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UNITED STATES ENVIRONMENTAL PROTECTION AGENCY 

WASHINGTON, D.C. 20460 

OFFICE OF 

PREVENTION, PESTICIDES AND 

TOXIC SUBSTANCES

PC Code: 044309

Date: October 21, 2009 

DP Barcode: 370427 

MEMORANDUM

SUBJECT: Clothianidin Registration of New Products and New Uses of Sepresto 

75WS and PROCEEDTM OPTIMUM: Addendum to Address Mitigation 

of Bee Hazard 

FROM: Allen W. Vaughan, Entomologist 

 Environmental Risk Branch V 

 Environmental Fate and Effects Division (7507P) 

THROUGH: Mah T. Shamim, Branch Chief 

 Environmental Risk Branch V 

 Environmental Fate and Effects Division (7507P) 

 

TO: Kable Davis, Risk Manager Reviewer 

 Venus Eagle, Risk Manager 

 Meredith Laws, Branch Chief 

 Insecticide-Rodenticide Branch 

 Registration Division (7505P) 

EFED recently conducted a risk assessment for a number of proposed new agricultural 

uses for clothianidin products, under DP355370. That assessment characterized the 

potential hazard to foraging pollinators from uses of clothianidin on flowering plants. 

This addendum addresses in more detail the potential hazards to pollinators by 

identifying hazards for each crop and specific application method, and suggests measures 

to mitigate hazards for foliar uses of clothianidin. Because of the extreme persistence of 

clothianidin in soil environments (half-life = 148 to 1,155 days) and the potential for 

translocation of this systemic pesticide to pollen and nectar, EFED does not believe that 

precautionary bee labeling language will effectively mitigate hazards from soil treatment 

or seed application of clothianidin to cucurbits and fruiting vegetables. In addition, 

succeeding berry crops or rotational crops that are planted following soil treatment or 

seed application have the potential to expose bees to residues of clothianidin in the soil. 
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Background:

Clothianidin is a systemic nicotinoid insecticide that may be applied via foliar, soil, or 

seed application. Due to its systemic properties, it may be present in/on plant tissues 

following any method of application. Clothianidin is also highly toxic to bees on both an 

acute contact and oral exposure basis (LD50 = 0.0439 and 0.0037 ug a.i./bee, 

respectively), and is extremely persistent in soil environments. Thus, there is a concern 

from the proposed soil and seed treatment uses as well as proposed foliar application 

uses. 

The new uses involved in this request are leafy vegetables, Brassica leafy vegetables, 

fruiting vegetables, cucurbits, and low-growing berries, except strawberries (both foliar 

and soil); tree nuts, figs, pomegranates, cotton, peaches, and soybeans (foliar only).

Attached is a table developed by David Brassard of BEAD which provides detailed 

information regarding the potential for bee exposure from the proposed new uses. The 

information in the attached table regarding relative risk may be summarized as follows: 

Low potential for exposure to bees: Brassica leafy vegetables and leafy vegetables 

(crops are harvested prior to bloom); figs (bees are unlikely to visit this crop). 

Moderate /high potential for exposure, but risk may be mitigated for foliar uses if 

label precautions (which prohibit application prior to and during bloom) are

followed: foliar application to low-growing berries, cotton, cucurbits, fruiting 

vegetables, peaches, pomegranates, soybeans, and tree nuts. 

Potential for exposure in pollen/nectar following soil treatment: cucurbits, fruiting 

vegetables, and berries. Because clothianidin is extremely persistent in soil and is a 

systemic pesticide, there is a potential for this chemical to be translocated from the soil 

up through the plant into pollen and nectar. Translocation of clothianidin from the soil to 

the pollen and nectar of canola has been demonstrated in field studies conducted with 

clothianidin-treated seeds. In addition, studies conducted by Bonmatin 2005 have found 

that the nitroguanidine neonicotinoid, imidacloprid, which is in the same chemical class 

as clothianidin, translocates from the soil to the pollen of corn and sunflower plants.1 

Thus, there is a risk concern for pollinators foraging on blooming plants following seed 

or soil treatment. In addition because clothianidin is persistent in soil, residues may 

remain in the soil and be translocated into the nectar and pollen of succeeding and 

rotational crops. The potential for exposure of pollinators to clothianidin via this route is 

significant, but mitigation measures have not been developed to protect bees from 

exposure to soil-applied systemic pesticides. 

 

1

 Bonmatin, J.M., P.A. Marchand, R. Charvet, I. Moineau, E.R. Bengsh, and M.E. Colin. 2005. 

Quantification of Imidacloprid Uptake in Maize Crops. J. Agric. Food Chem. 53: 5336-5341; 

Bonmatin, J.M., I. Moineau, R. Charvet, M.E. Colin, C. Fleche, E.R. Bengsch. 2005. Behavior of 

Imidacloprid in Fields. Toxicity for Honey Bees. In Environmental Chemistry: Green Chemistry and 

Pollutants in Ecosystems, ed. E. Lichtfouse, J. Schwarzbauer, D. Robert. New York: Springer. 
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Potential for Honeybee Exposure to Clothianidin by Crop and Application Method 

Crop/Crop Group Pests application method Likelihood of 

application during 

bloom1 

Potential for 

honeybee

visitation 2

berries (lowgrowing)Cranberry weevil, flea beetles, Foliar post bloom Low High

Soil post bloom None3 High

Brassica leafy 

vegetables

Aphids, flea beetles, leafhoppers, 

whiteflies

Foliar Low Low

Soil None Low

Cotton Aphids, Lygus bugs, whiteflies foliar High Moderate

Cucurbits Aphids, flea beetles, leafhoppers, 

whiteflies

Foliar High High

Soil Medium-High4 High

Figs Dried fruit beetle, fig scale, vinegar 

flies

Foliar post bloom Low Low

Fruiting 

vegetables

Aphids, Colorado potato beetle, flea 

beetles, leafhoppers, Lygus bugs, 

pepper weevil, stink bugs, whiteflies

Foliar High Moderate

Soil Medium-High4 Moderate

leafy vegetables Aphids, flea beetles, leafhoppers, 

whiteflies

Foliar Low Low

Soil None Low

Peaches Aphids, leafhoppers, plum curculio, 

scale, stink bugs

Foliar post bloom Low High

Pomegranates Aphids, leafhoppers, sharpshooters, 

whiteflies

Foliar post bloom Low Moderate

Soybeans Aphids, bean leaf beetle, leafhoppers, 

Lygus bugs, stink bugs, whiteflies

Foliar High Moderate

Tree Nuts Aphids, hickory shuckworm, 

leafhoppers, leafhoppers mealybugs, 

pecan nut casebearer, scale, whiteflies

Foliar post bloom Low High

1

 Likelihood of application during bloom primarily determined by the presence of damaging pest 

populations during the blooming period; if growers adhere to the label restrictions against application 

during bloom, all of the entries in this column would be "low" except for berries, cucurbits, and fruiting 

vegetables. 

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Potential for honeybee visitation: high: crop frequently pollinated by honeybees transported to the field 

by commercial migratory beekeepers; moderate: crop naturally pollinated by honeybees and other 

pollinator species; low: crop does not require pollination by honeybees to reach marketable stage 

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Soil application of clothianidin to succeeding berry crops or rotational crops may pose a hazard to bees 

from residues that remain in the soil. 

4 The current label allows clothianidin to be applied to cucurbits and fruiting vegetables as a soil treatment 

at any time from planting through 7 days pre-harvest. Because this chemical is persistent in soil 

environments and systemic, any soil treatment prior to or during bloom may result in residues in pollen and 

nectar. Thus, there is a potential for hazard to pollinators even if the application is not made during bloom. 

Mitigation measures have not been developed to protect bees from this route of exposure.