permaculture

[Lawrence London <lfljvenaura@gmail.com>]

These Pesticides Could Be Birth Control for Bees
http://news.nationalgeographic.com/2016/07/bee-sperm/

These Pesticides Could Be Birth Control for Bees
The world's most widely used insecticides leave drones with less sperm for
their queen. Could this be a factor in the worldwide collapse of honeybee
colonies?

By *Lindsey Konkel*
PUBLISHED July 26, 2016

The world’s most widely used pesticides may be acting as birth control for
male bees, according to new research published Tuesday.

Male honeybees exposed to neonicotinoid insecticides produced fewer living
sperm cells than unexposed males.

The study by scientists in Switzerland is the first to examine the effects
of this class of pesticides, which has been linked to honeybee die-offs in
recent years, on the fertility of male bees. “Our data highlight one
possible way that neonicotinoids can affect honeybees,” said senior study
author Geoff Williams, a bee researcher at the University of Bern in
Switzerland.

Male honeybees, called drones, serve one purpose—to mate with a queen.
Because their main contribution to the colony comes in the form of sperm,
they often are overlooked in studies of colony survival. Yet poor mating
can take a toll on the productivity of a queen bee and the success of a
colony.

Future research is needed to understand what the effects on sperm might
mean for honeybee reproduction in the natural environment, according to the
researchers.

*What exactly did the pesticides do to the males?*

The researchers tested drones from hives exposed to two insecticides,
thiamethoxam and clothianidin. They chose these two chemicals because their
use in the European Union is under review due to concern over pollinator
declines. The drones were exposed to amounts of pesticides that are
comparable to what honeybees could naturally encounter in pollen.

Compared to drones from colonies with no pesticide exposure, the test
drones produced 39 percent fewer living sperm. They also averaged 8 to 11
percent lower sperm viability, which takes into account the percentage of
living versus dead sperm. Queens only use living sperm to fertilize eggs.

*Is this the cause of widely reported colony failures?*

That remains unknown.

Over the past decade, beekeepers in North America and Europe have lost on
average about 30 percent of their hives each year. Declines in wild
pollinators, including bumblebees and Monarch butterflies, have occurred
over the same period. Researchers suspect there’s more than one cause for
colony failures. A number of important factors are beginning to emerge,
including disease, parasites, and habitat loss.
These corn seeds are coated with a neonicotinoid pesticide called
clothianidin. This class of pesticides is being evaluated by the U.S.
Environmental Protection Agency for potential harm to bees and other
pollinators.
Photograph by Anand Varma, National Geographic Creative

There’s a growing body of evidence, too, that neonicotinoids may have
sublethal effects, says Dennis vanEngelsdorp, a bee researcher at the
University of Maryland who was not involved in the new study. “There may
not be a pile of dead bees right away, but we’re beginning to find that
these exposures may be hurting and slowing down colonies in more insidious
ways,” he said.

Experts worry the problem may be bigger than one or two pesticides. Bees
are exposed to a number of chemicals as they forage for honey and nectar.
One recent study found 30 different pesticide residues in pollen stored in
beehives. “We know almost nothing about the additive effects or synergy
between all these different exposures,” said Dave Shutler, an ecologist at
Acadia University in Nova Scotia.

*What about the health of the queens?*

Honeybee queens, which will mate with several drones, store a small amount
of sperm from each mating. Then they use that stored sperm to lay eggs for
the rest of their lives. Fewer living sperm cells could spell trouble for
the colony if the queen can’t get enough viable sperm or if she has to
leave the safety of the hive to go on additional mating flights, explains
Lars Straub, a PhD student at the University of Bern.

Beekeepers in North America and Europe consistently report poor queen
health as a major cause of colony losses, but no one knows why, Williams
says. Queen bees that are in poor health often lay fewer fertilized eggs.
Previous research has linked neonicotinoids to impaired queen bee
reproduction and survival.

“I think this [sperm] study is another indication that exposures to these
chemicals may be having multiple effects,” vanEngelsdorp says.

*What are neonicotinoids and how are they used?*

Neonicotinoids kill pests by messing up their nervous systems. They were
introduced in the late 1980s as a safer alternative to older insecticides
that are more toxic.

Neonicotinoids are different than other pesticides because they get
absorbed into all of the plant’s tissues—from the sap to the leaves to the
pollen. This makes them really effective against sucking insects, such as
aphids.

In agriculture, neonicotinoids are applied as seed coatings to crops like
soy beans and corn. As the seed germinates, the chemical coating gets taken
up into the growing plant tissue.

They are used in lawn and garden treatments, too.

Crops like corn and soybeans depend on wind—not pollinators—to spread their
pollen. Honeybees can be exposed to neonicotinoids when pollen from these
plants blows onto nearby flowers where they may be foraging.

The U.S. Environmental Protection Agency is reviewing the effects of
several neonicotinoids on honeybees and other pollinators to determine
whether to restrict their use.

<><>
Pesticides may be lowering sperm count of bees

http://www.dw.com/en/pesticides-may-be-lowering-sperm-count-of-bees/a-19428882

New research has found that a controversial class of neurotoxins used in
agriculture for pest control significantly impairs the fertility of male
honeybees. Bee numbers in Europe and the US have been falling for years.

The Institute of Bee Health at the University of Bern, Switzerland has
carried out a study to explore the effects of two popular neonicotinoids,
thiamethoxam and clothianidin, on the sperm of drones, or male honey bees.

Lead researcher Lars Straub said the presence of the chemicals could be
"one reason behind the struggling bee numbers we've seen over the past 15
years in the northern hemisphere."

The pesticides are widely used in the USA. The European Commission is
currently reviewing a temporary ban it imposed in 2013.

There has been an alarming decline in the bee populations in North America
and Europe over the past 15 years. Bees account for an estimated 80 percent
of plant pollination by insects.

*'Inadvertent contraceptive effects'*

The researchers, led by Straub in Bern assigned batches of drones from 20
bee colonies to either insecticide exposure or control groups. They then
took semen samples from males once they had reached sexual maturity.

The study published in the British journal Proceedings of the Royal Society
B showed that widespread neonicotinoid use may have "inadvertent
contraceptive effects" on the insects which provide fertilisation worth
billions of dollars every year.

Male honey bees exposed to the neonicotinoids at levels found in fields
showed, on average, around 39 per cent less living sperm. In addition, the
mortality rate of the drones exposed to the pesticides during the study was
almost doubled.

Bee studies in Braunschweig

Honey bee queens make a single mating flight from the nest to collect sperm
from as many as 20 different males, which they store within a dedicated
organ over their entire lifespan. This is essential for the hive's survival
as it provides genetic diversity which is essential for resistance to
disease, parasites and environmental challenges.

"The process of the queen's mating flight is a one-time thing so it's
really important that she collects plenty of quality sperm," Straub said.
If she does not, then worker bees will sense the queen is ineffective and
kill her. "As the primary egg layer and an important source of colony
cohesion, the queen is intimately connected to colony performance," the
paper said.

The new study adds reduced sperm quality to the list of possible causes for
"colony collapse disorder" in Europe, North America and elsewhere, which
has alternatively been blamed on mites, a virus or fungus, pesticides or a
combination of all of them.

Previous studies have found neonicotinoids can cause bees to become
disorientated to the extent that they cannot find their way back to the
hive, and can lower their resistance to disease.

jm/kl (AFP, Royal Institute)