Why Are Bees Disappearing?

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Answer by Matan Shelomi, Entomology, Biology, Evolution

I [and pretty much all entomologists on earth] have been getting a lot of questions about the honey bees. "Are they in trouble?" "Why are they disappearing?" "How can I help?" Questions are fine, but what annoys me is when I get answers. "It's obviously GMO's!" "We must ban neonicotinoids!" "How do we stop the corporations that are killing bees?" Ugh. The problem is that journalism requires sensational issues and simple stories, and most people want to find a single answer for each problem. Biology doesn't work that way, however, and the truth cannot be boiled down into a single headline.

I've just heard a great talk by the venerable Dr. May Berenbaum, a wonderful entomologist and effectively the scientific spokesperson about Colony Collapse Disorder (CCD), the technical term for the phenomenon of vanishing bees. So I present here for you the current state of knowledge on CCD: its history, its causes, and what we can do so stop it.

tl;dr summary: CCD does not have one cause. There is no one chemical to ban or one company to censure or one critter to eradicate. Instead, CCD is the product of several factors whose whole is deadlier than the sum of its parts: a perfect storm of biological and cultural issues that are too much for the already genetically weak honeybees to handle. However, honeybees and bees themselves are not going extinct anytime soon.

The History of Honey Bees
Humans have been collecting honey from Apis mellifera, the Western honey bee, for millennia. Native to Europe, Asia, and Africa, the honey bee is a single species of bee that happens to be easily domesticated, not only for honey production at but also to pollinate crops. There is another honey bee, Apis cerana, native to Asia, but A. mellifera is the more common species worldwide. European honey bees were imported to the United States a few centuries ago, where they adapted well to the local plants. Without bees, certain crops (most notably almonds) could not be produced.

Beekeeping is not easy, however. Like all animals, bees get sick, and like all farmers, beekeepers will do whatever is necessary to keep their bees healthy and cure or prevent any problems. The biggest bee problem was foulbrood, a bacterial disease where the larvae (baby bees) turn into a disgusting, brown goop. To keep their baby bees from liquifying, beekeepers began to use antibiotics. There's also a fungus called Nosema that can destroy entire colonies, so beekeepers began using fungicides. The worst is the Varroa mite, Varroa destructor, an arachnid that attaches to the outside of bees and sucks their blood. That's bad enough (hence their name: destructor), but it gets worse. These wounds can become infected by bacteria, fungi, and viruses, including Deformed Wing Virus (DWV) which is actually spread by the Varroa mite. Varroa mites were accidentally brought into the US in 1987 from an Asiatic A. cerana, and have spread to most of the world (except Australia... for now). To control it, beekeepers began spraying the hives with miticides too.

Beekeeping practice also changed remarkably in the past century. Beekeepers realized the market for pollination, and began to transport their hives around the country following the crop seasons, first by rail and then by truck. The demand for bees was higher than the supply, however. In the USA, the Almond Board successfully lobbied Congress to allow the importation of bees from Australia, which was illegal at the time to prevent the importation of foreign bee diseases. As the world changed and more wild land was converted to agricultural land, then agricultural land to urban land, the amount of food for bees decreased. The natural diet of bees is honey and bee bread, which is fermented pollen. Fewer wild flowers meant less natural food for the bees, requiring other sources. To keep their bees alive, beekeepers started feeding sugar solutions to bees, including high fructose corn syrup.

Enter Colony Collapse Disorder
In 2006, many beekeepers across the USA began to report high losses of bees. Not deaths, but losses: the worker bees would just vanish, leaving the queen and brood behind. This is very unusual: honey bees don't leave their home and family behind like that. With the workers gone, the hive soon followed. It soon became evident that this was a nationwide problem, and one that eventually spread to Europe too. Because of the immense importance of bees in agriculture, groups from all over the US worked together, and solving the case of "Colony Collapse Disorder" became a priority.

Almost immediately, people found scapegoats. Organizations that were against genetically modified organisms blamed GMOs. Organizations that were against the government blamed the government. Contrail conspiracy theorists said the government was spraying things. Alien abduction activists said aliens were taking the bees. Some people blamed cell phones. Some blamed Osama bin Laden. One theory was that the US government was using soviet mind control technology against Americans to raise support for the Iraq War, and the American bees were also affected because Russian bees were not affected. All of these accusations came with calls for research to prove their "theories," though I doubt anyone who rushed to judgement like that would accept evidence that proved them wrong. Indeed, every claim mentioned above, from GMOs to cell phones, is wrong. We know for a fact that CCD is not caused by GMOs, cell phones, aliens, vehicle grilles, UV lights, EM radiation, terrorists, communists, capitalists, etc. We have no evidence for those theories (and ample evidence against some of them), and neither do the people who promote them. [Hint: If a website is claiming to show you the "real news" or the "facts they don't want you to know," it is almost certainly unreliable]. So what does the research actually say?

The Research
Coincidentally, a few months before CCD was described, the honey bee genome was published. So scientists used this new information to try and find a cause. They compared the genes of healthy bees and those left in collapsed hives to see what was different. What they found was not in the honey bee genome itself, but in a hitch-hiker attached to the genome: a virus. Specifically, the Israeli Acute Paralysis Virus (IAPV), which was found in collapsed hives more than in healthy ones. Though discovered in Israel (hence the name), the virus was thought to have entered the US via Australian bees: the ones we imported despite laws that were designed for the very purpose of preventing bee disease importation. So, had we done it? Was IAPV the cause of CCD?

No. It's true that Australian bees had IAPV... but they didn't have CCD. Australian hives were not collapsing. The nail in the coffin was when DNA tests on frozen bee specimens from the 1950's showed that American bees also had IAPV, long before we imported bees from Australia. So IAPV is not to blame.

What else did we discover. Some scientists looked at the bee microbiome. Like humans, bees have bacteria and other microbes living in their gut that help them digest food and do other things. There is a lot of research (and even more hype and pseudoscience) about how human microbiomes affect our health. What does the research say about bee microbes? The results found no differences between the microbes in healthy bees and collapsed bees. No link to CCD here. However, this was the first evidence that showed bees use microbes at all... and these microbes have been resistant to the antibiotics first used on bees for a long time. In 2005, however, a new antibiotic against foulbrood and others was introduced, which may have affected the honey bee microbiome. Also recall that bees depend on certain fungi to ferment pollen into bee bread, which they use as food.

Here is perhaps the biggest finding from the honey bee genome research: Honey bees are naturally lacking in immunity and detoxification genes. Compared to other insects, bees lack many natural defenses! Namely, they have fewer glutathione-S-transferases, carboxylesterases, and cytochrome P450's, which are the proteins animals (including humans) use to break down toxins. Bees eat pollen and honey, which are hardly toxic. In the millions of years of their evolution, they have lost many of these genes for defense, which means all honey bees are naturally weakened against diseases and chemicals.

How do bees survive, then? Well, they do still have a few P450's and other detox genes. Plus, they have a secret weapon: their food. Pollen contains several compounds that upregulate detox and immunization genes. That is, when bees eat pollen-containing food like bee bread or honey, they produce more of the proteins that defend against pathogens and metabolize toxic compounds! Since the natural diet of a bee is honey and bee bread, both of which contain pollen, they still have some defenses. [The same applies for humans, by the way: if you eat healthier food, your immunity improves]

You now know everything you need to figure out what is causing CCD.
I'll give you a hint: it's not one thing. No matter what you are reading, if you find any source that names only one cause for CCD -- a single chemical, a single pesticide, a single company, a single country-- then you should stop trusting that source. On anything. Ever. Science doesn't work that way, and, no, there is no one cause for CCD, nor is there one solution. Anyone who says otherwise is either pushing a certain viewpoint on you or hasn't done there research. Here's the big reveal.

What is causing Colony Collapse Disorder?
Of all the many theories posited, only four seemed likely: the increase in insecticide use since 1895, a pathogen or parasite, immune suppression due to management practices, and a decline in the nutritional adequacy of their diet. So, which one is to blame? All of them.

In 2012 a meta-analysis of the literature and several large scale studies of CCD was done. They could not find a cause of CCD, but did find several indicators that a colony would likely collapse soon. The fungus Nosema was not an indicator: on the contrary, its levels were higher in healthy colonies! Only Varroa and DWV (see above) seemed to be useful indicators, with Varroa being the most important. Recall that there is no Varroa mite in Australia, and no CCD either (though there is Varroa in Asia and New Zealand but no CCD there either). Is the Varroa mite the cause of CCD?

Here's what happens. Imagine a colony is infested with Varroa mites. The beekeeper must use miticides on the hive. Yet mites, unlike bacteria or fungi, are evolutionarily similar to bees. Both are arthropods. The same chemicals that can kill mites can probably kill bees too. While the miticides used today are more toxic to mites than honey bees, no compound that kills mites and is completely harmless to honey bees exists. Nothing in organic or conventional agriculture. There are some non-chemical techniques that can help, but these are more labor intensive and expensive, and beekeepers already work with marginal profits: you don't get into beekeeping for the money! So now the bees are exposed to miticides, often several at once... which overload the P450's. The bee only has a few P450's that can deal with miticides out of the few it can produce at all, so they can't deal with such onslaughts well. A single compound is one thing, but when two or more sprays are used it's too much.

Note that I haven't even brought up pesticides bees might encounter in the field... mostly because those aren't as big a problem. Those neonicotinoids in the news recently, banned in Europe due to public pressure? They are still used in many other countries that do not have CCD. In fact, not a single chemical used on crops-- not neonicotinoids, not Bt (in spray or GMO form), not clothianidin-- none of them have been linked to CCD, nor would we expect them to. Why would a crop spray affect bees more than a hive spray? It makes no sense and, in fact, is not true. Still, it all adds up. A recent study found that 100% of all wax in American beehives today has high levels of pesticides, among other chemicals: You remember the antibiotics and fungicides I mentioned? The same fungicides that kill Nosema may also kill the fungi that turn pollen to bee bread! Even if that isn't a problem, the end result is that hives are loaded with chemicals: even if you ban insecticides on crops, the hives themselves are treated and/or contaminated.

"But not all bees die when you use miticides," you say. Correct! The miticides may be toxic, but they aren't too terrible! The P450's can still handle most of the pesticides... if the bee is healthy. Remember that pollen stimulates the production of P450's, but bees don't have enough pollen in their diet anymore. The aforementioned habitat destruction I mentioned means there is not enough pollen to feed bees. Instead they are given sugar or corn syrup, which does not boost their immunity the way pollen does. To give you an idea of how bad the situation is, beekeepers in France once were alarmed to see blue honey. It turns out their bees were feeding not on flowers, but on sugary waste from an MnM factory nearby, and picking up the blue dyes with the "nectar." Likewise, a beekeeper in New York whose bees were making red honey discovered they were feeding at a Maraschino cherry factory. Without flowers to feed on, bees have poor nutrition. With poor nutrition, they have poor immunity... and when you factor in the stress of being transported across great distances, most of which don't have good food either, you see why bees are getting sick.

"Wait, what about the bees who are fed honey?" you ask. You're right, many beekeepers choose to feed their bees honey instead of corn syrup... or so they think. A major problem today is that most honey sold is not actually honey. Here's the problem: in 2000, America imposed anti-dumping taxes on Chinese honey, which lead to decreases in honey imports from China... and subsequent increases in imports from nations like Malaysia, India, Vietnam, Indonesia, etc. The problem is that those countries have no commercial beehives. How can we import honey from countries that don't produce it? Honey laundering. China was labeling their honey with other nations' stamps to avoid paying taxes! To avoid getting caught, they would use ultrafiltration to remove the pollen from the honey (because we can use the pollen to trace the honey back to its nation of origin) and adulterate the honey with corn syrup. Thus what you see labeled as "honey" may not be honey at all, and even if it was it no longer has pollen, which means it has no health benefits for the bees.

To summarize, CCD happens because bees have a naturally poor immunity to disease and to chemicals, both of which they are exposed to at higher rates and often together, and that immunity is made worse due to poor diet and stressful conditions. There is no one cause, nor is there one solution.

What Can We Do?
First off, let me reassure you that the bees are going to pull through. There is no danger of bees, even just Apis mellifera, going extinct. Wild bees are doing well: only the commercially reared honey bees are vanishing... and the rates of their loss are going down! Different years show different rates of decline, and some have shown upticks in total bee population. For example, the worst year for bees was 2012-2013, with many hives hit by CCD. The reason? That year there was a drought in the midwestern USA, so many flowers the bees otherwise fed on were gone. Poor nutrition and low water combined with a hard lifestyle means the bees are unable to handle the natural and artificial stressors in their environment (the pathogens and pesticides) and more likely to die. In other years the bees do better.

Still, that's no solace for the beekeeper who is losing his/her bees. What can you do to help? Two things. Plant flowers that bees like in your garden, if you have one. Help undo the damage of habitat loss by giving bees a source of food on your property. The second is to support your local beekeeper by buying local honey, if appropriate. Go to a farmers' market or otherwise get the honey from someone raising bees nearby. It will help them out, and you can ensure you are getting real honey and not laundered stuff.

What about the bigger problems? Well, until we find a miticide that's perfectly safe for bees, we will continue using what we have. Varroa mites are part of the problem and must be controlled, even if their solution is yet another part of the problem. As for banning chemicals, that is a terrible idea. Consider neonicotinoids: even if you ban those pesticides as they did in Europe, what then? Farmers will just use the other, older pesticides like pyrethroids, which are more toxic to bees than neonicotinoids! By banning certain pesticides, Europe has likely made their CCD problems much worse. Nice work, hero. If you are looking for public policy angles to pursue, I suggest fighting habitat destruction. That's always a good decision.

Which brings me to the final point. The best thing you can do is stay informed... and that doesn't mean finding one source of information and trusting them blindly. To stay informed means you will always need new information, and are never satisfied. It means always doubting every new news story that pops up, especially if it seems too good to be true or claims to "finally" answer a question. It means don't confuse a conspiracy theory website or an anti-agrotech blog, or even a news report, for actual scientific data. Nor should you trust one scientific paper above all others, especially if it's a single study and not a meta-analysis. Science is ever changing: look at how much our knowledge of bees changed since 2006, how many theories were tested, championed, then abandoned as new evidence came up. Even all I've posted here may one day change (though it's pretty well accepted so far). The story of the honey bees isn't over yet... but I promise it will not have a grand finale or a single climax, but rather will be complex and full of intertwining characters, and the ending, though perhaps not as spectacular, will be much more satisfying.

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