DP Barcode: D425260 MRID: 49535601 

1

Reference

Miller, A., Bowers, L., Dyer, D., and Jerkins, E. (2014). Determination of the Residues of Imidacloprid 

and its Metabolites 5-Hydroxy Imidacloprid and Imidacloprid Olefin in Bee Relevant Matrices 

Collected from Cherry Trees following Foliar Application of Imidacloprid over Two Successive Years.

Study ID EBNTY008. Bayer Crop Science, Research Triangle Park, NC. MRID 49535601

1. STUDY INFORMATION

Chemical: Imidacloprid PC Code 129099

Test Material Gaucho 600 FL Admire Pro 

Systemic Protectant (SC)

Purity 42.9 – 43.5% a.i. w.w.

Study Type: Non-Guideline field residue study on cherry to establish imidacloprid and 

metabolite levels in pollen, nectar, flowers, leaves and soil after two successive 

annual foliar applications. 

Sponsor: Bayer Crop Science AG

2 T. W. Alexander Drive 

Research Triangle Park, NC 

USA 27709

Performing Laboratories:

(Analytical; Pollen, Nectar): Bayer Crop Science 

AG, 2 T. W. Alexander Drive Research Triangle 

Park, NC USA 27709 

(Analytical; Leaf, Flower, Soil): SynTech Research 

Laboratory Services, 17745 S. Metcalf Ave, 

Stillwell, KS 66085

(Trial NT007 / NT008-12ZA): Reality Research, 

5916 South Ave, Williamson, NY 14589

(Trial NT016 / NT017-12ZA): Columbia Ag 

Research Inc. 5601 Binns Hill Dr., Hood River, OR 

97031)

Sponsor Study 

ID: EBNTY008

Study 

Completion 

Date: 12 December 2014

Experiment 

Start/End Date: 12 Aug. 2012 – 3 Sept. 2014

Study Location: 4 Field Trials:

Alton, NY (NT007); 

Lyons, NY (NT008); 

Mosier, OR (NT016 & 

NT017) 

GLP Status: GLP-compliant; protocol reviewed by EPA, PMRA, CDPR

2. REVIEWER INFORMATION

Primary Reviewer:

Signature:

Keith Sappington, M.S., Senior Biologist/Science Advisor, ERB5, 

Environmental Fate and Effects Division, Office of Pesticide Programs, USEPA

Date: 1/28/2016

3. EXECUTIVE SUMMARY

This study was designed to measure the magnitude of imidacloprid residues in bee-relevant pollen and 

nectar samples and in/on flowers, leaves, and soil from cherry trees after five post bloom foliar 

applications of 0.1 lb a.i./A conducted the previous growing season (current U.S. label rate). Four separate 

trials were conducted in NY (NT007, NT008) and OR (NT016, NT017) cherry orchards, each with a treated 

(TRTD) and untreated control (UTC) plot. Each year, five foliar applications (0.1 lb a.i./A x 5) were made, 

with a retreatment interval ranged from 8-11 days. The first year applications (2012) were made after 

cherry harvest in late summer/early fall (BBCH 91; shoot growth completed, green foliage). The second 

year applications were made prior to cherry harvest during June/July 2013 (BBCH stage 71-73). Samples 
DP Barcode: D425260 MRID: 49535601 

2

of flowers, pollen, nectar and leaves were made at various sampling times during the flowering period of 

the growing season after pesticide application. Soil samples were also collected. QA/QC included field 

and lab storage/stability samples, blanks, and matrix spikes to validate analyte recovery. 

Results indicate post-bloom, foliar application of approximately 0.1 lb a.i./A x 5 results in residues of total 

IMI (sum of IMI, IMI-olefin and 5-OH-IMI) in individual composite nectar samples of up to 10 ppb and 

1000 ppb in pollen. Mean residues of total IMI in nectar varied from 1.6 – 3.7 ppb and those for pollen 

varied from 1.7-422 ppb. Within each trial/year, total IMI residues in pollen were approximately 1-2 

orders of magnitude greater than those observed in nectar. Mean concentrations of total IMI in cherry 

nectar measured after foliar applications during the previous late summer/early fall (Year 1) were about 

2X those measured after foliar applications during late spring/early summer (year 2) across all trials. A 

larger difference was observed in mean pollen concentrations (about 10X) across trial years. It is not clear 

if this finding reflects seasonal differences in IMI translocation or longer intervals between pesticide 

application and residue measurement associated with year 2.

Mean concentrations of total IMI measured in pollen from the NY study trails were about 10X those 

measured in pollen from the OR trial sites. Similar results were observed with total IMI residues measured 

in flowers and leaves. Two metabolites of IMI (IMI-olefin and 5-OH-IMI) typically represented < 10% of 

total IMI residues in pollen and nectar. The predictability of total IMI residues in nectar and pollen based 

on measured concentrations in other plant matrices (flowers, leaves) was generally poor. Limited 

sampling of plant matrices over each growing season prevented determination of reliable estimates of 

dissipation kinetics (DT50) in plant matrices.

4. STUDY VALIDITY

Guideline Followed: Non-guideline study (protocol was reviewed by EPA/PMRA/CDPR)

Guideline Deviations: N/A

Other Deviations: Sample times to freezer storage sometimes exceeded the 4 hours 

specified in the protocol, but samples were maintained in a cooler with 

blue ice, so this deviation does not impact the study results.

Classification: ACCEPTABLE

Rationale: No major deviations were identified in this study that would affect the 

scientific integrity of this study 

Reparability: N/A

5. MATERIALS AND METHODS

Test Material Characterization

Test item: Gaucho 600 FL Admire Pro 

Systemic Protectant SC 

(Imidacloprid) 550 g a.i./L

CAS #: 138261-41-3

Description: N/A Purity: 42.9 %. & 43.5% w/w

Lot No./Batch No. Batch No. NK41BX0170;

NK41CX0578

Density: 1.41 – 1.54 g/mL

Material Source: Bayer Crop Science Cert. # 212PG1962; 213CJ2446

Material Receipt 

Date:

Not reported Analysis 

Date: 03/30/2012; 12/03/2012

Expiration Date: 03/31/2014; 12/3/2014 Solubility: 0.51-0.61 g/L
DP Barcode: D425260 MRID: 49535601 

3

Test Material Characterization

Storage of Test Mat’l: Ambient (47-83

o

F) Sample 

Storage: -13

o

to -18

o

F

5A. STUDY DESIGN

This study was designed to measure the magnitude of imidacloprid residues in bee-relevant pollen and 

nectar samples and in/on flowers, leaves, and soil from cherry trees following five pre-bloom foliar 

applications per year of ADMIRE PRO Systemic Protectant containing 550 g/L imidacloprid (IMI). In 

addition to quantifying the magnitude of residues, this study was designed to evaluate the following 

additional attributes:

1) The extent of year-to-year ‘carry over’ of pesticide residues measured in plant and soil 

matrices

2) The dissipation rates of IMI/metabolite residues over time in plant matrices

3) The extent to which toxicological relevant metabolites (IMI-olefin, 5-hydroxy-IMI) occurred in 

these matrices

4) The relationship of IMI/metabolite residues among different plant tissues (pollen, nectar, leaf, 

flower). 

Four separate trials were conducted, each with a treated (TRTD) and untreated control (UTC) plot. Each 

treated plot was divided into 5 subplots each with at least 3 trees (15 total trees). Each year, five foliar 

applications (0.1 lb a.i./A x 5) were made at intervals ranging from 8-11 days. The first year applications 

(2012) were made after cherry harvest in late summer/early fall (BBCH 91; shoot growth completed, 

green foliage). The second year applications were made prior to cherry harvest during June/July 2013 

(BBCH stage 71-73). Five composite samples of flowers, pollen, nectar and leaves were made at various 

sampling times during the flowering period from each TRTD plot/year. Nine composite soil samples were 

collected prior to treatment and at the end of the growing season from each TRTD plot/year. Control 

plots were sampled for all cherry matrices (two composites) and soil (9 composites) at the same time the 

TRTD plots were sampled. QA/QC included field and lab storage/stability samples, blanks, and matrix 

spikes to validate analyte recovery. 

5B. APPLICATION TIMING AND RATES

During each of the two successive years, five foliar applications of approximately 0.1 lb a.i./A were applied 

at intervals from 8-11 days apart at each of the four treatment sites (total annual application rate = 0.5 lb 

a.i./A). All applications were made with adjuvant (Dyne-Amic, 0.3%) using a ground-based air blast 

equipment. The volume of application was similar across trials and years (data not shown). In addition, a 

control (untreated) site was also included for each of the four trials. All FIRST YEAR applications were

made after cherry harvest at BBCH growth stages 91 (shoot growth completed, foliage still fully green). 

All YEAR TWO applications were initiated prior to cherry harvest between BBCH growth stages 73 and 75

(second fruit fall – fruit about half size). 

Information on application timing is shown in the Table 1.
DP Barcode: D425260 MRID: 49535601 

4

Table 1. Summary of foliar application rates and timing

Location Cherry

Variety

Year Appl. No. Appl. Date 

(DAFA/Stage)1

Individual Rate

(lb a.i./A)

Total Rate 

(lb a.i./A)

Trial NT007-12ZA

Alton, NY Montmorency

2012 1-5

8/31/2012 – 10/3/2012

(0-33/ BBCH 91) 0.100 0.50

2013 1-5

6/5//2013- 7/15/2013

(278-318/ BBCH 73-85) 0.100-0.102 0.50

Trial NT008-12ZA

Lyons, NY

Montmorency

2012 1-5

9/3/2012 – 10/8/2012

(0-35 / BBCH 91)

0.100 0.50

2013 1-5

6/5/2013 – 7/15/2013

(275-315 / BBCH 74-85)

0.100 0.50

Trial NT016-12ZA

Mosier, OR Skeena

2012 1-5

8/11/2012 – 9/13/2012

(0-33/ BBCH 91) 0.098-0.102 0.50

2013 1-5

6/5/2013 – 7/11/2013

(298-334 / BBCH 74-87)

0.099-0.102 0.50

Trial NT017-12ZA

Mosier, OR Bing

2012 1-5

8/11/2012 – 9/13/2012

(0-33/ BBCH 91) 0.101-0.102 0.51

2013 1-5

5/28/2013 – 7/1/2013

(290-324 / BBCH 75-87)

0.100-0.102 0.50

1 DAFA = days after 1st application; BBCH = plant growth stage.

5C. STUDY SITE LOCATION AND CHARACTERISTICS 

Various aspects of the study sites are summarized in Table 2. In general, soil type, plot size, row/plant 

spacing, and tree age were similar among the three study sites/trials. Three different varieties of cherry 

were used among the four trials. 

Table 2. Summary of Cherry study site characteristics (treated sites only).

Attribute Trial NT007-12ZA

Alton, NY

Trial NT008-12ZA

Lyons, NY

Trial NT016-12ZA

Mosier, OR

Trial NT017-12ZA

Mosier, OR

Plot ID TRTD12/13 TRTD12/13 TRTD12/13 TRTD12/13

Variety Montmorency Montmorency Skeema Bing

Crop Age 12 15 15 12

Soil Type Sandy loam Sandy loam Sandy loam Sandy loam

Plot Length 176 ft 272 ft 204 ft 170 ft

Plot Width 45 ft 60 ft 54 ft 60 ft

Plot Area 7920 ft2 16320 ft2 11016 ft2 20,200 ft2

Row Spacing 15 ft 20 ft 18 ft 20 ft

Plant 

Spacing 

8 ft 16ft 12ft 10ft
DP Barcode: D425260 MRID: 49535601 

5

Attribute Trial NT007-12ZA

Alton, NY

Trial NT008-12ZA

Lyons, NY

Trial NT016-12ZA

Mosier, OR

Trial NT017-12ZA

Mosier, OR

within Row

Lat. Long. NN43°10.568'

W76°57.674

N43°09.733'

W76°58.048

N45°40.617'

W121°22.094

N45°40.329'

W121°21.973

A summary of soil and meteorological data from the three study sites is shown in Table 3. Soil from trial 

NT007 contained the greatest amount of organic carbon (3.4%) while soils from the other trials ranged 

from 0.9 to 1.5% organic carbon. Soils from all four sites had similar % sand (53%-67%) but the % silt at 

site NT007 (17%) was about half that of the other sites (27-33%). Total precipitation was similar among 

sites, although year 2 data were unavailable from Trial NT017 because trees were removed by the grower 

in July 2013 from this site. 

The two NY trial sites (NT007 and NT008) were in close proximity as were the two OR sites (NT016 and 

NT017; see Appendix A). Therefore, the NY sites shared the same weather data as did the OR sites 

(Figure 1). Therefore, to the extent that variation in weather affects residue levels in cherry trees, the NY 

sites and OR sites can be considered replicates from a weather perspective. The NY trial sites were not 

irrigated during the study period while the OR sites were irrigated (2-6 in/month from May-Sept of each 

year).

Table 3. Soil and meteorological characteristics of the study sites* 

* (from Table 3 of study report)
DP Barcode: D425260 MRID: 49535601 

6

Figure 1. Monthly precipitation for the 4 study trial sites (NT007 & NT008 share the same weather data 

and NT016 and NT017 also share the same data for year 1 only)

5D. SAMPLE COLLECTION, HANDLING, PROCESSING

Plant Matrices. Samples that were treated in 2012 were harvested in 2013 (this period inclusively

considered year 1 of the study), and samples treated in 2013 were harvested in 2014 (year 2 of the study).

Each treated plot TRTD was divided into 5 subplots. In trials NT007-12ZA, NT008-12ZA, and NT016-12ZA, 

one composite (separate runs through each subplot) samples of cherry flowers for direct analysis, flowers 

to be processed for nectar and pollen, and leaves was collected by hand at each sampling period from 

each subplot (for 5 total samples) in both study years. In trial NT017-12ZA, no samples after the fall 2013

applications were collected because the trees were removed from the orchard by the grower. Samples 

were taken from the same trees at each sampling interval and in successive years. Cherry pollen and 

nectar samples were harvested by hand at the field trial site from the flowers collected for processing. 

Cherry flowers were collected when the trees were at growth stages of BBCH 61 and 65 (BBCH 61: 

beginning of flowering, about 10% of flowers open; BBCH 65: full flowering, at least 50% of flowers open 

and first petals falling), corresponding to 205 to 218 days after the last application (DAA) in year 1 and 274 

to 303 DAA in year 2. The exception is trial NT007-12ZA, which could not harvest BBCH 61 flowers in year 

2 due to weather. Cherry leaves were collected when the trees were at growth stages of BBCH 65 and 69 

(BBCH 69: end of flowering, all petals fallen), corresponding to 209 to 232 DAA in year 1 and 279 to 312 

DAA in year 2. 

Table 4. Sampling dates and cherry developmental stages for plant residue analysis

Pollen, Nectar and Flower Sampling Leaf Sampling

Year 1 Year 2 Year 1 Year 2

BBCH* DAA* BBCH DAA BBCH DAA BBCH DAA

NT007

61 212 61 302 65 215 65 302

65 215 --- --- 69 232 69 312

NT008

61 208 61 300 65 210 65 303

65 210 65 303 69 227 69 312
DP Barcode: D425260 MRID: 49535601 

7

Pollen, Nectar and Flower Sampling Leaf Sampling

Year 1 Year 2 Year 1 Year 2

BBCH* DAA* BBCH DAA BBCH DAA BBCH DAA

NT016

61 214 61 274 65 218 65 279

65 218 65 279 69 228 69 285

NT017

61 205 --- --- 65 209 --- ---

65 209 --- --- 69 223 --- ---

*BBCH = Biologische Bundesanstalt, Bundessortenamt und CHemische Industrie growth stage scale for cherry; DALA 

= days after last application

Soil. Nine soil samples were collected twice during the first year of the study, prior to the first a.i.

application in 2012 and after the last sampling per plot in 2013, with the exception of trials NT007-12ZA 

and NT008-12ZA, in which the last leaf collection took place after the year 1 2013 soil collection. Soil 

samples were also collected twice during the second year of the study, after the last application in 2013 

and after the last sampling in 2014, with the exception of trial NT017-12ZA, in which the 2014 samples 

were not collected due to the tree removal. Soil samples were collected from the surface (6 Inches or 15 

cm deep) of the plots using a soil core sampler and placed In a plastic bag. In each sampling period,

sample locations were randomly selected from the inner half of the plot (e.g. the inner 100 ft X 200 ft [30 

X 60 m] area of a 200 ft x 400 ft [60 x 120 m] plot).

Control Plots. Two composite samples of all cherry matrices and nine composite samples of soil were

collected from the control plot of each trial at the same sampling periods as for the treated samples of 

their sample type.

Sample Storage. All samples were protected from sunlight and placed in field coolers containing ice

substitute and the transit stability samples. Upon arrival at the site facility, all composite samples were 

placed directly into frozen storage except the flowers to be processed for nectar and pollen, which were 

processed for pollen and nectar by the field investigators. 

The flowers to be processed for nectar and pollen were processed within 3 days of collection. Processing 

delays occurred because the flowers had to be dried for several hours to allow pollen collection to occur

and the principal field investigators were under time constraints because blooming occurred 

simultaneously across multiple trials. To process the flowers, first nectar from the floral nectary was 

removed using a micropipette and placed into a glass collection vial. The flowers were left out to dry, and

then pollen was removed from the anthers of the same flower samples by vacuum aspiration with filter 

tips. All resulting nectar and pollen samples were labeled and placed in the freezer immediately after they 

were generated. In all trials, when sample times to freezer storage exceeded the 4 hours specified in the

protocol, the samples were kept cool in a cooler with blue ice. Composite samples were placed into 

labeled (study number and sample number) containers for shipment. Samples remained frozen until

receipt at the Bayer CropScience facility (Stilwell, KS or RTP, NC).

5E. ANALYTICAL METHODS

The residues of imidacloprid, 5-hydroxy imidacloprid, and imidacloprid olefin) were quantitated by high 

performance liquid chromatography/triple stage quadrupole mass spectrometry (LC/MS/MS) and LC/high 
DP Barcode: D425260 MRID: 49535601 

8

resolution mass spectrometry (LC/HRMS) using stable isotopically labeled internal standards. Details of 

the analytical methods are provided in the study report. 

The limit of detection (LOD) for the total residue is the highest LOD value for an individual analyte in a 

particular matrix. The limit of quantification (LOQ) for the total residue is the highest LOQ value for an 

individual analyte in a particular matrix. The LOD and LOQ values for each matrix are shown below in 

Table 5.

Table 5. Limits of quantification and detection for imidacloprid and metabolites

5F. QUALITY ASSURANCE 

Storage Stability. Storage stability studies and transit spikes indicate that the imidacloprid residues would

have been stable during frozen storage for at least 1080 days (36 months) in cherry flower and leaf 

matrices and for at least 1281 days (42 months) in soil matrices prior to analysis.

Transit Stability. To ensure that imidacloprid and its metabolites 5-hydroxy imidacloprid and imidacloprid

olefin were stable in nectar and pollen, sample sets of two pollen unfortified controls, four fortified pollen 

samples, two nectar surrogate controls, and four fortified nectar surrogate samples, were prepared yearly 

at Bayer CropScience and shipped frozen via FedEx to each test site. The transit stability samples, fortified 

with approximately 0.10 ppm each of imidacloprid and its metabolites 5-hydroxy imidacloprid and 

imidacloprid olefin, accompanied the respective study sample types throughout the sampling, shipping, 

and storage events of the field phase of the study. They were analyzed after all sample analyses of a given 

matrix and served to demonstrate stability of imidacloprid residues through the storage intervals and 

transport conditions encountered by the samples.

Spike Recovery. The method for determining imidacloprid, 5-hydroxy imidacioprid, and imidacloprid 

olefin residues in/on cherry and soil samples was validated by measuring the recovery of these analytes 

from control matrices fortified at their respective matrix LOQs. Additional recoveries at higher 
DP Barcode: D425260 MRID: 49535601 

9

fortification levels validated the method for the highest residues observed in individual matrices. 

Concurrent recoveries of imidacloprid, 5-hydroxy imidacloprid, and imidacloprid olefin from fortified 

samples were measured with each set of samples to verify method performance.

6. RESULTS:

6.A. QUALITY ASSURANCE RESULTS

Sample Storage. The maximum storage period of frozen samples in this study for imidacloprid was 452 

days for cherry flowers, 462 days for cherry leaves, 129 days for cherry nectar, 500 days for cherry pollen, 

and 668 days for soil prior to extraction. These storage times are within the bounds of the storage 

stability results described earlier and indicate that storage times are acceptable.

Transit Stability. The transit stability analyses indicate that the imidacloprid residues are stable (<30% 

decomposition) during concurrent freezer storage with the samples from this study. Mean transit 

recoveries for IMI, IMI-Olefin, and 5-hydroxy IMI range from 91%-96% in nectar and 88%-108% in pollen.

Matrix Spike Recoveries. As indicated in Table 5 of the study report, all matrix spike recoveries (pollen, 

nectar, flower, leaf, soil), the overall mean of the recoveries for each matrix was within the acceptable 

range of 70 to 120%, and the standard deviation values were below 20%. 

6.B. MAGNITUDE OF RESIDUES IN BEE-RELEVANT MATRICES 

Nectar. Summary statistics of the overall magnitude of IMI and related metabolites in cherry nectar is 

shown in Table 6. These statistics reflect analysis of individual composite samples (usually 5 replicates per 

sampling date) among the sampling times within each trial. Since IMI-olefin and 5-OH IMI are considered 

of similar toxicity as parent IMI, this discussion focuses on total IMI residues (sum of IMI, IMI-olefin and 5-

OH-IMI). Across all four trials, mean residues of total IMI in cherry nectar range from approximately 1.6 –

3.7 ppb while maxima range from 3.4 – 10 ppb. 

Table 6. Magnitude of IMI and related metabolites in cherry nectar (ppb).

Trial NT007 (n=15)* Trial NT008 (n=20)*

Olefin 5-OH IMI Total Olefin 5-OH IMI Total

Mean 0.45 1.9 1.3 3.7 0.41 0.55 1.6 2.5

SD 0.35 1.4 0.8 2.2 0.26 0.38 2.0 2.3

CV 78% 73% 56% 61% 62% 70% 123% 94%

Min. 0.32 0.33 0.50 1.1 0.32 0.33 0.17 0.81

Median 0.32 1.7 1.2 3.8 0.32 0.42 0.90 1.6

90th 0.79 3.7 2.5 6.5 0.56 1.1 3.9 4.8

Max. 1.5 4.4 2.8 8.3 1.2 1.6 7.8 10

Mean % of Total 12.3% 51.6% 36.8% --- 16.5% 22.0% 63.4%

Trial NT016 (n=20)* Trial NT017 (n=10)*

Olefin 5-OH IMI Total Olefin 5-OH IMI Total

Mean 0.60 0.40 1.5 2.5 0.32 0.33 0.96 1.6

SD 0.84 0.18 1.1 1.4 0.00 0.00 0.79 0.80

CV 141% 44% 75% 57% 0% 0% 83% 50%

Min. 0.32 0.33 0.50 1.1 0.32 0.33 0.17 0.81
DP Barcode: D425260 MRID: 49535601 

10

Trial NT007 (n=15)* Trial NT008 (n=20)*

Olefin 5-OH IMI Total Olefin 5-OH IMI Total

Median 0.32 0.33 1.2 2.2 0.32 0.33 0.50 1.1

90th 1.1 0.50 3.0 4.5 0.32 0.33 1.6 2.2

Max. 4.0 1.1 3.7 6.0 0.32 0.33 2.8 3.4

Mean % of Total 23.7% 16.0% 60.8% 20% 21% 61%

NOTES: IMI= imidacloprid, olefin = imidacloprid olefin, 5-OH = 5 hydroxy imidacloprid, Total = sum of IMI, olefin and 5-

OH (in bold). SD=standard deviation, CV = coefficient of variation.

* Values below the LOD were assumed equal to 1⁄2 the LOD. Values below the LOQ (but above the LOD) were 

assumed equal to 1⁄2 the LOQ.

Plots of the individual measured residues of total IMI in nectar for each trial year are shown in Figure 2A 

and 2B. Within each trial, it can be seen that applications during late summer/early fall resulted in 

greater residues measured in nectar during year 1 (2013) compared to applications made in late spring 

/ early summer as subsequent measurement in year 2 (2014). Mean values by residue trial and year are 

shown in Table 7 below. Mean residues measured during year 1 from the NY sites (3.9-4.8 ppb) are about

4X higher than those measured during year 2 and that from the year 1 of the OR site (3.4 ppb for NT016) 

is 2X the mean value measured during year 2 (1.7 ppb). The lower residue values measured during year 2 

may reflect the greater amount of time available for dissipation of IMI residues between application and 

residue measurement (275-300 days) compared to that from year 1 (about 205-215 days). Lower residues 

in year 2 may also reflect temporal differences in imidacloprid translocation to nectar when applied in late 

summer/early fall vs. spring/early summer. It should be noted that except for 1 value from trial NT016, 

residues of total IMI in nectar from year 2 (2014) largely reflect levels below the limit of analytical 

detection or quantification where 1⁄2 the LOD or LOQ was assumed. 

Table 7. Mean total IMI residue in cherry nectar (ppb) by trial and study year.

Study Year

Residue Trial

NY 

(NT007)

NY 

(NT008)

OR 

(NT016)

OR 

(NT017)

Year 1 (2013) 4.8 3.9 3.4 1.6

Year 2 (2014) 1.4 1.1 1.7 n.d.
DP Barcode: D425260 MRID: 49535601 

11

Figure 2. Total imidacloprid residues measured in cherry nectar for Trials NT007, NT008 (panel A) and 

NT016, NT017 (panel B).

Pollen. Mean residues of total IMI in cherry pollen are 1-2 orders of magnitude greater than those 

measured in nectar (Table 7). Mean residues of total IMI pollen vary from 9.3 – 220 ppb while maxima 

range from 38 - 1000 ppb. 

Table 8. Magnitude of IMI and related metabolites in cherry pollen (ppb).

Trial NT007 (n=15)* Trial NT008 (n=20)*

Olefin 5-OH IMI Total Olefin 5-OH IMI Total

Mean 5.4 6.9 97 109 8.9 7.4 203 220

SD 3.6 3.6 84 91 9.9 7.0 259 273

CV 66% 53% 86% 83% 111% 95% 127% 124%

Min. 0.50 1.7 3.6 5.8 0.16 0.50 5.9 6.9

Median 5.1 7.3 85 99 4.4 4.4 84 96

90th 7.7 9.8 166 180 22 16 524 566

Max. 15 15 320 350 32 23 970 1000

Mean % of Total 5.0% 6.3% 88.6% 4.1% 3.4% 92.4%

Trial NT016 (n=12)* Trial NT017 (n=6)*

Olefin 5-OH IMI Total Olefin 5-OH IMI Total

Mean 0.95 1.2 7.1 9.3 0.35 0.84 20 21

SD 1.9 2.0 9.9 11.1 0.47 0.48 24 24

CV 198% 168% 139% 119% 133% 57% 120% 116%

Min. 0.16 0.24 0.50 1.00 0.16 0.24 1.4 1.8

Median 0.16 0.24 4.6 5.0 0.16 0.85 11 12

90th 1.5 2.9 9.8 22.9 n.d. n.d. n.d. n.d.

Max. 6.7 7.0 37 38 1.3 1.3 65 67

Mean % of Total 10.2% 12.9% 75.9% 1.7% 4.0% 94.8%

NOTES: IMI= imidacloprid, olefin = imidacloprid olefin, 5-OH = 5 hydroxy imidacloprid, Total = sum of IMI, olefin and 5-

OH (in bold). SD=standard deviation, CV = coefficient of variation. “n.d.” = not determined due to small sample size

* Values below the LOD were assumed equal to 1⁄2 the LOD. Values below the LOQ (but above the LOD) were 

assumed equal to 1⁄2 the LOQ.
DP Barcode: D425260 MRID: 49535601 

12

It is clear from Table 9 and Figures 3A and 3B that total IMI in pollen from the NY study sites are about 

10X greater than those from the OR sites for both sampling years. Notably, such differences were not

observed for nectar residues (Table 7). However, it is evident that the NY sites were not irrigated during 

the trial period while sites in OR were irrigated. The influence of irrigation on IMI residues in pollen is not 

known and other factors may account for the differences between the NY and OR results. Although the 

basis of the 10X difference in pollen residue values between the NY and OR sites is not clear, such 

differences demonstrate the value of incorporating regional differences in study sites into the design of 

pollen/nectar residue studies. 

Table 9. Mean total IMI residue in cherry pollen (ppb) by trial and study year.

Study Year

Residue Trial

NY 

(NT007)

NY 

(NT008)

OR 

(NT016)

OR 

(NT017)

Year 1 (2013) 153 422 13.1 21

Year 2 (2014) 25 18 1.7 n.d.

Figure 3. Total imidacloprid residues measured in cherry pollen for Trials NT007, NT008 (panel A) and 

NT016, NT017 (panel B).
DP Barcode: D425260 MRID: 49535601 

13

Flowers. Across all trials, mean residues of total IMI in flowers range from 9.1-159 ppb in 2013 and 4.5-41 

ppb in 2014 (Table 10). Among all trials in 2013, mean residues in flowers were somewhat lower than 

those in pollen but the reverse is true for flower residues in 2014. Similar to the result for pollen, the NY 

study sites contained residues in flowers that were about 10X those reported for the OR sites. As 

described earlier, this same pattern of higher residues from the NY trial sites vs. OR sites was not evident 

for nectar. Plots of the raw data for residues in flowers are provided in Figures 4A and 4B.

Table 10. Mean concentrations of total IMI in cherry flowers (ppb).

Study Year

Residue Trial

NY 

(NT007)

NY 

(NT008)

OR 

(NT016)

OR 

(NT017)

Year 1 (2013) 98 159 12 9.1

Year 2 (2014) 38 41 4.5 n.d.

Figure 4. Total imidacloprid residues measured in cherry flowers for Trials NT007, NT008 (panel A) and 

NT016, NT017 (panel B).
DP Barcode: D425260 MRID: 49535601 

14

6.C. MAGNITUDE OF RESIDUES IN LEAVES AND SOIL 

Interestingly, mean residues of total IMI measured in leaves (Table 11) are lower than those measured for 

pollen and flowers (Tables 9 and 10, respectively), despite applications in 2012 performed when foliage 

was present (BBCH 91). This differs from results of other residue trials of foliar applications whereby 

concentrations in leaves are highest among the matrices sampled (e.g., Citrus, MRID 49521301). Residues 

in leaves from the NY study sites were higher than those from the OR sites.

Table 11. Magnitude of total IMI in cherry leaves (ppb).

Study Year

Residue Trial

NY 

(NT007)

NY 

(NT008)

OR 

(NT016)

OR 

(NT017)

Year 1 (2013) 64 53 11 9.3

Year 2 (2014) 34 38 5.0 n.d.

Unlike the other plant matrices sampled, the leaf residue data does span 6-17 days depending on the year 

of sampling. As seen in Figure 5A, concentrations of total IMI in leaves from the NY sites decline 

substantially over the two sampling events each year. Leaf residues measured from the OR sites do not 

show an obvious decline, although concentrations are much lower overall (Figure 5B). 

Figure 5. Total imidacloprid residues measured in cherry leaves for Trials NT007, NT008 (panel A) and 

NT016, NT017 (panel B).
DP Barcode: D425260 MRID: 49535601 

15

Residues of IMI measured in soil are low relative to most plant matrices, which is expected given the foliar 

method of pesticide application (Table 12). Levels were generally comparable across the four trials. Carry 

over from year to year was not evident based on sampling at the end of each growing season.

Table 12. Magnitude of IMI residues in soil (ppb).

Year Date Event DAFA1 Mean IMI in Soil 

(ppb)2

NT007

1 8/28/12 Prior to treatment -3 12

1 8/31/12 – 10/03/12 Foliar applications

1 5/10/13 End of 1

st growing season 252 113

2 6/5/13 – 7/15/13 Foliar applications

2 7/22/13 After last treatment 325 100

2 5/27/14 End of 2

nd growing season 634 62

NT008

1 8/31/12 Prior to treatment -3 <1

1 9/3/12 – 10/8/12 Foliar applications

1 5/10/13 End of 1

st growing season 249 61

2 6/5/13 – 7/15/13 Foliar applications

2 7/22/13 After last treatment 322 57

2 5/27/14 End of 2

nd growing season 631 50

NT016

1 8/10/12 Prior to treatment -1 26

1 8/11/12 – 9/13/12 Foliar applications

1 5/2/13 End of 1

st growing season 264 53

2 6/5/13 – 7/11/13 Foliar applications

2 7/15/13 After last treatment 338 98

2 4/28/14 End of 2

nd growing season 625 57

NT017

1 8/10/12 Prior to treatment -1 <1

1 8/11/12 – 9/13/12 Foliar applications

1 4/29/13 End of 1

st growing season 261 21

2 5/28/13 – 7/1/13 Foliar applications

2 7/4/13 After last treatment 327 84

1 DAFA = Days After First Application in Year 1

2 Mean of 3 soil composite samples for IMI only

6.D. YEAR TO YEAR ACCUMULATION IN POLLEN AND NECTAR

A qualitative evaluation of the potential for ‘year-to-year’ accumulation of total IMI residues in nectar and 

pollen could be conducted for 3 of the 4 trials, since data from year 2 were missing from trial NT017. 

Examination of Figures 2 and 3 (and Table 8 and 9) indicates that total IMI residues in nectar and pollen 

decline from year 1 to year 2. Similarly, residues of total IMI in flowers and leaves also decline from year 

1 to year 2. Although this suggests that year-to-year accumulation of total IMI is not evident, the impact 

of differences in pesticide application timing between year 1 to year 2 on the resulting residues in pollen 

and nectar is not clear. In other words, the lower residues measured in year 2 may reflect longer time 
DP Barcode: D425260 MRID: 49535601 

16

between pesticide application and residue sampling (and/or differences in pesticide translocation rates as 

a function of application timing). 

6.E. RESIDUE DECLINE (DT50) IN POLLEN AND NECTAR 

Due to the limited temporal coverage of residue sampling (2 sampling events/year with short sampling 

intervals), calculation of reliable dissipation half-life (DT50) values could not be conducted for nectar and 

pollen. 

6.F. OCCURRENCE OF RELEVANT IMI METABOLITES 

Nectar. Due to the low levels of parent IMI and metabolite residues measured in nectar, reliable 

estimates of the relative proportion of total IMI as parent or metabolites could not be determined, since 

such estimates would be unduly influenced by assumptions of 1⁄2 the LOD or 1⁄2 the LOQ.

Pollen. Suitable data for estimating the proportion of total IMI residues in pollen present as parent IMI or 

metabolites were available from Trials NT007 and NT008. In these trials, the mean % of total IMI as IMIolefin in pollen is 6% (range 2-17%). The mean % of total IMI as 5-OH IMI is 8% (range 2-29%). Parent IMI 

was present at 86% of total IMI in pollen on average (range 61-97%). 

6.F. RELATIONSHIP OF RESIDUES AMONG PLANT TISSUES

Predictability of Flower Residues. The relationship between mean residues of total IMI measured in 

flowers and total IMI measured in nectar and pollen on the same sampling day is shown in Figure 6A and 

6B, respectively. Total IMI residues in nectar are predicted within 2X for 12 out of 13 paired values using 

simple linear regression with flower data, although the r

2

(0.30) indicates a relatively weak correlation 

(Panel A). It is likely that assumptions regarding nectar concentrations measured below the LOD or LOQ 

confounded this relationship. The relationship to total IMI residues in pollen vs. flowers is stronger than 

that observed with the nectar data (r2=0.64, Panel B). However, this correlation likely reflects the 

occurrence of two large values recorded for NT008 and only 4/13 predicted resides in pollen are within 2X 

of the observed values in pollen. 

A
DP Barcode: D425260 MRID: 49535601 

17

Figure 6. Relationship between total IMI residues in flowers to those in nectar (A) and pollen (B)

Predictability of Leaf Residues. The relationship between mean residues of total IMI measured in cheery 

leaves and total IMI measured in pollen and nectar on the same sampling day is shown in Figure 7. A 

correlation was not made between nectar and leave residues because of the very low values measured in 

nectar and small sample size. Total IMI residues in pollen are predicted within 2X for only 2 of the 7 

paired pollen and leave values using simple linear regression with leaf data, and the overall relationship is 

relatively weak (r2 = 0.51). 

Figure 7. Relationship between total IMI residues in pollen to those in leaves

Pollen vs. Nectar. The relationship between total IMI residues measured in cherry nectar and pollen is 

shown in Figure 8. A weak relationship is observed (r2=0.44) and the range of nectar concentrations is 

quite small compared to that in nectar. 

B
DP Barcode: D425260 MRID: 49535601 

18

Caution is recommended when interpreting and applying these inter-tissue regression relationships to 

other situations since values here represent means of multiple composite samples and 2 of the 3 trials 

had nearly identical weather and soil conditions.

Figure 8. Relationship between total IMI residues in nectar to those in pollen
DP Barcode: D425260 MRID: 49535601 

19

7. STUDY STRENGTHS, LIMITATIONS AND CONCLUSIONS

In the context of documenting the magnitude of IMI residues in bee-related matrices of cherry, the 

following strengths are observed with this study. 

1. Analytical methods were sufficiently accurate and precise based on QA data

2. Concentrations were measured for toxicologically-relevant metabolites in multiple plant matrices

3. Application methods and rates were well documented

4. Sample replication and compositing were reasonable to account for natural variability

5. Residues were measured over two growing seasons to enable carry over to be assessed.

6. Sites were located in two different parts of the U.S. (NY, OR) with widely differing climate 

conditions

A number of limitations are also noted with this study, including:

1. Each of the two trials in NY and OR very close to each other thereby limiting the extent to which 

differences in weather conditions and soil properties could be assessed within each region. 

2. The limited temporal sampling did not enable calculation of DT50 values 

3. Differences in the timing of pesticide applications between year 1 and year 2 may confound the 

assessment of year to year carry over. 

4. Some samples were not taken for certain trials (NT007, NT017) which limited their utility 

Overall, considering the strengths and limitations of this study, the following conclusions can be drawn:

1. Post-bloom, foliar application of approximately 0.1 lb a.i./A x 5 result in residues of total IMI in 

individual composite samples of cherry nectar during the following year up to 10 ppb. 

2. Post-bloom, foliar application of approximately 0.1 lb a.i./A x 5 result in residues of total IMI in 

individual composite samples of cherry pollen during the following year up to 1000 ppb. 

3. Mean concentrations of total IMI in cherry nectar measured after foliar applications during the 

previous late summer/early fall (Year 1) were about 2X those measured after foliar applications 

during late spring/early summer (year 2) across all trials. A larger difference was observed in 

mean pollen concentrations (about 10X) across trial years. It is not clear if this finding reflects 

seasonal differences in IMI translocation or longer intervals between pesticide application and 

residue measurement associated with year 2.

4. Mean total IMI residues in pollen were approximately 1-2 orders of magnitude greater than those 

observed in nectar. 

5. Mean concentrations of total IMI measured in pollen from the NY study trails were about 10X 

those measured in pollen from the OR trial sites. Similar results were observed with total IMI 

residues measured in flowers and leaves.

6. Two metabolites of IMI (IMI-olefin and 5-OH-IMI) typically represented < 10% of total IMI residues 

in pollen and nectar. 

7. The predictability of total IMI residues in nectar and pollen based on measured concentrations in 

other plant matrices (flowers, leaves) was generally poor. 

8. STUDY VALIDITY/CLASSIFICATION 

Data from the four trials (NT007, NT008, NT016 and NT017) are considered scientifically sound and useful 

for risk assessment purposes, although these trials are highly similar in many respects do to their close 

proximity within the NY and OR study regions. Overall, this study is classified as ACCEPTABLE for 

quantitative use in risk assessment.
DP Barcode: D425260 MRID: 49535601 

20

Appendix A. Location of Cherry Residue Trials.

Figure A1. Locations of Trial NT007 (Alton, NY) and NT008 (Lyons, NY)

Figure A2. Locations of Trial NT016 and NT017 (Mosier, OR)

NT008

NT007