Wild Bees
Reject Genetically Engineered Crop--Potential Major Impact
on Pollination
Wild bee abundance and seed production in conventional,
organic, and genetically modified canola.
By Morandin, LA; Winston, ML; lora_morandin@sfu.ca
Ecological Applications [Ecol. Appl.]. Vol. 15, no. 3, pp. 871-881., Jun 2005
Web Note: The following is the abstract of a scientific paper
published in June 2005. Though this is not recent news, it is
very interesting in the context of the recent honeybee disappearances.
Abstract. The ecological impacts of agriculture are of concern,
especially with genetically modified and other intensive, modern
cropping systems, yet little is known about effects on wild bee
populations and subsequent implications for pollination. Pollination
deficit (the difference between potential and actual pollination)
and bee abundance were measured in organic, conventional, and
herbicide-resistant, genetically modified (GM) canola fields
(Brassica napus and B. rapa) in northern Alberta, Canada, in
the summer of 2002.
Bee abundance data were collected using pan traps and standardized
sweep netting, and pollination deficit was assessed by comparing
the number of seeds per fruit from open-pollinated and supplementally
pollinated flowers. There was no pollination deficit in organic
fields, a moderate pollination deficit in conventional fields,
and the greatest pollination deficit in GM fields. Bee abundance
was greatest in organic fields, followed by conventional fields,
and lowest in GM fields. Overall, there was a strong, positive
relationship between bee abundance at sampling locations and
reduced pollination deficits. Seed set in B. napus increased
with greater bee abundance. Because B. rapa is an obligate outcrossing
species, the lack of pollination deficit in the organic (B. rapa)
fields likely was due to the high bee abundance rather than a
lower dependence of B. rapa on pollinators than B. napus canola.
Our study illustrates the importance of wild bees to agricultural
production and suggests that some agroecosystems may better sustain
wild bee abundance, resulting in greater seed production.
Further research on why some cropping systems, such as genetically
modified, herbicide-resistant canola, have low wild bee abundance
would be useful for management of agroecosystems to promote sustainability
of food production. Key words: agriculture; bees; Brassica rapa;
Brassica napus; canola; conventional; genetically modified; organic;
pollination; sustainable development.
Manuscript received 3 September 2003; revised
3 September 2004; accepted 8 September 2004. Corresponding
Editor: C. R. Linder © Copyright
by Ecological Society of America 2005
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