Exploring the sense and nonsense of food and health

Bees and Pesticides

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English: Spraying pesticide in California

English: Spraying pesticide in California (Photo credit: Wikipedia)

Bee-assisted pollination helps produce about 30% of our food.  But bees are in trouble and have been for several years now.  According to the USDA, we’ve lost 3.5 million colonies to parasites, disease, genetics, poor nutrition and pesticide exposure since the late 1940’s when bee colonies were 5 million to 6 million strong. This phenomenon is collectively called colony collapse disorder (CCD) with unusually high losses of worker bees that die, disoriented, far from their hives.  Since 2006, up to 40% of the bee colonies in the US have suffered  CCD.   This problem has threatened much of our human food supply, including our vegetables and fruits, which must be pollinated by bees. It was observed that very few bee losses were reported among organic beekeepers which suggested that the principal difference between them is the use of pesticides.

Recent research indicates a link between CCD and the use of pesticides derived from nicotine called neonicotinoids that targets insects’ nervous systems and could impair their homecoming instincts.  These pesticides are used extensively on corn, soy, and other US crops. In May, the European Union approved a two-year restriction on nicotine-derived pesticides; U.S. officials have yet to take similar action.

However, neonicotinoids may not be the only pesticides involved in bee health. Some research has found that a pair of widely used fungicides are showing up prominently in bee pollen—and appear to be making bees significantly more likely to succumb to a fungal pathogen, called Nosema ceranae

Researchers attempted to investigate what exactly bees are bringing into their hives to feed their colonies by examining bee hives that had been hired out to pollinate seven crops: almonds, apples, blueberries, cranberries, cucumbers, pumpkins, and watermelons. They took pollen samples from the hives and tested them for pesticides that included insecticides, fungicides and herbicides.

However, the fungicides appeared to cause the most concern. Disease-free bees were divided into groups and given one of three kinds of diets: two control diets free of insecticides; the third diet contained pollen collected from the hives in the previous research. Then they exposed all the bees to Nosema fungal spores and observed which bees became infected and which fought off the disease.  The result – the more fungicide found in the pollen, the more likely the bees were infected with the fungus compared to the control bees. The fungicide pyraclostrobin was found to make bees three times as susceptible to Nosema.

More bad news: the use of fungicides on US farms is rising rapidly, according to a February report in the journal Environmental Health News.

Bee products like honey are also found to contain contaminants such as bacteria, trace amounts of heavy metals, PCBs, and even antibiotics.  Honey itself can pose some health problems. 

A well known risk is the threat of botulism. Honey should not be given to children until they are a year old because honey contains Clostridium botulinum spores which can grow and produce the deadly botulism toxin in an infant’s immature digestive tract.  Adults do not face this risk.

 A rare but natural condition can occur called “mad honey poisoning” caused by grayanotoxin, a poison found in the nectar of Rhododendron species common in northeast Turkey. This toxin and others are usually at low levels according to the National Institutes of Health, but it is recommended to be aware of the source of your sweetener.

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