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Best Management Practices for Farmers Using Seeds Treated With Neonicotinoid
Insecticides
Dr. Kimberly Stoner
Neonicotinoids are a group of insecticides that have a mode of action similar to that of nicotine
and are often used as seed treatments because they can travel from the seed into the plant and
control insects feeding on plants as well as on the seed. Honey bees, native bees such as bumble
bees and mason bees, and many other native pollinators are critically important to Connecticut’s
agricultural community. While the primary concern is acute exposure to neonicotinoid
insecticides, particularly from airborne dust associated with planting of treated seed, there is
growing concern regarding the chronic exposure to foraging bees from nectar, pollen, and plant
guttation which supplies water bees transport back to the hive.
Four neonicotinoid insecticides that are highly toxic to honey bees and native bees such as
bumble bees are regulated by Connecticut Public Act 16-17 (An Act Concerning Pollinator
Health): clothianidin, dinotefuran, imidacloprid, and thiamethoxam.
Some common trade names for insecticides used as seed treatments with these active ingredients
are (1):
Clothianidin: Poncho, NipsItInside, Poncho/VOTiVO
Thiamethoxam: Cruiser
Imidacloprid: Gaucho
Although neonicotinoid seed treatments are used on a wide range of crop plants, including
soybean, cotton, canola, wheat, sunflower, potato, and many vegetables (1,2), reported honey
bee kills from neonicotinoids have most often been associated with dust from corn seed released
by vacuum planters at planting time (3,4,5,6). In addition to affecting honey bees and native
bees, neonicotinoids applied as seed treatments may also affect other beneficial insects (7,8) and
contaminate groundwater, streams and wetlands (9,10,11). Treated seeds are also attractive to
birds, and the amount of neonicotinoid on one treated corn kernel is enough to kill a songbird
(12). Thus, there are many reasons to be careful in using neonicotinoid-treated seeds.
General Principles for Best Management Practices:
1. Do not use seed treated with neonicotinoids unless there is a specific pest problem that
can be effectively managed with a neonicotinoid seed treatment.
2. When the use of neonicotinoids is not warranted, purchase seed that is not treated with
this group of chemicals (seeds may be treated with fungicides or other pesticides). If seed
selection is limited, contact your seed company’s field representative to request increased
selection and availability of seed that is not treated with neonicotinoids.
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3. Before planting with seeds treated with neonicotinoids, notify any nearby beekeepers, so
that they can protect their bees. Also remove flowering plants from the field and field
edges by mowing or tillage.
4. Read and follow all instructions on the seed tag including personal protective equipment
to be used in handling seed and required buffer zones.
5. Keep the treatment on the seed during storage and handling. Avoid storing seed under
extreme temperatures and excessive humidity that may increase the breakdown of the
seed treatment.
6. Reduce insecticide dust produced at planting, keeping the treatment on the seed as much
as possible. Load treated seed into planter boxes in a manner that will minimize the dust
from becoming airborne. Minimize any drift of dust outside the field. Most problems
with neonicotinoid-contaminated dust drifting in the air have been with treated corn
planted using vacuum planters. There is currently no single solution to this problem.
Options, including using deflectors or filters on the planting equipment and changing the
lubricant mixed with the seed, are discussed below.
7. Avoid planting on windy days when any dust will blow into the environment, particularly
if wind is blowing toward bee hives, flowering trees or standing water sources used by
bees.
8. Dispose of any leftover treated seed properly, following directions on the seed tag.
Generally it is best to plant it or bury it in an appropriate place away from water bodies.
9. Dispose of any dust left over in seed bags and filters properly, following any instructions
on the seed bag or using the hazardous waste collection process in your municipality.
(Because this is farm waste rather than household waste, there may be a fee.)
Specific Information:
Seed treatment with neonicotinoids has advantages when compared to application of pesticides
by other methods, particularly when used to control insect pests that feed on seeds or seedlings
early in the season. Neonicotinoids have a combination of high toxicity to insects and low
toxicity to mammals that make them safer than many of the older insecticides, and application to
the seed allows the amount applied per area to be greatly reduced compared to soil or foliar
applications (6, 13). However, several studies have found that neonicotinoid seed treatments are
being widely used in crops and regions where there is little or no economic benefit (14, 15), and
in some cases even reducing yield by killing off the natural enemies of pests (8). The Integrated
Pest Management (IPM) approach would call for using a preemptive pesticide treatment only
when there is a high probability of a target pest causing economic damage or when rescue
treatments cannot keep the target pest under the economic injury level (15, 17). This approach
would greatly decrease the use of seed treatments (15, 16) and the associated unintended
consequences of overuse of pesticides including evolution of insecticide resistance, outbreaks of
non-target pests, resurgence of target pests, and negative effects on the environment (14 ,16).
For some crops, neonicotinoid seed treatments have been overused in part because seed
producers sold these as part of a “package” along with fungicide treatment or genetic
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modifications for resistance to insects not controlled by neonicotinoids (14, 16). According to
Canadian authorities, most seed companies can accommodate orders for non-insecticide treated
seed (16).
As with any application of an insecticide highly toxic to bees, drift of insecticide dust onto bee
hives and onto flowering plants being used by bees should be avoided. Although research has
shown that honey bees are mostly using flowering trees such as maple, willow, apple, cherry,
and hawthorn at the time of spring planting (17), other spring flowering weeds and wildflowers
like clovers, dandelions and mustards are also used by honey bees (17) and mustards and clovers
are very important to bumble bees and other native pollinators (18, 19).
Although seeds of many different crops have been treated with neonicotinoids, bee kills at
planting have generally been associated with treated corn (3, 4, 5, 6, 21). A few studies of
treated seeds of other crops have found much less insecticide dust in batches of sugar beet and
oil seed rape seeds than in corn (6), although another detailed study found that wheat may have
as much risk of dust drift as corn (22).
The most important factors affecting the amount of dust released into the air when planting
neonicotinoid treated corn seeds are the quality of the seed treatment, the equipment used for
planting, and the weather conditions at the time of planting (6, 17, 21). The quality of the seed
treatment depends on how well the seed has been cleaned before treatment; the formulation of
the treatment, including the active ingredient (insecticide), polymers used to stick the active
ingredient to the seed; and film coatings added to the outside (6,17). The quality of the seed
treatment has been shown to be variable across corn varieties and among batches in various
studies (17, 21), and this has been correlated with bee kills (21) or with high levels of dust
released at planting (17).
The equipment used for planting has also been found to be important. Most farmers growing
corn use pneumatic precision seed planters, also called vacuum planters (5, 6, 17, 21). A few
studies have compared vacuum planters to planters using a mechanical method or compressed air
to place the seed, and have found that the planters without a vacuum produce much less dust (16,
21) and less hazard to bees (21) than vacuum planters. In vacuum planters, corn seeds are
precisely spaced in the row by using a vacuum, generated by a central fan, to aspirate the seeds
onto a perforated disk, and to keep each seed sticking to a single hole in the disk until the seed
drops into the furrow (5, 21). The fan draws air in through an air intake, and then exhausts it
through an outlet that is typically 4 to 6 feet above the ground (5, 21). A lubricant, such as talc or
graphite, may be used to keep the seeds from sticking together, but also abrades the seed and
creates insecticide dust, which mixes with the lubricant (23). This mixture of lubricant and
insecticide dust travels in different directions: some travels into the furrow and is planted with
the seed, some is exhausted into the air, and some remains behind in the planting equipment (23).
Xue et al. (5) have also shown that field dust is sucked in through the air intake, abrades the seed,
and then is exhausted into the air. Because neonicotinoid insecticides break down slowly and are
so heavily used, the field dust already has residues of a neonicotinoid (clothianidin) before it
goes into the planter, but the carry-over pesticide accounts for only 5% of the insecticide residue
in the aerial dust; 95% of the neonicotinoid residues are from seed dust (5).
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The combination of defective seed treatment and the vacuum planter system can create the
problem of dust highly toxic to bees traveling into the air and potentially coming into contact
with bees or plants used by bees (5, 6, 17, 21, 23). Various modifications have been tried with
some degree of success. After a large bee kill in Germany associated with poor quality seed
treatment of corn and vacuum planters (21), Bayer (the pesticide manufacturer) instituted
standardization of seed treatment, training of workers, and testing of seeds to make sure that dust
was minimized, and also worked with European equipment manufacturers to create kits to
modify the vacuum planters to release the exhaust air, and thus the dust, at a lower air speed
close to the ground, ideally into the furrows (6, 21). These deflectors were required in some
European countries, but they generated such a large amount of dust close to the ground that
many farmers refused to use them (6).
The province of Ontario requires farmers to use a new lubricant, Bayer Fluency Agent (ethane, a
homopolymer), rather than talc or graphite, when planting neonicotinoid-treated seed of corn or
soybeans (20). However, a direct comparison of this lubricant compared to the lubricants chosen
by farmers (talc, graphite or a mixture of the two) showed no significant difference in dust
released (17). A change in lubricant may not be effective in reducing insecticide dust if field dust
is also entering the system and abrading the seed (5).
There are many points at which farmers could modify the planting system: using no-till planting
to avoid generating field dust (5), filtering the air intake to limit field dust coming into the
planter (5), using a new seed lubricant to reduce abrasion of the seed (20), diverting the dust into
the seed furrow during planting (6, 21) or filtering the air exhaust (5, 6, 21). In my discussions
with scientists researching these options, none is currently considered the single best option
(Reed Johnson, Ohio State University; Art Schaafsma, Guelph University; personal
communication).
Once the planting is finished, it is important to collect any spilled seed and dispose of spilled and
leftover seed properly. Seeds left on the soil surface are particularly a hazard to birds. According
to a study by the American Bird Conservancy, a single corn kernel treated with any of the
commonly used neonicotinoids can kill a songbird, and 1/10 of a treated corn kernel is enough to
reduce reproduction in a songbird (12). Seed disposal instructions should be on the seed tag.
Generally it is recommended to plant leftover seed in the headland or in double rows in the field
or to bury it away from water bodies.
At the end of planting, the farmer may be left with seed bags contaminated with insecticide dust,
or if filters have been used on the air exhaust of the planter, these filters will have collected the
insecticide dust. Dust may also be left behind in the planting equipment, and should be
vacuumed out using a vacuum with a filter. This then leaves the farmer with the problem of
disposing of bags and filters with insecticidal dust. If there are instructions on the seed tag or
label about how to dispose of the dust, those should be followed. Otherwise, seal the material
securely and dispose of it using the local hazardous waste process. Because this is farm waste
and not household waste, there may be a fee.
References:
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1. Douglas, M.R. and Tooker, J.F., 2015. Large-scale deployment of seed treatments has
driven rapid increase in use of neonicotinoid insecticides and preemptive pest management
in US field crops. Environmental science & technology, 49(8), pp.5088-5097.
Supplemental Information online: http://pubs.acs.org/doi/suppl/10.1021/es506141g
2. Krupke, C.H. and Long, E.Y., 2015. Intersections between neonicotinoid seed treatments
and honey bees. Current Opinion in Insect Science, 10, pp.8-13.
3. Pistorius, J., Bischoff, G., Heimbach, U. and Stähler, M. 2009. Bee poisoning incidents in
Germany in spring 2008 caused by abrasion of active substance from treated seeds during
sowing of maize. Julius-Kühn-Archiv, 423: 118-126.
4. Cutler, G.C., Scott-Dupree, C.D., and Drexler, D.M. 2014. Honey bees, neonicotinoids, and
bee incident reports: The Canadian situation. Pest Management Science 70: 779-783.
5. Xue, Y., Limay-Rios, V., Smith, J., Baute, T., Forero, L.G. and Schaafsma, A., 2015.
Quantifying Neonicotinoid Insecticide Residues Escaping during Maize Planting with
Vacuum Planters. Environmental science & technology, 49(21), pp.13003-13011.
6. Nuyttens, D., Devarrewaere, W., Verboven, P. and Foqué, D., 2013. Pesticide‐laden dust
emission and drift from treated seeds during seed drilling: a review. Pest management
science, 69(5), pp.564-575.
7. Pisa, L.W., Amaral-Rogers, V., Belzunces, L.P., Bonmatin, J.M., Downs, C.A., Goulson,
D., Kreutzweiser, D.P., Krupke, C., Liess, M., McField, M. and Morrissey, C.A., 2015.
Effects of neonicotinoids and fipronil on non-target invertebrates. Environmental Science
and Pollution Research, 22(1), pp.68-102.
8. Douglas, M.R., Rohr, J.R. and Tooker, J.F., 2015. Neonicotinoid insecticide travels through
a soil food chain, disrupting biological control of non‐target pests and decreasing soya bean
yield. Journal of applied ecology, 52(1), pp.250-260.
9. Goulson, D., 2013. Review: An overview of the environmental risks posed by
neonicotinoid insecticides. Journal of Applied Ecology, 50(4), pp.977-987.
10. Hladik, M.L., Kolpin, D.W. and Kuivila, K.M., 2014. Widespread occurrence of
neonicotinoid insecticides in streams in a high corn and soybean producing region, USA.
Environmental Pollution, 193, pp.189-196.
11. Main, A.R., Michel, N.L., Cavallaro, M.C., Headley, J.V., Peru, K.M. and Morrissey, C.A.,
2016. Snowmelt transport of neonicotinoid insecticides to Canadian Prairie wetlands.
Agriculture, Ecosystems & Environment, 215, pp.76-84.
12. Mineau, P. and C. Palmer. 2013. The impact of the nation’s most widely used insecticides
on birds. American Bird Conservancy. http://abcbirds.org/wp-
content/uploads/2015/05/Neonic_FINAL.pdf
13. Elbert, A., Haas, M., Springer, B., Thielert, W. and Nauen, R., 2008. Applied aspects of
neonicotinoid uses in crop protection. Pest management science, 64(11), pp.1099-1105
14. Myers, C. and Hill, E., 2014. Benefits of neonicotinoid seed treatments to soybean
production. United States Environmental Protection Agency, Washington, DC, USA
15. Douglas, M.R. and Tooker, J.F., 2015. Large-scale deployment of seed treatments has
driven rapid increase in use of neonicotinoid insecticides and preemptive pest management
in US field crops. Environmental science & technology, 49(8), pp.5088-5097.
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16. Baute, T. 2014. New 2014 BMPs for Pollinator Protection and Use of Insecticide Treated
Seed. http://fieldcropnews.com/2014/01/new-2014-bmps-for-pollinator-protection-and-use-
of-insecticide-treated-seed/
17. Corn Dust Research Consortium (2015). Corn Dust Research Consortium Preliminary
Report. Initial Findings for 2014.
http://www.pollinator.org/PDFs/July2015CDRCFINAL.pdf
18. Westphal, C., Steffan‐Dewenter, I. and Tscharntke, T., 2003. Mass flowering crops
enhance pollinator densities at a landscape scale. Ecology Letters, 6(11), pp.961-965.
19. Goulson, D. 2010. Bumblebees: Behaviour, Ecology, and Conservation. 2nd edition. Oxford
University Press.
20. Health Canada. 2014. Pollinator Protection and Responsible Use of Insecticide Treated
Seed. http://fieldcropnews.com/wp-content/uploads/2014/01/pollinator-protecton-Jan-
9final.pdf
21. Nikolakis, A., Chapple, A., Friessleben, R., Neumann, P., Schad, T., Schmuck, R., Schnier,
H.F., Schnorbach, H.J., Schöning, R. and Maus, C., 2010. An effective risk management
approach to prevent bee damage due to the emission of abraded seed treatment particles
during sowing of seeds treated with bee toxic insecticides. Julius-Kühn-Archiv, (423),
p.132.
22. Foqu, D., Devarrewaere, W., Verboven, P., Nuyttens, D., Anderson, P.G., Balsari, P.,
Carpenter, P.I., Cooper, S.E., Glass, C.R., Magri, B. and Miller, P.C.H., 2014. Physical and
chemical characteristics of abraded seed coating particles. Aspects of Applied Biology, 122,
pp.85-94.
23. Krupke, C.H., Hunt, G.J., Eitzer, B.D., Andino, G. and Given, K., 2012. Multiple routes of
pesticide exposure for honey bees living near agricultural fields. PLoS one, 7(1), p.e29268.
Appendix
Best Management Practices for Treated Seeds from other sources:
American Seed Trade Association
www.seed-treatment-guide.com
For Farmers
http://seed-treatment-guide.com/wp-content/uploads/2014/12/ASTA-Seed-Guide-Farmers.pdf
Health Canada
Pollinator Protection and Responsible Use of Insecticide Treated Seed.
http://fieldcropnews.com/wp-content/uploads/2014/01/pollinator-protecton-Jan-9final.pdf
