> Eight months later, Theobald found the study online. In an article he wrote for Bee Culture, he summarized it as follows: "Here's what the life cycle study of bees and canola consisted of: four colonies of bees were set in the middle of one hectare (2 1/2 acres) of canola planted from treated seed, with the bees free to forage over thousands of surrounding acres in bloom with untreated canola, which they most surely did. What do you think the results were? They were exactly what Bayer wanted of course."

I assume he is referring to this study, which was done by G. CHRISTOPHER CUTLER AND CYNTHIA D. SCOTT-DUPREE
Department of Environmental Biology, Ontario Agricultural College, University of Guelph.

We conducted a long-term investigation to ascertain effects on honey bee, Apis mellifera L., colonies during and after exposure to flowering canola, Brassica napus variety Hyola 420, grown from clothianidin-treated seed. Colonies were placed in the middle of 1-ha clothianidin seed-treated or control canola fields for 3 wk during bloom, and thereafter they were moved to a fall apiary. 

There were four treated and four control fields, and four colonies per field, giving 32 colonies total. Bee mortality, worker longevity, and brood development were regularly assessed in each colony for 130 d from initial exposure to canola. Samples of honey, beeswax, pollen, and nectar were regularly collected for 130 d, and the samples were analyzed for clothianidin residues by using high-performance liquid chromatography with tandem mass spectrometry detection. 

Overall, no differences in bee mortality, worker longevity, or brood development occurred between control and treatment groups throughout the study. Weight gains of and honey yields from colonies in treated fields were not significantly different from those in control fields. Although clothianidin residues were detected in honey, nectar, and pollen from colonies in clothianidin-treated fields, maximum concentrations detected were 8- to 22-fold below the reported no observable adverse effects concentration. Clothianidin residues were not detected in any beeswax sample. 

Assessment of overwintered colonies in spring found no differences in those originally exposed to treated or control canola. The results show that honey bee colonies will, in the long-term, be unaffected by exposure to clothianidin seed-treated canola.

Both pollination by bees and pesticide treatments are essential components of modern agriculture. Unfortunately, these two elements of agroecosystems are sometimes incompatible, with bees and the beekeeping industry having sustained losses through pesticide poisoning. 

Although use of systemic insecticide seed treatments is generally regarded a more ecologically sound alternative to foliar insecticide applications, systemic insecticides may be translocated to pollen or nectar during development of the seed-treated crop, meaning pollinators foraging on these plants could be exposed to toxin. 

Concerns of adverse effects of imidacloprid seed treatments on pollinators has been a subject of much debate (Schmuck et al. 2001, Maus et al. 2003, Faucon et al. 2005), but our knowledge of potential impacts of clothianidin, a new chloronicotinyl insecticide, on pollinators is minimal. 

In the current study we attempted to use a realistic, worst-case scenario for honey bee exposure to clothianidin seed-treated canola. Seed was successfully treated with clothianidin at the highest recommended commercial rate for Canada and planted at a high seeding rate in 1-ha fields, ensuring ample forage for worker bees. 

Honey bee colonies were placed in the middle of canola fields during the bloom period, ensuring maximum exposure, and then they were moved to a fall apiary near bloom end. Little alternative forage was available to workers while in canola fields, and workers actively foraged on the canola. 

To assess potential long-term impacts, data were collected intensely over 130 d during summer and fall, and again in the spring. Overall, we found no differences between colonies from clothianidin-treated and control fields.

Exposure to Clothianidin Seed-Treated Canola Has No Long-Term Impact on Honey Bees. 

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