Q. I have recently heard that pesticides are to blame for all the honeybees dying in the United States. Is this true?
A. Certain pesticides are toxic to honeybees, but they are only part of the bigger issue when it comes to declines in honeybee populations in the U.S. and across the world. Honeybees pollinate more than 65 percent of the worlds crops and actually increase yields in crops to the tune of $16 billion a year. If there were no honeybees to pollinate crops, a major food crisis would ensue.
Introduced Varroa mites and brood diseases have decimated honeybee populations in the last 15 years. Varroa mites are introduced parasites that weaken the honeybees and make them more susceptible to virus and other pathogens. Varroa mites alone reduced populations of honeybees in hives 50 percent or more during the mid- to late-1990s.
Pesticides have also played a role in declining bee populations. Many pesticides used by homeowners and pesticide applicators are toxic to bees. Recently, bee specialist Dr. Greg Hunt at Purdue University conducted studies on the effect of neo-nicatoid pesticides on honeybee populations in the Midwest. Neo-nicatoid pesticides are systemic pesticides applied to corn and soybean seed used by farmers in the U.S. and other regions of the world. These pesticides in theory are taken up by the plant as it develops and protect the corn or soybean from various insect pests. The treated seeds are sticky, and a talc-powder is added so the vacuum seeders used by farmers dont clog. As the seed is planted, clouds of dust are produced. Often the dust is blown away from the field to other areas; including areas near the fields filled with dandelions and other flowers visited by honeybees.
Even tiny amounts of neo-nicatoid insecticides are extremely toxic to honeybees. Less than lethal amounts have been found by researchers to disorient bees and make them sick or weak. Hunt and his team found lethal amounts of neo-nicatoids in the dust, in flowers near the fields, and in field soil three years after the initial planting. Scientists have also found neo-nicatoids in the pollen gathered by bees from corn plantings.
Homeowners also use neo-nicatoids in landscapes – most notably imaclorplyrid, which is present in products used to control a wide variety of insect pests including lawn grubs and emerald ash borer. I would advise homeowners to use extreme care regarding the use of imaclorplyrid or any other systemic insecticide on plants that produce flowers that may be visited by bees. Further research is being conducted to determine how homeowners use of these products could affect honeybee populations.
Pesticides alone are not the smoking gun that totally explain the dramatic losses of honeybee populations worldwide. Greater care is needed when using pesticides potentially harmful to bees.
Read your pesticide label carefully before using pesticides, and never use any pesticide on a flower that may be visited by our valuable honeybees.