Increasing suspicion is falling on glyphosate herbicides'
effects on microbes in the gut of consumers.
The innards of all animals are teeming with bacteria whose
quantity and diversity exert multiple influences on health. Many of these microbes have enzymes in common
with plants, and, like plants, can be harmed when glyphosate interferes with
them.
Our major pollinators, honey bees and bumble bees, can easily be exposed to glyphosate when foraging on weeds which have been sprayed or wild-flowers which have been caught in spray drift, or on GM herbicide-tolerant crops which accumulate the glyphosate applied to them.
When American scientists fed environmentally-relevant doses
of glyphosate to honey bees, they noted a reduction in the presence of all
eight bacterial species normally dominant in the bee gut. Such microbes play a vital part in the
healthy development, nutrition and immune system of bees. Perturbation of the gut community won't kill
the bee, but will make it vulnerable to environmental stressors which can be
lethal. Moreover, since newly-emerged
worker bees effectively inherit their gut microbes through social interaction
with older workers, they may acquire a sub-optimal gut flora during the
earliest part of their lives when their health can be most easily damaged, and
even before they visit any contaminated flowers.
Further experiments investigating the implications for the
bees' immune system when their gut microbe balance is disturbed found that
glyphosate-treated bees became susceptible to opportunistic pathogens. The loss of one dominant glyphosate-sensitive
bacterium in particular is thought to have major implications for
immunity. This microbe produces
anti-microbial substances which could protect against infection, and, because
it forms a lining on the gut wall, could act as a physical barrier to pathogen
invasion. It's also thought to play a
critical role in enabling the healthy gut flora to assemble.
Interestingly, in parallel to a study of rats fed glyphosate
[1], the bees' gut flora seemed to be more affected by the lower
dose of the herbicide. Like the previous
study, this hasn't been explained, but in the present case it's possible the
worst-affected bees never made it back to the hive to be tested, either because
they were dead or because they were too befuddled [2,3].
The very real possibility of nutritional impairment due to
poor feeding [3] or poor digestion when glyphosate was present in the bees'
food wasn't addressed.
More than a decade ago, US beekeepers began finding their
hives decimated by what became known as 'colony collapse disorder'. Millions of bees mysteriously disappeared
leaving farms with fewer pollinators
for crops. Explanations for the
phenomenon have included exposure to pesticides or antibiotics, habitat loss,
and infections. Regulatory guidelines
assume a weed-killer won't harm bees.
This latest study suggests otherwise.
The bigger picture is that 40% of pollinator species
including butterflies and bees are facing extinction, and glyphosate might be
another nail in their coffin.
OUR COMMENT
Glyphosate is known to arrest bacterial growth without
killing them. None of the adverse gut
effects described above are directly toxic, but could contribute significantly
to a fatal outcome in all sorts of indirect ways.
This study casts an interesting new light on the vanishing
Monarch butterflies in America [4]: habitat and food-loss certainly play a part,
but indirect effects of glyphosate on their gut flora too could make a
significant contribution to disaster.
There's no reason to think that humans will fare any better
on a glyphosate-laden diet than do the butterflies and bees.
Background
[1] INDIRECT HEALTH EFFECTS OF ROUNDUP - March 2018
[2] BEES WITH DEMENTIA - September 2015
[3] BEFUDDLED BEES - June 2018
[4] FLUTTERING INTO OBLIVION? - March 2017
SOURCES:
·
Glyphosate linked to bee deaths, GM Watch
25.09.18
·
Erick V. S. Motta, et al., 2018, Glyphosate
perturbs the gut microbiota of honey bees, PNAS
·
Kathy, Good Energy On: Climate - The
Butterfly Thief, Living Earth, Winter 2017
Photo Creative Commons
No comments:
Post a Comment
Thanks for your comment. All comments are moderated before they are published.