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to both the fate and toxicity of imidacloprid. A recent review of the current literature after the 

completion of the Final Work Plan provides further insight into the potential for imidacloprid to 

concentrate in plant reproductive parts. While open literature data reviewed by EFED to date 

primarily focuses on only a few crops, they reveal that imidacloprid will move into the plant 

parts at different concentrations based on the type of plant (i.e. corn pollen will have different 

concentrations of imidacloprid compared to sunflower pollen) and the part of the plant (i.e.

pollen will have different concentrations of imidacloprid compared to nectar). Therefore, the 

EFED concludes that information on imidacloprid concentrations, in various plant parts for 

different crops is essential to understanding the potential effects of imidacloprid to terrestrial 

non-target invertebrates. 

To determine the sites on which to require residue data, the Agency considered several variables, 

such as the estimated usage, the application method, and if the crop was relevant to managed 

pollinators (i.e., whether the crop relied on managed pollinators for propagation, or whether 

managed pollinators relied on the crop as a food source). Five crops were selected based on 

these criteria: corn, citrus, stone fruit (cherry), bushberry (blueberry), and cotton. While 

imidacloprid is registered on a large number of crops, data on all crops (or from the same crop in 

different regions) is not considered necessary at this time. The Agency will use the subject data 

on a select number of sites as surrogate information for other imidacloprid use sites for which 

data is not being required. 

EFED believes that a better understanding of the fate and expression of imidacloprid in different 

plant matrices on crops is necessary to support a national level assessment, which therefore 

establishes reason for the EFED to amend its data requirements for the imidacloprid registration 

review. The DCI justification is provided below for the various crops. 
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Guideline Number: Non-guideline 

Study Title: Field Residue Test of Leaves, and/or Nectar, and/or Pollen in Citrus, 

Bushberry (Blueberry), Cotton, Corn and Stone Fruit (Cherry) 

Rationale for Requiring the Data 

At the present time, EPA does not have scientifically valid exposure data for imidacloprid to assess the 

risk of this pesticide to pollinators. Imidacloprid is a systemic pesticide that is extremely toxic to bees on 

an acute basis and has also shown sublethal and chronic toxicity. It is also persistent in soil environments 

and translocates from the soil to the pollen and nectar of flowering plants. While open literature data 

reviewed by EFED to date primarily focuses on only a few crops, they reveal that imidacloprid will move 

into the plant parts at different concentrations based on the type of plant (i.e. corn pollen will have 

different concentrations of imidacloprid compared to sunflower pollen) and the part of the plant (i.e.

pollen will have different concentrations of imidacloprid compared to nectar). EPA therefore needs 

residue data in the leaves, and/or pollen, and/or nectar of several crops in order to estimate the exposure of 

bees to imidacloprid. The EPA selected five crops based on certain selective criteria, which includes 

several variables such as the estimated usage, the application method, and if the crop was relevant to 

managed pollinators (i.e., whether the crop relied on managed pollinators for propagation, or whether 

managed pollinators relied on the crop as a food source). Sampling of citrus, blueberry, and stone fruit 

must include leaves, pollen and nectar; sampling of cotton must include leaves and nectar; and, sampling 

of corn (seed treatment) must include leaves and pollen. These studies are intended to provide information 

on the levels of imidacloprid that may be found in different plant matrices and which may lead to exposure 

to insect pollinators. Without exposure data, EPA cannot assess risk to pollinators. 

Practical Utility of the Data 

How will the data be used? 

The data will be used to assess exposure and risk of imidacloprid to non-target endangered and nonendangered insect species, including pollinators. Exposure data is an integral part of the risk equation for 

determining the impact of pesticides to beneficial insect communities through direct exposure from their 

food sources. 

How could the data impact the Agency’s future decision-making? 

EPA is required by section 7(a)(2) of the ESA to ensure that any action it authorizes or takes “...is not 

likely to jeopardize the continued existence of any endangered or threatened species or result in the 

destruction or adverse modification of critical habitat” and “to use the best scientific data available” in 

carrying out this obligation. The data EPA intends to call in are necessary to inform the determination 

required by the ESA as to whether continued registration of a pesticide is not likely to jeopardize the 

species or its critical habitat. Absent this data EPA may not be able to conclude that this pesticide will not 

harm endangered species and may therefore need to consider other limitations on the use of the pesticide 

in order to fulfill the Agency’s statutory obligations under the ESA. The lack of these data will limit the 

flexibility that the Agency and registrants have in coming into compliance with the ESA and could result 

in use restrictions which are unnecessarily severe. In addition, the lack of these data may result in an 

uncertain assumed risk and potential mitigation of imidacloprid formulations under FIFRA.