MN Fruit & Vegetable IPM News - Vol. 4, No. 2

honeybee Most of us are aware of the expanded use and adoption of genetically engineered Bt corn, transformed to express various proteins of the soil-borne bacterium, Bacillus thuringiensis. One benefit of Bt corn is the highly selective/specific toxicity to larval pests, in this case, insects within the order Lepidoptera. Consequently, Bt corn in the U.S. has been very effective for managing the European corn borer (ECB) and other larval (Lepidopteran) insect pests in Minnesota, throughout the U.S. and in other countries. Unless you have been on vacation for several months, you are also aware of a complex problem and potentially devastating problem associated with honey bees, identified last fall as Colony Collapse Disorder (CCD). Many hypotheses have been promoted regarding possible explanations for CCD. With regard to recent discussions or implications about Bt corn, we want to provide a brief report released earlier this month by Dr. Galen Dively, University of Maryland.

Given the specificity of the Bt proteins in Bt corn, honey bees (distinct order, Hymenoptera), should not be adversely affected. However, honey bees do reflect one of the many “non-target” species that are evaluated for possible lethal or sub-lethal effects, as part of the registration process with the Environmental Protection Agency (U.S. EPA). Several laboratory studies have evaluated the possible impact of Bt pollen on honey bees. However, a two-year field study (soon to be published in the international bee journal Apidologie) conducted by Dr. Dively and his graduate student represents the first attempt to expose functional colonies of honey bees to Bt corn pollen under open field conditions. In this Maryland study, colonies placed in Bt sweet corn plots were allowed to forage on corn pollen and also fed Bt pollen cakes for 28 days. The pollen cake consumption alone represented approximately 44% of the expected daily pollen requirements of each exposed hive. Results showed no adverse effects on bee weight, foraging activity, colony bee strength and brood development. Although there is no evidence thus far of any lethal or sub-lethal effects of the currently used Bt endotoxins on honey bees, insecticidal products expressed by other transgenes in crops may need extended field testing on a case-by-case basis to assess the longer term consequences of sub-lethal changes in colonies and subtle modifications in bee behavior.

Editor’s note: The possibility of Bt crops affecting honey bees, and particularly CCD, has been one of many hypotheses recently posed. We refer to this current study from Dr. Dively’s work, to provide our audience with the most recent, research-based information on this important topic. See complete press release and info at:
http://www.americanfarm.com/TopStory5.01.07f.html

To review the overall concern with CCD, to date, see last week’s article by Dr. Marla Spivak, Dept. of Entomology, University of Minnesota.

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ACKNOWLEDGEMENTS

Co-Editors: Bill Hutchison (hutch002@umn.edu), Department of Entomology, University of Minnesota, Jeanne Ciborowski, Minnesota Department of Agriculture, Ag. Resources Management and Development Division, and Suzanne Wold-Burkness (woldx018@umn.edu), Department of Entomology, University of Minnesota

The Newsletter is published weekly from May through August, cooperatively, by the Minnesota Department of Agriculture (MDA) and the University of Minnesota (U of MN). Reports are posted on the U of MN and MDA web sites on Fridays. If you have suggestions and/or comments, please send your contributions by 4 p.m., Wednesday to Jeanne Ciborowski, 651-201-6217, jeanne.ciborowski@state.mn.us , MDA, 625 Robert St. North, St. Paul, MN 55155. You can access the Newsletter at the U of MN web site in htm format at: www.vegedge.umn.edu/MNFruit&VegNews/mnindex.htm and at the MDA web site in pdf format at: www.mda.state.mn.us/plants/pestmanagement/ipm/ipmnews.htm

Partial funding for this publication is provided through partnership agreements with the Minnesota Fruit and Vegetable Growers Association (MFVGA) and the United States Department of Agriculture – Risk Management Agency (RMA). These institutions are equal opportunity providers.

DISCLAIMER

Reference to products in this publication is not intended to be an endorsement to the exclusion of others which may have similar uses. Any person using products listed in this publication assumes full responsibility for their use in accordance with current manufacturer directions.

Last Revised May, 2007 by woldx018@umn.edu
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