The danger of losing one of the world’s most efficient
pollinators is imminent- honeybees, (Apis
mellifera), are on the decline in many parts of the world.
During the winter of 2006-2007, unusually high losses of
30-90% of bee hives were reported by
bee farmers. Farmers
noted that the worker bee population had vanished, leaving the
queen and young behind. Oddly,
the missing bees are never found dead around the hive- they disappear. Without the
worker bees in a colony, the hive eventually dies. This sequence of events is known as colony
collapse disorder (CCD).
CCD is now described as
“a serious problem threatening the health of bees and the economic stability of
commercial beekeeping and pollination operations”. Bees are integral to sustaining the world’s
food supply as one-third of
the food we eat is directly or indirectly affected by pollination. It is estimated that bee pollination is
responsible for more than $15
billion in increased crop value each year.
With bees on the decline, several studies over the past
eight years have been trying to determine the cause of CCD. The New
York Times reports on a USDA
publication which describes CCD as having several
factors to the decline of honeybees. A complex
set of stressors and pathogens are thought to contribute to CCD, which are
described in the following figure.
Pesticides, especially the insecticide class of neonicotinoids, are
thought to be a primary driver for CCD.
Neonicotinoids are systemic insecticides, as they are
taken up by the plant’s vascular system and distributed throughout the plant. Generally, neonicotinoids are applied to the
seeds of crops, but crops can also receive spray applications. Pests ingest the toxin as they consume parts
of the plant, and die as the central nervous system is affected, causing
paralysis and death. Although bees are
not the target pest, the pollen and nectar of the plants contain the
insecticide, which is then transported to the rest of the hive, which may induce
CCD. Other
effects may include disruptions in bee mobility, navigation,
feeding behavior, foraging activity, memory and learning, and overall hive
activity.
Discussions of placing a ban on neonicotinoids are not uncommon. A recent report
stated that the European Union (EU) has discussed placing a ban on these
insecticides in hopes of boosting bee populations. Although a majority of the EU (15 countries) voted for
banning the insecticides, 8 countries voted against the ban and 4 countries
abstained, because of the lacking scientific data.
John Atkins, Chief Operating Officer of Syngenta,
the world’s foremost producer of neonicotinoids agrees that more scientific
data is needed before a ban on neonicotinoids is instated. He states, “…a
ban on neonicotinoids would simply close the door to understanding the problem’
[of bee populations declining]’’. Syngenta
also states on its page concerning decreasing bee
populations, “Neonicotinoids are some of the most effective forms of crop
protection technology available and have been used safely across millions of
hectares of European crops. Many years of independent monitoring prove that
when used properly – as they consistently are – neonicotinoids do not damage
the health of bee populations”. A
YouTube video by Syngenta outlining the benefits of neonicotinoid use and
potential problems with a ban is located here.
On the contrary, several studies indicate that the effect
of neonicotinoids on bees is devastating in more ways than one. In addition to possible CCD effects, a French
study noted that exposure makes it harder for bees to return
to their hive as the neonicotinoids cause confusion. A British
study found that bees do not collect enough food to sustain
their hive, therefore compromising the health of the colony. Another
study linked neonicotinoid exposure to depressed immune system
function. With a
depressed immune system, honeybees are more susceptible to viral and bacterial
attack.
Not only do neonicotinoid exposure affect bee health, but
a myriad of other pesticides do as well, according to this EcoNews
article. The
study’s findings supplement the USDA’s
report on several factors affecting bee populations. In addition to the USDA’s findings, the
researchers found 35 different pesticides in pollen with samples averaging 9
different pesticides ranging from neonicotinoids, pyrethroids, carbamates, organophosphates,
and more. The study suggests that
neonicotinoids are not just to blame- there are other chemicals present that
may cause just as much harm to bee populations.
Over the years, studies have confirmed that there are
several factors that contribute to CCD.
Pesticides like neonicotinoids are currently to blame for the rapid
decrease in bee populations among the other causes of CCD. Is the banning of neonicotinoids or other
pesticides the best option to save the honeybee? Or will CCD eliminate our crucial pollinators
by increasing the incidence of biological elements beyond human control?
