Colony collapse disorder
Colony Collapse Disorder (CCD) is a phenomenon in which worker bees from a beehive or European honey bee colony abruptly disappear. While such disappearances have occurred throughout the history of apiculture, and were known by various names (disappearing disease, spring dwindle, May disease, autumn collapse, and fall dwindle disease), the syndrome was renamed colony collapse disorder in late 2006 in conjunction with a drastic rise in the number of disappearances of Western honeybee colonies in North America. European beekeepers observed similar phenomena in Belgium, France, the Netherlands, Greece, Italy, Portugal, and Spain, and initial reports have also come in from Switzerland and Germany, albeit to a lesser degree while the Northern Ireland Assembly received reports of a decline greater than 50%.
Colony collapse is significant economically because many agricultural crops worldwide are pollinated by European honey bees. According to the Agriculture and Consumer Protection Department of the Food and Agriculture Organization of the United Nations, the worth of global crops with honeybee’s pollination was estimated to be close to $200 billion in 2005. Shortages of bees in the US have increased the cost to farmers renting them for pollination services by up to 20%.
The mechanisms of CCD and the reasons for its increasing prevalence remain unclear, but many possible causes have been proposed: pesticides (in particular, those of the neonicotinoid class); infections with Varroa and Acarapis mites; malnutrition; various pathogens; genetic factors; immunodeficiencies; loss of habitat; changing beekeeping practices; or a combination of factors.
- 1 History
- 2 Signs and symptoms
- 3 Scope and distribution
- 4 Possible causes
- 4.1 European Food Safety Authority statement
- 4.2 Pesticides
- 4.3 Pathogens and immunodeficiency theories
- 4.4 Antibiotics and miticides
- 4.5 Bee rentals and migratory beekeeping
- 4.6 Selective commercial breeding and lost genetic diversity in industrial apiculture
- 4.7 Malnutrition
- 4.8 Electromagnetic radiation
- 4.9 Parasitic phorid fly
- 4.10 Genetically modified crops
- 5 Management
- 6 Consequences
- 7 Media
- 8 See also
- 9 References
- 10 Further reading
- 11 External links
Limited occurrences resembling CCD have been documented as early as 1869 and this set of symptoms has, in the past several decades, been given many different names (disappearing disease, spring dwindle, May disease, autumn collapse, and fall dwindle disease). Most recently, a similar phenomenon in the winter of 2004/2005 occurred, and was attributed to varroa mites (the "vampire mite" scare), though this was never ultimately confirmed. The cause of the appearance of this syndrome has never been determined. Upon recognition that the syndrome does not seem to be seasonally restricted, and that it may not be a "disease" in the standard sense—that there may not be a specific causative agent—the syndrome was renamed.
There was a well-documented outbreak of colony losses spreading from the Isle of Wight to the rest of the UK in 1906. These losses later were attributed to a combination of factors, including adverse weather, intensive apiculture leading to inadequate forage, and a new infection, the chronic bee paralysis virus;  but, at the time, the cause of this agricultural beekeeping problem was similarly mysterious and unknown.
Reports show this behavior in hives in the US in 1918 and 1919. Coined "mystery disease" by some, it eventually became more widely known as "disappearing disease". Oertel, in 1965, reported that hives afflicted with disappearing disease in Louisiana had plenty of honey in the combs, although there were few or no bees, discrediting reports that attributed the disappearances to lack of food.
From 1972 to 2006, dramatic reductions continued in the number of feral honey bees in the U.S. and a significant though somewhat gradual decline in the number of colonies maintained by beekeepers. This decline includes the cumulative losses from all factors, such as urbanization, pesticide use, tracheal and Varroa mites, and commercial beekeepers' retiring and going out of business. However, in late 2006 and early 2007, the rate of attrition was alleged to have reached new proportions, and the term "colony collapse disorder" began to be used to describe this sudden rash of disappearances (sometimes referred to as "spontaneous hive collapse" or the "Mary Celeste syndrome" in the United Kingdom).
Losses had remained stable since the 1990s at 17%–20% per year attributable to a variety of factors, such as mites, diseases, and management stress. The first report of CCD was in mid-November 2006 by a Pennsylvania beekeeper overwintering in Florida. By February 2007, large commercial migratory beekeepers in several states had reported heavy losses associated with CCD. Their reports of losses varied widely, ranging from 30% to 90% of their bee colonies; in some cases, beekeepers reported losses of nearly all of their colonies with surviving colonies so weakened that they might no longer be viable to pollinate or produce honey.
Losses were reported in migratory operations wintering in California, Florida, Oklahoma, and Texas. In late February, some larger nonmigratory beekeepers in the mid-Atlantic and Pacific Northwest regions also reported significant losses of more than 50%. Colony losses also were reported in five Canadian provinces, several European countries, and countries in South and Central America and Asia. In 2010, the USDA reported that data on overall honey bee losses for 2010 indicated an estimated 34% loss, which is statistically similar to losses reported in 2007, 2008, and 2009.
Signs and symptoms
In collapsed colonies CCD is suspected when a complete absence of adult bees is found in colonies, with no or little buildup of dead bees in the hive or in front of the hive. A colony which has collapsed from CCD is generally characterized by all of these conditions occurring simultaneously:
- Presence of capped brood in abandoned colonies: Bees normally will not abandon a hive until the capped brood have all hatched.
- Presence of food stores, both honey and bee pollen:
- Presence of the queen bee: If the queen is not present, the hive died because it was queenless, which is not considered CCD.
Precursor symptoms that may arise before the final colony collapse are:
- Insufficient workforce to maintain the brood that is present
- Workforce seems to be made up of young adult bees
- The colony members are reluctant to consume provided feed, such as sugar syrup and protein supplement.
Scope and distribution
The National Agriculture Statistics Service reported that there were 2.44 million honey-producing hives in the United States as of February 2008, down from 4.5 million in 1980, and 5.9 million in 1947, though these numbers underestimate the total number of managed hives as they exclude several thousand hives managed for pollination contracts only, and also do not include hives managed by beekeepers owning fewer than 5 hives. This under-representation may be offset by the practice of counting some hives more than once; hives that are moved to different states to produce honey are counted in each state's total and summed in total counts.
Non-CCD winter losses as high as 50% have occurred in some years and regions (e.g., 2000–2001 in Pennsylvania). Normal winter losses are typically considered to be in the range of 15–25%. In many cases, beekeepers reporting significant losses of bees did not experience true CCD, but losses due to other causes.
In 2007 in the US, at least 24 different states as well as portions of Canada had reported at least one case of CCD. In a 2007 survey of 384 responding beekeepers from 13 states, 23.8% met the specified criterion for CCD (that 50% or more of their dead colonies were found without bees and/or with very few dead bees in the hive or apiary).
A 2007–2008 survey of over 19% of all colonies revealed a total loss of 35.8%. Operations that pollinated almonds lost, on average, the same number of colonies as those that did not. The 37.9% of operations that reported having at least some of their colonies die with a complete lack of bees had a total loss of 40.8% of colonies compared to the 17.1% loss reported by beekeepers without this symptom. Large operations were more likely to have this symptom suggesting that a contagious condition may be a causal factor. Sixty percent of all colonies that were reported dead in this survey died without the presence of dead bees in the hive, and thus possibly suffered from CCD.
In 2010, the USDA reported that data on overall honey bee losses for the year indicate an estimated 34% loss, which is statistically similar to losses reported in 2007, 2008, and 2009. In 2011, the loss was 30%. In 2012–2013, CCD was blamed for the loss of about half of the US honeybee hives, far more than the 33% losses observed on average over previous years.
According to the European Food Safety Authority (EFSA), in 2007 the United Kingdom had 274,000 hives, Italy had 1,091,630, and France 1,283,810. In 2008, the British Beekeepers Association reported that the bee population in the United Kingdom dropped by around 30% between 2007 and 2008, and an EFSA study revealed that in Italy the mortality rate was 40–50%. However, EFSA officials point out that the figures are not very reliable because before the bees started dying there was no harmonisation in the way different countries collected statistics on their bee populations. At that time (2008), the reports blamed the high death rate on the varroa mite, two seasons of unusually wet European summers, and some pesticides.
In 2010, David Aston of the British Beekeepers’ Association stated, "We still do not believe CCD (which is now better defined) is a cause of colony losses in the UK, however we are continuing to experience colony losses, many if not most of which can be explained". He feels that recent studies suggest "further evidence to the evolving picture that there are complex interactions taking place between a number of factors, pathogens, environmental, beekeeping practices and other stressors, which are causing honey bee losses described as CCD in the US".
In 2009, Tim Lovett, president of the British Beekeepers' Association, said: "Anecdotally, it is hugely variable. There are reports of some beekeepers losing almost a third of their hives and others losing none. John Chapple, chairman of the London Beekeepers' Association, put losses among his 150 members at between a fifth and a quarter. "There are still a lot of mysterious disappearances; we are no nearer to knowing what is causing them." The government's National Bee Unit continued to deny the existence of CCD in Britain; it attributes the heavy losses to the varroa mite and rainy summers that stop bees foraging for food.
Bee keepers in Scotland also reported losses for the past three years. Andrew Scarlett, a Perthshire-based bee farmer and honey packer, lost 80% of his 1,200 hives during the 2009 winter. He attributed the losses to a virulent bacterial infection that quickly spread because of a lack of bee inspectors, coupled with sustained poor weather that prevented honeybees from building up sufficient pollen and nectar stores.
In Germany, where some of the first reports of CCD in Europe appeared, and where, according to the German national association of beekeepers, 40% of the honey bee colonies died, there was no scientific confirmation; as of early May 2007[update], the German media were reporting that no confirmed CCD cases seemed to have occurred in Germany.
At the end of May 2012, the Swiss government reported that about half of the bee population had not survived the winter. The main cause of the decline was thought to be the parasite Varroa destructor.
The mechanisms of CCD are still unknown, but many causes have been proposed as causative agents: malnutrition, pathogens, immunodeficiencies, mites, fungus, pesticides, beekeeping practices (such as the use of antibiotics, or long-distance transportation of beehives) and electromagnetic radiation. Whether any single factor or a combination of factors (acting independently in different areas affected by CCD, or acting in tandem) is responsible is still unknown; however most recent information suggests a combination of factors is most likely. It is likewise still uncertain whether CCD is a genuinely new phenomenon as opposed to a known phenomenon that previously only had a minor impact.
In 2006, the Colony Collapse Disorder Working Group, based primarily at Pennsylvania State University, was established. Their preliminary report pointed out some patterns but drew no strong conclusions. A survey of beekeepers early in 2007 indicated that most hobbyist beekeepers believed that starvation was the leading cause of death in their colonies while commercial beekeepers overwhelmingly believed that invertebrate pests (Varroa mites, honey bee tracheal mites, and/or small hive beetles) were the leading cause of colony mortality. A scholarly review in June 2007 similarly addressed numerous theories and possible contributing factor, but left the issue unresolved.
- survey and data collection;
- analysis of samples;
- hypothesis-driven research; and
- mitigation and preventive action.
In July 2009, the first annual report of the U.S. Colony Collapse Disorder Steering Committee was published. It suggested that colony collapse may be caused by the interaction of many agents in combination.
Similarly, in 2009 the CCD Working Group published a comprehensive descriptive study that concluded: "Of the 61 variables quantified (including adult bee physiology, pathogen loads, and pesticide levels), no single factor was found with enough consistency to suggest one causal agent. Bees in CCD colonies had higher pathogen loads and were co-infected with more pathogens than control populations, suggesting either greater pathogen exposure or reduced defenses in CCD bees."
The second annual Steering Committee report was released in November 2010. The group reported that although many associations, including pesticides, parasites, and pathogens have been identified throughout the course of research, "it is becoming increasingly clear that no single factor alone is responsible for [CCD]". Their findings indicated an absence of damaging levels of the parasite Nosema or parasitic Varroa mites at the time of collapse.
They did find an association of sub-lethal effects of some pesticides with CCD, including two common miticides in particular, coumaphos and fluvalinate, which are pesticides registered for use by beekeepers to control varroa mites. It was reported that studies also identified sub-lethal effects of neo-nicotinoids and fungicides, pesticides that may impair the bee's immune system and may leave the bee more susceptible to bee viruses.
A large 2010 survey of healthy and CCD-affected colonies also revealed elevated levels of pesticides in wax and pollen, but the amounts of pesticides were similar in both failing and healthy hives. They also confirmed suspected links between CCD and poor colony health, inadequate diet, and long-distance transportation. Studies continue to show very high levels of pathogens in CCD-affected samples and lower pathogen levels in non-affected samples, consistent with the empirical observation that healthy honey bee colonies normally fend off pathogens. These observations have led to the hypothesis that bee declines are resulting from immune suppression.
In the 29 March 2012, issue of the journal Science, two separate studies found that neonicotinoids (insecticides) may interfere with bees' natural homing abilities, causing them to become disoriented and preventing them from finding their way back to the hive.
European Food Safety Authority statement
In 2012, several peer reviewed independent studies were published showing that neonicotinoids had previously undetected routes of exposure affecting bees including through dust, pollen, and nectar and that sub-nanogram toxicity resulted in failure to return to the hive without immediate lethality, the primary symptom of CCD. Research also showed environmental persistence in agricultural irrigation channels and soil. These reports prompted a formal peer review by the European Food Safety Authority, which stated in January 2013 that some neonicotinoids pose an unacceptably high risk to bees, and identified several data gaps not previously considered. Their review concluded, "A high acute risk to honey bees was identified from exposure via dust drift for the seed treatment uses in maize, oilseed rape and cereals. A high acute risk was also identified from exposure via residues in nectar and/or pollen." David Goulson, an author of one of the studies which prompted the EFSA review, has suggested that industry science pertaining to neonicotinoids may have been deliberately deceptive, and the UK Parliament has asked manufacturer Bayer Cropscience to explain discrepancies in evidence they have submitted to an investigation.
According to the U.S. Department of Agriculture, pesticides may be contributing to CCD. Scientists have long been concerned that pesticides and possibly some fungicides may have sub-lethal effects on bees, not killing them outright but instead impairing their development and behavior. Of special interest is the class of insecticides called neonicotinoids, which contain the active ingredient imidacloprid, and similar other chemicals, such as clothianidin and thiamethoxam. Honey bees may be affected by such chemicals when they are used as a seed treatment because they are known to work their way through the plant up into the flowers and leave residues in the nectar. Scientists note that the doses taken up by bees are not lethal, but they are concerned about possible chronic problems caused by long-term exposure. Most corn grown in the US is treated with neonicoticoids and a 2012 study found high levels of clothianidin in pneumatic planter exhaust. In the study, it was found that the insecticide was present in the soil of unplanted fields near those planted with corn and on dandelions growing near those fields. Another 2012 study done in Italy also found clothianidin and imidacloprid in the exhaust of pneumatic seeding equipment.
A 2010 survey reported 98 pesticides and metabolites detected in aggregate concentrations up to 214 ppm in bee pollen—this figure represents over half of the individual pesticide incidences ever reported for apiaries. It was suggested that "while exposure to many of these neurotoxicants elicits acute and sublethal reductions in honey bee fitness, the effects of these materials in combinations and their direct association with CCD or declining bee health remains to be determined."
It is particularly difficult to evaluate pesticide contributions to CCD for several reasons. First, the variety of pesticides in use in the different areas reporting CCD makes it difficult to test for all possible pesticides simultaneously. Second, many commercial beekeeping operations are mobile, transporting hives over large geographic distances over the course of a season, potentially exposing the colonies to different pesticides at each location. Third, the bees themselves place pollen and honey into long-term storage, effectively meaning that there may be a delay of anywhere from days to months before contaminated provisions are fed to the colony, negating any attempts to associate the appearance of symptoms with the actual time at which exposure to pesticides occurred.
Pesticides used on bee forage are far more likely to enter the colony via the pollen stores rather than via nectar (because pollen is carried externally on the bees, while nectar is carried internally, and may kill the bee if too toxic), though not all potentially lethal chemicals, either natural or man-made, affect the adult bees: many primarily affect the brood, but brood die-off does not appear to be happening in CCD. Most significantly, brood are not fed honey, and adult bees consume relatively little pollen; accordingly, the pattern in CCD suggests that if contaminants or toxins from the environment are responsible, it is most likely to be via the honey, as it is the adults that are dying (or leaving), not the brood (though possibly effects of contaminated pollen consumed by juveniles may only show after they have developed into adults).
To date, most of the evaluation of possible roles of pesticides in CCD have relied on the use of surveys submitted by beekeepers, but it seems likely that direct testing of samples from affected colonies will be needed, especially given the possible role of systemic insecticides such as the neonicotinoid imidacloprid (which are applied to the soil and taken up into the plant's tissues, including pollen and nectar), which may be applied to a crop when the beekeeper is not present. The known effects of imidacloprid on insects, including honey bees, are consistent with the symptoms of CCD; for example, the effects of imidacloprid on termites include apparent failure of the immune system, and disorientation.
In Europe, the interaction of the phenomenon of "dying bees" with imidacloprid has been discussed for quite some time. A study from the "Comité Scientifique et Technique (CST)" was at the center of discussion, and led to a partial ban of imidacloprid in France. The imidacloprid pesticide Gaucho was banned in 1999 by the French Minister of Agriculture Jean Glavany, primarily due to concern over potential effects on honey bees. Subsequently when fipronil, a phenylpyrazole insecticide and in Europe mainly labeled "Regent", was used as a replacement, it was also found to be toxic to bees, and banned partially in France in 2004.
In February 2007, about forty French deputies, led by UMP member Jacques Remiller, requested the creation of a Parliamentary Investigation Commission on Overmortality of Bees, underlining that honey production was decreasing by 1,000 tons a year for a decade. As of August 2007[update], no investigations were yet opened. Five other insecticides based on fipronil were also accused of killing bees. However, the scientific committees of the European Union are still of the opinion "that the available monitoring studies were mainly performed in France and EU-member-states should consider the relevance of these studies for the circumstances in their country".
Around the same time French beekeepers succeeded in banning neonicotinoids, the Clinton administration permitted pesticides which were previously banned, including imidacloprid. In 2004, the Bush Administration reduced regulations further and pesticide applications increased.
In 2005, a team of scientists led by the National Institute of Beekeeping in Bologna, Italy, found pollen obtained from seeds dressed with imidacloprid contains significant levels of the insecticide, and suggested the polluted pollen might cause honey bee colony death. Analysis of maize and sunflower crops originating from seeds dressed with imidacloprid suggest large amounts of the insecticide will be carried back to honey bee colonies. Sublethal doses of imidacloprid in sucrose solution have also been documented to affect homing and foraging activity of honey bees. Imidacloprid in sucrose solution fed to bees in the laboratory impaired their communication for a few hours. Sublethal doses of imidacloprid in laboratory and field experiment decreased flight activity and olfactory discrimination, and olfactory learning performance was impaired.
Research, in 2008, by scientists from Pennsylvania State University found high levels of the pesticides fluvalinate and coumaphos in samples of wax from hives, as well as lower levels of 70 other pesticides. These chemicals have been used to try to eradicate varroa mites, a bee pest that itself has been thought to be a cause of CCD. Researchers from Washington State University, under entomology professor Steve Sheppard in 2009, confirmed high levels of pesticide residue in hive wax and found an association between it and significantly reduced bee longevity.
The WSU work also focused on the impact of the microsporidian pathogen Nosema ceranae, the build-up of which was high in the majority of the bees tested, even after large doses of the antibiotic fumagillin. Penn State's Dr. Maryann Frazier said, "Pesticides alone have not shown they are the cause of CCD. We believe that it is a combination of a variety of factors, possibly including mites, viruses and pesticides."
In 2010, Fipronil was blamed for the spread of colony collapse disorder among bees, in a study by the Minutes-Association for Technical Coordination Fund in France, which found that even at very low nonlethal doses, this pesticide still impairs the ability to locate the hive, resulting in large numbers of foragers lost with every pollen-finding expedition, though no mention was made regarding any of the other symptoms of CCD; other studies, however, have shown no acute effect of Fipronil on honey bees. Fipronil is designed to eliminate insects similar to bees, such as yellowjackets (Vespula germanica) and many other colonial pests by a process of toxic baiting, whereby one insect returning to the hive spreads the pesticide among the brood.
In 2012, researchers announced findings that sublethal exposure to imidacloprid rendered honey bees significantly more susceptible to infection by the fungus Nosema, thereby suggesting a potential link to CCD, given that Nosema is increasingly considered to contribute to CCD.
Also, in 2012, researchers in Italy published findings that the pneumatic drilling machines that plant corn seeds coated with clothianidin and imidacloprid release large amounts of the pesticide into the air, causing significant mortality in foraging honey bees. According to the study, "Experimental results show that the environmental release of particles containing neonicotinoids can produce high exposure levels for bees, with lethal effects compatible with colony losses phenomena observed by beekeepers." Commonly used pesticides, such as the neonicotinoid imidacloprid reduce colony growth and new queen production in experimental exposure matched to field levels. Lu et al. (2012) reported they were able to replicate CCD with imidacloprid. Another neonicotinoid thiamethoxam causes navigational homing failure of foraging bees, with high mortality.
A 2012 in situ study provided strong evidence that exposure to sub-lethal levels of imidacloprid in high fructose corn syrup (HFCS) used to feed honey bees when forage is not available causes bees to exhibit symptoms consistent to CCD 23 weeks post imidacloprid dosing. The researchers suggested that "the observed delayed mortality in honey bees caused by imidacloprid in HFCS is a novel and plausible mechanism for CCD, and should be validated in future studies".
In March 2013, two studies were published showing that neonicotinoids affect bee long term and short term memory, suggesting a cause of action resulting in failure to return to the hive. In another study done in 2013, scientists reported that experiments suggested that exposure to the neonicotinoid pesticides clothianidin and imidicloprid results in increased levels of a particular protein in bees that inhibits a key molecule involved in the immune response, making the insects more susceptible to attack by harmful viruses. Growth in the use of neonicotinoid pesticides has roughly tracked rising bee deaths.
In 2013, researchers collected pollen from hives on the east coast and fed it to healthy bees. The pollen had an average of nine different pesticides and fungicides. Further, the researchers discovered that bees that ate pollen with fungicides were three times more likely to be infected by parasites. Their study shows that fungicides, thought harmless to bees, may actually play a significant role in CCD. Their research also showed that spraying practices may need to be reviewed because the bees sampled by the authors foraged not from crops, but almost exclusively from weeds and wildflowers, suggesting that bees are more widely exposed to pesticides than thought.
Neonicotinoids banned by European Union
Early in 2013, the European Food Safety Authority issued a declaration that three specific neonicotinoid pesticides pose an acute risk to honeybees, and the European Commission (EC) proposed a two-year ban on them. David Goulson, who led one of the key 2012 studies at the University of Stirling said that the decision "begs the question of what was going on when these chemicals were first approved." The chemical manufacturer Bayer said it was "ready to work with" the EC and member states. In April 2013, the European Union voted for a two-year restriction on neonicotinoid insecticides. The ban will restrict the use of imidacloprid, clothianidin, and thiamethoxam for use on crops that are attractive to bees. Eight nations voted against the motion, including the British government which argued that the science was incomplete.
Initiatives to ban neonicotinoids in the United States
In March 2013, professional beekeepers and environmentalists jointly filed a lawsuit against the United States Environmental Protection Agency (EPA) for continuing to allow the use of neonicotinoids in the United States. The suit specifically asks for suspension of clothianidin and thiamethoxam. The lawsuit follows a dramatic die off of bees in the United States, with some beekeepers losing fifty percent of their hives. The EPA responded to the suit by issuing a report blaming the Varroa mite for the decline in bees and claiming that the role of neonicotinoids in bee extinction has been overstated.
Also in 2013, the Save America's Pollinators Act of 2013 (H.R. 2692) was introduced in Congress. The proposed act, spearheaded by Representatives John Conyers (D, MI) and Earl Blumenauer (D, OR), and co-sponsored by Rep. Lucille Roybal-Allard (D, CA) and Rep. Carol Shea-Porter (D, NH), asks that neonicotinoids be suspended until a full review of their impacts has occurred. The Save America's Pollinators Act was drafted immediately following the largest documented die off of bees in the United States which took place in the parking lot of a department store in June 2013. The neonicotinoid Safari, which had been sprayed on linden trees, was suspected of killing the bees.
In March 2014, Minneapolis-based Bachman’s gardening centers announced that they plan to no longer sell neonicotinoids or use them at their nurseries and outdoor growing areas. Bachman's vice president of production and wholesale said it was not an easy decision, but after receiving numerous calls from concerned gardeners they "decided to take precautionary action." 
Pathogens and immunodeficiency theories
Early researchers commented that the pathway of propagation functions in the manner of a contagious disease; however, there was some sentiment that the disorder may involve an immunosuppressive mechanism, potentially linked to "stress" leading to a weakened immune system. Specifically, according to research done in 2007 at the Pennsylvania State University: "The magnitude of detected infectious agents in the adult bees suggests some type of immunosuppression". These researchers initially suggested a connection between Varroa destructor mite infestation and CCD, suggesting that a combination of these bee mites, deformed wing virus (which the mites transmit) and bacteria work together to suppress immunity and may be one cause of CCD.
When a colony is dying, for whatever cause, and there are other healthy colonies nearby (as is typical in a bee yard), those healthy colonies often enter the dying colony and rob its provisions for their own use. If the dying colony's provisions were contaminated (by natural or man-made toxins), the resulting pattern (of healthy colonies becoming sick when in proximity to a dying colony) might suggest to an observer that a contagious disease is involved. However, it is typical in CCD cases that provisions of dying colonies are not being robbed, suggesting that at least this particular mechanism (toxins being spread via robbing, thereby mimicking a disease) is not involved in CCD. Additional evidence that CCD is an infectious disease came from the following observations: the hives of colonies that had died from CCD could be reused with a healthy colony only if they were first treated with DNA-destroying radiation, and the CCD Working Group report in 2010 indicated that CCD-exhibiting hives tended to occur in proximity to one another within apiaries.
According to a 2007 article, the mite Varroa destructor remains the world's most destructive honey bee killer, due in part to the viruses it carries including deformed wing virus and acute bee paralysis virus, which have both been implicated in CCD. Affliction with Varroa mites also tends to weaken the immune system of the bees. Dr. Enesto Guzman, an entomological researcher at the University of Guelph in Canada, studied 413 Ontario bee colonies in 2007–08. About 27% of hives did not survive the winter, and the Varroa mite was identified as the cause in 85% of the cases. As such, Varroa mites have been considered as a possible cause of CCD, though not all dying colonies contain these mites.
Israeli acute paralysis virus
In 2004, Israeli acute paralysis virus (IAPV), was discovered in Israel and at one time it was considered the cause of CCD. It was named after the place it was first identified; its place of origin is unknown. In September 2007, results of a large-scale statistical RNA sequencing study of afflicted and unafflicted colonies were reported. RNA from all organisms in a colony was sequenced and compared with sequence databases to detect the presence of pathogens. All colonies were found to be infected with numerous pathogens, but only the IAPV virus showed a significant association with CCD: the virus was found in 25 of the 30 tested CCD colonies, and only in one of the 21 tested non-CCD colonies.
Recent research in 2009 has found that an indicator for an impaired protein production is common among all bees affected by CCD, a pattern consistent with IAPV infection. It is conjectured that Dicistroviridae, like the IAPV, cause degradation of the ribosomes, which are responsible for protein production of cells, and that this reduced ribosomal function weakens the bees, making them more vulnerable to factors that might not otherwise be lethal.
Some have suggested that the syndrome may be an inability by beekeepers to correctly identify known diseases such as European foulbrood or the microsporidian fungus Nosema. The testing and diagnosis of samples from affected colonies (already performed) makes this highly unlikely, as the symptoms are fairly well known and differ from what is classified as CCD. A high rate of Nosema infection was reported in samples of bees from Pennsylvania, but this pattern was not reported from samples elsewhere.
Mariano Higes, a scientist heading a team at a government-funded apiculture centre in Guadalajara, Spain, has reported that when hives of European honey bees were infected with Nosema ceranae, a microsporidian fungus, the colonies were wiped out within eight days. Higes has extrapolated from this research to conclude that CCD is caused by N. ceranae. Higes and his team have worked on this problem since 2000, and claim to have ruled out many other potential causes. However, a 2009 comprehensive survey of CCD-affected bee populations in the United States suggested that CCD likely involves an interaction between pathogens and other stress factors. They reported that their survey found only about half of the colonies sampled, both in CCD and control populations, were infected with N. ceranae.
The primary antifungal agent used against Nosema is fumagillin, which has been used in a German research project to reduce the microsporidian's impact, and is mentioned as a possible remedy by the CCDWG. Higes also claims to have successfully cured colonies with fumagillin. A review of these results in the journal Nature described these results as promising, but cautioned "N. ceranae may not be to blame for all cases of colony collapse". Various areas in Europe have reported this fungus, but no direct link to CCD has yet been established.
Highly preliminary evidence of N. ceranae was recently reported in a few hives in the Merced Valley area of California (USA). The researcher did not, however, believe this was conclusive evidence of a link to CCD; "We don't want to give anybody the impression that this thing has been solved". A USDA bee scientist has similarly stated, "while the parasite Nosema ceranae may be a factor, it cannot be the sole cause. The fungus has been seen before, sometimes in colonies that were healthy". Likewise, a Washington State beekeeper familiar with N. ceranae in his own hives, discounts it as being the cause of CCD.
In the United States, N. ceranae has been detected in honey bees from Nebraska, Wisconsin, Arkansas, New York and South Dakota using PCR of the 16S gene. In New York, N. ceranae was detected in 49 counties, and of the 1,200 honey bee samples collected, 528 (44%) were positive for Nosema, from which, PCR analysis of 371 spore positive samples revealed 96% were N. ceranae, 3% had both N. ceranae and N. apis, and 1% had N. apis only.
Viral and fungal combination
A University of Montana and Montana State University team of scientists headed by Jerry Bromenshenk and working with the US Army's Edgewood Chemical Biological Center published a paper in October 2010 saying that a new DNA virus, invertebrate iridescent virus or IIV6, and the fungus Nosema ceranae were found in every killed colony the group studied. In their study they found that neither agent alone seemed deadly, but a combination of the virus and N. ceranae was always 100% fatal. Information about the study was released to the public in a front page article in The New York Times. A few days later, an article was published in Fortune Magazine with the title, "What a scientist didn't tell the New York Times about his study on bee deaths". Professor of entomology at Penn State University James Frazier, who is currently researching the sublethal impact of pesticides on bees, said that while Bromenshenk's study generated some useful data, Bromenshenk has a conflict of interest as CEO of a company developing scanners to diagnose bee diseases. A few months later, the methods used to interpret the mass spectrometry data in the Bromenshenk study were called into question, raising doubts as to whether IIV6 was ever correctly identified in any of the samples examined.
Antibiotics and miticides
Most beekeepers affected by CCD report that they use antibiotics and miticides in their colonies, though the lack of uniformity as to which particular chemicals are used makes it seem unlikely that any single such chemical is involved. However, it is possible that not all such chemicals in use have been tested for possible effects on honey bees, and could therefore potentially be contributing to the CCD phenomenon.
Bee rentals and migratory beekeeping
Since U.S. beekeeper Nephi Miller first began moving his hives to different areas of the country for the winter of 1908, migratory beekeeping has become widespread in America.
Bee rental for pollination is a crucial element of U.S. agriculture, which could not produce anywhere near its current levels with native pollinators alone. U.S. beekeepers collectively earn much more from renting their bees out for pollination than they do from honey production.
Researchers are concerned that trucking colonies around the country to pollinate crops, where they intermingle with other bees from all over, helps spread viruses and mites among colonies. Additionally, such continuous movement and re-settlement is considered by some a strain and disruption for the entire hive, possibly rendering it less resistant to all sorts of systemic disorder.
Selective commercial breeding and lost genetic diversity in industrial apiculture
Most of the focus on CCD has been toward environmental factors. CCD is a condition recognised for greatest impact in regions of 'industrial' or agricultural use of commercially bred bee colonies. Natural breeding and colony reproduction of wild bees is a complex and highly selective process, leading to a diverse genetic makeup in large populations of bees, both within and between colonies. Genetic diversity through sexual reproduction is a significant evolutionary factor in resistance to parasites and infectious diseases. Many artificially bred species, especially domestic and agricultural species, suffer from lack of genetic variation, resulting in increased risk of hereditable diseases, loss of vitality or vigour, and heightened uniform susceptibility to infectious diseases. There may be an analogy in artificially introduced invasive ants, which displace native species by their ecological release and supercolonies (a manifestation of genetic homogeneity), only to suffer collapse of colonies attributed to lack of genetic diversity. Displaced indigenous species rebounded from residual populations.
Industrial apiculture has adopted simple breeding programs for uniform desired traits, and seasonal transportation of colonies over vast distances causes increased infectious exposures from mixing of these domestic and residual displaced wild populations. Brood incubation conditions may be stressful with respect to deficient nutrition, temperature and other basics. This combination of ecological factors, especially the host factor of loss of genetic variation and hybrid vigor, may account for the apparent multifactorial environmental 'causes' of CCD including concurrent infections.
In 2007, one of the patterns reported by the CCD Study Group at Pennsylvania State was that all producers in a preliminary survey noted a period of "extraordinary stress" affecting the colonies in question prior to their die-off, most commonly involving poor nutrition and/or drought. This was the only factor that all of the cases of CCD had in common in the report; accordingly, there appeared to be at least some significant possibility that the phenomenon was correlated to nutritional stress that may not manifest in healthy, well-nourished colonies. This was similar to the findings of another independent survey done in 2007 in which small-scale beekeeping operations (up to 500 colonies) in several states reported their belief that malnutrition and/or weak colonies was the factor responsible for their bees dying in over 50% of the cases, whether the losses were believed to be due to CCD or not.
Some researchers have attributed the syndrome to the practice of feeding high-fructose corn syrup (HFCS) to supplement winter stores. The variability of HFCS may be relevant to the apparent inconsistencies of results. One European writer has suggested a possible connection with HFCS produced from genetically modified corn. If this were the sole factor involved, however, this should also lead to the exclusive appearance of CCD in wintering colonies being fed HFCS, but many reports of CCD occur in other contexts with beekeepers who do not use HFCS.
Other researchers state that colony collapse disorder is mainly a problem of feeding the bees a monoculture diet when they should receive food from a variety of sources/plants. In winter, the bees are given a single food source such as corn syrup (high-fructose or other), sugar and pollen substitute. In summer, they may only pollinate a single crop (e.g., almonds, cherries, or apples).
A study published in 2010 found that bees that were fed pollen from a variety of different plant species showed signs of having a healthier immune system than those eating pollen from a single species. Bees fed pollen from five species had higher levels of glucose oxidase than bees fed pollen from one species, even if the pollen had a higher protein content. The authors hypothesised that CCD may be linked to a loss of plant diversity.
A 2013 study found that p-coumaric acid, which is normally present in honey, assists bees in detoxifying certain pesticides. Its absence in artificial nutrients fed to bees may therefore contribute to CCD.
Despite considerable discussion on the Internet and in the lay media, there have been few studies published in peer reviewed scientific literature on effects of electromagnetic radiation on honey bees. In 2004, an exploratory study was conducted by investigators at the University of Landau on the non-thermal effects of radio frequency ("RF") on honey bees (Apis mellifera carnica). The investigators did not find any change in behavior due to RF exposure from DECT cordless phone base stations embedded in them, operating at 1880–1900 MHz. In 2006, these same investigators extended this study and this time suggested that the close-range electromagnetic field ("EMF") may reduce the ability of bees to return to their hive; they also noticed a slight reduction in honeycomb weight in treated colonies. In the course of their study, one half of their colonies broke down, including some of their controls which did not have DECT base stations embedded in them. In April 2007, news of this study appeared in various media outlets, beginning with an article in The Independent, which stated that the subject of the study included mobile phones and had related them to CCD. Though cellular phones were implicated by other media reports at the time, they were not covered in the study. Researchers involved have since stated that their research did not include findings on cell phones, or their relationship to CCD, and indicated that the Independent article had misinterpreted their results and created "a horror story".
In October 2011, a review study was published by the Indian government's Ministry of Environment and Forests that looked at 919 peer-reviewed scientific studies investigating impacts of EMF on birds, bees, humans, animals/wildlife, and plants. Only 7 of the 919 studies involved honey bees, and 6 of these claimed negative effects from exposure to EMF radiation, but none specifically demonstrated any link to CCD. The review noted that according to one study, when active mobile phones were kept inside beehives, worker bees stopped coming to the hives after ten days. The same study also found drastic decrease in the egg production of queen bees in these colonies and goes on to claim that "electromagnetic radiation exposure provides a better explanation for Colony Collapse Disorder (CCD) than other theories". In view of evidence from this and several other studies, the review authors concluded: "existing literature shows that the EMRs are interfering with the biological systems in more ways than one" and recommended recognising EMF as a pollutant. However, they also noted that "these studies are not representative of the real life situations or natural levels of EMF exposure. More studies need to be taken up to scientifically establish the link, if any, between the observed abnormalities and disorders in bee hives such as Colony Collapse Disorder (CCD)".
Parasitic phorid fly
While there are many possible causes of this CCD, research has not shown why the workers abandon the hive, one of the key markers of CCD. In January 2012, a researcher discovered Apocephalus borealis larvae, a parasitic fly known to prey on bumble bees and wasps, in the test tube of a dead honey bee believed to have been affected by CCD. Since that time, it has been suggested that the phorid fly may be one of the causes of CCD. The fly lays eggs on the bees' abdomen and they hatch after feeding on the bee. Infected bees act oddly, foraging at night and gathering around lights like moths. Eventually the bee leaves the colony to die. The phorid fly larvae then emerge from the neck of the bee.
Genetically modified crops
There is no data in the scientific literature supporting direct or indirect damage to bees caused by currently approved GM crops engineered to make Bt proteins. For example, in 2008 a meta-analysis of 25 independent studies assessing effects of Bt Cry proteins on honeybee survival (mortality) showed that Bt proteins used in commercialized GE crops to control lepidopteran and coleopteran pests do not negatively impact the survival of honeybee larvae or adults. Additionally, larvae consume only a small percent of their protein from pollen, and there is also a lack of geographic correlation between GM crop locations and regions where CCD occurs.
As of 1 March 2007[update], the Mid-Atlantic Apiculture Research and Extension Consortium (MAAREC) offered the following tentative recommendations for beekeepers noticing the symptoms of CCD:
- Do not combine collapsing colonies with strong colonies.
- When a collapsed colony is found, store the equipment where you can use preventive measures to ensure that bees will not have access to it.
- If you feed your bees sugar syrup, use Fumagillin.
- If you are experiencing colony collapse and see a secondary infection, such as European Foulbrood, treat the colonies with oxytetracycline, not tylosin.
Another proposed remedy for farmers of pollinated crops is simply to switch from using beekeepers to the use of native bees, such as bumble bees and mason bees. Native bees can be helped to establish themselves by providing suitable nesting locations and some additional crops the bees could use to feed from (e.g. when the pollination season of the commercial crops on the farm has ended).
A British beekeeper successfully developed a strain of bees that are resistant to varroa mites. Russian honey bees also resist infestations of varroa mites but are still susceptible to other factors associated with colony collapse disorder, and have detrimental traits that limit their relevance in commercial apiculture.
In the United Kingdom, a national bee database was set up in March 2009 to monitor colony collapse as a result of a 15% reduction in the bee population that had taken place over the previous two years. In particular, the register, funded by the Department for Environment, Food and Rural Affairs and administered by the National Bee Unit, will be used to monitor health trends and help establish whether the honey industry is under threat from supposed colony collapse disorder. Britain's 20,000 beekeepers have been invited to participate. In October 2010, David Aston of the British Beekeepers’ Association stated, ‘We still do not believe CCD is a cause of colony losses in the UK, however we are continuing to experience colony losses, many if not most of which can be explained. The approach being taken in UK beekeeping is to raise the profile of integrated bee health management, in other words identifying and trying to eliminate factors which reduce the health status of a colony. This incorporates increasing the skill level of beekeepers through training and education, raising the profile of habitat destruction and its effect of forage (nectar and pollen) availability, and of course research on the incidence and distribution of diseases and conditions in the UK together with more applied research and development on providing solutions."
The phenomenon is particularly important for crops such as almond growing in California, where honey bees are the predominant pollinator and the crop value in 2006 was $1.5 billion. In 2000, the total U.S. crop value that was wholly dependent on honey bee pollination was estimated to exceed $15 billion.
Honey bees are not native to the Americas, therefore their necessity as pollinators in the U.S. is limited to strictly agricultural/ornamental uses, as no native plants require honey bee pollination, except where concentrated in monoculture situations—where the pollination need is so great at bloom time that pollinators must be concentrated beyond the capacity of native bees (with current technology).
They are responsible for pollination of approximately one third of the United States' crop species, including such species as almonds, peaches, apples, pears, cherries, raspberries, blackberries, cranberries, watermelons, cantaloupes, cucumbers, and strawberries. Many, but not all of these plants, can be (and often are) pollinated by other insects in small holdings in the U.S., including other kinds of bees (e.g., squash bees on cucurbits), but typically not on a commercial scale. While some farmers of a few kinds of native crops do bring in honey bees to help pollinate, none specifically need them, and when honey bees are absent from a region, there is a presumption that native pollinators may reclaim the niche, typically being better adapted to serve those plants (assuming that the plants normally occur in that specific area).
However, even though on a per-individual basis, many other species are actually more efficient at pollinating, on the 30% of crop types where honey bees are used, most native pollinators cannot be mass-utilized as easily or as effectively as honey bees—in many instances they will not visit the plants at all. Beehives can be moved from crop to crop as needed, and the bees will visit many plants in large numbers, compensating via saturation pollination for what they lack in efficiency. The commercial viability of these crops is therefore strongly tied to the beekeeping industry. In China, hand pollination of apple orchards is labor intensive, time consuming, and costly.
A number of documentaries have been produced in which possible causes of CCD have been explored.
- Silence of the Bees (October 2007) is a part of the Nature television series and covers several recent investigative discoveries.
- The 2009 documentary Vanishing of the Bees pointed to neonicotinoid pesticides as being the most likely culprit, though the experts interviewed concede that no firm data yet exists.
- Colony is a 2009 feature length documentary focusing on several beekeepers in the United States coping with colony collapse disorder.
- The 2010 feature length documentary Queen of the Sun: What are the bees telling us? features interviews with beekeepers, scientists, farmers, and philosophers.
- The 2012 documentary, Nicotine Bees, appears to offer substantial anecdotal and scientific proof that the class of neo nicotinoid pesticides are principally responsible for Colony Collapse Disorder.
- More than Honey, a 2012 documentary, examines the relationship between humans and bees and explores the possible causes of CCD.
- Bees and toxic chemicals
- Centre for Integrative Bee Research (CIBER)
- Diseases of the honey bee
- Imidacloprid effects on bee population
- Mid-Atlantic Apiculture Research and Extension Consortium
- Pesticide misuse
- Pesticide toxicity to bees
- Pollinator decline
- Regent (insecticide)
- Vanishing of the Bees
- Oldroyd, Benjamin P. (2007). "What's Killing American Honey Bees?". PLoS Biology 5 (6): e168. doi:10.1371/journal.pbio.0050168. PMC 1892840. PMID 17564497.
- Dennis vanEngelsdorp, Diana Cox-Foster, Maryann Frazier, Nancy Ostiguy, and Jerry Hayes (5 January 2006). "Colony Collapse Disorder Preliminary Report". Mid-Atlantic Apiculture Research and Extension Consortium (MAAREC) – CCD Working Group. p. 22. Retrieved 2007-04-24.
- "Honey Bee Die-Off Alarms Beekeepers, Crop Growers and Researchers". Pennsylvania State University College of Agricultural Sciences. 29 January 2007.
- Gaëlle Dupont, Les abeilles malades de l'homme, Le Monde, 29 August 2007 (French).
- Petra Steinberger (12 March 2007). "Das spurlose Sterben" (in German). sueddeutsche.de. Retrieved 2010-12-31.
- "Minutes of Northern Ireland Assembly". Theyworkforyou.com. 8 June 2009. Retrieved 2010-06-22.
- Spotlight: Protecting the pollinators. Fao.org. Retrieved on 2014-04-12.
- Wines, Michael (28 March 2013). "Mystery Malady Kills More Bees, Heightening Worry on Farms". New York Times. Retrieved 31 March 2013.
- "Multiple causes for colony collapse – report". 3 News NZ. May 3, 2013.
- Robyn M. Underwood and Dennis van Engelsdorp. "Colony Collapse Disorder: Have We Seen This Before?". The Pennsylvania State University, Department of Entomology. Retrieved 2010-05-02.
- Benjamin Lester (7 March 2007). "Mystery of the dying bees". Cosmos Online.
- Dennis vanEngelsdorp, Diana Cox-Foster, Maryann Frazier, Nancy Ostiguy, and Jerry Hayes (5 January 2006). "Colony Collapse Disorder Preliminary Report". Mid-Atlantic Apiculture Research and Extension Consortium (MAAREC) – CCD Working Group. p. 22. Retrieved 2007-04-24.
- [dead link]
- Anonymous (1918). "Strange Behavior". American Bee Journal 58: 353. Retrieved 23 July 2012.
- Anonymous (1919). "Bees leave hive". American Bee Journal 59: 385.
- Mraz, Charles (1965). "The Mystery Disease". Gleanings in Bee Culture 93: 422–424.
- Mraz, Charles (1977). "Disappearing Disease in Mexico". Gleanings in Bee Culture 105: 198.
- Oertel, E. (1965). "Many bee colonies dead of an unknown cause". American Bee Journal 105: 48–49.
- Watanabe, M. (1994). "Pollination worries rise as honey bees decline". Science 265 (5176): 1170. Bibcode:1994Sci...265.1170W. doi:10.1126/science.265.5176.1170. PMID 17787573.
- "Wild bee decline 'catastrophic'". BBC News. 23 April 2008.
- Johnson, Renée (7 January 2010). "Honey Bee Colony Collapse Disorder". Congressional Research Service. Retrieved 2012-05-24.
- "Colony Collapse Disorder Progress Report". United States Department of Agriculture. June 2010. Retrieved 2012-05-24.
- "Discussion of phenomenon of Colony disorder collapse". Canadian Honey Council. 27 January 2007. Archived from the original on 29 July 2007.
- Vanengelsdorp, Dennis; Hayes, Jerry; Underwood, Robyn M.; Pettis, Jeffery (2008). "A Survey of Honey Bee Colony Losses in the U.S., Fall 2007 to Spring 2008". PLoS ONE (Plos One) 3 (12): e4071. doi:10.1371/journal.pone.0004071. PMID 19115015.
- Amy Sahba (29 March 2007). "The mysterious deaths of the honeybees". CNN Money. Retrieved 2007-04-04.
- Van Engelsdorp, D., Underwood, R., Caron, D. Hayes, Jr., J. (2007) An Estimate of Managed Colony Losses in the Winter of 2006–2007: A Report Commissioned by the Apiary Inspectors of America. American Bee Journal.
- "2011 CCD Progress Report", United States Department of Agriculture, Agricultural Research Service. Retrieved on 13 April 2012
- "Why are Europe's bees dying?". BBC News. 20 November 2008.
- Douglas, Ian (8 October 2010). "Study finds causes of Colony Collapse Disorder in bees". The Daily Telegraph (London).
- Benjamin, Alison (2 May 2010). "Fears for crops as shock figures from America show scale of bee catastrophe". The Guardian (London).
- Paul Mga, La mort des abeilles met la planète en danger, Les Echos, 20 August 2007 (French).
- n-tv: Immer weniger Imker – Deutschen Bienen geht es gut Version of 11 May 2007.
- Alison Benjamin (2 May 2010). "Fears for crops as shock figures from America show scale of bee catastrophe | Environment | The Observer". London: Guardian. Retrieved 2010-06-22.
- "Hiver fatal pour la moitié des colonies d'abeilles en Suisse". Radio Télévision Suissse. 22 May 2012. Retrieved 22 May 2012.(French)
- "Colony Collapse Disorder Action Plan" (PDF). USDA. 20 June 2007.
- "CCD Steering Committee, ''Colony Collapse Disorder Progress Report'' (US Department of Agriculture, Washington, DC, 2009)" (PDF). Retrieved 2010-06-22.
- Ratnieks, F. L. W.; Carreck, N. L. (2010). "Clarity on Honey Bee Collapse?". Science 327 (5962): 152–3. Bibcode:2010Sci...327..152R. doi:10.1126/science.1185563. PMID 20056879.
- Vanengelsdorp, D.; Evans, J.; Saegerman, C.; Mullin, C.; Haubruge, E.; Nguyen, B.; Frazier, M.; Frazier, J.; Cox-Foster, D.; Chen, Y.; Underwood, R.; Tarpy, D. R.; Pettis, J. S. (2009). "Colony collapse disorder: a descriptive study". In Brown, Justin. PLoS ONE 4 (8): e6481. Bibcode:2009PLoSO...4.6481V. doi:10.1371/journal.pone.0006481. PMC 2715894. PMID 19649264.
- Dennis vanEngelsdorp, Why are the bees dying?, The Real News Network, 2013.08.04
- Dennis vanEngelsdorp, Stop Selling Bee-Harming Plants, The Real News Network, 2014.02.14
- Neonicotinoid Pesticide Reduces Bumble Bee Colony Growth and Queen Production
- Kelland, Kate (29 March 2012). "Studies show how pesticides make bees lose their way". Reuters. Retrieved 2012-05-24.
- A Common Pesticide Decreases Foraging Success and Survival in Honey Bees
- Tapparo, Andrea; et al. (31 January 2012). "Assessment of the Environmental Exposure of Honeybees to Particulate Matter Containing Neonicotinoid Insecticides Coming from Corn Coated Seeds". Environmental Science and Technology 46 (5): 2592–9. Bibcode:2012EnST...46.2592T. doi:10.1021/es2035152. PMID 22292570. Retrieved 27 March 2013.
- Schneider, Christof W.; et al. (11 January 2012). "RFID Tracking of Sublethal Effects of Two Neonicotinoid Insecticides on the Foraging Behavior of Apis mellifera". In Chaline, Nicolas. PLOS One 7 (1): e30023. Bibcode:2012PLoSO...730023S. doi:10.1371/journal.pone.0030023. PMC 3256199. PMID 22253863. Retrieved 27 March 2013.
- Pettis, Jeffery S.; et al. (February 2012). "Pesticide exposure in honey bees results in increased levels of the gut pathogen Nosema". Naturwissenschaften 99 (2): 153–8. Bibcode:2012NW.....99..153P. doi:10.1007/s00114-011-0881-1. PMC 3264871. PMID 22246149. Retrieved 27 March 2013.
- Krupke, Christian H.; et al. (3 January 2012). "Multiple Routes of Pesticide Exposure for Honey Bees Living Near Agricultural Fields". In Smagghe, Guy. PLOS One 7 (1): e29268. Bibcode:2012PLoSO...729268K. doi:10.1371/journal.pone.0029268. PMC 3250423. PMID 22235278.
- European Food Safety Authority (16 January 2013) "Conclusion on the peer review of the pesticide risk assessment for bees for the active substance clothianidin" EFSA Journal 11(1):3066.
- European Food Safety Authority (2012) "Assessment of the scientific information from the Italian project 'APENET' investigating effects on honeybees of coated maize seeds with some neonicotinoids and fipronil" EFSA Journal 10(6):2792
- Damian Carrington (16 January 2013) "Insecticide 'unacceptable' danger to bees, report finds" The Guardian
- USDA CCD Report
- "Honeybee problem nearing a 'critical point' | Environment | guardian.co.uk". London: Guardian. 13 January 2012. Retrieved 2012-05-24.
- "High Levels of Miticides and Agrochemicals in North American Apiaries: Implications for Honey Bee Health". Plos One. Retrieved 2012-05-24.
- Philipp Mimkes (February 2003). "Französische Regierung verlängert Teilverbot von Gaucho – Bienensterben jetzt auch in Deutschland" (in German). CGB Network.
- Sven Preger (23 November 2003). "Verstummtes Summen – Französische Forscher: Insektizid ist Grund für Bienensterben" (in German). CGB Network.
- "Betrayed and sold out – German bee monitoring – Walter Haefeker, Deutscher Berufs- und Erwerbsimkerbund". 12 August 2000. Retrieved 2007-04-26.
- "Schadet Imidacloprid den Bienen – von Eric Zeissloff" (in German). 2001. Retrieved 2007-04-26.
- "Gaucho – ein Risiko, Studie: Mitschuld des Bayer-Pestizids für Bienensterben (Neues Deutschland)" (in German). 23 November 2003. Retrieved 2007-04-26.
- "Imidaclopride utilisé en enrobage de semences (Gaucho®) et troubles des abeilles – Rapport final – 18 septembre 2003" (PDF) (in French). 18 September 2003. Archived from the original on 30 November 2006. Retrieved 2007-04-26.
- "France: Governmental report claims BAYER's pesticide GAUCHO responsible for bee-deaths Coalition against Bayer-Dangers is calling for a ban". December 2003. Retrieved 2007-04-26.
- "Millions of bees dead – Bayer's Gaucho blamed". 26 November 2003. Retrieved 2007-04-26.
- "Alarm Sounds on Bee-Killing Pesticides (by Julio Godoy)". 2004. Retrieved 2007-05-06.
- Maria Mancilla, Les abeilles sont-elles en train de disparaître?, Rue 89, 29 August 2007 (French).
- "EFSA Scientific Report (2006) 65, 1–110, Conclusion regarding the peer review of the pesticide risk assessment of the active substance fipronil" (PDF). 3 March 2006. Archived from the original on 16 June 2007. Retrieved 2007-04-26.
- RE-REGULATION OF PESTICIDES PBS
- State notes small increase in pesticide use Western Farm Press
- Pesticide Use Reporting California Department of Pesticide Regulation
- Bonmatin JM, Marchand PA, Charvet R, Moineau I, Bengsch ER and Colin ME (29 June 2005). "Quantification of imidacloprid uptake in maize crops". J Agric Food Chem. 53 (13): 5336–41. doi:10.1021/jf0479362. PMID 15969515.
- Rortaisa A, Arnolda G, Halmbm M and Touffet-Briensb F. (2005). "Modes of honeybees exposure to systemic insecticides: estimated amounts of contaminated pollen and nectar consumed by different categories of bees". Apidologie 36 (1): 71–83. doi:10.1051/apido:2004071.
- Bortolotti L, Monanari R, Marcelino J and Porrini P. (2003). "Effects of sub-lethal imidacloprid doses on the homing rate and foraging activity of honey bees". Bulletin of Insectology 56 (1): 63–67.
- Medrzycki P, Monntanari L, Bortolotti L, Sabatinin S and Maini S. "Effects of imidacloprid administered in sub-lethal doses on honey bee behaviour. Laboratory tests". Bulletin of Insectology 56 (1): 59–62.
- Thompson H. (2003). "Behavior effects of pesticides in bees-their potential for use in risk assessment". Ecotoxicology 12 (1/4): 317–30. doi:10.1023/A:1022575315413.
- "Scientists Untangle Multiple Causes of Bee Colony Disorder". Environment News Service. 2009. Retrieved 20 January 2011.
- "Colony Collapse Disorder linked to Fipronil". Retrieved 2010-06-17.
- "No acute mortalities in honey bee colonies (Apis mellifera) after the exposure to sunflower cultures". Retrieved 2010-06-27.
- Sackmann, P; Rabinovich, M; Corley, JC (2001). "Successful removal of German yellowjackets (Hymenoptera: Vespidae) by toxic baiting". Journal of economic entomology 94 (4): 811–6. doi:10.1603/0022-0493-94.4.811. PMID 11561837.
- Whitehorn, Penelope R.; O'Connor, Stephanie; Wackers, Felix L.; Goulson, Dave (29 March 2012). "Neonicotinoid Pesticide Reduces Bumble Bee Colony Growth and Queen Production". Sciencexpress. p. 1. doi:10.1126/science.1215025.
- Lu, Chensheng et al (13 March 2012) In situ replication of honey bee colony collapse disorder Bulletin of Insectology 65 (1), 2012, ISSN 1721-8861, Accessed 7 April 2012
- Henry, Mickaël; Beguin, Maxime; Requier, Fabrice; Rollin, Orianne; Odoux, Jean-François; Aupinel, Pierrick; Aptel, Jean; Tchamitchian, Sylvie et al. (29 March 2012). "A Common Pesticide Decreases Foraging Success and Survival in Honey Bees". Sciencexpress. p. 1. doi:10.1126/science.1215039.
- "Pesticide tied to bee colony collapse | Harvard Gazette". News.harvard.edu. Retrieved 2012-05-24.
- Chensheng Lu, Kenneth M. Warchol, & Richard A. Callahan (2012). "In situ replication of honey bee colony collapse disorder". Bulletin of Insectology 65 (1): 1–8.
- Palmer, Mary J.; et al. (27 March 2013). "Cholinergic pesticides cause mushroom body neuronal inactivation in honeybees". Nature Communications 4: 1634. Bibcode:2013NatCo...4E1634P. doi:10.1038/ncomms2648. Retrieved 31 March 2013.
- Williamson, Sally M.; Geraldine A. Wright (7 February 2013). "Exposure to multiple cholinergic pesticides impairs olfactory learning and memory in honeybees". Journal of Experimental Biology 216 (10): 1799–807. doi:10.1242/jeb.083931. PMC 3641805. PMID 23393272. Retrieved 31 March 2013.
- Scientists Discover Key Molecule Linking Neonicotinoids to Honey Bee Viruses
- Dodd, Scott (30 March 2013). "Bees to EPA: Where's your sting?". Salon. Retrieved 31 March 2013.
- PLOS ONE: Crop Pollination Exposes Honey Bees to Pesticides Which Alters Their Susceptibility to the Gut Pathogen Nosema ceranae
- Warner, Bernhard (19 February 2013). "To Revive Honey Bees, Europe Proposes a Pesticide Ban". Bloomberg BusinessWeek. Retrieved 6 March 2013.
- Carrington, Damian (16 January 2013). "Insecticide 'unacceptable' danger to bees, report finds". The Guardian. Retrieved 9 March 2013.
- Charlotte McDonald-Gibson (29 April 2013). "'Victory for bees' as European Union bans neonicotinoid pesticides blamed for destroying bee population". The Independent. Retrieved 1 May 2013.
- Wozniacka, Gosia (21 March 2013). "Beekeepers sue EPA to ban pesticide, protect bees". Associate Press. Retrieved 22 August 2013.
- Boyle, Alan (2 May 2013). "Pesticides aren't the biggest factor in honeybee die-off, EPA and USDA say". NBC News. Retrieved 22 August 2013.
- "Blumenauer Announces Legislation to Protect Pollinators, Prevent Mass Bee Die-Offs". Blumenauer.house.gov. United States House of Representatives. Retrieved 27 August 2013.
- Sheldon, Mary (3 August 2013). "Pesticides are not what bees need". Lexington Herald-Leader. Retrieved 22 August 2013.
- Haugen, Stephanie (15 August 2013). "Hillsboro bee deaths still a mystery". Portland Leader. Retrieved 27 August 2013.
- Twin Cities garden centers ban pesticide thought to harm bees | Star Tribune
- "Colony Collapse Disorder". Fruit Times (Pennsylvania State University) 26 (1). 23 January 2007.
- "Bee Mites Suppress Bee Immunity, Open Door For Viruses And Bacteria".
- JR Minkel (7 September 2007). "Mysterious Honeybee Disappearance Linked to Rare Virus". Science News (Scientific American). Retrieved 2007-09-07.
- Welsh, Jennifer (7 June 2012) Mites and Virus Team Up to Wipe Out Beehives Live Science, Retrieved 11 June 2012
- Guzmán-Novoa, E., Eccles, L., Calvete, Y., Mcgowan, J., Kelly, P. G., and Correa-Benítez, A. (2009). Varroa destructor is the main culprit for the death and reduced populations of overwintered honey bee (Apis mellifera) colonies in Ontario, Canada. Apodologie. Published online 8 January 2010 at Apidologie
- Dr. Jamie Ellis (16 April 2007). "Colony Collapse Disorder (CCD) in Honey Bees". University of Florida.
- Andrew C. Refkin (7 September 2007). "Virus Is Seen as Suspect in Death of Honeybees". The New York Times. Retrieved 2007-09-07.
- Genomic Study Yields Plausible Cause Of Colony Collapse Disorder at Science Daily on 2009-8-25
- Johnson, R. M.; Evans, J. D.; Robinson, G. E.; Berenbaum, M. R. (2009). "Changes in transcript abundance relating to colony collapse disorder in honey bees (Apis mellifera)". Proceedings of the National Academy of Sciences 106 (35): 14790–5. Bibcode:2009PNAS..10614790J. doi:10.1073/pnas.0906970106. PMC 2736458. PMID 19706391.
- Higes, M; Martin, R; Meana, A (2006). "Nosema ceranae, a new microsporidian parasite in honeybees in Europe". Journal of Invertebrate Pathology 92 (2): 93–5. doi:10.1016/j.jip.2006.02.005. PMID 16574143.
- Asian Parasite Killing Western Bees – Scientist, Planet Ark, SPAIN: 19 July 2007
- Maria Mancilla, Les abeilles sont-elles en train de disparaître?, Rue 89, 29 August 2007 (French)
- Dennis vanEngelsdorp, M.Frazier, and D. Caron (1 March 2007). "Tentative Recommendations for Hives Experiencing CCD" (PDF). Mid-Atlantic Apiculture Research and Extension Consortium.
- Higes, Mariano; Martín-Hernández, Raquel; Garrido-Bailón, Encarna; González-Porto, Amelia V.; García-Palencia, Pilar; Meana, Aranzazu; Del Nozal, María J.; Mayo, R. et al. (2009). "Honeybee colony collapse due to Nosema ceranaein professional apiaries". Environmental Microbiology Reports 1 (2): 110–113. doi:10.1111/j.1758-2229.2009.00014.x. PMID 23765741.
- Cure For Honey Bee Colony Collapse? Science Daily article
- Featherstone, D (2009). "Microbiology: Colony collapse cured?". Nature 458 (7241): 949. Bibcode:2009Natur.458T.949.. doi:10.1038/458949d. PMID 19396099.
- Dr Wolfgang Ritter. "Nosema ceranae – Asiatischer Nosema-Erreger festgestellt—neu verbreitet oder erst jetzt entdeckt?" (in German). Albert-Ludwigs-Universität Freiburg.
- Dr Wolfgang Ritter. "Nosema ceranae – Asian Nosema Disease Vector Confirmed—is this a new infestation or only now discovered?" (in translated into English). Albert Ludwigs University of Freiburg. Archived from the original on 14 February 2007.
- Sabin Russell (26 April 2007). "UCSF scientist tracks down suspect in honeybee deaths". San Francisco Chronicle.
- "Scientists Identify Pathogens That May Be Causing Global Honeybee Deaths" (PDF) (Press release). Edgewood Chemical and Biological Center. 25 April 2007.
- Jia-Rui Chong and Thomas H. Maugh II (26 April 2007). "Experts may have found what's bugging the bees". Los Angeles Times. Retrieved 2010-12-31.
- Seth Borenstein (2 May 2007). "Honeybee Die-Off Threatens Food Supply, The Associated Press (5/2/2007)". Associated Press. Archived from the original on 5 May 2007. Retrieved 2007-05-07.
- Paul Boring (25 April 2007). "Whidbey hives collapse". Whidbey News-Times.
- Chapon, L., M.D. Ellis, and A.L. Szalanski. 2009. Nosema and tracheal mites in the north central region – 2008 survey. Proceedings of the American Bee Research Conference. American Bee Journal 149: 585–586.
- "Population genetics and distribution of ''N. ceranae'' in the United States, University of Arkansas Insect Genetics Lab". Comp.uark.edu. Retrieved 2010-06-22.
- Szalanski, A.L., J. Whitaker, and P. Cappy. 2010. Molecular diagnostics of Nosema ceranae and N. apis from honey bees in New York. Proceedings of the American Bee Research Conference. American Bee Journal 150: 508
- Leal, Walter S.; Bromenshenk, Jerry J.; Henderson, Colin B.; Wick, Charles H.; Stanford, Michael F.; Zulich, Alan W.; Jabbour, Rabih E.; Deshpande, Samir V. et al. (2010). "Iridovirus and Microsporidian Linked to Honey Bee Colony Decline". In Leal, Walter S. PLoS ONE 5 (10): e13181. Bibcode:2010PLoSO...513181B. doi:10.1371/journal.pone.0013181. PMC 2950847. PMID 20949138.
- Johnson, Kirk (6 October 2010). "Honeybee Killer Found by Army and Entomologists". The New York Times.
- Drew Armstrong (7 October 2010). "Bee-Killing Disease May Be Combination Attack, Researchers Say". BusinessWeek. Retrieved 2010-11-21.
- Kirk Johnson (6 October 2010). "Scientists and Soldiers Solve a Bee Mystery". The New York Times. Retrieved 2010-11-21.
- Eban, Katherine (8 October 2010). "What a scientist didn't tell the NY Times on honeybee deaths". Money.cnn.com. Retrieved 2010-11-21.
- Foster, Leonard (1 March 2011). "Interpretation of data underlying the link between CCD and an invertebrate iridescent virus". mcponline.org. Retrieved 2011-01-04.
- Knudsen, Giselle; Chalkley, Robert (14 June 2011). "The Effect of Using an Inappropriate Protein Database for Proteomic Data Analysis". Public Library of Science. Retrieved 2011-06-14.
- Hawthorne DJ, Dively GP (2011). "Killing Them with Kindness? In-Hive Medications May Inhibit Xenobiotic Efflux Transporters and Endanger Honey Bees". In Smagghe, Guy. PLoS ONE 6 (11): e26796. Bibcode:2011PLoSO...6E6796H. doi:10.1371/journal.pone.0026796.
- Berenbaum, Prof. May R. (29 March 2007). "Colony Collapse Disorder and Pollinator Decline". Presentation to Subcommittee on Horticulture and Organic Agriculture, U.S. House of Representatives. The National Academies. Retrieved 2007-10-22., specifically, "Close to 100 crop species in the U.S. rely to some degree on pollination services provided by this one species—collectively, these crops make up approximately 1/3 of the U.S. diet [...] Although economists differ in calculating the exact dollar value of honey bee pollination to American agriculture, virtually all estimates are in the range of billions of dollars".
- Alexi Barrionuevo (27 February 2007). "Honeybees, Gone With the Wind, Leave Crops and Keepers in Peril". New York Times.
- "Levels of polyandry and intracolonial genetic relationships in Apis koschevnikovi – International Bee Research Association". Ibra.org.uk. 21 April 2010. Retrieved 2012-05-24.
- Sponsored by (3 December 2011). "Invasive species: Boom and bust". The Economist. Retrieved 2012-05-24.
- Cooling, Meghan; Hartley, Stephen; Sim, Dalice A.; Lester, Philip J. "The widespread collapse of an invasive species: Argentine ants (Linepithema humile) in New Zealand".
- [dead link]
- Oldroyd BP (2007) What's killing American honey bees? PLoS Biol 5(6):e168. doi:10.1371/journal.pbio.0050168
- Pickert, Kate (12 March 2009). "Postcard from Hughson". Time Magazine. Retrieved 12 December 2009.
- Bee decline linked to falling biodiversity Richard Black, BBC News, 20 January 2010
- Mao W, Schuler M A, Berenbaum M R; Schuler; Berenbaum (2013). "Honey constituents up-regulate detoxification and immunity genes in the western honey bee Apis mellifera". Proceedings of the National Academy of Sciences of the United States of America 110 (29 April 2013): 8842. Bibcode:2013PNAS..110.8842M. doi:10.1073/pnas.1303884110.
- Stever, H. J., Kuhn (2004). How Electromagnetic Exposure can influence Learning Process – Modelling Effects of Electromagnetic Exposure on Learning Processes.
- Harst, W., Kuhn, J., Stever, H. (2006). "Can Electromagnetic Exposure Cause a Change in Behaviour? Studying Possible Non-Thermal Influences on Honey Bees – An Approach within the Framework of Educational Informatics". Acta Systemica 6 (1): 1–6.
- Are mobile phones wiping out our bees? The Independent.
- Eric Sylvers (22 April 2007). "Wireless: Case of the disappearing bees creates a buzz about cellphones". International Herald Tribune.
- Chloe Johnson (22 April 2007). "Researchers: Often-cited study doesn't relate to bee colony collapse". Foster's Online.
- Report on possible impact of communication tower on wildlife birds and bees Ministry of Environment and Forests, GOI 2011
- Sainudeen Sahib, S. (2011). "Impact of mobile phone on the density of Honey Bees" (PDF). Mun. Ent. Zool. Vol. 6, No. 1.
- "Zom-bees? Parasitic fly of bees different from fire-ant attacker". Uaex.edu. 13 January 2012. Retrieved 2012-05-24.
- "A New Threat to Honey Bees, the Parasitic Phorid Fly Apocephalus borealis". Retrieved 2012-09-06.
- "Parasitic fly spotted in honeybees, causes workers to abandon colonies". Retrieved 2012-09-06.
- Duan JJ, Marvier M, Huesing J, Dively G, Huang ZY. 2008. A meta-analysis of effects of Bt crops on honey bees (Hymenoptera: Apidae). PLoS ONE 3:e1415
- Peggy G. Lemaux: Genetically Engineered Plants and Foods: A Scientist's Analysis of the Issues (Part II). Annual Review of Plant Biology Vol. 60: 511–559. available online
- "Alternative Pollinators: Native Bees (Summary)". Attra.ncat.org. 12 October 2011. Retrieved 2012-05-24.
- "Alternative Pollinators: Native Bees". Scribd.com. Retrieved 2012-05-24.
- "Establishing a healthy population of native bees on your land". Conservationinformation.org. Retrieved 2010-06-22.
- Madrigal, Alexis (5 June 2009). "Use of native bees to counter colony collapse disorder". Wired.com. Retrieved 2010-06-22.
- Briton sends bee world abuzz with cure for killer bug. Dailyexpress.co.uk (25 August 2010). Retrieved on 2010-10-19.
- Beekeeper Ron Hoskins breeds 'indestructible bees' in Swindon. Metro.co.uk (24 August 2010). Retrieved on 2010-10-19.
- A+ for British Beekeeper as He Develops Mite-Resistant Strain of Honeybee. Fast Company (24 August 2010). Retrieved on 2010-10-19.
- New Honeybee Breed Key to Combating Colony Collapse Disorder. TreeHugger. Retrieved on 2010-10-19.
- National Bee Database to be set up to monitor colony collapse from Telegraph.com. Retrieved 10 March 2009.
- Morse, R.A.; Calderone, N.W. (2000). "The value of honey ees as pollinators of US crops in 2000" (PDF). Cornell University.
- Tepedino, Vincent J. (April 1981). "The Pollination Efficiency of the Squash Bee (Peponapis pruinosa) and the Honey Bee (Apis mellifera) on Summer Squash (Cucurbita pepo)". Journal of the Kansas Entomological Society 54 (2): 359–77. JSTOR 25084168.
- Partap, Uma Partap and Tej. Pollination of apples in China. 2 September 2005
- Partap, U.M.A., T.E.J. Partap and H.E. Yonghua (2001). "Pollination failure in apple crop and farmers management strategies in Hengduan Mountains, China". Acta Horticulturae (561): 225–230.
- The Silence of Bees (2008)
- "2009 documentary ''Vanishing of the Bees''". Vanishingbees.co.uk – website explores possible causes of CCD. Retrieved 2010-06-22.
- "What Are the Bees Telling Us? | The Story". Queen of the Sun. Retrieved 2012-05-24.
- Pierre Terre Production, 2012, viewable on You Tube
- "More than Honey – about the film". Retrieved 2013-07-28.
- Jacobsen, Rowan (2009). Fruitless fall : the collapse of the honey bee and the coming agricultural crisis. New York: Bloomsbury. ISBN 978-1-59691-537-4.
- Colony Collapse Disorder
- "MYSTERIOUS BEE-HAVIOR". Science 315 (5818): 1473a. 2007. doi:10.1126/science.315.5818.1473a.
- Cox-Foster, Diana; Vanengelsdorp, Dennis (April 2009). "Saving the Honeybee". Scientific American 300 (4): 24. Bibcode:2009SciAm.300d..40C. doi:10.1038/scientificamerican0409-40.
- Renée Johnson (26 March 2007). "Recent Honey Bee Colony Decline" (PDF). Congressional Research Service Testimony given before 110th Congress.
||This article's use of external links may not follow Wikipedia's policies or guidelines. (July 2013)|
- Beediseases Honey bee diseases website by Dr. Guido Cordoni.
- PBS: Silence of the Bees
- CCD – University of Florida
- Colony health – Beeologics
- CCD, USDA Plans, news releases, videos, audios On the Florida Pest Alert site – see entry for 05/06/08
- COLOSS.org website of a worldwide group of researchers collaborating on CCD
- Kim Flottum (3 May 2008). "1.1 Million Bee Colonies Dead This Year..". The Daily Green. p. 1.
- Kevin Berger (29 May 2007). "Who killed the honeybees?". Salon.com.
- Rick Weinzierl (10 May 2007). "Neonicotinoids and Honey Bee Colony Collapse Disorder" 13 (5). Illinois Fruit and Vegetable News.
- Barrionuevo, Alexei (24 April 2007). "Bees Vanish, and Scientists Race for Reasons". New York Times. "subscription required"
- Deborah Zabarenko (22 April 2007). "Vanishing honeybees mystify scientists". Reuters.
- Honey bees in U.S. facing extinction Michael Leidig. Telegraph, 2007-03-03
- "Bee vanishing act baffles keepers". BBC News. 27 February 2007.
- Genaro C. Armas (11 February 2007). "Mystery Ailment Strikes Honeybees". Washington Post.
- "Alarm sounded over bee die-off". Wikinews. 10 February 2007.
- "NHB Funds Research for "Colony Collapse Disorder"". National Honey Board. 5 February 2007. Archived from the original on 6 February 2007.
- "Tiny mite responsible for bee colony deaths". CTV News. 3 March 2010.
- Chensheng Lu, Kenneth M. Warchol, & Richard A. Callahan (2012). "In situ replication of honey bee colony collapse disorder". Bulletin of Insectology 65 (1): 1–8.