Neonicotinoids and colony collapse disorder - err on the side of caution, or just a distraction??

The cause of colony collapse disorder (CCD) in honey bees is not yet understood, but even so the European Commission decided on Monday to ban the use of neonicotinoid insecticides starting in December, for at least the next two years.  This past winter was particularly hard on bees in the US, even given the losses over the last 10 years or so since CCD was first described, with 40 to 50 percent and more decline in the bee population around the country, and the EPA is being asked to reconsider the use of these compounds in the US as well.

CCD, the sudden disappearance of worker bees from a beehive or colony, is characterized by little or no build-up of dead bees in or around the affected hives, and by the early death of adult worker bees away from the hive, leaving affected hives populated primarily by young adults.  The queen is usually still there, but without worker bees the colony can't sustain itself, and the remaining bees eventually die.

Varroa mite on honeybee larva;
Wikimedia

It's possible that a build-up of factors causes CCD. Mite and parasite infestation seems to contribute, as do viral infection and the widespread use of pesticides and fungicides, and there's some thought that the stresses involved in frequently moving hives used for pollination of commercial crops might also contribute.  Bees might be able to survive just mites or a viral infection, but if they are already weakened by one or more stressors they are more likely to succumb when more are piled on. 

A third of everything we eat depends on pollinators, so the losses are significant commercially, with the potential to become even more significant.  Many people are becoming increasingly concerned about the impact of CCD on the world food supply.  Just this spring California almond growers have had to scramble to find enough bees to pollinate their crop, after a particularly hard winter for bees, but additional crops worldwide are at risk.   

It was to prevent agricultural losses that the European Commission decided to act. “I pledge to my utmost to ensure that our bees, which are so vital to our ecosystem and contribute over 22 billion Euros [$29 billion] annually to European agriculture, are protected,” said European Union Health Commissioner Tonio Borg.

Do they or don't they?
Neonicotinoids, as we wrote in a recent post, are the newest class of insecticides in use today, and the most widely used.  They affect insect nervous systems, though are less toxic to mammals than older classes of insecticides.  Derived from nicotine and developed 2-3 decades ago, seeds are coated with these compounds and they remain within the plant as it grows, or they are sprayed on fields.

More than 30 studies have demonstrated a connection between bee deaths and neonicotinoid usage.  Two high profile studies determined that they are likely to have a negative effect on bees.  A paper published online in Science March 29, 2012 (Whitehorn et al.) reported growing evidence that neonicotinoids are involved.  Researchers exposed bees in the laboratory to levels of insecticide that mimicked what bees would encounter in the field, and found reduced growth rates and an 85% reduction in new queens produced.

A second paper published in Science at the same time  (Henry et al.) found effects of a sublethal dose of a neonicotinoid on the homing behavior of honeybees.  One of the hallmarks of CCD is that whole hives empty out, suggesting that bees might be disoriented and unable to retrace their flight paths home. 

The definitive role of neonicotinoids in CCD has not been demonstrated, but the evidence seems to be mounting.  Pesticides are at "unprecedented levels" in honeybee colonies, and because neonicotinoids are the most frequently used pesticide today, and are applied on "approximately 75 percent of the acres devoted" to the most important fruit and vegetable crops grown in the US, their role has to be considered. 

On the other hand, these compounds are in widespread use in Canada and Australia, and CCD is not nearly the problem in these countries as it is in the US and Europe, though mites are not a problem in Australia either, so it's impossible to know which essential variable in the CCD equation is missing.  Indeed, a number of studies have not shown a definitive link, or suggest other causes (e.g., this paper reporting that metals in the soil, due to vehicle exhaust, might be the cause.)  

Manufacturers maintain that neonicotinoids are safe if used as directed -- applied to seeds, in small amounts.  They will break down as the plant develops, and no longer be biologically active when pollinators are visiting the plants.  But two nicotinoids have been found in the pollen and nectar of flowers of squash plants after being applied to soil as directed, and they've been found on riverbanks as well, suggesting that the compounds aren't breaking down as supposed.

To some, there is enough evidence of the detrimental effects of neonicotinoids on bees that it is time to ban their use.  Several European countries had already done so before the European Commission banned them through the EU, and the EU ban is welcomed by many.

To others, there is insufficient evidence that these compounds are a core cause of CCD, and this ban is premature and even detrimental because it means that farmers will now have to use older insecticides, whose effects on bees have not been studied.  It's no surprise that neonicotinoid manufacturers lobbied hard against the ban and are among those most vociferously protesting it.

Win-lose or lose-lose?
The New York Times reports that worldwide sales of neonicotinoids is in the billions of dollars.  Bayer CropScience and Syngenta are two European companies that make these compounds.  The Times reports their representatives saying:

“The proposal is based on poor science and ignores a wealth of evidence from the field that these pesticides do not damage the health of bees,” John Atkin, Syngenta’s chief operating officer, said Monday in a statement. “Instead of banning these products, the commission should now take the opportunity to address the real reasons for bee health decline: disease, viruses and loss of habitat and nutrition.”

Bayer CropScience called the commission’s plan “a setback for technology, innovation and sustainability,” and warned of “crop yield losses, reduced food quality and loss of competitiveness for European agriculture.”

The view of the industry, and their interpretation of the science of CCD, and in particular the role of neonicotinoids, is of course colored by their vested interests.  But, the view of the European Commission and agribusiness is also colored by their vested interests.  They just happen to be diametrically opposed to those of the neonicotinoid industry.
 
In all of this, it is rather surprising that something that seemed to have come on suddenly just a few years ago and hence might be expected to have a rather simple, strong cause, is so hard to understand, despite many large, carefully designed studies.  A lot of the evidence we just mentioned would indeed suggest that neonicotinoids really are not the cause, or even a cause, of CCD (whether or not they should be used, based on other considerations).  Erring on the side of caution, which is what the ban is doing, may be risky because of the other costs that entails, but the problem is so serious that any chance of improving it is probably worth taking.  This is another instance of the elusive problem of identifying natural causation, and as so often happens, the evidence is largely statistical and hence difficult to interpret.

As with climate change, this has become not a strictly scientific decision but a political decision driven by business interests.  The science is rather more equivocal than with climate change, but still the approach should be the same.  When the stakes are so high, and perhaps even irreversible, the precautionary principle, erring on the side of caution, should drive decision making.  Which is just what happened with this ban.  Whether or not a two year ban is enough time to pin down the science is certainly a question, but if neonicotinoids might be part of the problem, they should be banned.

Make a bee-line for truly important research!

You may think it's been too cold too long, but this was a really hard winter for honeybees.  Winters take their toll on bees even in a good year, with 5 - 10% mortality, but with the 'colony collapse disorder' (CCD) that has been affecting honeybees since it was first reported after the winter of 2006-7, mortality has risen to 20-30% and more.  If you like to eat, that's already pretty ominous news, since bees fertilize much of our food sources, but a story in The New York Times last week reports that this year 40 to 50% of all hives were wiped out (the accompanying video is worth a look), and no one is sure why.

“They looked so healthy last spring,” said Bill Dahle, 50, who owns Big Sky Honey in Fairview, Mont. “We were so proud of them. Then, about the first of September, they started to fall on their face, to die like crazy. We’ve been doing this 30 years, and we’ve never experienced this kind of loss before.”

This is of course devastating to beekeepers, but it's also going to be devastating to farmers who depend on bees to pollinate their crops -- almonds in California are a huge such crop.  A story at NBCNews.com reports that bee pollination is responsible for $15 billion in increased food value every year, perhaps a quarter of all foods.  And food losses will mean higher prices.  If this keeps getting worse, our own species itself could be in danger of starvation.  So of course we look hopefully to science to explain, and stop, the devastation of our buzzing friends.

According to the US Environmental Protection Agency, and this list of possible causes is fairly standard,

There have been many theories about the cause of CCD, but the researchers who are leading the effort to find out why are now focused on these factors: 

• increased losses due to the invasive varroa mite (a pest of honeybees);
• new or emerging diseases such as Israeli Acute Paralysis virus and the gut parasite Nosema;
• pesticide poisoning through exposure to pesticides applied to crops or for in-hive insect or mite control;
• bee management stress;
• foraging habitat modification
• inadequate forage/poor nutrition and
• potential immune-suppressing stress on bees caused by one or a combination of factors identified above.
• potential immune-suppressing stress on bees caused by one or a combination of factors identified above.

Additional factors may include poor nutrition, drought, and migratory stress brought about by the increased need to move bee colonies long distances to provide pollination services.

These possibilities have been proposed since the onset of CCD, and they are still live possibilities, but most have proven less explanatory than they'd seemed, and they don't explain why this winter was particularly hard.  Perhaps it was the drought in the midwest followed by a hard winter, though some beekeepers are reporting heavy losses despite good summer conditions.  The increase in pesticide resistant mites is another possibility, or viruses.  Or, perhaps it's a number of stressors in combination.

The explanation getting the most play these days is the increasing use of pesticides, fungicides and herbicides, although the EPA says there is no definitive evidence that pesticides are the cause ("To date, we’re aware of no data demonstrating that an EPA-registered pesticide used according to the label instructions has caused CCD."). And indeed, each of the chemicals now used on crops has been certified safe, but are our guardian officials being too lenient?  For example, any given combination may have unforeseen effects, and combinations haven't been tested.  Of particular concern is the only new class of pesticides developed in the last 50 years, neonicotinoids, derived from nicotine and developed in the 1980s and 90s.

A paper published online in Science March 29, 2012 (Whitehorn et al.) reported that neonicotinoids indeed do have a negative effect on bees.

Growing evidence for declines in bee populations has caused great concern because of the valuable ecosystem services they provide. Neonicotinoid insecticides have been implicated in these declines because they occur at trace levels in the nectar and pollen of crop plants. We exposed colonies of the bumble bee Bombus terrestris in the laboratory to field-realistic levels of the neonicotinoidimidacloprid, then allowed them to develop naturally under field conditions. Treated colonies had a significantly reduced growth rate and suffered an 85% reduction in production of new queens compared with control colonies. Given the scale of use of neonicotinoids, we suggest that they may be having a considerable negative impact on wild bumble bee populations across the developed world.

A second paper published in Science at the same time  (Henry et al.) tested the effects of a sublethal dose of a single one of these compounds on the homing behavior of honeybees, suspecting that it might affect the bee's ability to find its way home because of how it affects the insect nervous system.

They are highly potent and selective agonists of nicotinic acetylcholine receptors, which are important excitatory neurotransmitter receptors in insects.  Effects of sublethal neonicotinoid exposures in honey bees may include abnormal foraging activity, reduced olfactory memory and learning performance, and possibly impaired orientation skills.

They found that the neonicotinoid they tested affected forager survival, which may indeed have severe consequences for the survival of the hive.

Neonicotinoids are applied to the seed, and then travel through the sap to all parts of the plant as it grows.  They are said to be less toxic to mammals than other pesticides, and so have been used more liberally.  Because of the suspicion that they may be at least one of the agents responsible for colony collapse disorder, they've been banned in some European countries, and the ban may widen throughout Europe.  Indeed, Whitehorn et al. conclude their paper "...we suggest that there is an urgent need to develop alternatives to the widespread use of neonicotinoid pesticides on flowering crops wherever possible."

Several of these compounds are now under review by the EPA to determine whether they still meet requirements for certification.  If we were to bet, we'd bet they do.  Big agriculture relies heavily on chemicals to grow the food we eat.  Much less of this would be needed in more traditional, smaller-scale less corporately-tied agricultural practices, that many argue could still feed the earth.  Enough said.

Priorities when there's too much on our plate
We are currently pouring research resources into massive but mildly incremental topics like genomic disease and personalized genomic medicine (PGM).  Many, if not all, of these are the common diseases we get after living a long time in a sedate, well-fed (or over-fed) lifestyle.  These diseases are consequences of ease and privilege, and could clearly be  prevented, or greatly delayed, by basically painless changes in how we life.  They are not 'genetic' in any serious sense.  As a result, the payoff of these studies, in most cases, even if things were to work out as promised by PGM's advocates, would with some exceptions be exceedingly not-exceeding.  Indeed, it would be minor.  Minor relative to using the experience of relatives (heritability) rather than individualized genomes, minor relative to the baseline risk, minor relative to environmental exposures, and minor because genomic risk doesn't generally lead to gene-specific treatment.

Meanwhile, we really do have an important problem, one with orders of magnitude more potential for harm if not understood quickly and enormous potential for human good: colony collapse in bees.  A sane research policy would be aimed at solving societal problems in a rational priority order, rather than the vested-interest order that so predominates today.  These areas pale in importance compared to the problem of having adequate food.  That's even more important than climate change, though climate change may be a major threat to agriculture and our food sources as well.

Major problems often turn out to be complex and difficult to solve, and CCD may or may not turn out to be simple.  But it is an example, along with others like antibody resistance and overpopulation that are huge threats to our essential well-being.  Why aren't we pulling funds from what is sexy and media-exploitable research, but is entrenched and in many ways about problems of privilege, to areas that are much closer to the nitty-gritty of our very survival?