’air, et je suis arrivé avec M. SAINTE-LAGUE a cette conclusion que leur vol est impossible.

This means:

First prompted by the fact of aviation, I have applied the laws of the resistance of air to insects, and I arrived, with Mister Sainte-Lague, at the conclusion that their flight is impossible.

Magnan refers to his assistant André Sainte-Laguë who was, apparently, an engineer.

It is believed that the calculations which purported to show that bumblebees cannot fly are based upon a simplified linear treatment of oscillating aerofoils. The method assumes small amplitude oscillations without flow separation. This ignores the effect of dynamic stall, an airflow separation inducing a large vortex above the wing, which briefly produces several times the lift of the aerofoil in regular flight. More sophisticated aerodynamic analysis shows that the bumblebee can fly because its wings encounter dynamic stall in every oscillation cycle.

Another description of a bee’s wing function is that the wings work similarly to helicopter blades, “reverse-pitch semirotary helicopter blades”.

Bees beat their wings approximately 200 times a second, which is 10-20 times as fast as nerve impulses can fire. They achieve this because their thorax muscles do not expand and contract on each nerve firing, but rather vibrate like a plucked rubber band.

One common, yet incorrect, assumption is that the buzzing sound of bees is caused by the beating of their wings. The sound is actually the result of the bee vibrating its flight muscles, and this can be achieved while the muscles are decoupled from the wings-a feature known in bees but not other insects. This is especially pronounced in bumblebees, as they must warm up their bodies considerably to get airborne at low ambient temperatures. Bumblebees have been known to reach an internal thoracic temperature of 30 degrees Celsius (86 degrees Fahrenheit) using this method.

The distinctive buzz of a flying Bumblebee has inspired the orchestral interlude “Flight of the Bumblebee“.

List of crop plants pollinated by bees

Pollination by insects is called entomophily. Entomophily is a form of pollination whereby pollen is distributed by insects, particularly bees, Lepidoptera (e.g. butterflies and moths), flies and beetles. Note that honey bees will pollinate many plant species that are not native to areas where honey bees occur, and are often inefficient pollinators of such plants.

Common name  

Latin name  


Commercial product
of pollination  


number of
honey bee hives
per acre  

Geography of cultivation  

Okra Abelmoschus esculentus Honey bees (incl. Apis cerana), Solitary bees (Halictus spp.) fruit 2-modest temperate
Kiwifruit Actinidia deliciosa Honey bees, Bumblebees, Solitary bees fruit 4-essential
Bucket orchid Coryanthes Male Euglossini bees (Orchid bees)
Onion Allium cepa Honey bees, Solitary bees seed temperate
Cashew Anacardium occidentale Honey bees, Stingless bees, bumblebees, Solitary bees (Centris tarsata), Butterflies, flies, hummingbirds nut 3-great tropical
Atemoya, Cherimoya, Custard apple Annona squamosa Nitidulid beetles fruit 4-essential tropical
Celery Apium graveolens Honey bees, Solitary bees, flies seed temperate
Strawberry tree Arbutus unedo Honey bees, bumblebees fruit 2-modest
Pawpaw Asimina triloba Carrion flies, Dung flies fruit 4-essential temperate
Carambola, Starfruit Averrhoa carambola Honey bees, Stingless bees fruit 3-great tropical
Brazil nut Bertholletia excelsa Bumblebees, Orchid bees (Euglossini), Carpenter bees nut 4-essential tropical
Beet Beta vulgaris Hover flies, Honey bees, Solitary bees seed 1-little temperate
Mustard Brassica alba, Brassica hirta, Brassica nigra Honey bees, Solitary bees (Osmia cornifrons, Osmia lignaria) seed 2-modest temperate
Rapeseed Brassica napus Honey bees, Solitary bees seed 2-modest temperate
Broccoli Brassica oleracea cultivar Honey bees, Solitary bees seed temperate
Cauliflower Brassica oleracea Botrytis Group Honey bees, Solitary bees seed temperate
Cabbage Brassica oleracea Capitata Group Honey bees, Solitary bees seed temperate
Brussels sprouts Brassica oleracea Gemmifera Group Honey bees, Solitary bees seed temperate
Chinese cabbage Brassica rapa Honey bees, Solitary bees seed temperate
Turnip, Canola Brassica rapa Honey bees, Solitary bees (Andrena ilerda, Osmia cornifrons, Osmia lignaria, Halictus spp.), flies seed 3-great 1 temperate
Pigeon pea, Cajan pea, Congo bean Cajanus cajan Honey bees, solitary bees (Megachile spp.), Carpenter bees seed 1-little
Jack bean, Horse bean, Sword bean Canavalia spp. Solitary bees, Carpenter bees (Xylocopa confusa) seed 2-modest
Chile pepper, Red pepper, Bell pepper, Green pepper Capsicum annuum, Capsicum frutescens Honey bees, stingless bees (Melipona spp.), bumblebees, solitary bees, hover flies fruit 1-little (pollinators important in green houses to increase fruit weight, but less in open fields)
Papaya Carica papaya Honey bees, thrips, large sphinx moths, Moths, Butterflies fruit 1-little
Safflower Carthamus tinctorius Honey bees, Solitary bees seed 1-little
Caraway Carum carvi Honey bees, Solitary bees, flies seed 2-modest temperate
Chestnut Castanea sativa Honey bees, Solitary bees nut 2-modest temperate
Star apple, Cainito Chrysophyllum cainito Insects, bats fruit 1-little tropical
Watermelon Citrullus lanatus Honey bees, bumblebees, solitary bees fruit 4-essential 1-3 temperate
Tangerine Citrus reticulata Honey bees, bumblebees fruit 1-little sub-tropical
Tangelo Citrus spp. Honey bees, Bumblebees fruit 1-little sub-tropical
Coconut Cocos nucifera Honey bees, Stingless bees nut 2-modest tropical
Coffea spp. Coffea arabica, Coffea canephora Coffea spp. Honey bees, Stingless bees, Solitary bees fruit 2-modest tropical
Cola nut Cola nitida, Cola vera, Cola acuminata flies nut 3-great
Coriander Coriandrum sativum Honey bees, Solitary bees seed 3-great
Crownvetch Coronilla varia L. Honey bees, Bumblebees, Solitary bees seed (increased yield from pollinators) temperate
Hazelnut Corylus cornuta var. californica Honey bees, Solitary bees nut temperate
Azarole Crataegus azarolus Honey bees, Solitary bees fruit 1-little
Cantaloupe, Melon Cucumis melo L. Honey bees, Squash bees, bumblebees, Solitary bees (Ceratina spp.) fruit 4-essential 2-4 temperate
Cucumber Cucumis sativus Honey bees, Squash bees, Bumblebees, Leafcutter bee (in greenhouse pollination), Solitary bees (for some parthenocarpic gynoecious green house varieties pollination is detrimental to fruit quality) fruit 3-great 1-2 temperate
Squash (plant), Pumpkin, Gourd, Marrow, Zuchini Cucurbita spp. Honey bees, Squash bees, Bumblebees, Solitary bees fruit 4-essential 1 temperate
Guar bean, Goa bean Cyamopsis tetragonoloba Honey bees seed 1-little
Quince Cydonia oblonga Mill. Honey bees fruit temperate
Carrot Daucus carota Flies, Solitary bees seed temperate
Hyacinth bean Dolichos spp. Honey bees, Solitary bees seed 2-modest
Longan Dimocarpus longan Honey bees, Stingless bees 1-little
Persimmon Diospyros kaki, Diospyros virginiana Honey bees, Bumblebees, Solitary bees fruit 1-little
Durian Durio zibethinus Bats, birds 3-great tropical
Oil palm Elaeis guineensis Weevils, thrips seed 1-little tropical
Cardamom Elettaria cardamomum Honey bees, Solitary bees 3-great
Loquat Eriobotrya japonica Honey bees, Bumblebees fruit 3-great
Buckwheat Fagopyrum esculentum Honey bees, Solitary bees seed 3-great 1 temperate
Feijoa Feijoa sellowiana Honey bees, Solitary bees fruit 3-great tropical
Fig Ficus spp. Fig wasps (incl. Blastophaga psenes)[1][2] fruit (syconium) 2-modest sub-tropical
Fennel Foeniculum vulgare Honey bees, Solitary bees, flies seed 3-great temperate
Strawberry Fragaria spp. Honey bees, Stingless bees, Bumblebees, Solitary bees (Halictus spp.), Hover flies fruit 2-modest 1 temperate
Soybean Glycine max, Glycine soja Honey bees, bumblebees, Solitary bees seed 2-modest temperate
Stanhopea Stanhopea Male Euglossini bees (Orchid bees)
Cotton Gossypium spp. Honey bees, Bumblebees, Solitary bees seed, fiber 2-modest
Sunflower Helianthus annuus Honey bees, bumblebees, Solitary bees seed 2-modest 1 temperate
Walnut Juglans spp. Honey bees, Solitary bees nut temperate
Flax Linum usitatissimum Honey bees, Bumblebees, Solitary bees seed 1-little temperate
Lychee Litchi chinensis Honey bees, flies fruit 1-little
Lupine Lupinus angustifolius L. Honey bees, Bumblebees, Solitary bees seed temperate
Macadamia Macadamia ternifolia Honey bees, Stingless bees (Trigona carbonaria), Solitary bees (Homalictus spp.), Wasps, Butterflies nut 4-essential tropical
Acerola Malpighia glabra Honey bees, Solitary bees fruit (minor commercial value)
Apple Malus domestica, or Malus sylvestris Honey bees, orchard mason bee, Bumblebees, Solitary bees (Andrena spp., Halictus spp., Osmia spp., Anthophora spp.), Hover flies (Eristalis cerealis, Eristalis tenax) fruit 3-great 1, 2 semi dwarf, 3 dwarf temperate
Mammee Mammea americana Bees fruit 2-modest tropical
Mango Mangifera indica Honey bees, Stingless bees, flies, ants, wasps fruit 3-great sub-tropical
Sapodilla Manikara zapotilla thrips fruit 4-essential tropical
Alfalfa Medicago sativa Alfalfa leafcutter bee, Alkali bee, Honey bees seed 1 temperate
Rambutan Nephelium lappaceum Honey bees, Stingless bees, flies fruit


Cactus, Prickly pear Opuntia spp. Bumblebees, Solitary bees fruit 2-modest
Sainfoin Onobrychis spp. Honey bees, Solitary bees seed temperate
Passion fruit. Maracuja Passiflora edulis Carpenter bees, Solitary bees, bumblebees, humming birds fruit 4-essential tropical
Avocado Persea americana Honey bees, Stingless bees, Solitary bees fruit 3-great
Lima bean, Kidney bean, Haricot bean, Adzuki bean, Mungo bean, String bean Phaseolus spp. Honey bees, Solitary bees fruit, seed 1-little
Scarlet runner bean Phaseolus coccineus L. Bumblebees, Honey bees, Solitary bees, Thrips seed
Allspice Pimenta dioica Honey bees, Solitary bees (Halictus spp., Exomalopsis spp., Ceratina spp.) 3-great
Apricot Prunus armeniaca Honey bees, Bumblebees, Solitary bees, flies fruit 3-great 1 temperate
Sweet Cherry Prunus avium spp. Honey bees, Bumblebees, Solitary bees, flies fruit 3-great temperate
Sour cherry Prunus cerasus Honey bees, Bumblebees, Solitary bees, flies fruit 3-great temperate
Plum, Greengage, Mirabelle, Sloe Prunus domestica, Prunus spinosa Honey bees, Bumblebees, Solitary bees, flies fruit 3-great 1 temperate
Almond Prunus dulcis, Prunus amygdalus, or Amygdalus communis Honey bees, bumblebees, Solitary bees (Osmia cornuta), flies nut 3-great 2-3 temperate
Peach, Nectarine Prunus persica Honey bees, Bumblebees, Solitary bees, flies fruit 3-great 1 temperate
Guava Psidium guajava Honey bees, Stingless bees, Bumblebees, Solitary bees (Lasioglossum spp.) fruit 2-modest tropical
Pomegranate Punica granatum Honey bees, Solitary bees, beetles fruit 2-modest
Pear Pyrus communis Honey bees, Bumblebees, Solitary bees, Hover flies (Eristalis spp.) fruit 3-great 1 temperate
Black currant, Red currant Ribes nigrum, Ribes rubrum Honey bees, Bumblebees, Solitary bees fruit 2-modest temperate
Rose hips, Dogroses Rosa spp. Honey bees, Bumblebees, Carpenter bees, Solitary bees, Hover flies 3-great temperate
Boysenberry Rubus spp. Honey bees, Bumblebees, Solitary bees fruit temperate
Raspberry Rubus idaeus Honey bees, Bumblebees, Solitary bees, Hover flies (Eristalis spp.) fruit 3-great 1 temperate
Blackberry Rubus fruticosus Honey bees, Bumblebees, Solitary bees, Hover flies (Eristalis spp.) fruit 3-great temperate
Elderberry Sambucus nigra Honey bees, Solitary bees, flies, Longhorn beetles fruit 2-modest temperate
Sesame Sesamum indicum Honey bees, Solitary bees, wasps, flies seed 2-modest
Eggplant Solanum melongena Honey bees, Bumblebees, Solitary bees fruit 2-modest (pollinators important in green houses, but less in open fields) temperate
Naranjillo Solanum quitoense Bumblebees, Solitary bees fruit 3-great tropical
Rowanberry Sorbus aucuparia Honey bees, Solitary bees, Bumblebees, Hover flies fruit 4-essential temperate
Service Tree Sorbus domestica bees, flies fruit 2-modest
Hog plum Spondias spp. Honey bees, Stingless bees (Melipona spp.) fruit 1-little
Tamarind Tamarindus indica Honey bees (incl. Apis dorsata) fruit 1-little
Cocoa Theobroma cacao Midges 4-essential tropical
Clover (not all species) Trifolium spp. Honey bees, Bumblebees, Solitary bees seed 1 temperate
White clover Trifolium alba Honey bees, Bumblebees, Solitary bees seed 1 temperate
Alsike clover Trifolium hybridum L. Honey bees, Bumblebees, Solitary bees seed 1 temperate
Crimson clover Trifolium incarnatum Honey bees, Bumblebees, Solitary bees seed 1
Red clover Trifolium pratense Honey bees, Bumblebees, Solitary bees seed 1 temperate
Arrowleaf clover Trifolium vesiculosum Savi Honey bees, Bumblebees, Solitary bees seed 1 temperate
Blueberry Vaccinium spp. Honey bees, Alfalfa leafcutter bees, Southeastern blueberry bee, Bumblebees (Bombus impatiens), Solitary bees (Anthophora pilipes, Colletes spp., Osmia ribifloris, Osmia lignaria) fruit 3-great 3-4 temperate
Cranberry Vaccinium oxycoccus, Vaccinium macrocarpon Honey bees, Bumblebees (Bombus affinis), Solitary bees (Megachile addenda, Alfalfa leafcutter bees) fruit 3 temperate
Vanilla Vanilla planifolia, Vanilla pompona Solitary bees fruit 4-essential tropical
Tung tree Vernicia fordii Honey bees seed
Broad bean Vicia faba Honey bees, Bumblebees, Solitary bees seed 2-modest
Vetch Vicia spp. Honey bees, Bumblebees, Solitary bees seed temperate
Cowpea, Black-eyed pea, Blackeye bean Vigna unguiculata Honey bees, Bumblebees, Solitary bees seed 1-little
Karite Vitellaria paradoxa Honey bees nut 2-modest tropical
Grape Vitis spp. Honey bees, Solitary bees, flies fruit 0-no increase temperate
Jujube Zizyphus jujuba Honey bees, Solitary bees, flies, beetles, wasps fruit 2-modest

Click to hear a bumblebee buzz: