Myths and truths about bees: There is no ‘dangerous decline’ in the global honeybee population – in fact, bee hive populations are rising in North America and globally – and a class of pesticides known as neonicotinoids are not fostering a global pollinator crisis. However, honeybees and perhaps bumble bees do face a range of health threats that are serious cause for worry, and they need to be addressed.
For years, some environmental advocacy groups have been warning of an impending “bee-pocalypse.” Their claim, repeated in press releases and media headlines, is that honeybee populations are rapidly declining–honeybees may soon go extinct, some have claimed–and because bees pollinate much of the food we eat, the world could soon be starving. The prime culprit in this narrative is a relative new class of insecticide known as neonicotinoids, or “neonics,” for short.
It’s a frightening scenario. What are the facts?
Colony Collapse Disorder
The honey bee population did face a temporary challenge in 2006, when some US beekeepers began discovering that their bees had mysteriously abandoned many of their colonies, leaving behind the queen bee, attended by too few, immature worker bees to sustain the colony, yet with ample viable brood and stored food. This phenomenon was dubbed Colony Collapse Disorder (CCD). First genetically modified crops and later neonicotinoid pesticides were fingered as the presumed causal agents.
Scientists dispensed of the GMO argument, as each GM crop is different and there is no plausible explanation why a phenomenon noted in the US would not also show up in other countries using similar modified crops. The focus on neonicotinoids was more complicated. Neonics are a class of systemic pesticide introduced in the early 1990s and popular in the US, Australia, Europe and elsewhere to help corn, soy, cotton and canola farmers. They have been embraced as a less toxic replacement of organophosphate pesticides, which are known to kill bees and wildlife (and have been linked to health problems in workers). Applied to the soil, sprayed on the crop or used as a seed treatment, neonics eventually reach the pollen and nectar, which is ingested by insects, discouraging pests from wrecking havoc on crops. The seed treatment lowers the amount of the neonic used 10 to 20 fold, decreasing the need for open spraying of the plant, a genuine sustainability benefit.
Did the use of pesticides or neonics in particular cause or contribute to CCD? The scientific consensus now firmly says ‘no.’ Upon further investigation, CCD was shown to be a centuries-old, periodic phenomenon that, by other names, has occurred in specific locales, ranging from Egypt to Europe and the British isles to North America. What made CCD’s appearance in the United States stunning and alarming was that episodes were being reported from widely separated states across the continent.
The precise causes of the latest CCD incident remains undetermined. Most likely, the combinations of factors that affect honeybee colony health more generally (discussed below) are involved. But CCD has now come and gone, as it has many times over the centuries. According to the University of Maryland’s Dennis van Engelsdorp (who was part of the team that coined the modern term “CCD”), no case of CCD has been reported from the field for the last five years.
But the direction of the media narrative, like the travel path of a 250,000 ton ocean liner, was established in the late 2000s, and you don’t turn that around very easily. Despite claims to the contrary, bee populations aren’t declining; they’re rising. According to statistics kept by the US Department of Agriculture, Statistics Canada and the UN Food and Agriculture Organization, honeybee populations in the United States, Canada and Europe have been stable or growing for the two decades neonics have been on the market. Furthermore, the worldwide trajectory for bee colonies has been on an upward trajectory for over half a century.
Said simply: Honeybees are not on the verge of extinction or irreversible decline and the world will not face mass starvation. That’s scare rhetoric. As the Washington Post reported in two separate features in 2015–‘Call Off the Bee-pocalypse: U.S. Honeybee Colonies Hit a 20-Year High’ and ‘Believe It of Not, the Bees Are Doing Just Fine’–advocacy group claims amplified in the media are just plan wrong. Here are a few charts that illustrate the trends that overlap the introduction and use of neonics, the central target of anti-chemical environmental groups.
What about overwinter and summer losses?
The spikes in bee losses in some parts the world that were seen a decade ago are now mostly a thing of the past, although because of variances in nature, there will always be one region or another with higher than normal losses.
It is completely normal for beekeepers to lose a percentage of their hives every year, especially in the winter time, due to weather, disease or the exhaustion of stored food supplies. (For that matter, it is entirely normal for the number of bee hives to fluctuate annually as individual beekeepers make decisions about how many colonies they will maintain in light of changing market demand for different types and grades of honey.) However, misrepresentations of over-winter bee losses, or the adding together of winter and summer loss numbers, makes it seem as if the mid-2000s CCD event is ongoing.
Typical wintertime losses were in the neighborhood of 10 to 15 percent before 1987, when the US was hit by the varroa mite, a deadly parasite that decimates hives and vectors in over a dozen viruses and diseases into honeybee hives. Since the varroa infestation began, loses have risen in some years to 30 to 35 percent. But this does not mean that the honeybee population is in fatal decline and certainly does not support the pesticides-as-killer hypothesis.
Over-winter losses are made up each spring, as bees reproduce rapidly. Each queen lays more than 1,000 eggs per day and a worker bee’s lifespan is six weeks in warm weather months. Moreover, beekeepers can split their healthy hives in the spring, adding a new queen bee (purchased for about $25). Soon, as the bees build up from foraging on spring flowers, there are two hives where formerly there was only one. While making up for over-winter losses adds cost and work for beekeepers, this is an economic challenge for beekeepers, and not an economic or ecological crisis.
Honeybee health problems are multi-factorial, with varroa most significant
Some claim that bees are not troubled at all, and that hive numbers are up, implying that all bee problems are behind us. That’s not accurate. Relying solely on hive numbers, instead of percent losses, or actual bee numbers, can be misleading. Splitting a hive in two and buying a new queen does not have to be a sign of true improvement in bee health or numbers. The honeybee industry is coping with the situation, but the problems are real and in need of solutions. A number of bumblebee species also may be in decline, but there is so far no clear indication of a widespread threat, considering that the status of so many species is unknown and little tracking data exists. There is increasing concern that wild bees are in fact taking a hit thanks to competition and, most of all, disease epidemics spread by commercial honey bee populations.
Most scientists cite multiple factors involved in bee health problems. According to the USDA, by far the number one problem is the varroa destructor mite, which the agency calls “the single most detrimental pest of honey bees..”
Since the 1980s, honey bees and beekeepers have had to deal with a host of new pathogens from deformed wing virus to nosema fungi, new parasites such as Varroa mites, pests like small hive beetles, nutrition problems from lack of diversity or availability in pollen and nectar sources, and possible sublethal effects of pesticides. These problems, many of which honey bees might be able to survive if each were the only one, are often hitting in a wide variety of combinations, and weakening and killing honey bee colonies. CCD may even be a result of a combination of two or more of these factors and not necessarily the same factors in the same order in every instance.
The parasite poses unique challenges to beekeepers and scientists. It sucks the bees’ hemolymph’ (blood-equivalent), compromise the bees’ immune system, and vector more than a dozen viruses into bee colonies–making diseases virulent that would normally be easily controllable. Worse, varroa rapidly develop resistance to different mite treatments, making control difficult. Resistance in turn prompts the wide use of bee-toxic mite-control pesticides–the most prevalent chemicals found in beehives—where they accumulate in beeswax. (“In virtually any residue analysis of bee bread or beeswax these days in any country with varroa, the most prevalent toxins are the beekeeper-applied varroacides.”).
A recent study by Purdue University scientists indicates that European honeybees may face a new and more dangerous varroa threat in the near future. Another species–varroa jacobsoni, up to now solely a predator of the Asian honeybee (Apis ceranae)–has demonstrated the ability to switch hosts to the European honeybee (Apis mellifera), just as the varroa destructor mite did 60 years ago. So far, this genetic adaptation of the varroa jacobsoni mite has been observed only in Papua New Guinea. But the varroa destructor scourge also originated in Asia and, thanks to global commerce, spread rapidly to every continent except Australia, sending honeybee populations plummeting and blighting the beekeeping industry worldwide for at least three decades now.
Other pathogens–notably the gut fungus Nosema ceranae–is a major health challenge to honeybee hives today, and recent research by a team led by Kristin Traynor and including Dennis van Engelsdorp and the USDA’s Jeff Pettis has demonstrated that varroa mites are more prevalent in U.S. bee colonies than previously believed. As van Engelsdorp has explained, “We knew that varroa was a problem, but it seems to be an even bigger problem than we first thought. … Moreover, varroa’s ability to spread viruses presents a more dire situation than we suspected.”
Other factors–poor nutrition, stemming from diminishing availability of varied, clean forage; the dwindling genetic diversity of European honeybees; and almost three dozen other parasites, viruses, bacteria and diseases–all make it difficult to sustain health honeybee hives.
Environmental activists focus single-mindedly on pesticides. But, of all the agricultural chemicals detected in honeybee hives–including the miticides beekeepers use to control varroa infestations — neonics are generally among the lowest trace amounts detected.
Statistics compiled by France’s Ministry of Agriculture underscore the multi-factorial sources of bee health problems. The most frequent causes of bee loss reports received were found to be: ‘pathogenic infections’ (diseases)–by far the largest source of which was varroa mites; bad beekeeping practices; starvation; and phytosanitary products. Probable or definite pesticide ‘intoxication’ were among the least frequent loss report causes–and, of course, neonics are only one of many classes of pesticides to which such losses can be attributed.
The French Agriculture Ministry’s statistics point to another neglected source of bee health complications: modern beekeeping practices. The United States is the only nation in the world that annually transports half or more of all its honeybee colonies (60+%) to a single location–California’s Central Valley–where they pollinate the lucrative almond crop. From January through March, bees are trucked in from around the country, and mostly from distant Florida. The bees, which have barely emerged from their winter cluster, are often stressed to the breaking point. Then bees from around North America are mixed with one another, ensuring that a disease that surfaces in one part of the country soon spreads to California and beyond.
These stresses have been highlighted by the USDA and other oversight bodies, and the research, although preliminary, suggests bee management practices are a key health concern. A 2016 paper by a Swiss-Dutch team led by Peter Neumann and Tjeerd Blacquiere maintains that current beekeeping practices interfere with the process of natural selection and are weakening managed honeybees’ resistance to diseases. They specifically point to practices such as combating varroa mites with pesticides and culling drones for varroa control as inhibiting the development by natural selection of bees more resistant to varroa and its infections, as well as to weakening honeybees genetic diversity.
Lab vs. Field: Realistic studies and real-life experience demonstrate pesticides and bees co-exist
Large-scale field studies, mostly focused honeybees but several on bumble bees, all foraging in neonic-treated crops, have been published in the last roughly dozen years. These studies–four in Canada, one in the UK, eight in Europe, most done using Good Lab Practices–have reached a similar conclusion: there is no observable adverse effect on bees at the colony level from field-realistic exposure to neonicotinoid-treated crops.
At least two other recent field-type studies led by scientists sharply critical of the use of neonics support these findings. The studies aimed to document ever more subtle sub-lethal effects on either honey bees or bumble bees foraging in neonic treated crops, including learning, navigation and motor function impairments in individual bees. But both studies also reported no observable adverse effects at the colony level to field-realistic neonic exposure.
Scientists believe this is because the bee hive constitutes what amounts to a super-organism: the various specialized functions of the hives tens of thousands of individual bees endows it with detoxifying and new brood producing capabilities that overpower potential negative impacts on individual insects. In other words, low-level exposures by bees is unlikely to have a serious deleterious effect on bees or overall colony health
These field study findings have been reinforced by at least four reviews of the scientific literature–by J.S. Cresswell et al. (2011); Randy Oliver (2012); Ann Fairbrother et al. (2014. and Carreck & Ratnieks (2014)–all concluding that neonics are unlikely to be responsible for the health challenges plaguing managed bee populations in recent years. The conclusions have been further reinforced by the 2015 University of Maryland/USDA study on the effects of one nemonic pesticide, imidacloprid, on honeybee colony health. That study found negligible effects on colony health from the most likely high range field-relevant neonic exposures encountered by bees in seed-treated crops–again indicating that neonics are unlikely to be a significant cause of bee colony losses.
Real world experience coincides with large-scale field study results. In Australia–aside from Antarctica, it’s Earth’s last varroa-free continent–the government’s authoritative report confirmed that honeybees are thriving despite the widespread and increasing use of neonics in agriculture. In western Canada, honeybees are thriving despite annually pollinating Canada’s 19 million acres of 100 percent neonic-treated canola.
In contrast, almost all of the research purporting to show that neonics are negatively impacting bees were conducted in artificial environments, often in the laboratory in what are called ‘caged-bee’ studies. Most of these studies grossly overdosed bees. Mikael Henry, the French researcher whose study was cited by the EU when it enacted its ban, recently acknowledged, “We have no real clues of what proper, realistic dose you should use in such an experiment,” and, “The dose we have used might overestimate the dose on the field.”
As the “bee-pocalypse” narrative has run up against reports of stable, recovering or even rising honeybee populations, advocacy environmentalists have upped the ante, branding neonics the new DDT and claiming that they are responsible for widespread ecological collapse. The cited foundation for this claim is largely the work of the European IUCN Task Force on Systemic Pesticides. It helped spawn two congressional letters to the EPA–one signed by 60 members of the House, the other by 10 Senators–that prominently cited IUCN findings among the reasons for an immediate ban on neonics.
But the IUCN Task Force’s credibility has been challenged by a scandal now known as “Bee-Gate.” A report in the London Times and numerous other publication quoted a leaked memo from Task Force scientists conspiring to fabricate their studies as part of a “campaign” to have neonics banned.
Wild bees appear fine, but should be monitored as hard evidence scanty
There are no reliable population numbers on wild bees. Data have simply never been collected at that level of detail, in the US or around the world, on the tens of thousands of different wild bee species that exist. Most of these species are usually peculiar to a specific locale and are highly specialized in feeding from and pollinating non-crop plants found there. This paucity of data has opened the door to abundant speculation–and some research–into wild bee health.
Two of the field studies on bees in Europe mentioned above also included experiments on bumble bees and wild bees. Both were led by Swedish researcher Maj Rundloff. The first, conducted in 2015, found no adverse effects on honeybees at the colony level from field-realistic neonic exposure. A separate part of the experiment did note adverse effects from neonic exposure on bumble bees, solitary bees and wild bees. This part of the study, however, was criticized at the time for a lack of robustness due to a very small sample size.
In response, the team attempted to repeat of the same study a year later. That second study confirmed the previous ‘no observable adverse effect’ result for honeybees at the colony level. However, the bumble bee experiment failed, yielding inadequate data, and no results have yet been reported for solitary and wild bees. While inconclusive at best, at least these studies attempted to obtain some actual data about neonics’ effects on wild bees–which is more than another study that has gained widespread attention.
There were reports of a link neonics to adverse impacts on wild bee species in the UK in a study published in 2016. Researchers at the UK’s Center for Ecology and Hydrology correlated patchy sightings of wild bees that amateurs had submitted to a website with the usage pattern of primarily one neonic pesticide. The authors then crunched this data in a model–not made public–and then produced a complicated correlation of large data sets. Most media failed to note that the study collected no actual observational or experimental evidence. Apart from the fact that ‘correlation is not causation,’ no effort was made to account for the numerous other circumstances, including changes in land use, pathogens and other environmental factors that could also have accounted for, or contributed to, the estimates of wild bee population decline that their model produced.
Theoretical models and failed studies notwithstanding, the available data that does exist suggest there is no wild bee crisis. A 2013 study published in the Proceedings of the National Academy of Sciences looked at US native bee populations over a 140-year period. Of the 187 native species analyzed individually, only three declined steeply, likely due to the introduction of a pathogen.
A 2015 study of wild bees’ contribution to crop pollination concluded that only 2% of wild bee species accounted for 80% of all crop pollination attributable to wild bees–and that these 2% of wild bee species, which of course would come into the most extensive contact with neonics–were the most ubiquitous and widespread of wild bees, showing no signs of population decline or endangerment.
Ironically, two recent studies conducted by the Swedish researcher noted above–Maj Rundloff– have demonstrated that managed honeybee hives are one of the primary threats to wild bees, including bumblebees, and other insects. The first study found that honeybees “outcompete wild bees by depleting common resources,” while the second study found that the adverse impact on the surrounding ecosystem is even more widespread: “We demonstrate that honeybee addition depresses the densities of wild insects (bumblebees, solitary bees, hoverflies, marchflies, other flies, and other flying and flower-visiting insects) even in a massive flower resource such as oilseed rape.”
All these factors notwithstanding, many experts studying wild bees are not in panic mode, awaiting more data. According to US Geological Survey’s Sam Droege, one of the foremost authorities on native bees in the U.S., most wild bees appear to be doing fine.
Despite the reassuring evidence about both managed and wild bee populations, and given the critical role that pollinators play in nature and agriculture, the government is wise to continue closely monitoring the bee population in the coming years.
Report compiled by Jon Entine and GLP staff and contributing writers