Page 6

Connecticut Researchers Study Pesticides in Pollen

By Matt Milkovich, Managing Editor www.vegetablegrowersnews.com

Pollen is the major source of nutrition for most wild bees and honeybees, making them particularly vulnerable to pollen contaminated with pesticides.

Researchers from The Connecticut Agricultural Experiment Station in New Haven have studied the pesticide content in pollen collected from trees, shrubs, native plants, weeds and crops in their state. Kimberly stoner and Brian Eitzer, from the station’s entomology and analytical chemistry departments, wrote a report summarizing the 2007 findings (2008 samples haven’t been analyzed yet).

The study sought to answer this question: What pesticides are found, and in what quantities, in pollen collected from honeybee colonies in a few representative locations in Connecticut?

“We started this project because of concern about imidacloprid and other insecticides in the same class (neonicotinoids),” according to the report. “These insecticides are systemic – they travel in the vascular system through the plant. Thus, they can be applied as a seed treatment, a soil drench or a foliar spray or in many other ways, and they will control insect pests all over the plant. This movement through the plant also means that they will move to some extent into pollen and nectar and thus may affect any insect feeding on pollen and nectar – including pollinators and many other beneficial and pest insects.”

France, Germany, Italy and Slovenia have banned imidacloprid as a seed treatment because it is suspected of having a role in bee die offs – a conclusion that has caused some controversy, according to the report.

Honeybees also are exposed to pesticides by beekeepers seeking to control varroa mites. That’s why the insecticide/acaricides coumaphos and fluvalinate are included in the researchers’ pesticide screen, according to the report.

“We studied pollen collected by honeybee colonies under normal circumstances, and thus collected baseline data,” according to the report. “We did not study collapsing colonies, and none of the colonies in the study died, so we cannot say anything about Colony Collapse Disorder or other bee die-offs.”

The researchers described their methods: “Honeybees collect pollen into structures called pollen baskets on their hind legs,” according to the report. “Normally, they pack the pellets of pollen they collect into cells in the hive, mixed with a little honey, microbes and enzymes, and the pollen ferments into a food called bee bread. Newly emerged worker bees eat the bee bread and produce the high protein food need by the larvae to keep the colony going.”

According to the report, the researchers collected pollen pellets from the honeybees using a pollen trap mounted at the bottom of the hive. A pollen trap is a series of screens that the returning forager bees must pass in order to get back into the hive. The trap knocks the pollen pellets off the hind legs of the bee and collects the pellets in a drawer.

The researchers collected the pollen twice a week from four locations in Connecticut. Pollen samples were analyzed by a multi-residue technique developed by Steven J. Lehotay at USDA. The samples were treated with a series of solvents to separate the pesticides from the rest of the pollen, and the extracts were analyzed by high-performance liquid chromatography/mass spectrometry, according to the report.

They concluded with their results: In the 102 samples analyzed, 37 pesticides were detected: 15 insecticide/acaricides, 11 fungicides, 10 herbicides and one plant growth regulator. All samples had at least one pesticide detected. The most commonly detected pesticide was coumaphos. Carbaryl and phosmet, both considered highly toxic to bees, were the most commonly detected field pesticides. Imidacloprid was detected 30 times, mostly at low levels. The pesticides found at the highest levels were both fungicides: myclobuntanil and boscalid.

“we are in the process of separating this sample into components based on the color and texture of the pollen pellets, analyzing the components and identifying the pollen in the different pellet types to determine the plant sources,” according to the report.

Drawing Winner

John Humke of Ackley was the winner of the drawing from the Annual Meeting participants that filled out an evaluation of the meeting. John will receive free registration for the 2009 Annual Meeting of the IHPA to be held in Marshalltown on October 30th and 31st. John is a former district director for the IHPA. Congratulations John and thanks for filling out an evaluation form! The evaluation forms are very helpful to the committee planning the program.