Field and laboratory tests of the effects of fipronil on adult female bees of Apis mellifera, Megachile rotundata and Nomia melanderi
Author(s)
D F Mayer; J D Lunden
Abstract
The toxicity of fipronil (5-amino-1[2,6-dichloro-(trifluoromethyl)phenyl-4(trifluorormethyl)sulfinyl]-1H-pyrazola-3-carbonitrate), to adult emale bees was least to the alkali bee, Nomia elanderi, (LD50 = 1.130 µg/bee), intermediate to the honey bee, Apis mellifera, (0.013 µg/bee) and greatest to the alfalfa leafcutter bee, egachile rotundata, (0.004 µg/bee), both in topical tests and tests involving fipronil residues on alfalfa (Medicago sativa) foliage. Adding an adjuvant to fipronil sprays changed the toxicity of fipronil to bees in residue bioassay studies with varying results with adjuvant and species of bee. Fipronil at 100 ppm and 500 ppm in feeders containing a sucrose/honey syrup caused a significant reduction in honey bee visitation. Spraying fipronil at 0.014 or 0.028 kg a.i./ha on flowering canola (Brassica napus cv. Legend) did not cause significant mortality of adult honey bees or reduce bee visitation.
