OK – here’s part two of an impartial investigation into whether neonicotinoids (neoincs) are harmful to honey bees. I have nothing to gain from a position on either side of this debate and have looked into it with an open mind. If you search the scientific literature there are many papers on the subject but actually very few that claim that these insecticides are not a problem for bees. So what I think I’ll do is take one of these rare papers and see if it makes a solid case in favor of continuing to use neonicotinoids as normal. But first, a little bit about regulation.
Regulation of Neonicotinoids
- In the EU, the three major neonicotinoid pesticides – Bayer’s imidacloprid and clothianidin and Syngenta’s thiamethoxam – were banned for use on flowering crops in December 2013. The ban was temporary and is probably going to be up for evaluation this year.
- Bayer and Syngenta reacted strongly to the 2013 ban, with Syngenta threatening to sue individual EU officials behind the report and warning that the production of key crops would fall by “up to 40%.” But, as shown in the last post, crop yields in France were unaffected by the country’s imidacloprid ban.
- In the US, the EPA has been slow to take action. In Jan 2017, they released a policy that boils down to suggestions for stricter labeling of neonicotinoid products – there is no sign of a ban.
- The chance of the US EPA being able to do very much under the current administration seems pretty remote. In March, the EPA decided not to go ahead with a ban on the pesticide chlorpyrifos, a decision that many suspect is related to the close ties (and funding) between Dow Chemical and the Trump administration. In April the EPA called for suggestions for any regulations that are not needed in order (according to President Trump’s executive order) “to alleviate unnecessary regulatory burdens” on the American people.
So, a lot may be determined in the coming year with a report expected from the European Food Safety Authority (EFSA) and the ongoing changes in the US EPA. With the prospect of deterioration in environmental protection standards (particularly in the US) our choices and actions as consumers become even more important – I’ll cover these in Part 3 (the final part, honest!).
The Case for Neonicotinoids Being Safe for Honey Bees
If you look for evidence that neonicotinoids pose no threat, you will find some material in the form of headlines. A surprising number of these were written by one person: Jon Entine, a journalist (not a scientist) who runs the Genetic Literacy Project. I’m all in favor of education on science, but a quick look at their site will reveal they are more about pushing specific agendas (e.g., in favor of Big Ag and against organic farming) than education. I’ve found a few reports, such as one from Finland’s Neomehi project, but their data is unclear and it has not been published in a science journal. I’ve even found a story book for kids called Toby and The Bees, published by Bayer to highlight the risks that the Varroa mite pose to bees. But I haven’t found much in the line of peer-reviewed scientific literature.
Assessment of Chronic Sublethal Effects of Imidacloprid on Honey Bee Colony Health
This 2015 paper is the best research I can find that claims that the most popular insecticide, imidacloprid, has “negligible effects” on bee health. I’m also picking it because it’s carried out by respected entomologists from the University of Maryland together with an analytical chemist from the EPA and a principal investigator from the USDA Bee Research Lab.
“Given the weight of evidence, chronic exposure to imidacloprid at the higher range of field doses (20 to 100 µg/kg) in pollen of certain treated crops could cause negative impacts on honey bee colony health and reduced overwintering success, but the most likely encountered high range of field doses relevant for seed-treated crops (5 μg/kg) had negligible effects on colony health and are unlikely a sole cause of colony declines.”
Jon Entine was all over the story, with a write up for the Huff Post:
“Independent researchers, publishing in PLOS ONE, politely slammed many past studies that hyped pesticides, neonics in particular, as the likely driving cause of declining bee health.”
“What did they find? Even at the highest dose of pesticide exposure, the researchers found no difference in the performance of the treated and untreated hives.”
If that’s as far as you read, you may be convinced that concern over neonics is unfounded.
But take a look at the key figure in the paper – Fig. 9:
The figure shows percentage survival in honey bee colonies fed a control diet, or food spiked with imidacloprid.
“Pooled over both years, colony survival in March averaged 82.4, 58.8, 47.1 and 52.9% in the control, 5, 20 and 100 μg/kg treatment groups, respectively”
So 82% of the control bees (grey bars) survived until March – that’s about the expected winter loss (18%) for bee colonies. The authors conclude that imidacloprid is harmful at the two higher doses (20 and 100 µg/kg) – this makes sense when you look at the last two bars in each set (blue and brownish) – around 50% survival rate, significantly less than the control group.
The group fed with 5 µg/kg imidacloprid (bright red bars) show about 59% survival into March – 41% winter loss, more than twice the normal rate. Why would they draw the conclusion that doses in this range “had negligible effects on colony health and are unlikely a sole cause of colony declines”?
It comes down to their statistical analysis (p-value) for the 5 µg/kg imidacloprid data – it’s (apparently) not significant at the 95% confidence level. Are we going to wait for the perfect study with 95% significance before taking precautionary measures as the EU has done?
I think the majority of scientists would look at this graph and say that the evidence suggests feeding with 5 μg/kg imidacloprid results in increased winter colony losses. I don’t know anyone who would use the words “negligible effects” or even come close to claiming this.
Even if you reject the data for 5 μg/kg imidacloprid, the authors state that the 20 and 100 μg/kg levels do cause reduced overwintering success (even though Entine, quoted above, reports the exact opposite). As mentioned in the last post, researchers have found concentrations of imidacloprid in pollen at 28 μg/kg (or ppb) and above.
And remember, this is one of the few papers that I found that claim neonicotinoids are safe !
Update: I just came across another paper published in the same journal with the same first author, and found this disclaimer:
“Galen Dively has received financial support for other research or consulting from companies including Syngenta, Monsanto, Bayer CropScience, Dow AgroScience, and Pioneer/DuPont.”
But in the 2015 paper I just discussed they declared “The authors have declared that no competing interests exist.”
A bit of an oversight there.
I’ll conclude on this in part 3 by looking at research on the more subtle effects of neonics, together with some findings beyond neonics and honey bees. And finally, some suggestions for consumer action!