Choosing Organic Pesticides over Synthetic Pesticides May Not Effectively Mitigate Environmental Risk in Soybeans

C. A. Bahlai¹, Y. Xue¹, C. M. McCreary¹, A. W. Schaafsma² and R. H. Hallett^1*

OACC Note: While the products described as 'organic' in this paper have been proposed for use in organic production, they are not registered for use in Canada on soybean, nor have they been accepted on the Permitted Substances List of Canada's Organic Standard."

Abstract
Background: Selection of pesticides with small ecological footprints is a key factor in developing sustainable agricultural systems. Policy guiding the selection of pesticides often emphasizes natural products and organic-certified pesticides to increase sustainability, because of the prevailing public opinion that natural products are uniformly safer, and thus more environmentally friendly, than synthetic chemicals.

Methodology/Principal Findings: We report the results of a study examining the environmental impact of several new synthetic and certified organic insecticides under consideration as reduced-risk insecticides for soybean aphid (Aphis glycines) control, using established and novel methodologies to directly quantify pesticide impact in terms of biocontrol services. We found that in addition to reduced efficacy against aphids compared to novel synthetic insecticides, organic approved insecticides had a similar or even greater negative impact on several natural enemy species in lab studies, were more detrimental to biological control organisms in field experiments, and had higher Environmental Impact Quotients at field use rates.

Conclusions/Significance: These data bring into caution the widely held assumption that organic pesticides are more environmentally benign than synthetic ones. All pesticides must be evaluated using an empirically-based risk assessment, because generalizations based on chemical origin do not hold true in all cases.

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Source
PLoS ONE 5(6): e11250
DOI:10.1371/journal.pone.0011250


Author Locations and Affiliations
(1) School of Environmental Sciences, University of Guelph, Guelph, Ontario, Canada
(2) Department of Plant Agriculture, University of Guelph, Ridgetown, Ontario, Canada
* Corresponding author, E-mail rhallett@uoguelph.ca


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Posted July 2010