Hive collapse: what is causing the deaths of bees?
By Robert and Sonia Vogl
President and Vice President, Illinois Renewable Energy Association
Yesterday we watched as our dog snapped unsuccessfully at a big bumblebee lazily buzzing past her. While it was amusing to watch her unsuccessful attempts at catching just one bee, the unplanned deaths of millions of honeybees and total collapse of hives is not.
We depend on bees. The deaths of countless hives affect more than the beekeepers whose livelihoods depend on them. They affect farmers who depend on bees to pollinate their crops; they affect the millions of people who eat fruits and vegetables that must be pollinated by bees to produce food.
Honeybees are needed to pollinate about one-third of American food crops. Without bees, fruits and seeds of many food crops would not form. When local honeybees are not available, others must be imported in order to do their work, increasing the expense of raising crops, in turn raising the cost of food for consumers.
Einstein is quoted as saying that if bees disappeared, humanity would disappear within four years. While that may be an overstatement, it causes concern. How different life would be without apples, pears, tomatoes and the many other fruits, vegetables, nuts and grains we enjoy.
Although colony collapses have been recorded since 1869, the name “Colony Collapse Disorder’ was coined in 2006. It has been estimated that half of the world’s bees have disappeared within the past few years; 40% of American honeybee hives have suffered Colony Collapse Disorder. Possible causes have been suggested, including bad weather, malnutrition, habitat loss and others. Varroa mites, nicknamed “vampire mites” were considered as a cause since they carry a virus that can infect a colony as the mites eat on larval bees. However, scientists believe that the mites are not the cause of vast collapses. Their part in Colony Collapse Disorder in the winter of 2004 – 2005 was never actually verified.
Recent research has cast light on what appears to be the major culprit in this disaster scenario. While herbicides and pesticides are known to damage and kill insects, a single group – neonicotinoid (similar to nicotine) pesticides developed in the 1990s are emerging as the most damaging.
While neonicotinoides affect higher animals, they are especially damaging to the nervous systems of insects. Bees have many more nicotinic acetylcholine receptors than most target insects, including mosquitos, making them more sensitive to neurotoxins in pesticides; receptors are permanently blocked. At sub-lethal levels, small doses disorient bees without killing them. “Drunk” and disoriented, they are not able to find their way back to the hive which depends on the cooperative work of its members to survive. Affected bees also stopped feeding.
Researchers have observed bees to discover the effects of neonicotinoids. A colony in a treated field had smaller nests, weaker offspring, and lower production of young queen bee development than bees in a non-treated field. Following microchipped bees revealed that affected bees’ mortality rate was several times higher than non-affected bees.
Apiaries near fields in northern Italy treated with neonicotinoids experienced high mortality. Once the pesticide was banned, bee populations stopped declining. In 2008, after a pesticide was applied to seeds, over 300 milion bees died in Germany.
French scientists experimented with bees exposed to low concentrations of one of the neonicotinoids, imidacloprid, to determine its effect. Their sense of smell and memory were blocked, affected feeding behavior. Within a few days, they stopped feeding and the number of hive members dropped. Often breakdown products are more damaging than the original chemical.
Neonicotinoids are dusted on seeds of many crops. As the plants grow the chemicals move into the entire plant, including pollen and nectar which the bees accumulate.
They also are used in lawn and garden products. As satisfying as it is to spray and watch those pesty pests fall, other ways exist to deal with them. Try milky spore for Japanese beetles and garlic guard as an insect repellant.
Drs. Robert and Sonia Vogl can be reached via e-mail at firstname.lastname@example.org.