Glycophosphate & Neonicotinoid: Impact on Pollinators
Excerpted from: Dancing With Bees, a journey back to nature, by Brigit Strawbridge Howard
Many studies have demonstrated that the nation’s most-used weed killer, RoundUp, is lethal to pollinators.
In 1962, Rachel Carson published The Silent Spring which was a warning of the dangers of a
revolutionary new pesticide DDT. She had noticed that in the 1950s and 1960s it was responsible for,
among other things, the crashing of bird populations. DDT was banned in the United States in 1972
but it appears that history is repeating itself and we are fast approaching a time when it might be said,
"The summer afternoons are strangely silent when they were once filled with the gentle bussing of
bees."
A film documentary called 'Rachel Carson' produced by American Experience may be seen on Amazon Prime.
Glyphosate, the main ingredient in RoundUp® is a non-selective herbicide, meaning it will kill
most plants. It prevents the plants from making certain proteins that are needed for plant growth. Glyphosate
stops a specific enzyme pathway, the shikimic acid pathway.
Glyphosate was first registered for use in the U.S. in 1974. Glyphosate is one of the most widely used
herbicides in the United States. People apply it in agriculture and forestry, on lawns and gardens, and for
weeds in industrial areas. Some products containing glyphosate control aquatic plants.
The enzyme that RoundUp® targets is also used by some bacteria, including a microbiome found in the
intestines of most bees. When pollinators come in contact with glyphosate, the chemical reduces this
gut bacteria, leaving bees vulnerable to pathogens and premature death.
A scientific study compared several products, most of which contained the herbicide glyphosate, which
is best known as the active ingredient in Roundup® products. They found highly variable toxicity to bumble
bees, including one formulation that killed 96% of the bees within 24 hours.
The culprit this time is another revolutionary group of pesticides called Neonicotinoids ('neonics' for short).
They were first introduced in the 1990s and are currently the world's most widely used insecticide. Over
140 different crops including soy, corn wheat, cotton, legumes, potatoes, sugar beets, sunflowers,
rapeseed and flax are treated with neonics.
Effects On Bees
Interferes with their navigation systems
Disrupts their foraging behavior
Disrupts their ability to communicate
Impairs their immune systems
Reduces reproductive success
Residues in nests of solitary bees may be linked to fewer egg cells.
Neonics are neurotoxins designed to attack an insect's central nervous system causing paralysis and
eventually death. There were designed specifically to target agricultural pests such as vine weevils,
aphids, whiteflies, Colorado potato beetles and termites. The damage they have caused over the last
two decades to other insects, including bees, has been devastating.
Neonics are neurotoxins designed to attack an insect's central nervous system causing paralysis and
eventually death. The damage they have caused over the last two decades to insects, including bees,
has been devastating.
In the past, we were able to 'see' pesticides since they were sprayed onto crops and we could wash
off many of the contact chemicals. With neonics, though some are sprayed onto foliage, the majority
are invisible to since they are applied as seed and bulb dressings or as solid dressings. Neonics
are systemic, which means the chemicals are taken up by the entire plant — roots, leaves, fruits,
flowers, pollen and nectar.
Previous forms of pesticide tended to be applied reactively, that is, after a pest had been identified in
an area. In contrast, neonics are used prophylactically, which means crops (e.g., between
80-100% of US corn) are now grown from treated seeds or treated soil. This is being done as a safeguard
against the possibility of an attack by the pesticide's target insect. This is like taking antibiotics
throughout the year in case you might catch a cold.
Neonics are water soluble which means they can remain in the soil for a number of years. Only
5% of what is applied to the seeds is actually taken up by the plants. The remaining 95% of the pesticides
leach into the soil. Because they are water soluble they migrate via the ground water into nearby streams
and waterways.
Neonics also get sucked up from contaminated soil — not only by subsequent years of crops grown
in the treated field but also by the wild flower margins along the edges of the fields. Many of those wild
flower margins were planted or allowed to grow specifically to support pollinators.
Margins and waterways weren't intended to be treated with neonics, but they have been which has resulted
in sustained exposure to bees, moths, butterflies, hoverflies and aquatic invertebrates. Declines in the
insects can cause shortages in the food chain for insect-eating bats, amphibians and birds.
Early studies of the effects of neonics appeared to show that they were safe for bees. However, that was
because only the immediate lethal effects of the pesticide were investigated. Unfortunately the sub-lethal
effects were NOT tested before they were used in our fields.
When the effect of neonics first began to be notices, concerns were focused on honey bees. This was
around the time of Colony Collapse Disorder (CCD) and neonics were suspected to be one of the root
causes. But now it is clear that bumble bees and other invertebrates are also affected. This group of
insecticides are NOT safe for bees despite reassurances. When bees collect pollen and nectar for
their brood to feed on, neither they nor their larvae can escape the neurotoxin's effects.
Neonics are water soluble which means they can remain in the soil for a number of years. Only
5% of what is applied to the seeds is actually taken up by the plants. The remaining 95% of the pesticides
leach into the soil.
In response to concerns about both the lethal and sub-lethal effects of neonics on wildlife, the EU banned
three of the most widely used neonics in 2018.
Scientific evidence collected over the last decade or so proves that neonics produce numerous
chronic symptoms in bees such as:
Interferes with their navigation systems
Disrupts their foraging behavior
Disrupts their ability to communicate
Impairs their immune systems
Reduces reproductive success
Residues in nests of solitary bees may be linked to fewer egg cells.
A recent study appears to show that neonicotinoids may be a contributing cause of the
population decline of Monarch butterflies due to its ability to reduce the number of
milkweed plants. The Monarch caterpillars feed almost exclusively on milkweed plants,
making abundance of Monarch butterflies critically dependent on milkweed availability.
Yet, milkweed is being destroyed by glycosate treatment of GM crops
There are some who believe that key crops will fail if seeds, plants and soils are NOT treated with neonics.
It is true that failing crops are a concern however, it is also a concern if there are no pollinators left to
pollinate the crops
RoundUp® products kill exposed Bumble Bees at high rates, according to a new study published in the
Journal of Applied Ecology,
which points to undisclosed inert ingredients as the primary culprit. A “no glyphosate” formulation
of RoundUp® being sold in the United States in a product line called RoundUp®® for Lawns which contains
four different main active ingredients: dicamba, MCPA, quinclorac, and sulfenzatrone. The study reported
that this product was found to kill 96% of exposed pollinators which was at a significantly higher rate
than RoundUp® with glyphosate.
Nearly 60 years ago we learned the painful consequences of using DDT from Rachel Carson and her
world-changing book. It is important for us to listen — and really hear — whether the world's
soundscapes are again growing silent.
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