gm-canola/report-6

Fewer wild bees were observed in glyphosate-resistant canola fields.

Manipulated Organism: anola (Brassica napus).

Inserted Transgenes: Resistance to the herbicide glyphosate (Roundup) has been engineered into canola with a combination of two genes: (1) a gene from Agrobacterium strain CP4 that produces a resistant form of the EPSPS enzyme targeted by glyphosate, and (2) a modified glyphosate oxidase gene from the bacterium Ochrobactrum, which accelerates the degradation of glyphosate.

Goal of This Study: Investigate bee abundance and activity in organic, conventional (non-GM), and GM canola fields in western Canada.

Results of This Study:

Across the three farming systems, a negative correlation was observed between bee abundance and "pollination deficit," defined as the improvement in seed set for hand-pollinated flowers compared with naturally pollinated flowers. The most bees were collected in the organic fields (342), which also had the lowest average pollination deficit (7% more seeds per pod by hand-pollination). The lowest number of bees were found in the GM canola fields (101), where hand-pollination improved seed set by 33%. In the conventional canola, 230 bees and an average pollination deficit of 21% were observed.
A complicating factor in this study was the fact that the canola in the "conventional and GM fields were different varieties, and therefore the greater seed deficit in GM fields could have been due to a higher dependence on pollinators for pollen transfer and seed set than the conventional variety examined. However, from our data, it seems unlikely that the conventional canola variety had a lower requirement for pollinators because at collection sites with low bee abundance, pollination deficit values were comparable to pollination deficit values in GM fields with similar pollinator abundances.... Our data suggests that the low number of pollinators in the GM fields resulted in the high pollination deficits" (p. 878).
The reduced bee abundance in the GM canola fields could be due to intrinsic qualities of the plants or the result of management practices. The authors suggest the latter: "Although insecticide treatments were similar between GM and conventional fields, GM fields were treated with Roundup, a highly effective herbicide, which resulted in lower weed diversity and abundance [and thus less forage for bees] within GM fields than in conventional fields" (p. 880).

Source: Morandin, L. A., and M. L. Winston (2005). "Wild Bee Abundance and Seed Production in Conventional, Organic, and Genetically Modified Canola," Ecological Applications vol. 15, pp. 871-81.

Author Affiliations: Simon Fraser University, British Columbia, Canada.

Funding: Bayer, Monsanto, the British Columbia Honey Producers Association, and the Canadian government.

Product Status: Glyphosate-resistant canola is grown on millions of acres in the U.S. and Canada.

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Seth JordanAugust 26, 2020