[Pollinator] Fwd: Lithium chloride could kill Varroa destructor mites without harming bees

[Laurie Adams]

>From Mary Clock Rust.  Thank you.


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---------- Forwarded message ----------
From: Clock-Rust, Mary <Clock-Rust.Mary at epa.gov>
Date: Wed, Jan 17, 2018 at 8:11 AM
Subject: Lithium chloride could kill Varroa destructor mites without
harming bees
To: Laurie Adams <lda at pollinator.org>


FYI!  For pollinator list serv





https://geneticliteracyproject.org/2018/01/16/tackling-bees-
greatest-threat-lithium-chloride-kill-varroa-destructor-mites-without-
harming-bees/
Tackling bees' greatest threat: Lithium chloride could kill Varroa
destructor mites without harming bees

Ross Pomeroy <https://geneticliteracyproject.org/writer/ross-pomeroy/>
| Genetic
Literacy Project
<https://geneticliteracyproject.org/source/genetic-literacy-project/> |
January 16, 2018

[image:
https://geneticliteracyproject.org/wp-content/uploads/2018/01/bee_varroa_mite-1024x683.jpg]

German scientists primarily based out of the University of Hoffenheim have
stumbled upon a simple solution that could deal a blow to honeybees' greatest
threat <https://phys.org/news/2016-06-insights-bees-deadly-varroa-mite.html>.
They've found that a tiny dose of the compound lithium chloride kills *Varroa
destructo*r mites without harming bees.

The scientists detailed
<https://www.nature.com/articles/s41598-017-19137-5> their
incredible findings in the January 12th publication of *Scientific Reports
<https://www.nature.com/srep/>*.

*[image: varroa 32432]V. destructor,* more commonly known as the *Varroa*
 mite
<https://www.realclearscience.com/blog/2017/11/29/the_biggest_myth_about_the_bee_apocalypse.html>,
is a scourge of honeybees across the globe
<https://www.livescience.com/20815-honeybee-collapse-mite-virus.html>. Upon
infiltrating a colony, the mites latch on to bees, sucking their hemolymph
<https://www.realclearscience.com/journal_club/2016/06/08/bees_commit_suicide_to_save_colony_from_parasites_109664.html>
(essentially
blood) and spreading the diseases they carry. According to the USDA
<http://time.com/4885569/honeybee-population-increase/>, 42 percent of
commercial hives in the U.S. were infested in summer 2017, and 40 percent
of beekeepers said the parasite seriously harmed their colonies. By
comparison, only 13 percent reported harm from pesticides.

Chemical compounds exist to combat the parasites but they are outdated and
growing increasingly ineffective, the researchers write, adding that no new
active compounds have been registered in the last 25 years.

The dearth of options prompted scientists
<http://journals.plos.org/plospathogens/article?id=10.1371/journal.ppat.1003035>
at
The Hebrew University of Jerusalem to experiment with a technique called
RNA interference. In their study, they fed bees double-stranded RNA via a
sugar solution to knockout vital genes in *Varroa *mites. The mites
ingested the lethal RNA via bees' hemolymph and subsequently died.

Inspired by those results, the German researchers sought to replicate them
by repeating the experiment with slightly tweaked methods. Indeed, mites
infesting bees that were fed sugar water with the designed RNA rapidly
died, but so did mites in a control group given another RNA that should
have been ineffective. The astonishing results prompted the researchers to
suspect that the lithium chloride used to produce the RNA – and thus
present in the sugar water – was actually killing the parasites. A battery
of subsequent examinations confirmed their hypothesis.

The scientists then carried out numerous experiments testing lithium
chloride against *Varroa* mites, including ones that approximated field
studies. They found that feeding honeybees minuscule amounts of lithium
chloride (no more than 25 millimoles
<https://www.convertunits.com/info/millimole>) over 24 to 72 hours wiped
out 90 to 100 percent of *Varroa* mites without significantly increasing
bee mortality. (Below: The figure shows the surviving proportion of bees
and mites fed lithium chloride compared to those not fed lithium chloride.)

[image:
https://geneticliteracyproject.org/wp-content/uploads/2018/01/439595_5_.png]
<https://geneticliteracyproject.org/wp-content/uploads/2018/01/439595_5_.png>Ziegelmann
et al. / Scientific Reports

According to the researchers, lithium chloride could be put to use very
quickly as it is easily applied via feeding, will not accumulate in
beeswax, has a low toxicity for mammals, and is reasonably priced. However,
wider studies on free-flying colonies testing long-term side effects are
required first, as well as analyses of possible residues in honey.

Francis Ratnieks, a Professor of Apiculture at the University of Sussex,
expressed skepticism about the new finding.

"We can kill 97% of the *Varroa* in a brood less hive with a single
application of oxalic acid
<http://www.beeculture.com/oxalic-acid-effective-easy-on-bees-but/>, which
takes five minutes to apply and is already registered and being used by
beekeepers," he told *RCScience* via email. "I think it will be difficult
in practice to apply lithium salts to colonies to kill varroa and get the
same level of control... There are also the wider issues of registration
and potential contamination of the honey with a product that would not
normally be there."

Still, the Hoffenheim researchers are hopeful.

"Lithium chloride has potential as an effective and easy-to-apply treatment
for artificial and natural swarms and particularly for the huge number of
package bees used for pollination in the United States," they conclude.

*Ross Pomeroy is Chief Editor of RealClearScience and a zoologist and
conservation biologist by training. Follow him on Twitter @SteRoPo
<https://twitter.com/SteRoPo>*

*This article was originally published at Real Clear Science as "Accidental
Discovery Could Save Bees From Their Greatest Threat
<https://www.realclearscience.com/quick_and_clear_science/2018/01/15/accidental_discovery_could_save_bees_from_their_greatest_threat.html>"
and has been republished here with permission.*
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