Apidologie 36 (2005) 623-633
DOI: 10.1051/apido:2005048

Contact and oral toxicity to honey bees (Apis mellifera) of agents registered for use for sweet corn insect control in Ontario, Canada

Janisse Bailey^a, Cynthia Scott-Dupree^a, Ron Harris^a, Jeff Tolman^b and Brenda Harris<sup>c

a</sup>  University of Guelph, Department of Environmental Biology, Guelph, ON, Canada N1G 2W1
^b  Agriculture and Agri-Food Canada, Southern Crop Protection and Food Research Center, 1391 Sandford St., London, ON, Canada N5W 4T3
^c  Dow AgroSciences Canada Inc., #201 - 1144 29th Av. N.E., Calgary, AB, Canada T2E 7P1

(Received 12 August 2005 - revised 1 March 2005 - accepted 1 April 2005; Published online: 15 November 2005)

Abstract - Assays were conducted to compare direct and residual contact and oral toxicities to honey bees of sweet corn insecticides and of Bt-sweet corn. Direct contact assays focusing on LC₅₀ determined that technical grade clothianidin was most toxic, > carbofuran, > imidacloprid = spinosad, > lambda-cyhalothrin, > Bacillus thuringiensis. In residual contact assays, forager age bees were exposed to treated non-transgenic sweet corn tassels. Carbofuran treated tassels caused significant mortality up to 2 and 3 days after treatment (DAT) in 2002 and 2003, respectively. Lambda-cyhalothrin treated tassels had no impact on honey bees in 2002; in 2003, their toxicity was significantly higher than the untreated control tassels for 1 DAT. In both years, spinosad, imidacloprid and clothianidin or Bt-sweet corn tassels had no impact on honey bee mortality. Pollen collected from insecticide field treated corn and fed to honey bees had no impact on mortality.

Key words: Apis mellifera / sweet corn / foliar insecticides / seed treatment / Bt-sweet corn / toxicity

Corresponding author: Cynthia Scott-Dupree cscottdu@uoguelph.ca

© INRA, DIB-AGIB, EDP Sciences 2005