VIII SIMPOSIO INTERNAZIONALE ICPBR

HAZARDS OF PESTICIDES TO BEES

Bologna, 4-6 Settembre 2002

Effetti dell’imidacloprid sulle api

Imidacloprid, honey bees, and potatoes in Atlantic Canada: is there a connection?

James R. Kemp (1) and Richard E. L. Rogers (2)

(1) PhD, Dept of Biology, University of Prince Edward Island, 550 University Avenue, Charlottetown, Prince Edward Island, Canada C1A 4P3. E-mail: jkemp@upei.ca
(2) MSc, Pag, Wildwood Labs Inc, 53 Blossom Drive, Kenville, Nova Scotia, Canada B4N 3Z1

In April 1999, imidacloprid was approved for use on potato crops across Canada as a broad spectrum insecticide. It is presently registered in 120 countries for use on over 140 crops. The good water solubility and systemic properties of imidacloprid makes it an ideal candidate for use on potatoes and numerous other crops for the treatment of a broad range of insect pests, including Colorado potato beetles. With the release of information from France that expressed concerns about a link between honey bee mortality and imidacloprid, some beekeepers in Prince Edward Island and New Brunswick, complained of similar problems with their bee colonies that were placed near clover fields that had been previously treated with ADMIRE®. Subsequently, Prince Edward Island beekeepers requested a moratorium on the use of Admire® on Prince Edward Island. With this concern expressed, it was important to determine if imidacloprid soil residue levels following use in potato fields was negatively affecting honey bee health on Prince Edward Island.

The objectives of this study were to determine if residue levels (ppb) of imidacloprid applied in-furrow, plus two metabolites, (hydroxy-imidacloprid and olefin-imidacloprid), were present one and two years following application of Admire in: 1) soil, clover leaves, clover flowers, and wild flowers, 2) pollen, and nectar collected from honey bees foraging in previously treated clover fields, and 3) uncapped honey collected from the hives placed in previously treated clover fields. Three classifications of fields were used in this study: 1) potato fields (Year 1 field), 2) underseeded grain fields (Year 2 field), 3) first and second flowering clover fields (Year 3 field), and 4) runoff areas of year 1 and year 2 fields were subcategories for soil and wildflower sampling. Samples were analyzed by High Performance Liquid Chromatography-Electrospray Ionization Mass Spectrometry (HPLC-MS/MS).

Residue levels of imidacloprid were detected in soil in all treated fields. The edges of sloped fields in first year rotation (i.e. potato fields) exhibited only one case of residue in the soil. Metabolites were not included in the soil analysis because honey bees are not exposed to them in the soil. Three fields had residue levels of imidacloprid in clover leaves at just above detectable levels. Otherwise, all clover flowers, wildflowers, pollen, nectar, and uncapped honey did not have detectable levels (<2 ppb) of imidacloprid or its hydroxy and olefin metabolites.

Honey bee colonies placed in clover fields that were previously treated with Admire®, did not show adverse effects during the time frame of this study. While residual levels of imidacloprid do not appear to be available to foraging honey bees, colony decline in Atlantic Canada continues for some beekeepers. While many beekeepers reported strong colonies by the end of the 2001 summer, preliminary information (Spring 2002) indicates colony losses (pollinator loss) may be higher than in 2001.

Beekeepers are presently reporting losses between 10 % (acceptable) and 90% (devastating), and need answers. The issue of honey bee decline throughout the Atlantic Region and Canada is critical, and needs to be solved before the pollination of regionally economically important crops is impacted. Therefore, an extensive monitoring project is scheduled in 2002/2003. This monitoring project will focus on honey bee management practices, diseases, and pesticides (including herbicides and fungicides) that may impact on honey bee mortality. The design of this multifactorial study and some preliminary findings are outlined during this presentation.