New study just out states:
> A significant correlation was found between the presence of fungicide residues and honeybee colony disorders. A significant positive link could also be established between the observation of disorder and the abundance of crop surface around the beehive. According to our results, the role of fungicides as a potential stressor for honeybee colonies should be further studied, either by their direct and/or indirect impacts on bees and bee colonies.
Citation: Simon-Delso N, San Martin G, Bruneau E, Minsart L-A, Mouret C, et al. (2014) Honeybee Colony Disorder in Crop Areas: The Role of Pesticides and Viruses. PLoS ONE 9(7): e103073
This has been an ongoing topic on Bee-L, but has been eclipsed by the anxiety over neonics. Here are some highlights of the discussion, going back ten years:
Sun, 20 Apr 2014 18:56:36 -0400
> Despite those on BEE-L which say there are not problems in beekeeping today other than what has been throughout history
I don't know anyone who fits this description. The world is constantly changing; new and unexpected challenges face us every day. However, very early on several of us pointed out that neonics are far safer than older formulations, and that all the attention being paid them was a distraction from several other problems, which were potentially far more serious.
Early on, we were raising the flag about the non-systemic foliar spraying of chemicals that are presumed to be non-lethal to bees, namely fungicides, antibiotics and the various adjuvants that radically increase the effects of some of these toxins. In fact, many pesticides are tested alone even though the eventual formulation is known to be far more toxic due to the actions of "non-toxic inerts."
Two years ago this was published:
The almond pollination in the Central Valley of California is the single largest pollination event in the world. Agrochemicals applied to these almond trees are therefore likely to have the greatest impact on honey bee health relative to other cropping systems. Furthermore, some pesticides – especially fungicides – are applied to almonds while the flowers are in bloom. Given that foragers visit open flowers to collect pollen and nectar, this scenario represents the greatest potential hazard to foraging honey bees in terms of exposure to agrochemicals.
We have demonstrated here, for the first time, that agricultural spray adjuvants – and organosilicone surfactants in particular – do indeed cause significant learning impairment when ingested by honey bees. Their perceived status as ‘inert’ materials that can do no harm to biological organisms should be reconsidered. Field tests will need to be conducted to confirm these results on a colony-level, as events in the laboratory do not always translate to an organism’s natural setting.
Ciarlo, Timothy J., et al. "Learning impairment in honey bees caused by agricultural spray adjuvants." PloS one 7.7 (2012): e40848.
More recent work by Chris Mullin and James Frazier shines the spotlight on the interaction between commonly used miticides which are present in combs, and the fungicide chlorothalonil.
Recently, the widespread distribution of pesticides detected in the hive has raised serious concerns about pesticide exposure on honey bee (Apis mellifera L.) health. A larval rearing method was adapted to assess the chronic oral toxicity to honey bee larvae of the four most common pesticides detected in pollen and wax - fluvalinate, coumaphos, chlorothalonil, and chloropyrifos - tested alone and in all combinations. All pesticides at hive-residue levels triggered a significant increase in larval mortality compared to untreated larvae by over two fold, with a strong increase after 3 days of exposure.
The current study demonstrates the chronic oral and mixture toxicity of common pesticides at hive levels to honey bees at the larval stage. Most notable are the chronic larval toxicities of the fungicide chlorothalonil and its synergistic combinations with frequently used in-hive miticides, and the unexpected high toxicity of the formulation ingredient N-methyl-2-pyrrolidone. Considering the extensive detection of chlorothalonil and its coexistence with other pesticides in diverse combinations especially in hive pollen and wax, and its substantial larval toxicity alone and in mixtures shown here, the application of this and other fungicides during crop bloom cannot be presumed innocuous to pollinating honey bees.
Zhu, W., Schmehl, D. R., Mullin, C. A., & Frazier, J. L. (2014). Four Common Pesticides, Their Mixtures and a Formulation Solvent in the Hive Environment Have High Oral Toxicity to Honey Bee Larvae. PloS one, 9(1), e77547.
If you are still reading, I would add a bit about organosilicone surfactants:
Organosilicates are not exactly new; they were developed in the 1970s, and have many uses including silicone-based sprays for waterproofing. About 10 years ago, their use as spray adjuvants for crop production was discovered. Some research suggests that the wetting properties of these surfactants are so good that they can also allow bacteria and fungi to more easily invade plants (via stomata).
[while this does not mention insects specifically, the last sentence about allowing bacteria and fungi to penetrate is most troubling]
PLB
* * *
Mon, 16 Feb 2004 17:15:03 +1300
What's the deal with these fungicides? The manufactures don't give any label
warnings for bee kill but they sure blow a few over. I'm talking about
Antracol and also Manzate with one grower mixed with Bond Extra as the
sticker (surfactant).
I got the grower to not apply the sticker but he still got a good kill
spraying in the daytime. He agreed to not spray after that.
I warned another grower of these problems so he sprayed Antracol at 4 am to
get it dried by the time bees flew but when I were there at 2 pm the bees
were dropping out of the sky dead and dying in front of the hive. He agreed
not to spray any more.
Another grower sprayed Antracol in the evenings after bee flying times and I
never saw any bee kill but the hives did no good.
Why no warnings on the label? Is it up to me to sort these fungicide
manufacturers out? The growers had no warning of the damage they were
inflicting and if I hadn't stopped them they would have put their own crops
in even more risk.
* * *
Hi Kevin,
I dont know which fungicides are being used in the almonds here.I have
seen some dead bees in front of the hives,but so far havent seen any
substantial bee kills.Captan is probably the worst from what I hear,but
may be banned.The problem here is that several types of fungus can do
severe damage to the almond bloom,and in a wet Feb(like this one may
be)the growers feel they have to spray during every break in the
weather.Its a trade off .The trees arent going to have much bee activity
right after spraying,and I think the growers know it.Anyone pollinating
almonds should be aware that some bees will be killed by fungicides ,and
decide if they can tolerate the loss.
---Mike(watching the rain pour down and the creeks rising)
* * *
Are you sure it is the fungicide that is killing the bees? There is a
published paper from New Zealand that shows that wetting agents will kill
bees. So if they are putting wetting agent in the fungicide that could be
the problem.
Trevor Weatherhead
AUSTRALIA
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