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Neonicotinoid adversely affects insect immunity and promotes replication of a viral pathogen


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Neonicotinoid clothianidin adversely affects insect immunity and promotes replication of a viral pathogen in honey bees

 

Authors: Gennaro Di Prisco, Valeria Cavaliere, Desiderato Annoscia, Paola Varricchio, Emilio Caprio, Francesco Nazzic, Giuseppe Gargiulo, and Francesco Pennacchio

 

Significance

 

Honey bees are exposed to a wealth of synergistically inter- acting stress factors, which may induce colony losses often associated with high infection levels of pathogens. Neon- icotinoid insecticides have been reported to enhance the im- pact of pathogens, but the underlying immune alteration is still obscure. In this study we describe the molecular mechanism through which clothianidin adversely affects the insect im- mune response and promotes replication of a viral pathogen in honey bees bearing covert infections. Our results shed light on a further level of regulation of the immune response in insects and have implications for bee conservation.

 

For full paper: Neonicotinoid clothianidin adversely affects insect immunity and promotes replication of a viral pathogen in honey bees

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let's hope the research stands up in court.

does anyone here experience problems near tree nurseries?

does anyone have information on use of neonics in nurseries?

apparently they also use a lot of fungicides and the combo with neonics is specially bad.

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Neonicotinoid clothianidin adversely affects insect immunity and promotes replication of a viral pathogen in honey bees

 

Gee that's a difficult paper Otto. Can you help out here!

 

From what I get from the paper part of the immune response producing defensive proteins requires NF-kB signaling, this is affected by an LRR gene which is impaired during an immune challenge like inoculation with a yeast.

 

A gene in a fly looks similar to one in a human T-Cell (known to be involved in this kind of immune response) and behaves in the same way when challenged by a yeast. The fly gene is therefore thought to be a remnant functionally similar to the more complex vertebrate one and they propose that it is one of these LRR genes

 

By then using a transgenic variant of the fly species that produces a fluorescent protein by the same pathway and exposing the transgenic fly to the neonicotinoid clothainidin they observed a diminution of the fluorescing protein when inoculated with a yeast. They conclude it was because the pathway and the signaling that controls it was impaired by the clothianidin. Why wasn't it because the yeast impaired the LRR gene? The yeast and clothainidin seem to have the same effect?

 

In the honey bee the antimicrobial protein Apidaecin was used as the indicator and they found quantity of the protein was lower upon exposure to example of two different neonicotinoids, but not for some reason to an organophosphate. At the same time they observed an increase in the activity of a particular gene which looked similar to the fly gene. The honey bee gene must therefore also be an LRR gene.

 

Because the signaling affects a pathway that produces a wide variety of products they propose that this mechanism will have quite widespread effects on the response of a honey bee (including multiple symptoms with a single cause). I don't understand why they would predict that one of these effects would increase viral replication. I don't know what they mean exactly by 'stress'(why DWV causes 'stress' and why the LRR gene and NF-kB signaling should be affected by it). I can see that it might render a bee more vulnerable to gut pathogens (nosema).

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I was sent this yesterday - had a brief read and took the following points from it:

- the viral pathogen they measured/quantified was Deformed Wing Virus (DWV)

 

I don't understand why they would predict that one of these effects would increase viral replication. I don't know what they mean exactly by 'stress'(why DWV causes 'stress' and why the LRR gene and NF-kB signaling should be affected by it). I can see that it might render a bee more vulnerable to gut pathogens (nosema).

 

- whether or not they predicted it prior to their finding, upon challenging lightly infected bees with different dose levels of clothianidin or imidacloprid, the levels of DWV rose in proportion to the amount of neonic. Not so with an organophosphate

 

- to me it meant the 'control varroa, control the viruses' wasn't the whole story - other agents (viral strain, neonics, other stressors?) are affecting viral levels/hive mortality

 

- this may explain why we detect low levels of DWV in many samples but they don't go on to show any issues - until they get 'another hit' from a neonic. It may also explain the rather low levels of Nosema seen to date, Dave. Why do you think this would make bees more vulnerable to gut pathogens rather than viruses?

 

Hope @@Otto will fill in the (many) gaps! ;) Or I could read it more carefully . . .

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Dave. Why do you think this would make bees more vulnerable to gut pathogens rather than viruses?. .

It's not that it think one is more likely than the other, just that have explained the former more clearly than the later. They explain this possibility this way; "...insecticide-induced alteration of the innate immune response may also influence gut microbial pathogens. Indeed, innate immunity in the gut epithelia of Drosophila actively controls gut-microbe homeostasis through a subtle modulation of NF-kB signaling." so there is a clear mechanism proposed. As far as DWV was concerned this was the relevant part; "based on our recently proposed honey bee stress model and the observed negative impact of clothainidin on NF-kB activation, it is possible to predict that this insecticide may promote the replication of DWV..." I guess when I hear a paper invoke 'stress' (unqualified) it immediately makes me wonder, and why it should be part of a prediction about virus replication (rather than innoculation) isn't clear to me. I take your point about the dose related effect they observed, maybe it doesn't matter how they formed the working hypothesis.

 

I could read it more carefully... ;)

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"I could read it more carefully... ;)

 

and please don't forget to report back to us.

i won't even bother trying to read this. blessed are the simple minded - or something like that.

but i would like to know if there is some real substance to this.

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This paper is looking at the role neonicotinoids have in ######ing up the immune responses of insects. The authors have shown that neonics cause changes in gene expression that negatively impact the ability of bees to mount an effective immune response, therefore making them more susceptible to viruses if they've been exposed to these insecticides.

 

I don't understand why they would predict that one of these effects would increase viral replication.

 

They've shown that neonics have a negative effect on the bees ability to mount an immune response. It is probably important to point out that we're talking about an immune response similar to our own innate immunity. This is a non-specific immune response to something foreign (like a virus, bacteria, toxin...). Impaired innate immunity would likely result in higher susceptibility to any of these things. The next step is to actually show knock-on effects of this. Looking at the effects of neonics on the ability of a virus to replicate is trying to prove there model that neonics impair immunity. I would expect that if they looked at gut pathogens like Nosema they'd get similar results. I assume DWV was easier for them to look at and quantify.

 

Main conclusion: For bees, exposure to sub-lethal amounts of neonics could have serious consequences for their ability to cope with subsequent challenges by pathogens such as DWV (and Nosema etc).

 

Let's say their hypothesis and conclusions are correct. They would have proved that insecticide can be harmful to an insect, in this case bees.

 

No surprises there.

 

This is a little short-sighted. We're trying to develop an understanding of how different factors affect the health of a bee colony. Of course an insecticide is harmful to an insect. Unfortunately we don't necessarily know exactly how all insecticides work and what all the negative consequences might be. We know neonics primary mode of action is on the nervous system but the links between this and knock-on effects on the immune system had yet to be explored.

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. We know neonics primary mode of action is on the nervous system but the links between this and knock-on effects on the immune system had yet to be explored.

 

i hope they "explored"that for humans before they've let it loose on us.

thanks very much for your clarifications, Otto.

great to have guys like you on the forum. and Dave, John and Alastair amongst others.

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Let's say their hypothesis and conclusions are correct. They would have proved that insecticide can be harmful to an insect, in this case bees.

 

No surprises there.

 

I think the interesting part of this Alastair is the challenges for the companies. Eg if they were testing Confidor, it's likely on healthy hives. Perhaps little effect as the companies claim. But the immune response knocked down and viral infection could be the middle ground for those claiming neonics the devil's brew vs companies suing the EU. !

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i'm not a scientist nor do i claim to be objective.

but the change that bee health has experienced in the small little area i keep my bees is significant and has happened in the last few years and there doesn't seem to be a varroa related pattern really.

 

- to me it meant the 'control varroa, control the viruses' wasn't the whole story - other agents (viral strain, neonics, other stressors?) are affecting viral levels/hive mortality

 

i think that article of bayer how they described neonics to deal to termites says it all really.

 

does anyone here know if native trees that you buy in nurseries are also neonic treated and how long would the nics still "leak out" into nectar and pollen after planting?

do we actually know the main sources for bee contamination by neonic here in nz?

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Almost as a counter-point this study was published yesterday. To keep @@Alastair 'on-side' ;) the discussion(conclusion) begins "Neonicotinoids are insecticides and as such are toxic to bees..."

 

These field trials ended in 2010 so it seems to take a long time to publish but there we go. They concluded that no effect was observed either of thiamethoxam or of the metabolite clothianidin and the hive losses were a maximum of 2.7 for 60 colonies during the four years. Essentially, in a 'field-relevant' situation the 'dose' was too small to be detrimental.

 

I was surprised at the rate of queen loss I must say, and that they had no comment to make about it.

 

Pilling E, Campbell P, Coulson M, Ruddle N, Tornier I (2013) A Four Year Field Program Investigating Long-Term Effects of Repeated Exposure of Honey Bee colonies to Flowering Crops Treated with Thiamethoxam. PLoS ONE 8(10): e77193. doi:10.1371/journal.pone.0077193

 

No one needs to write to me and tell me the authors are employed by the patent holder for thiamethoxam Syngenta either. Just saying.

 

do we actually know the main sources for bee contamination by neonic here in nz?

Do you have evidence that there is any?

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I think the interesting part of this Alastair is the challenges for the companies.

That is an interesting angle. So if I'm a farmer/grower using a 'nic and your bees invade my property from afar commiting suicide using my pesticide do I threaten you with trespass or theft! :)

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Almost as a counter-point this study was published yesterday. To keep @@Alastair

 

 

Do you have evidence that there is any?

 

are you asking me this seriously or rhetoric?

 

what wanders me a bit is how anyone can even set up a conclusive trial on nics these days.

from my understanding you need test colonies not effected by nics, but no one even knows whats around him and what might be stored in his hives. the stuff seems to be just everywhere and no one even knows about it.

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Best not to get into too much 'wandering"! Do what everyone else does ie concentrate on making money & having fun however you can & accept that we exist in an increasingly toxic bubble in the universe. Let the next generation sort it !

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are you asking me this seriously or rhetoric?

 

what wanders me a bit is how anyone can even set up a conclusive trial on nics these days.

from my understanding you need test colonies not effected by nics, but no one even knows whats around him and what might be stored in his hives. the stuff seems to be just everywhere and no one even knows about it.

It wouldn't be too hard, that's why you set up control colonies to test. There are practical difficulties setting up and maintaining pertinent 'real world' trials but that isn't one of them. Nor is it the case that the 'stuff' is everywhere and no one knows'. Unless you are assuming there is a conspiracy to hide it all we pretty much know what is available to use, what crops it is used on, and who is applying it (apart from the odd gardener). As to 'conclusive', is applied science ever conclusive? The point is that it is always there to be re-evaluated.

 

And no my question wasn't rhetorical.

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do we actually know the main sources for bee contamination by neonic here in nz?

 

i think this is a fair and relevant question and nobody seems to have an answer to it

 

 

 

Do you have evidence that there is any?

do i have evidence that bees get contaminated by nics? of cos not.

i didn't think it was in question. nics are being used, so bees get contaminated by it.

so i think it's fair to assume that bees get contaminated by nics. but no evidence, sorry.

 

do i know for sure this is causing them problems? now that's the million dollar question.

and obviously i can't answer it.

but i came to believe that it's the nics that are pushing the bees over the edge in some locations here and i assume that it might be the same scenario with for example what has become known as the Gizzy flat disease.

you could probably say that i have chosen to believe the nics are evil just as others have chosen to believe they are harmless.

i believe without the existence of viruses like dwv or nosema the nics might be relatively harmless.

also if there was no varroa there might not be much of a problem with the nics.

maybe all it needs is good weather and plenty of pollen from uncontaminated sources for the bees to cope with nics.

but we have the mites and dwv and the weather sometimes turns to:crap:

 

i sometimes meet beeks here that have kept bees here for longer than i have and they only scratch their heads and say that luckily they have areas that do much better.

bees used to boom here once and swarming was our main concern. now just keeping them reasonably healthy seems a big ask.

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