failure after exposure to treated crops was estimated to be twice that of natural
death [56].
Outside Europe and North America, a study conducted in Japan drew a more
direct connection between neonicotinoid pesticides and CCD. Three field experiments were conducted between July 2010 and August 2012 using approximately
10,000 adult bees across ten hives. The scientists observed effects of two
neonicotinoids, which were primarily used in rice fields, upon foraging bees. They
found that foraging bees were killed instantly wherever the insecticides were
sprayed. The immediate death of foraging worker bees stressed the colonies and
forced a role change from house worker bees to foraging bees in an effort to find
sufficient food. However, the lack of house bees led to an imbalance in the workings
of the colony; house bees are adult worker bees responsible for cleaning the hive,
feeding the brood, caring for the queen, building, and so on. This social structure
imbalance stressed the queen, which led to a decrease in egg-laying and eventually,
due to constant mortality of adult foraging bees from the pesticide, collapse of the
colony.
The Japan study found that even if foraging bees escaped instant death due to a
sublethal dose of pesticide, the surviving forager bees returned to the hive with
contaminated nectar and pollen. Hive members including the queen ingested and
accumulated enough of the pesticide that CCD would still eventually be triggered
[7, 57].
There have been numerous studies concerning varying effects of insecticides,
particularly neonicotinoids, upon bee pollinator health and other ecosystem effects,
though not all conclusions can be extrapolated to all situations. There are still
knowledge gaps, but significant information now exists that indicates much greater
caution should be exercised or alternatives sought [55].
4.2.3 Fungicides
According to the American Phytopathological Society in 2004, fungi are the number
one cause of crop loss worldwide. Fungicides thus have an important place in
agriculture, functioning to control crop diseases, which affect not only plant development but can be fatal to humans; increase plant productivity and reducing blemishes that affect market value; and improve the plants’ storage life and quality [58].
The fungicides involved in preventing postharvest losses due to fungus-induced
spoilage are primarily for the immediate benefit of human and animal consumption,
but those chemicals applied on crops before harvest can have sublethal effects upon
the crop pollinators.
A 2013 study that analyzed pollen from bees responsible for pollinating certain
major fruit crops (apples, watermelons, pumpkins, cucumbers, blueberries or cranberries) found that fungicides were the most frequently found chemical substances,
and the most common fungicide among the samples was chlorothalonil, which is
widely used on apples and other crops. Bees that consumed the chlorothaloniltainted pollen were found to be three times more susceptible to Nosema infection,
22
C. Li
death [56].
Outside Europe and North America, a study conducted in Japan drew a more
direct connection between neonicotinoid pesticides and CCD. Three field experiments were conducted between July 2010 and August 2012 using approximately
10,000 adult bees across ten hives. The scientists observed effects of two
neonicotinoids, which were primarily used in rice fields, upon foraging bees. They
found that foraging bees were killed instantly wherever the insecticides were
sprayed. The immediate death of foraging worker bees stressed the colonies and
forced a role change from house worker bees to foraging bees in an effort to find
sufficient food. However, the lack of house bees led to an imbalance in the workings
of the colony; house bees are adult worker bees responsible for cleaning the hive,
feeding the brood, caring for the queen, building, and so on. This social structure
imbalance stressed the queen, which led to a decrease in egg-laying and eventually,
due to constant mortality of adult foraging bees from the pesticide, collapse of the
colony.
The Japan study found that even if foraging bees escaped instant death due to a
sublethal dose of pesticide, the surviving forager bees returned to the hive with
contaminated nectar and pollen. Hive members including the queen ingested and
accumulated enough of the pesticide that CCD would still eventually be triggered
[7, 57].
There have been numerous studies concerning varying effects of insecticides,
particularly neonicotinoids, upon bee pollinator health and other ecosystem effects,
though not all conclusions can be extrapolated to all situations. There are still
knowledge gaps, but significant information now exists that indicates much greater
caution should be exercised or alternatives sought [55].
4.2.3 Fungicides
According to the American Phytopathological Society in 2004, fungi are the number
one cause of crop loss worldwide. Fungicides thus have an important place in
agriculture, functioning to control crop diseases, which affect not only plant development but can be fatal to humans; increase plant productivity and reducing blemishes that affect market value; and improve the plants’ storage life and quality [58].
The fungicides involved in preventing postharvest losses due to fungus-induced
spoilage are primarily for the immediate benefit of human and animal consumption,
but those chemicals applied on crops before harvest can have sublethal effects upon
the crop pollinators.
A 2013 study that analyzed pollen from bees responsible for pollinating certain
major fruit crops (apples, watermelons, pumpkins, cucumbers, blueberries or cranberries) found that fungicides were the most frequently found chemical substances,
and the most common fungicide among the samples was chlorothalonil, which is
widely used on apples and other crops. Bees that consumed the chlorothaloniltainted pollen were found to be three times more susceptible to Nosema infection,
22
C. Li