The truth about bees and pesticides
Two researchers tell spiked that green activists have been a little too keen to blame pesticides for the not-so-great bee die-off.
Everybody likes bees. Okay, they can be a bit alarming when you think they might sting you, but otherwise they’re out there, buzzing away, pollinating our crops and making honey (you know, sugar for posh people). God bless them. Sadly, however, an evil German corporation is not only killing them, probably cackling away as the money rolls in, but is also running rings around feeble-minded government departments to ensure it can carry on this war on our little stripy friends.
That, it seems, just about sums up the recent coverage of the problem of ‘colony collapse disorder’ (CCD), a phenomenon that seems to have caused beekeepers to suffer substantial losses in bee numbers. According to the US Department of Agriculture, from October 2006 ‘some beekeepers began reporting losses of 30-90 per cent of their hives. While colony losses are not unexpected during winter weather, the magnitude of loss suffered by some beekeepers was highly unusual.’ The article continues: ‘The main symptom of CCD is simply no or a low number of adult honey bees present but with a live queen and no dead honey bees in the hive. Often there is still honey in the hive, and immature bees (brood) are present.’
Why does this matter, apart from making honey more expensive? Because bees are crucial in pollinating many food crops. So the USDA website notes: ‘Bee pollination is responsible for $15 billion in added crop value, particularly for specialty crops such as almonds and other nuts, berries, fruits, and vegetables. About one mouthful in three in the diet directly or indirectly benefits from honey bee pollination. While there are native pollinators (honey bees came from the Old World with European colonists), honey bees are more prolific and the easiest to manage for the large-scale pollination that US agriculture requires.’
The immediate impact of CCD is to make the pollination of food crops more expensive because more hives are required to pollinate the same amount of crops. But some green activists think this is all a portent of something much worse, namely massive die-offs of honey bees that threaten important chunks of our food supply. And campaigners are pointing the finger at pesticides as the chief culprit.
This mood was reinforced by a study published last week in PLoS One - a peer-reviewed, open-access research source - by researchers at Purdue University in Indiana. The study showed how bees might be exposed to a particular class of insecticides, called neonicotinoids, at higher levels than previously thought.
Neonicotinoids are a relatively new class of pesticides and have a similar action to nicotine - itself a popular pesticide in the past. (Apparently, you can make your own pesticide by soaking tobacco or cigarette butts in water, then spraying the liquid on to your plants.) In recent years, the seeds of major crops like maize and soya have been coated in neonicotinoid pesticides before being planted.
As Christian Krupke, one of the authors of the Purdue report, explained to me, neonicotinoids have a number of advantages: ‘They have relatively low mammalian toxicity - which is good for worker safety - they’re systemic and they’re persistent. So, you have a material that you can put on the seed but that is also expressed in the growing plant. So, you get protection from the very early days of the plant, which is very desirable from the pest-management point of view.’ But Krupke adds that ‘no one has ever disputed that they are extremely toxic to honey bees and other pollinators’.
If they are so deadly to bees, however, then why were they granted a license? Indeed, in some European countries, neonicotinoid use has been suspended for periods of time because of fears about the impact on bees. However, there must have seemed little reason to expect that bees would ever receive a large dose of these insecticides because they are coated on the seeds and inserted directly into the ground. Regulators, says Krupke, no doubt assumed that bees were safe from direct contact. ‘It goes from the planter into the ground and gets covered up. Why would the bee ever come into contact with it? Bees aren’t interested in cornfields, certainly not unplanted ones. Where would the intersection happen?’ That still leaves the possibility that bees may be exposed to sub-lethal doses as they forage around the fully grown plants. What effect, if any, such lower doses have is still a matter of debate.
The interesting twist in the Purdue research is the possibility of another mechanism by which bees may get exposed to larger doses of pesticide. Krupke summarises what they found: ‘Our planters here are what are called “vacuum” or “air” planters. These planters rely on air to move the seeds around. To prevent treated seeds from sticking together, it’s recommended that something – usually talc, though it can be graphite – be added to the mix.’
He continues: ‘That talc comes into contact with the treated seed and then it basically takes some of the seed-coating off.’ Then, when air leaves the machine, it takes the talc with it, blowing it out into the surrounding air and land. ‘That talc has become an insecticide because it becomes so highly toxic. So you have something that is very light, like baby powder, and very mobile and very toxic to insects on a windy, flat, Midwestern plain.’ In short, the machinery is blowing out a fine insecticide power which is ending up on other plants and flowers that bees are interested in, and in large enough quantities to kill those bees.
What we have here is an unintended consequence. In theory, the pesticide should get nowhere near bees. In practice, because of the way it is applied to seeds and the way those seeds are planted, it is being transmitted into the environment in larger quantities than intended. For Krupke, this is part of the learning process in agriculture: ‘We run into this very often in large-scale agriculture: “We didn’t think of that, did we?” And then we have to make a correction. Sometimes the corrections are inconvenient and cost someone money, but I think it’s important to take the long view.’ This problem of toxic talc could be reduced easily enough if the planters were modified or a different, heavier material was used to keep the seeds separate.
So is that it? Is that what has been causing the great honey bee die-off? Pesticides are, in fact, just one possible factor in CCD - if the term CCD is even appropriate. Krupke’s colleague Greg Hunt, the bee expert on the research team, is more forthright. He tells me that the problem of CCD is overblown. ‘It is not clear that the syndrome called “colony collapse disorder” is anything new and whatever it is, it was probably over-reported. Very few honey bee researchers have ever seen these particular symptoms, including myself.’
In fact, the dominant factor in the relatively high rate of bee mortality is likely to be something else entirely: the way in which some parasites that are deadly to bees have switched to attacking honey bees. ‘The annual hive mortality rate has been around 30 per cent nationwide since a time that corresponds roughly to the first finding of Varroa mites and tracheal mites in the US’, Hunt tells me. ‘Before that it was about 10 per cent. Varroa mites switched hosts from Asian honey bees (Apis cerana) to the species we use, Apis mellifera. Now, most bees have sufficient resistance to tracheal mites, but not to Varroa mites. So for the past 20 years we have had high losses, before and after the CCD reports.’
It is the Varroa mites that Hunt describes as ‘public enemy no.1’, a view he thinks most other bee researchers would concur with. This problem may be exacerbated by migratory beekeeping, where beekeepers move their hives to another part of the country in winter to boost productivity and to earn money from pollinating crops. Unfortunately, moving bees around like that has probably aided the spread of Varroa mites, too.
That said, Hunt asks if we really need these pesticides when other anti-pest measures are already in use. ‘Considering that virtually every corn seed in the Midwest is coated with enough clothianidin [a neonicotinide] to kill a colony of tens of thousands of bees, there is a lot of this going into the environment. It is probably impacting insect populations in the Midwest near corn and soybean.’ Given that these crops already have genetic modifications to protect them against pests, Hunt wonders if the additional protection of the pesticide is really necessary.
In short: we have pesticides that are useful in protecting crops, but those pesticides appear to be a factor - but by no means the most important factor - in a significant loss of bees, too. This problem could be mitigated in a number of ways. Modifying the planting machines to produce less toxic talc would be one method. And a more concerted effort to tackle the various bee parasites would help, too. There is no simple, black-and-white answer to this problem.
One thing that definitely won’t help, however, is trying to use this as a morality tale to beat up Big Agriculture. These bee losses are not going to devastate our food supply. They do mean that, until the problem is solved, more bees are going to be needed to allow for such losses, which will make the pollination process more expensive for farmers (and, ultimately, consumers). It’s not the end of the world, but a solution to these bee losses would be very welcome.
Yet this is just the latest problem to be turned into a tale of feeble regulators and rapacious corporations. So, writing for Mother Jones, Tom Philpott argues that German biotech company Bayer essentially managed to sneak its product past the Environmental Protection Agency (EPA) thanks to some dubious research and a great deal of regulatory inertia. There’s a lot at stake: these pesticides are so ubiquitous that they represent an important market for Bayer.
However, in Europe, there have been restrictions placed on neonicotinoids - but many of those restrictions have since been lifted, suggesting that the problem was not as important as first thought or that solutions have been found. If risk-averse Europe, which has run a mile from allowing genetically modified crops to be grown, can still allow most of these compounds to be used, it suggests that the problem is not as significant as Philpott and others would have us believe. In any event, the EPA has already committed to reviewing this entire class of pesticides in 2012.
Rather than this childish view of evil capitalists, murdered bees, downtrodden beekeepers and threatened consumers, it would be far better to do something greens aren’t very keen on: find solutions that give us the advantages of large-scale agriculture without the occasional, unexpected side effects.What's up with the bees?, spiked