Bees are complicated. So is the on-going conversation about pollinator health.
No doubt you’ve heard some buzz about bees in the media lately. Stories (tending on the more dramatic side) have have even used the phrase “bee-pocalypse” to describe the tragic demise of honey bees. While honey bees have been struggling, it seems the media, as usual, is glossing over a lot of the subtle details to create headlines.
Environmental activists, unsurprisingly, are quick to blame agriculture. Specifically, a class of insecticides called neonicotinoids, or neonics for short. They continue to ignore studies showing neonics have no real effect on bees at realistic doses and that the number of bees is actually increasing.
Out of all the factors affecting bees – and there are a lot of them – scientists put pesticides at the bottom of the list. We do a disservice to bees by scapegoating pesticides for pollinator health problems.
But before we get there, what exactly is happening to bees?
The Role of Pollinators
Aside from disrupting our picnics, bees actually play an important role in helping us produce a lot of our favorite agricultural products. As pollinators, bees move from plant to plant collecting nectar and pollen and fertilizing the plants for reproduction. They’re an absolutely crucial part in the production of many fruits and vegetables, including some of my favorites likes peaches and cantaloupe. In fact, according to the USDA, one-third of the foods Americans eat each day started with a plant that was pollinated by a bee.
No doubt this impact in agriculture and our food is exactly the reason people are so worried about the bees. Bees are kinda a big deal, especially for farmers and agriculture!
In the past decade, honey bee health has been a hot topic due to two distinct problems: Colony Collapse Disorder and higher than usual overwinter losses.
Colony Collapse Disorder & Its Causes
Starting in 2006, beekeepers started to notice a strange phenomenon in their hives. Adult bees were leaving the colony and not returning, only leaving younger bees in a hive. The phenomenon is now referred to as Colony Collapse Disorder, or CCD, and is recognized as a rapid loss of adult bees in a colony. Usually, the adult bees go out to forage for pollen and never return to the hive. Now, one of the cool things about bees is that they can apparently tell when they are sick and they won’t return to the hive, which protects the rest of the colony from getting sick too. Unfortunately,it is then difficult for us to figure out what actually happened to those bees that just never returned.
The general consensus from the scientific community, to the extent there is a consensus about CCD, is that there are multiple things that cause the bees to never return. These include pathogens, parasitic mites, – especially the varroa mite – poor nutrition, pesticide exposure, stress, and loss of habitat. Recent research has even included sunspots and the tobacco ringspot virus.
Colony Collapse Disorder is a new name for an old phenomenon. There are instances of large-scale colony losses dating back to 1868. And then again in 1872, 1906, 1910, and so on. It was previously called autumn collapse, fall dwindle disease, and May disease.
The good news is that we may be on the other side of the cycle. According to Dennis vanEngelsdorp, a researcher in the Department of Entomology at the University of Maryland, there has not been any CCD detected for the past 3 to 4 years.
The number of honeybee colonies is actually increasing now. According the the Food and Agriculture Organization of the United Nations, there were about 50 million honey bee hives in the world in 1960. Today, despite annual winter losses, there are about 80 million honeybee hives worldwide. Honeybee populations are increasing or stable in the U.S., Europe, and Canada.
Overwinter Losses & Its Causes
Like I said before, bees have faced two big issues in the past decade. Colony Collapse Disorder is one, the other are higher than usual over winter losses. Each winter, beekeepers can expect that a certain number of bees will die before spring. According to the USDA, an over winter loss of 18.7% or more is considered “economically unsustainable.”
In the past five years, beekeepers have lost between 21% and 33% of their hives over the winter. Obviously, that’s high enough to be considered economically unsustainable. But beekeepers can recover because bee colonies reproduce fairly quickly. It’s an economic cost, for sure, but there’s no chance honeybees will go extinct from these losses.
Like colony collapse disorder, there is likely a conglomeration of causes for higher than usual overwinter losses.
Chief among these causes is the Varroa destructor. The mite started in Asia and over the last 50 years has managed to spread across the globe. (The Guardian) The presence of the mites allows for viruses, specifically the Deformed Wing Virus (DWV) to spread rapidly among colonies. Unfortunately, if the beekeepers don’t take care to keep the number of mites in the colony down, the hive can suffer significant losses in population.
The Rise of Neonicotinoids
Ok, so we’ve discussed the problems facing bees – high overwintering losses and the phenomenon known as CCD. What’s the connection with insecticides?
In the 1990’s there was a shift in agriculture that most people never even noticed. Farmers started moving away from using organophosphates and pyrethroids as an insecticide, and instead started choosing neonicotinoids to combat pests. Neonicotinoids are now the predominant and mostly commonly used class of insecticides in the United States, Europe, and Australia.
The switch from these older, broad spectrum insecticides to neonicotinoids actually came with a lot of benefits. Neonics are primarily used as seed treatments. (I explained more about why farmers use seed treatments and whether they’re safe here.) As the plant grows, the neonic is taken up into the leaves, roots and stems, and becomes a part of the plant’s internal defense against insect pests. Very little neonic ends up in the flowers. This process has a lot of benefits to both farmers and the environment. Neonics are much safer for mammals, including human farm workers, which is a big plus often overlooked by urban based environmental groups that seem to have rarely even visited a real farm.
With neonics, farmers also need to spray much less, which means there’s less drift and less of these chemicals in the environment. And significantly less pesticide is used. With the introduction of seed treatments, we now use 10 to 20 fold less insecticide than we did previously. (Forbes)
But the Story Doesn’t End There….
As detailed in several other articles (like this one and this one), activist organizations and other special interests have attempted to use questionable research to blame neonicotinoids as the primary cause of CCD and overwintering losses. But the scientific data on this topic is far from conclusive and, quite frankly, some of it just isn’t that good. In fact, the best data available seems to suggest otherwise.
In fact, 8 large-scale field studies – 4 in Canada, 1 in the UK, and 4 in Europe – have concluded there are little no observable effects on honeybees from realistic exposure to neonics. These studies highlight the failure of many other studies: realistic exposure to insecticides.
In one study, the conclusions of which were just released in March of 2015, researchers – including Jeff Pettis of USDA — set out to see whether bees were harmed by the insecticides when using real world exposure rates. To start, the researchers pointed out the lack of scientific data linking these rates to CCD: “To date, no field study has shown that [the neonicotinoid] imidacloprid adversely affects honey bee colony health when directly exposed to field realistic dietary doses.”
For two years, over the course of 12 weeks, the scientists provided the colonies a pollen diet substitute that was either untreated or spiked with imidacloprid. Detailed assessments of the colonies were taken in October, and then again in January, February, and March to assess how the bees did over the winter period.
[W]e conclude that chronic exposure to imidacloprid at the higher range of field doses (20 to 100 μg/kg) in the pollen of certain treated crops could contribute to reduced overwintering success but the most likely encountered field doses of 5 μg/kg, especially relevant for seed-treated crops, have negligible effects on honey bee colony health. Currently there is wide agreement that sublethal exposure to imidacloprid can cause adverse effects on honey bees in laboratory studies but no evidence that this widely used insecticide is the major stressor causing colony declines. Our findings agree with a causal analysis by Staveley et al. that judged neonicotinoid pesticides to be an unlikely sole cause of colony declines.
(Full study here. Emphasis added.) In other words, when honeybees were exposed to doses of the insecticide only found in a laboratory, they found the overall health of the bees was affected. However, when the honeybees were chronically exposed to the most likely encountered field doses, which tend to be much lower than the doses in a lab, the effects on the colony’s health was negligible.
However, that hasn’t stopped activists from claiming otherwise and, unfortunately, their constant campaigning against neonics is having an effect on agencies and governments around the world. Most recently, the EPA announced it was reassessing the use of neonicotinoids and has stopped issuing permits allowing new uses of the insecticides. Other local governments across the country have stopped using these insecticides for landscaping projects.
In her article, The Complicated Story of Colony Losses and Pesticides, bee expert and scientist Kirsten Traynor explains that blaming a certain class of pesticides is faulty logic. She states:
Pesticides do kill hives and I am concerned about their risk to honey bee health, which is incredibly difficult to untangle. However, I firmly believe that beekeepers not actively controlling the mite population lose many more hives to varroa and varroa transmitted viruses than pesticides. Weak from varroa, bees are probably less able to detoxify the pesticides they do encounter.
To reduce colony losses, beekeepers need a mite management strategy and they need to actively monitor infestation levels. Even good beekeepers can lose hives to varroa, especially when other colonies collapse in the vicinity and hitch a ride into your healthy colonies.
In the end, it is frustrating that activists have latched onto the insecticide blame game, because it prohibits us from assessing the problems facing bees properly. While activists and governments attempt to make neonicotinoids a scapegoat, an important tool for agriculture is being threatened at the behest of problematic and questionable scientific conclusions. Whatever the agenda, banning neonicotinoids won’t end the farmer’s need for pest protection; without neonicotinoids, we will inevitably end up using much greater quantities of older, broad spectrum pesticides that are more toxic to humans and considerably worse for the environment – including bees. I think that makes this conundrum important enough that we make sure to get the science right first.
At the end of the day, farmers care about the plight of honey bees, too. As explained, they’re an important piece in producing many of our favorite fruits and vegetables. On a personal level, and especially for fruit growers, beekeepers are people that we work with on a regular basis. Farmers are mindful of this and try to act accordingly. For example, we try to apply pesticides at times of the day when bees are more likely in the hive and not foraging. We also leave buffer strips along fields and other areas to grow up and provide sources of food for the bees.
Like I said, bees are complicated, and there isn’t just one easy answer as to why honey bees are struggling or how we can prevent it from happening in the future. Any other hasty conclusion does a disservice to the pollinators.
russ hendryx says
Many thanks, Amanda. Very thorough, informative and easy to read. I don’t know how you get much else done
Neil Barr says
Yes, this is an interesting area. To help, here is a recent review of the situation in Australia. At the risk of simplifying some serious risk assessment, Australia has neonics, but no varroa mite and no CCD. Beekeepers here are very worried about that mite arriving and much less worried about the neo-nicotinoid insecticides.
Also very intriguing is the finding that the addictive qualities of nicotine are reflected in the neo-nicotinids, such that they may actually attract bees. Its just another twist in a complex issue.