Consumption of field-realistic doses of a widely used mito-toxic fungicide reduces thorax mass but does not negatively impact flight capacities of the honey bee (Apis mellifera)

Authors: GLASS, JORDAN - Arizona State University; FISHER, ADRIAN - Arizona State University; FEWELL, JENNIFER - Arizona State University; DeGrandi-Hoffman, Gloria; OZTURK, CAHIT - Arizona State University; HARRISON, JON - Arizona State University

Submitted to: Environmental Pollution
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 1/5/2021
Publication Date: 1/20/2021
Citation: Glass, J.R., Fisher, A., Fewell, J.H., Hoffman, G.D., Ozturk, C., Harrison, J.F. 2021. Consumption of field-realistic doses of a widely used mito-toxic fungicide reduces thorax mass but does not negatively impact flight capacities of the honey bee (Apis mellifera). Environmental Pollution. 274. Article 116533. https://doi.org/10.1016/j.envpol.2021.116533.
DOI: https://doi.org/10.1016/j.envpol.2021.116533

Interpretive Summary: Populations of honey bees (Apis mellifera) are in decline, but the causes, including the role of agrochemicals in colony losses, remain unclear. In this study, we investigated the effects on morphology and flight performance of honey bee workers that consumed pollen containing a widely used fungicide Pristine ®. We fed field colonies pollen with a concentration of Pristine ® (2.3 ppm) in the low range of levels found in corbicular pollen collected from bees foraging in California almond orchards sprayed with this fungicide. We also tested concentrations two orders of magnitude higher (230 ppm). Both doses produced bees with smaller thoraxes, potentially reducing flight muscle size and maximal flight performance. To challenge flight behavior and elicit near maximal metabolic rate, we measured flight quality and metabolic rates of bees in two lower-than-normal air densities. Chronic consumption of 230 ppm Pristine ® reduced flight performance and metabolic rates in low-density air, but we found no evidence that the field-relevant dose (2.3 ppm) reduced flight metabolic rates or capacities.

Technical Abstract: Populations of honey bees (Apis mellifera) are in decline, but the causes, including the role of agrochemicals in colony losses, remain unclear. In this study, we investigated the effects of chronic consumption of pollen containing a widely used fungicide on the morphology and flight performance of honey bee workers. We fed field colonies pollen with a concentration of Pristine ® (2.3 ppm) in the low range of levels found in corbicular pollen collected from bees foraging in California almond orchards sprayed with this fungicide, and a concentration two orders of magnitude higher (230 ppm). Both doses produced bees with smaller thoraxes, potentially reducing flight muscle size and maximal flight performance. To challenge flight behavior and elicit near maximal metabolic rate, we measured flight quality and metabolic rates of bees in two lower-than-normal air densities. Chronic consumption of 230 ppm Pristine ® reduced flight performance and metabolic rates in low-density air, but we found no evidence that the field-relevant dose (2.3 ppm) reduced flight metabolic rates or capacities.