Neonicotinoid-treated maize poses risks
for honey bees and non-target organisms without consistent crop yield benefit
New Study:
Krupke, C. H., Holland, J. D., Long, E. Y. and Eitzer, B. D. (2017),
Planting of neonicotinoid-treated maize poses risks for honey bees and
other non-target organisms over a wide area without consistent crop
yield benefit. J Appl Ecol. doi:10.1111/1365-2664.12924
Summary
1. Neonicotinoid insecticides are routinely used as seed treatments on most grain and oilseed crops in the USA, yet the extent and likelihood of spread of insecticide residues during planting has not previously been quantified.
2.
Honey bees,
Apis
mellifera,
are highly mobile and highly sensitive to neonicotinoid residues, presenting an
opportunity to estimate non-target exposures to neonicotinoids in mobile insects.
We measured neonicotinoid dust drift during maize sowing and used sites of
maize fields, apiary locations and honey bee foraging radii to estimate
likelihood of forager exposure. We performed a concurrent multi-year field
assessment of the pest management benefits of neonicotinoid-treated maize.
3.
Our results
indicate that over 94% of honey bee foragers throughout the state of Indiana are
at risk of exposure to varying levels of neonicotinoid insecticides, including
lethal levels, during
sowing of maize. We documented no benefit of the insecticidal seed treatments
for crop
yield during the study.
4. Synthesis and applications. We demonstrate movement of neonicotinoid residues well beyond planted fields occurs during maize sowing in Indiana. Based on locations of maize fields and apiaries in the state, the likelihood of neonicotinoid exposure for foraging honey bees is high.
Other non-target organisms are also likely to encounter neonicotinoid residues; we conservatively estimate that deposition of neonicotinoid residues on non-target lands and waterways will occur on over 42% of the state of Indiana during the period of maize sowing.
However, we also demonstrate that the risk to pollinators and other non-target organisms may be rapidly and dramatically reduced without yield penalties, by aligning use rates of neonicotinoid insecticides with pest incidence.
To read the study, copy and paste this link into your browser: http://onlinelibrary.wiley.com/doi/10.1111/1365-2664.12924/full
Other studies also raise doubts about the benefit of neonicotinoids to crop yield. Read more: What's the point of neonicotinoids?
Pssst ... spread the word!
