MRID 49090503 CDPR IMI Tomato (2011)

1

1. STUDY INFORMATION

Chemical: Imidacloprid PC Code 129099

Test Material: Admire Pro Percent Active 

Ingredient: 42.8% A.I.

Study Type:

Non-Guideline field residue study on tomato to establish imidacloprid and 

metabolite levels in anthers and leaves in site locations that have been treated at 

least once per year for two successive years.

Sponsor:

Bayer CropScience

2T.W. Alexander Drive

Research Triangle Park, NC 

USA 27709

Experiment Start and

End Date:

July 30, 2010 –

January 14, 2011

Sponsor Study 

ID: EBNTL056-01

Study Locations:

9 Field Trials in Kern 

and Kings County 

located in California. Study 

Completion 

Date:

March 31, 2011

GLP Status: Non-GLP; Final protocol was submitted to CDPR for review.

[CDPR study ID 254887, Data Volume 51950-0757, Tracking ID# 241047]

2. REVIEWER INFORMATION

Study Reviewed by: 

California Department 

of Pesticide Regulation 

Richard Bireley, Sr. Environmental Scientist (Specialist) 

John Troiano, Ph.D., Research Scientist III

Alexander Kolosovich, Environmental Scientist 

Brigitte Tafarella, Environmental Scientist

Denise Alder, Sr. Environmental Scientist (Specialist) 

Russell Darling, Environmental Scientist 

3. EXECUTIVE SUMMARY

Nine trials were conducted in clay or loam soils classified as fine (“heavy”) or “medium” to determine the

residues of imidacloprid and its metabolites (5-hydroxy imidacloprid and imidacloprid olefin) in anthers 

(pollen) and leaves collected from tomato plants grown at locations treated with imidacloprid at least 

once per year for two years. All soils had received previous chemigation applications of Admire Pro at 

total rates ranging from 0.18 to 0.25 Ib. a.i./acre (5.0 to 7.0 fl oz formulated product/acre) in 2009. 

Reference

Freeseman, P.L.; Harbin, A. (2011) Determination of the Residues of Imidacloprid and its Metabolites 

5-Hydroxy Imidacloprid and Imidacloprid Olefin in Bee Relevant Matrices Collected from Tomato, a 

Fruiting Vegetable, Grown at Locations Treated with Imidacloprid at Least Once Per Year During Two 

Successive Years: AMENDED. Project Number: EBNTL056/05/1/AMENDED. Unpublished study 

prepared by Bayer Cropscience and California Agricultural Research, Inc. 144p. MRID 49090503, CDPR 

Study ID 259130, Data Volume 51950-0786, Tracking ID# 246252
MRID 49090503 CDPR IMI Tomato (2011)

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Each trial received applications of Admire Pro in 2010 at the same rates as in 2009. The six sites located

in Kings County received two applications of Admire Pro at 3.5 fI oz formulated product/application (0.13 

Ib. imidacloprid/acre/application) for a total seasonal rate of 7.0 fI oz formulated product/acre (0.25 Ib.

a.i./acre). The first applications were made at or closely following transplant with the second application

occurring 52 to 57 days following the first applications. The three sites located in Kern County received a 

single application of Admire pro at 0.18 lb. imidacloprid/acre (5.0 fl oz formulated product/acre) 2 to 25 

days following transplant. Kern County is identified as North American Free Trade Agreement (NAFTA) 

Region 10.

Plant growth stage was not documented at the time of application. However, the first applications likely 

occurred at growth stages of BBCH* 21 to 51 (first primary shoot to first inflorescence visible) and BBCH

61 to BBCH 69 (flowering but prior to fruiting) for the second applications. All applications were made 

through drip chemigation (buried lines). *BBCH = Biologische Bundesanstalt, Bundessortenamt und 

CHemische Industrie growth stage scale for tomato.

Composite samples of tomato anthers (pollen) and tomato leaves were collected from tomato plants 72 

to 102 days following the last treatment (DALT) at indeterminate flowering and fruiting growth stages 

(BBCH 61 to BBCH 79) and analyzed for residues of imidacloprid. 

The residue(s) of imidacloprid, 5-hydroxy imidacloprid, and imidacloprid olefin were quantitated by high 

performance liquid chromatography/triple stage quadrupole mass spectrometry (LC/MS/MS) using stable 

isotopically labeled internal standards. The individual analyte residues were summed to give a total 

imidacloprid residue.

4. STUDY VALIDITY

Guideline Followed: Non-guideline study (final protocol submitted by CDPR)

Guideline Deviations: N/A

Other Deviations: N/A

Classification: Supplemental

Rationale: N/A

Reparability: N/A

5. MATERIALS AND METHODS

Test Material Characterization

Test item: Admire Pro Percent Active 

Ingredient: 

42.8% A.I. 

Description: Suspension concentrate (SC) Density: 1.41-1.54 g/mL

Material Source: Bayer Corporation Solubility: 0.51 to 0.61 g/L

CAS #: 138261-41-3 pH (24°C): 7.8

5A. STUDY DESIGN

The field and sampling phases of this study were not conducted under GLP. The experimental start date

was July 30, 2010 (collection of the control anthers and leaves), and the experimental end date was

January 14, 2011 (last analysis). The field sampling phase of the study was conducted by California 

Agricultural Research, Inc. 
MRID 49090503 CDPR IMI Tomato (2011)

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Data from nine tomato trials conducted in fine (“heavy”) or “medium” soils are presented in the subject

report. All sites were located in California, located in either Kings County (four heavy soil and two 

medium soil trials) or Kern County (three medium soil trials). All had received applications of 

imidacloprid (Admire Pro) in the preceding year (2009). Imidacloprid use in 2008 and prior years was 

unknown. The application history/pattern is shown in Table 1.

The analytical phase of this study was conducted under GLP and was initiated on December 3, 2010 (leaf 

sample homogenization). Homogenization of the leaves and analysis of all samples from the subject

study were performed at the Bayer Research Park (BRP) located in Stilwell, KS. Report preparation was 

performed at BRP. 

5B. APPLICATION TIMING AND RATES

The Admire Pro application rate used at the six sites located in Kings County was 3.5 fl oz formulated 

product/acre/application (0.13 Ib. imidacloprid/acre/application) for a total seasonal rate of 7.0 fI oz 

formulated product/acre (0.25 Ib. a.i./acre). The first applications were made at or closely following 

transplanting (March 22 to 27, 2010) with the second applications 52 to 57 days following the first 

application (May 13 to 20, 2010).

Single applications of Admire Pro were made at the three sites located in Kern County at 5.0 fl oz 

formulated product/acre (0.18 Ib imidacloprid/A). Applications were made 2 to 25 days following 

transplant. The growth stages of the plants at the times of applications were not documented but likely 

occurred at growth stages of BBCH 21 to 51 (first primary shoot to first inflorescence visible) for the first 

applications and BBCH61 to BBCH69 (flowering but prior to fruiting) for the second applications. 

All applications were made through drip chemigation (buried lines). The test substance use pattern for 

imidacloprid in 2010 for each site is described in Table 1 below.

Table 1. Study Use Pattern for 2010 Application of Admire Pro on Tomatoes. Trial Identification Location (City, State) End-Use Product (Formulation) Plot Name Method Application Number Timing/Growth Stage 

(BBCH)Rate lb a.i./A(oz Formulated Product/A) aInterval Between Applications (Days) bTotal Rate lb a.i./A(oz Formulated Product/A)

NT041 Kings 

County, 

CA

Admire 

Pro

Armona 

Loam 

(Fine)

Chemigation 1 BBCH

21-51

0.13

(3.5)

NA 0.25

(7.0)

2 BBCH

61-69

0.13

(3.5)

52

NT043 Kings 

County, 

CA

Admire 

Pro

Westcamp 

Loam 

(Fine)

Chemigation 1 BBCH

21-51

0.13

(3.5)

NA 0.25

(7.0)

2 BBCH

61-69

0.13

(3.5)

54
MRID 49090503 CDPR IMI Tomato (2011)

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Trial IdentificationLocation (City, State)End-Use Product (Formulation)Plot NameMethodApplication NumberTiming/Growth Stage (BBCH)Rate lb a.i./A(oz Formulated Product/A) aInterval Between Applications (Days) bTotal Rate lb a.i./A(oz Formulated Product/A)

NT044 Kings 

County, 

CA

Admire 

Pro

Houser Clay 

(Fine)

Chemigation 1 BBCH

21-51

0.13

(3.5)

NA 0.25

(7.0)

2 BBCH

61-69

0.13

(3.5)

54

NT045 Kings 

County, 

CA

Admire 

Pro

Tulare Clay 

(Heavy)

Chemigation 1 BBCH

21-51

0.13

(3.5)

NA 0.25

(7.0)

2 BBCH

61-69

0.13

(3.5)

57

NT046 Kings 

County, 

CA

Admire 

Pro

Boggs Sandy 

Loam 

(Medium)

Chemigation 1 BBCH

21-51

0.13

(3.5)

NA 0.25

(7.0)

2 BBCH

61-69

0.13

(3.5)

52

NT047 Kings 

County, 

CA

Admire 

Pro

Lemoore 

Sandy Loam 

(Medium)

Chemigation 1 BBCH

21-51

0.13

(3.5)

NA 0.25

(7.0)

2 BBCH

61-69

0.13

(3.5)

52

NT048 Kern 

County, 

CA

Admire 

Pro

Wasco 

Sandy Loam 

(Medium)

Chemigation 1 BBCH

61-69

0.18

(5.0)

NA 0.18

(5.0)

NT049 Kern 

County, 

CA

Admire 

Pro

MacFarland 

Loam 

(Medium)

Chemigation 1 BBCH

61-69

0.18

(5.0)

NA 0.18

(5.0)

NT050 Kern 

County, 

CA

Admire 

Pro

Milham 

Sandy Loam 

(Medium)

Chemigation 1 BBCH

61-69

0.18

(5.0)

NA 0.18

(7.0)

a Rates and spray volumes that were provided in the application order/recommendation. 

b Interval between the first and second applications. NA = Not Applicable; only one application occurred.

5C. STUDY SITE LOCATION AND CHARACTERISTICS 

All site locations were in Kern or Kings counties in California, NAFTA Region 10. The trial site conditions 

including soil types are listed in Table 2. All sites used agronomic practices typical for commercial 

production of tomatoes. 

Temperatures and rainfall recorded during the field phase of the study were similar to average historical 

records, with no significantly unusual weather conditions that would affect the conclusions of the study. 

Irrigation supplemented normal rainfall as needed for all trials. Temperature and precipitation data for 
MRID 49090503 CDPR IMI Tomato (2011)

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each trial were obtained from the nearest California Irrigation Management Information System (CIMIS) 

weather station. 

Table 2. Trial Site Conditions for Imidacloprid on Tomatoes

Trial Identification

Trial Location

(County, State) Soil Typea Rainfallb (in)

Temperature 

Rangeb (°F)

NT041 Kings County, CA Armona Loam 

(Fine)

1.51 40-77

NT043 Kings County, CA Westcamp Loam 

(Fine)

1.51 40-77

NT044 Kings County, CA Houser Clay 

(Fine)

1.51 40-77

NT045 Kings County, CA Tulare Clay 

(Fine)

1.50 42-79

NT046 Kings County, CA Boggs Sandy Loam 

(Medium)

1.51 40-77

NT047 Kings County, CA Lemoore Sandy 

Loam (Medium)

1.51 40-77

NT048 Kern County, CA Wasco Sandy 

Loam (Medium)

1.45 41-97

NT049 Kern County, CA MacFarland Loam 

(Medium)

1.45 41-97

NT050 Kern County, CA Milham Sandy 

Loam (Medium)

1.45 41-97

a A total of nine tomato trials were conducted; four in fine (“heavy”) soils and five in “medium” soils. Classification

of the soils was obtained from the Soil Survey Geographic (SSURGO) Database provided by the Natural Resources 

Conservation Service. “Heavy” class represents soil with slow drainage capacity. b Data is for the interval of the month of first application through the month of last sampling. Meteorological data 

were obtained from nearby government weather stations.

5D. SAMPLE COLLECTION, HANDLING, PROCESSING

Quadruplicate samples of tomato anthers and leaves were collected from tomato plants at

indeterminate flowering and fruiting growth stages as typical for solanaceous fruits (BBCH 61 to BBCH

79). The intervals from last imidacloprid application to sampling ranged from 72 to 102 days for the nine 

trials.

Anthers and leaves were collected from the same plants. A sample weight of approximately 0.5 g

anthers was collected from a minimum of 20 plants. For every anther collected, a leaf sample was also

collected. Leaf samples were a composite from high, low, inside, and outside areas of the plant. The 

person collecting the anther samples did not touch any leaves or other plant parts with their hands or 

any sampling equipment. All samples were protected from sunlight and placed on either dry ice or blue 

ice in coolers during field collection. Anther samples were collected in amber glassware and leaf samples 

were collected in bags. All samples were placed in frozen storage upon receipt at California Agricultural 

Research, Inc. Samples were shipped frozen via Agricultural Chemicals Development Services and 

remained frozen until receipt at BRP. 
MRID 49090503 CDPR IMI Tomato (2011)

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Transit stability samples accompanied the field samples during all sample handling and preparation 

steps to ensure the validity of the sampling practices.

Sample Storage.

Upon arrival at BRP, all samples were immediately transferred to frozen storage. The treated leaf 

samples were homogenized with dry ice using a Robot Coupe (Jackson, MS) chopper (control and field 

fortification samples were not homogenized prior to analysis; the entire sample was blended during 

extraction). All samples were returned to frozen storage immediately following homogenization and the 

samples remained frozen at all times except during subsampling for analysis. A summary of collection, 

shipment, and homogenization dates for the trials was recorded in a field report.

5E. ANALYTICAL METHODS

The analytical method used in this study measured the residues of imidacloprid, 5-hydroxy imidacloprid, 

and imidacloprid olefin in tomato anthers and leaves.4

All neat analytical reference standards were stored frozen when not in use and all solutions were stored 

refrigerated. Analytical standard solutions used in this study were not stored for longer than 

approximately two (2) months and have been shown to be stable for this period of time.5 All reference 

standard solutions were prepared in parent imidacloprid equivalents and corrected for purity during 

initial preparation.

For the determination of imidacloprid, 5-hydroxy imidacloprid (5-OH) and imidacloprid olefin (olefin) in 

tomato anthers (pollen) or homogenized tomato leaves, an aliquot of tissue was extracted by blending

the sample with water (H20) first, then with acetonitrile. The sample was amended with stable, 

isotopically labeled internal standards, anhydrous magnesium sulfate (MgSO4) and sodium chloride 

(NaCI). The sample was shaken vigorously followed by centrifugation. The organic supernatant was 

decanted or transferred to a centrifuge tube containing BONDESIL-PSA (solid-phase extraction sorbent, 

primary and secondary amine) and MgSO4 and mixed, followed again by centrifugation. An aliquot of the

supernatant was subjected to a C-18 Solid Phase Extraction bond elute cartridge and the eluate was 

evaporated. The solids were reconstituted with mobile phase [(9:1 v/v) water (H2O)/methanol (MeOH)]. 

The sample was filtered with a 0.45 μm nylon syringe filter and analyzed by high performance liquid

chromatography/triple stage quadrupole mass spectrometry (LC/MS/MS).

Quantitation of each analyte was based on the daughter ion transitions of the analytes and the

respective internal standard analogs. The responses of LC/MS/MS system to each analyte and its 

internal standard were measured in samples and in standards, and a relative response was calculated as 

the ratio of the analyte and the stable isotopically labeled internal standard responses. The relative 

response of the analyte in each sample was compared to the relative response of the analyte in the 

standards.

The relative responses of imidacloprid, 5-hydroxy imidacloprid, and imidacloprid olefin in solvent were 

measured over the range of 1 ppb to 1000 ppb for each analyte. The coefficients of determination (r2

) 

were calculated using linear regression analysis (LCQUAN 2.5 TM, Microsoft Excel).
MRID 49090503 CDPR IMI Tomato (2011)

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The total imidacloprid residue is the sum of the individual measured residue values of imidacloprid, 5-

hydroxy imidacloprid, and imidacloprid olefin in parent equivalents. For the purpose of calculating total 

imidacloprid residues where individual analyte residue values were less than the limit of detection 

(LOD), the residues were assigned a finite value of 1⁄2 the value of the respective LOD. This value is only 

an estimate of potential residue in a sample, not a measured value.

The method for determining imidacloprid, 5-hydroxy imidacloprid, and imidacloprid olefin residues 

in/on tomato anthers and leaves was validated by measuring the recovery of these analytes from 

control matrices fortified at the limit of quantitation (LOQ) (2 ppb). Additional recoveries at higher 

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

Concurrent recoveries of imidacloprid, 5-hydroxy imidacloprid, and imidacloprid olefin were measured 

with each set of samples to verify method performance.

The control anther and leaf samples (approximately 0.5 g and 5 g, respectively) were not homogenized 

prior to extraction; the entire contents of the container were extracted by first blending the sample with 

water, followed by blending with acetonitrile. Aliquots of the extracts (equivalent to approximately 0.5 g 

control leaf) were further purified.

5F. QUALITY ASSURANCE RESULTS

The responses of the LC/MS/MS system to imidacloprid, 5-hydroxy imidacloprid, and imidacloprid olefin 

were linear in solvent over the range of 1.0 ppb to 1,000 ppb for each analyte. The coefficients of 

determination were >0.992.

All control interferences for each analyte in tomato anthers and leaves were less than the LOQ (<2 ppb). 

All control interferences for were also less than the respective LODs for each analyte in each matrix with 

the exception of 5-hydroxy imidacloprid in one of the control leaf samples, where an apparent residue 

of 0.5 ppb was observed.

All recoveries were corrected for any interference in corresponding controls. The overall mean values of 

the recoveries for each matrix were within the acceptable range of 70% to 120%, and the relative 

standard deviation (RSD) values were below 20%.

The LOQ is defined as the lowest fortification level of an analyte at which acceptable recovery has been 

achieved. The LOQ for total residue is the highest of the LOQ values assigned to the individual analytes 

for a particular matrix.

The LOD is defined as the lowest concentration of an analyte that can be determined to be statistically 

different from a blank. The LODs for individual analytes in the anthers and leaves are detailed in the 

table below, along with the LODs for total imidacloprid residues (equal to the highest LOD of any of the 

analytes for each matrix). The LODs were determined from method validation data obtained from 

control samples fortified at the analyte LODs. The LODs were calculated by multiplying the standard 

deviation of recovery measurements at the LOD by t0.99 [where t0.99 is the one-tailed t-statistic at the 99% 

confidence level for the number of replicates (n)] 6

. The LODs determined in Bayer CropScience Study 

EBNTL056-017 for cotton leaves were used as the LODs for tomato leaves since these are similar 

matrices. The LOD for the total imidacloprid residue in each matrix is the highest LOD value of any 

individual analyte for that particular matrix.
MRID 49090503 CDPR IMI Tomato (2011)

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The LOQs and LODs are summarized in Table 3 below.

Table 3. Summary of LOQs and LODs

Matrix Analyte LOQ (ppb) LOD (ppb)

Tomato Anthers 

(Pollen)

Imidacloprid 2.0 0. 4

5-hydroxy Imidacloprid 2.0 0.5

Imidacloprid Olefin 2.0 0.7

Total Imidacloprid 2.0 0.7

Tomato Leaves

Imidacloprid 2.0 0.6

5-hydroxy Imidacloprid 2.0 0.9

Imidacloprid Olefin 2.0 0.6

Total Imidacloprid 2.0 0.9

Any individual analyte or total residue measured to be less than the Limit of Quantitation (LOQ) was 

reported as <2 ppb for anthers and leaves. Any residue value that was below the LOD was reported as 

less than the LOD and measured residue values between the LOQ and LOD are provided in Appendix 4 of 

the study report.

6. RESULTS:

Summary results for concentrations of imidacloprid in anthers and leaves are summarized in Table 4 and 

the total imidacloprid residue data for tomato anthers and leaves are provided in Table 5. The average 

total imidacloprid residue found in tomato anthers grown in fine-textured soil was 21 ppb (n=8). The 

average total imidacloprid residue found in tomato anthers grown in medium-textured soil was 34 ppb

(n=10). The average total imidacloprid residue found in tomato leaves grown in fine-textured soil was 

93 ppb (n=8). The average total imidacloprid residue found in tomato leaves grown in medium-textured

soil was 110 ppb (n=10).

The maximum total residues in tomato anthers were measured to be 30 ppb (mean ± SD, 21 ± 5) and 

54 ppb (mean ± SD, 34 ± 12) in tomato anthers grown in fine and medium-textured soils, respectively. 

Concentrations were similar between the two soil types.

Table 4. Magnitude of total imidacloprid residues in tomato anthers and leaves.

Commodity

Soil Texture 

Categorya

Days After 

Last 

Treatment 

(DALT)b

Total Imidacloprid Residue Levels (ppb)c

N Min Max

Highest 

Avg. 

Site 

Residue Median Mean

Standard 

Deviation

Tomato Anthers Fine 72-79 8 14 30 27 22 21 5

Tomato Anthers Medium 79-102 10 16 54 46 36 34 12

Tomato Leaves Fine 72-79 8 57 140 120 89 93 26

Tomato Leaves Medium 79-102 10 38 230 200 100 110 61 a Classification of the soils was obtained from the Soil Survey Geographic (SSURGO) Database provided by the 

Natural Resources Conservation Service and converted to soil texture categories.

b All trials received one or two applications of Admire Pro. DALT are the days following the last application when 

two applications were made.
MRID 49090503 CDPR IMI Tomato (2011)

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c Abbreviations used are as follows: Min is the lowest treated residue value; Max is the highest treated residue 

value; Median is the geometric median of the treated residue values; Mean is the mathematical average of the 

treated residue values; Standard Deviation is the standard deviation for a small population of “N” samples.

Table 5. Imidacloprid Residue Data in Tomatoes Trial Identification Location (City, State) Plot Name 2009 Total Rate, lb a.i./A (oz FP/Acre)a

2010 Total Rate, lb a.i./A

(oz FP/Acre)a

Residue Sample 

Collection DALTb

Imidacloprid Residue 

(ppb)

5-Hydroxy Imidacloprid 

Residue (ppb)

Imidacloprid Olefin 

Residue (ppb)

Total Imidaclopridc

Residue (ppb)

Anthers Residue (ppb)

NT041 Kings 

County, CA

Armona Loam 0.25

(7.0)

0.25

(7.0)

78 14.3 <2.0 <2.0 17

18.2 <2.0 <2.0 21

Average

19

NT043 Kings 

County, CA

Westcamp 

Loam

0.25

(7.0)

0.25

(7.0)

71 16.6 <2.0 <2.0 19

19.7 2.1 <2.0 23

Average

21

NT044 Kings 

County, CA

Houser Clay 0.25

(7.0)

0.25

(7.0)

71 20.9 <2.0 <2.0 24

26.7 <2.0 <2.0 30

Average

27

NT045 Kings 

County, CA

Tulare Clay 0.25

(7.0)

0.25

(7.0)

71 20.9 <2.0 <2.0 24

12.3 <2.0 <2.0 14

Average

19

NT046 Kings 

County, CA

Boggs Sandy 

Loam

0.25

(7.0)

0.25

(7.0)

78 13.6 <2.0 <2.0 16

31.5 2.2 <2.0 36

Average

26

NT047 Kings 

County, CA

Lemoore 

Sandy Loam

0.25

(7.0)

0.25

(7.0)

78 24.9 2.5 <2.0 28

33.0 2.3 <2.0 37

Average

33

NT048 Kern County, 

CA

Wasco Sandy 

Loam

0.18

(5.0)

0.18

(5.0)

100 48.7 3.5 2.0 54

33.9 2.6 <2.0 38

Average

46

NT049 Kern County, 

CA

Macfarland 

Sandy Loam 

0.18

(5.0)

0.18

(5.0)

92 33.3 2.8 <2.0 38

23.4 <2.0 <2.0 26

Average

32
MRID 49090503 CDPR IMI Tomato (2011)

10

Trial Identification

Location (City, State)

Plot Name

2009 Total Rate, lb a.i./A

(oz FP/Acre)a

2010 Total Rate, lb a.i./A

(oz FP/Acre)a

Residue Sample 

Collection DALTb

Imidacloprid Residue 

(ppb)

5-Hydroxy Imidacloprid 

Residue (ppb)

Imidacloprid Olefin 

Residue (ppb)

Total Imidaclopridc

Residue (ppb)

NT050 Kern County, 

CA

Milham Sandy 

Loam

0.18

(5.0)

0.18

(5.0)

77 16.3 <2.0 <2.0 19

42.8 4.1 2.1 49

Average

34

Leaves Residue (ppb)

NT041 Kings 

County, CA

Armona Loam 0.25

(7.0)

0.25

(7.0)

78 46.9 2.9 7.2 57

72.5 4.0 8.5 85

Average

71

NT043 Kings 

County, CA

Westcamp 

Loam

0.25

(7.0)

0.25

(7.0)

71 84.5 2.5 6.3 93

102 3.1 9.7 110

Average

100

NT044 Kings 

County, CA

Houser Clay 0.25

(7.0)

0.25

(7.0)

71 101 3.6 7.6 110

121 3.5 10.4 140

Average

120

NT045 Kings 

County, CA

Tulare Clay 0.25

(7.0)

0.25

(7.0)

71 71.0 2.0 6.1 79

59.2 2.6 7.7 70

Average

71

NT046 Kings 

County, CA

Boggs Sandy 

Loam

0.25

(7.0)

0.25

(7.0)

78 32.8 <2.0 5.1 38

109 2.6 10.3 120

Average

80

NT047 Kings 

County, CA

Lemoore 

Sandy Loam

0.25

(7.0)

0.25

(7.0)

78 54.0 <2.0 7.1 63

57.3 <2.0 5.4 65

Average

64

NT048 Kern County, 

CA

Wasco Sandy 

Loam

0.18

(5.0)

0.18

(5.0)

100 213 4.9 14.4 230

162 3.9 8.9 170

Average

200

NT049 Kern County, 

CA

Macfarland 

Sandy Loam 

0.18

(5.0)

0.18

(5.0)

92 105 3.2 10.5 120

104 4.1 6.9 120

Average

120
MRID 49090503 CDPR IMI Tomato (2011)

11

Trial Identification

Location (City, State)

Plot Name

2009 Total Rate, lb a.i./A

(oz FP/Acre)a

2010 Total Rate, lb a.i./A

(oz FP/Acre)a

Residue Sample 

Collection DALTb

Imidacloprid Residue 

(ppb)

5-Hydroxy Imidacloprid 

Residue (ppb)

Imidacloprid Olefin 

Residue (ppb)

Total Imidaclopridc

Residue (ppb)

NT050 Kern County, 

CA

Milham Sandy 

Loam

0.18

(5.0)

0.18

(5.0)

77 42.6 <2.0 4.2 48

77.0 <2.0 5.8 85

Average

66 a Applications during the 2009 and 2010 growing seasons; a.i. = imidacloprid; formulated product (FP) = Admire 

Pro.

bDALT = Days After Last Treatment.

c

Total imidacloprid is the sum of imidacloprid, 5-hydroxy imidacloprid, and imidacloprid olefin.

7. STUDY VALIDITY/CLASSIFICATION AND STUDY LIMITATIONS 

Classification/Utility for Bee Risk Assessment. The study is considered to be SUPPLEMENTAL and 

informative but does not represent the worst-case application scenario due to the low test rates. The 

tested rate of 0.18 lb. a.i./Acre (equivalent to 202 g a.i./ha) is lower than the labeled maximum soil 

application rate for tomato in the U.S. (0.5 lb. a.i./Acre) and Canada (559.9 g a.i./ha). This study will be 

considered as an additional line of evidence for the estimation of exposure to bees.

Temporal Variability in Residues. The intervals from the last imidacloprid application to sampling 

ranged from 72 to 102 days for the nine trials. This study was not designed to measure temporal 

variability in residues.

Spatial Variability in Residues. All sites were located in Kern or Kings County. The sites in Kern County 

typically had a higher average maximum temperature than those located in Kings County; however, total 

rainfall was similar between all sites. There were no analyses of effects of soil type or location on 

imidacloprid residues in plant matrices in this study. However, it seems that imidacloprid residues in 

both anthers and leaves are slightly higher in tomatoes grown in medium soil compared to heavy soil.

Pesticide Carryover. This study was not designed to measure pesticide carryover. All samples were 

obtained in 2010, 72 to 102 days after the last application.

8. CONCLUSION

Studies were conducted to determine the residues of imidacloprid and its metabolites (5-hydroxy 

imidacloprid and imidacloprid olefin) in anthers (pollen) and leaves collected from tomato plants grown 

at locations treated with imidacloprid at least once per year for two years. Nine trials were conducted in 

fine-textured clayey or medium-textured loamy soils, classified as fine (“heavy”) or “medium” 

respectively, in the study report. All sites were located in California, in either Kings County (four finetextured soils and two medium-textured soils) or Kern County (three medium-textured soils). The sites 
MRID 49090503 CDPR IMI Tomato (2011)

12

in Kern County typically had a higher average maximum temperature than those located in Kings 

County, however total rainfall was similar between all sites. Each site was irrigated as needed.

Each trial received application(s) of Admire Pro in 2010 at the same rates as in 2009. The six sites located 

in Kings County received two applications of Admire Pro at 3.5 fl oz product/Acre/application (0.13 lb.

a.i./Acre/application) for a total seasonal rate of 7.0 fl oz product/Acre (0.25 lb. a.i./Acre). The first 

applications were made at or closely following transplanting with the second applications 52 to 57 days 

following the first applications. The three sites located in Kern County received a single application of 

Admire Pro at 0.18 lb. a.i./Acre (5.0 fl oz product/Acre) 2 to 25 days following transplanting.

The average total imidacloprid residue found in tomato anthers grown in fine-textured soil was 21 ppb

(n=8). The average total imidacloprid residue found in tomato anthers grown in medium-textured soil 

was 34 ppb (n=10). The average total imidacloprid residue found in tomato leaves grown in finetextured soil was 93 ppb (n=8). The average total imidacloprid residue found in tomato leaves grown in 

medium-textured soil was 110 ppb (n=10).

The maximum total residues in tomato anthers were measured to be 30 ppb (mean ± SD, 21 ± 5) and 

54 ppb (mean ± SD, 34 ± 12) in tomato anthers grown in fine and medium-textured soils, respectively. 

Concentrations were similar between the two soil types.

9. REFERENCES

1. Hoelscher, A. 1998. Physical and chemical properties of the active ingredient imidacloprid. Bayer 

CropScience Report No. MO-03-006885, M-105510-01-1. 

2. Talbott, T. D. 1991. Product Chemistry of BAY NTN 33893 Technical. Bayer CropScience Report No. 

MRID M004227-01-1. 

3. Krohn, J. 1993. Vapour Pressure Curve of lmidacloprid. Bayer CropScience Laboratory Project ID 

142000804. Report No. M-004042-01-1. 

4. Brungardt, Jaime 2010. An Analytical Method for the Determination of Residues of lmidacloprid and 

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

LC/MS/MS. Bayer Report No. NT-005-P10-01. 

5. Schoning, R. 1999. Residue Analytical Method for the Determination of Residues of lmidacloprid, 

Hydroxy-lmidacloprid, Olefin-lmidacloprid, YRC 2894, YRC 2894-Amide, and 4-Hydroxy-YRC 2894-Amide 

in Plant Material by HPLC with Electrospray MS/MSDetection. Method No. 00573. Report No. MR853/98.

6. Office of Pesticide Programs, US EPA. 2000. Assigning values to non-detected/non

quantified pesticide residues in human health food exposure assessments. EPA Docket #OPP-00570A.

7. Beedle, Ellen C. and A. M. Harbin. 2011. Determination of the Residues of Imidacloprid and its 

Metabolites 5 Hydroxy Imidacloprid and lmidacloprid Olefin in Bee Relevant Matrices Collected from 

Cotton, Grown at Locations Treated with Imidacloprid at Least Once Per Year During Two Successive 

Years. Bayer CropScience Report EBNTL056-01.