MRID 49103301 CDPR IMI Cotton (2011)

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Reference

Beedle, E.; Harbin, A. (2011) Determination of Residues of Imidacloprid and its Metabolites 5-Hydroxy 

Imidacloprid and Imidacloprid Olefin in Bee Relevant Matrices Collected from Cotton, Grown at 

Locations Treated with Imidacloprid at Least Once Per Year During Two Successive Years: Final Report. 

Project Number: EBNTL056/01, M/404577/01/1. Unpublished study prepared by Bayer CropScience 

and California Agricultural Research Inc. 149 p. MRID 49103301, CDPR Study ID 259129, Data Volume 

51950-0785, Tracking ID# 246252

1. STUDY INFORMATION

Chemical: Imidacloprid PC Code 129099

Test Material: Provado 1.6F Percent Active 

Ingredient:

17.4% A.I.

Study Type:

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

metabolite levels in nectar and leaves in site locations that have been previously 

treated by chemigation for two successive years followed by a foliar spray

application.

Sponsor:

Bayer CropScience

2T.W. Alexander Drive

Research Triangle Park, NC 

USA 27709

Experiment Start and

End Date:

August 13, 2010 –

January 13, 2011

Sponsor Study 

ID: EBNTL056-01

Study Locations:

5 Field Trials in Kern 

and Kings County 

located in California. Study 

Completion 

Date:

March 31, 2011

GLP Status: Non-GLP; No final protocol was submitted to CDPR for review and approval. 

[CDPR study ID 254886, Data Volume 51950-0758, Tracking ID# 241026]

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

Five trials were conducted in clay soils classified as ‘heavy’ to determine the residues of imidacloprid and 

its metabolites (5-hydroxy imidacloprid and imidacloprid olefin) in nectar and leaves collected from 

cotton plants grown at locations treated with imidacloprid at least once per year for two years. All soils 

had received previous application(s) of Admire Pro by chemigation at rates ranging from 0.18 to 0.38 lb. 

a.i./acre in the prior year(s) and received one aerial foliar spray application of imidacloprid (Provado 1.6 

F, 17.4% imidacloprid by weight) in 2010 during flowering (BBCH61, beginning of flowering to BBCH67, 

flowering finished and majority of flowers faded).
MRID 49103301 CDPR IMI Cotton (2011)

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Composite samples of cotton nectar and cotton leaves were collected two to seven days prior to the 

2010 imidacloprid application (pre-application) and six days following the 2010 application (postapplication). Nectar and leaves were collected from the same cotton plants. 

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) using stable 

isotopically labeled internal standards. 

4. STUDY VALIDITY

Guideline Followed: Non-guideline study (final protocol was never reviewed 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: Provado 1.6F Percent Active 

Ingredient: 

17.4% A.I. 

Description: Flowable Concentrate Density: 1.41-1.54 g/mL

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

CAS #: 138261-41-3 Expiration Date: 05/09/2012

5A. STUDY DESIGN

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

was August 13, 2010 (collection of the control nectar and leaves), and the experimental end date was 

January 13, 2011 (last analysis). The field sampling phase of the study was conducted by California 

Agricultural Research, Inc. 

Data from five cotton trials conducted in "heavy" soils are presented in this report. All sites were located 

in either Kern County (sites 1, 2 and 3) or Kings County (sites 4 and 5) of California. All had received 

applications of imidacloprid in the preceding year (2009); sites 1, 2, 3, and 5 also received imidacloprid 

applications in 2008.

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 the all samples from this study 

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

performed at BRP.

All raw data associated with this study are retained along with the protocol, protocol amendments and 

the final report under Notebook Number EBNTL056-01 at locations specified by Bayer CropScience.
MRID 49103301 CDPR IMI Cotton (2011)

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5B. APPLICATION TIMING AND RATES

The cotton was grown in locations treated with one aerial application of imidacloprid in 2010 and at 

least one chemigation application in preceding years. The 2010 aerial application rate of Provado 1.6F at 

all five sites was 0.063 lb. a.i./acre (well below the maximum label rate of 0.5 lb. a.i./acre). The 

applications were made during flowering (BBCH61, beginning of flowering to BBCH67, flowering 

finished, majority of flowers faded). All aerial applications of Provado 1.6F were made at approximately 

10 GPA. The test substance use pattern for imidacloprid in 2010 for each site is described in Table 1.

Table 1. Study Use Pattern for 2010 Application of Provado 1.6 F on Cotton.* Trial Identification Location (City, State, NAFTA, Region) End-Use Product (Formulation) Plot Name Method Timing/Growth Stage (BBCH)

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

NT001

Heavy Soil, 

Kern County, 

CA, NAFTA 

Region 10

Provado 

1.6F

Site 1 

Buttonwillow 

Clay, (Heavy)

Aerial 

Foliar

BBCH

61-67

(Flowering)

10 0.063

(5.0)

NA 0.063

(5.0)

NT002

Heavy Soil, 

Kern County, 

CA, NAFTA 

Region 10

Provado 

1.6F

Site 2 

Lokern Clay

(Heavy)

Aerial 

Foliar

BBCH

61-67

(Flowering)

10 0.063

(5.0)

NA 0.063

(5.0)

NT003

Heavy Soil, 

Kern County, 

CA, NAFTA 

Region 10

Provado 

1.6F

Site 3

Lokern Clay

(Heavy)

Aerial 

Foliar

BBCH

61-67

(Flowering)

10 0.063

(5.0)

NA 0.063

(5.0)

NT004

Heavy Soil, 

Kings 

County, CA, 

NAFTA 

Region 10

Provado 

1.6F

Site 4

Houser Clay

(Heavy)

Aerial 

Foliar

BBCH

61-67

(Flowering)

10 0.063

(5.0)

NA 0.063

(5.0)

NT005

Heavy Soil, 

Kings 

County, CA, 

NAFTA 

Region 10

Provado 

1.6F

Site 5

Tulare Clay

(Heavy)

Aerial 

Foliar

BBCH

61-67

(Flowering)

10 0.063

(5.0)

NA 0.063

(5.0)

a Rates and spray volumes that were provided in the application order/recommendation. See Appendix 3 of the 

study report in study report for field trial summary data. b Interval between the first and second applications. NA = Not Applicable; only one application occurred.

*Table 4 of the study report
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Chemigation applications in previous years (2009 and/or 2008) ranged from 0.22 to 0.38 lb ai/acre/year. 

Four of the five sites had chemigation applications in 2008 and 2009 (trial NT001, NT002, NT003, NT005) 

using the end product Admire Pro.

5C. STUDY SITE LOCATION AND CHARACTERISTICS 

Three of the five trial sites were located in Kern County, California while the other two trial sites were 

located in Kings County, California. The trial site conditions including soil characteristics can be found 

below in Table 2. All five trial sites were conducted on clay soils classified as “heavy” and used 

agronomic practices typical for commercial production of cotton. For a control group, untreated nectar 

and leaf samples used for validation of the analytical method and for transit stability samples were 

obtained from a nearby organic farm.

Temperature and precipitation data for each trial were obtained from the nearest California Irrigation

Management Information System (CIMIS) weather station. Irrigation supplemented normal rainfall as 

needed for all trials. Field report summaries for each trial detailing the site location, record of 

imidacloprid use, maintenance chemicals, climatic data, and irrigation data are located in Appendix 3 of 

the study report.

Table 2. Trial Site Conditions for Imidacloprid on Cotton*

Trial Identification 

Trial Location

(County, State) Soil Typea Rainfall b (in)

Temperature 

Range b (°F)

NT001 Kern County, CA

Buttonwillow Clay 

(Heavy) 0.00 63-95

NT002 Kern County, CA

Lokern Clay 

(Heavy) 0.00 63-95

NT003

Kern County, CA

Lokern Clay 

(Heavy) 0.00 59-93

NT004

Kings County, CA

Houser Clay 

(Heavy) 0.00 59-93

NT005

Kings County, CA

Tulare Clay 

(Heavy) 0.00 64-96

a 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.

*Table 3 of study report

5D. SAMPLE COLLECTION, HANDLING, PROCESSING

At each sampling interval, quadruplicate samples of cotton nectar and leaves were collected from the 

plot during flowering (BBCH 61, beginning of flowering to BBCH 67, flowering finished and majority of 

flowers faded). Pre-application samples were collected two to seven days prior to application and postapplication samples were collected six days following application.
MRID 49103301 CDPR IMI Cotton (2011)

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Nectar and leaves were collected from the same plants, but by different individuals to prevent 

contamination. The same number of treated leaves was collected from each plant as necessary to 

achieve a minimum sample weight of 500 g. Each leaf sample was a composite from high, low, inside, 

and outside areas of the plant. Nectar was sampled from a minimum of twenty plants to obtain a 

minimum sample weight of 1 g. The individual collecting nectar samples did not touch 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. All samples were placed in frozen 

storage upon receipt at California Agricultural Research, Inc. Samples were shipped frozen via 

Agricultural Chemicals Development Services (ACDS) and remained frozen until receipt at BRP.

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 leaf samples were 

homogenized with dry ice using a Robot Coupe chopper (Jackson, MS). The leaf samples were returned 

to frozen storage immediately following homogenization, and all samples remained frozen at all times 

except during subsampling for analysis. A summary of collection, shipment, and homogenization dates 

for the trials is given in Appendix 2 of the study report.

5E. ANALYTICAL METHODS

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

and imidacloprid olefin in cotton nectar and leaves.4

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

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

approximately 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 (5-0H) and imidacloprid olefin (olefin) in 

cotton nectar, an aliquot of the nectar was diluted with mobile phase [(9:1 v/v) water (H20)/ methanol 

(MeOH) containing 10 mM ammonium bicarbonate (NH4HC03)] containing the stable, isotopically 

labeled internal standards. The samples were analyzed, by high performance liquid 

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

For the determination of imidacloprid, 5-0H and olefin in cotton leaves, a ~0.50-g aliquot of 

homogenized cotton leaves was extracted by vigorously shaking first with water; followed by 

acetonitrile (ACN). The sample was amended with stable, isotopically labeled internal standards, 

anhydrous magnesium sulfate (MgS04) 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 MgS04 and 

mixed, followed again by centrifugation. An aliquot of the supernatant was subjected to a C-18 SPE bond 

elute cartridge and the eluate was evaporated. The solids were reconstituted with mobile phase. The 

sample was filtered with a 0.45 um nylon syringe filter and analyzed by LC/MS/MS.
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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 (Appendix 4 in the study report).

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

measured over the range of 1 ppb to 2000 ppb for each analyte. The coefficients of determination (r2

) 

were calculated using linear regression analysis (LCQUAN 2.5 TM, Microsoft Excel 2002).

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 cotton nectar and leaves was validated by measuring the recovery of these analytes from control 

matrices fortified at their respective LOQs. 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.

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 ppb to 2000 ppb for each analyte. The coefficients of 

determination were >0.993. 

All control interferences for each analyte in cotton nectar and leaves were less than their respective 

LODs.

The recovery data for imidacloprid, 5-hydroxy imidacloprid, and imidacloprid olefin residues are 

summarized in Table 3. 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 analytical data summaries are 

located in Appendix 4 of the study report.
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Table 3. Summary of Recoveries of Imidacloprid from Cotton*

Crop Matrix Analytea Spike Level 

(ppm)

Sample 

Size (n)

Recoveries (%)b Mean % 

Recovery

Standard 

% 

Deviation

Cotton Leaves

5-OH

0.002 7 107, 93, 93, 126, 88, 83, 105 99 15 

0.010 1 95 95 NA

0.750 3 96, 106, 99 100 5

1.750 3 105, 103, 98 102 4

Imidacloprid 

0.002 7 99, 95, 97, 108, 105, 101, 114 103 7

0.010 1 85 85 NA

0.750 3 90, 95, 86 90 5

1.750 3 97, 103, 89 97 7

Olefin

0.002 7 107, 109, 96, 113, 91, 96, 94 101 9

0.010 1 91 91 NA

0.750 3 95, 90, 98 94 4

1.750 3 94, 100, 86 93 7

Cotton Nectar

5-OH

0.001 7 92, 93, 96, 99, 69, 96, 82 90 10

0.050 3 101, 101, 101 101 0.3

0.075 3 98, 99, 99 99 0.5

Imidacloprid

0.001 7 99, 98, 94, 102, 111, 99, 98 100 5

0.050 3 101, 101, 102 101 0.4

0.075 3 98, 99, 99 98 0.7

Olefin

0.001 7 97, 83, 94, 100, 81, 100, 85 91 8

0.050 3 102, 102, 101 102 0.3

0.075 3 100, 101, 100 100 0.6 a Analytes are abbreviated: 5-0H = 5-Hydroxy imidacloprid, Olefin = imidacloprid Olefin. b See Appendix 4 of the study report for the analytical data summaries and refined data used to prepare this 

summary. 

 Mean Recovery = mathematical average of all recoveries.

*Table 6 in study report

The limit of quantitation (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 limit of detection (LOD) is defined as the lowest concentration of an analyte that can be determined 

to be statistically different from a blank. The LODs were determined from method validation data 

obtained from control samples fortified at the respective analyte LOQs. The LODs were calculated by 

multiplying the standard deviation of recovery measurements at the LOQ by t0.99 [where t0.99 is the onetailed t-statistic at the 99% confidence level for the number of replicates (n)] 6

. The LOD for the total 

imidacloprid residue in each matrix is the highest LOD value of any individual analyte for that particular 

matrix.
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Summary of LOQs and LODs

Matrix Analyte LOQ (ppb) LOD (ppb)

Cotton Nectar

Imidacloprid 1.0 0. 1

5-hydroxy Imidacloprid 1.0 0.3

Imidacloprid Olefin 1.0 0.3

Total Imidacloprid 1.0 0.3

Cotton 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

6. RESULTS:

Total imidacloprid was calculated as the sum of imidacloprid, 5-hydroxy imidacloprid, and imidacloprid 

olefin in parent equivalents. Summary statistics of the overall magnitude of total imidacloprid in cotton 

nectar and leaves are shown below in Table 4. In cases where individual analyte residues were less than 

the LOD, a value of half the LOD was used to calculate total imidacloprid. The average total imidacloprid 

residue in cotton leaves in the five sites ranged from 4.3 ppb to 23 ppb before the 2010 aerial (foliar) 

application. Then, six days after application, the average total imidacloprid residue in leaves ranged from 

230 ppb to 1700 ppb. The average total imidacloprid residue in nectar ranged from 1.4 ppb to 4.2 ppb 

prior to the 2010 aerial application. Then, six days after application, the average total imidacloprid 

residue in nectar ranged from 16 ppb to 56 ppb.

The total imidacloprid residue data for cotton nectar and leaves are provided below in Table 5A and 5B.

Table 4. Magnitude of total imidacloprid residues in cotton nectar and leaves.

Commodity

Soil Texture 

Category a

Days After 

Treatment 

(DAT)b

Total Imidacloprid Residue Levels (ppb)c

N Min Max

Highest 

Avg. Site 

Residue Median Mean

Standard 

Deviation

Cotton Nectar Heavy Soil Pre-App

(-7 to -2 DAT)

10 1.2 4.3 4.2 2.7 2.8 1.0

Cotton Nectar Heavy Soil Post-App

(6 DAT)

10 13 66 56 21 29 18

Cotton Leaves Heavy Soil Pre-App

(-7 to -2 DAT)

10 3.3 25 23 14 14 7.8

Cotton Leaves Heavy Soil Post-App

(6 DAT)

10 150 1900 1700 360 770 670

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 Duplicate samples of nectar and leaves from the five trials were analyzed at pre- and postapplication sample intervals. 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.
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Table 5A. Imidacloprid Residue Data from Pre-Application Cotton* Trial Identification Location (City, State, Region) Plot Name Commodity Rate, lb a.i./A (2008 and 2009)b Residue Sample Collection DAT (Days after 2010 

Tratement)c

Imidacloprid Residue (ppb)

5-Hydroxy Imidacloprid 

Residue (ppb)

Imidacloprid Olefin Residue 

(ppb)

Total Imidacloprid Residue 

(ppb)

Nectar Pre-Application Residue (ppb) a

NT001 Kern County, 

CA NAFTA 

Region 10

Buttonwillow

Clay, Site S1 

(Heavy)

Nectar, 

Pre-App

0.72 -7 2.7

3.5

<1

<1

<1

<1

3.0

3.8

Average

3.4

NT002 Kern County, 

CA NAFTA 

Region 10 2010

Lokern Clay, Site 

S2 (Heavy)

Nectar, 

Pre-App

0.76 -3 2.6

2.0

<1

<1

<1

<1

2.9

2.3

Average

2.6

NT003 Kern County, 

CA NAFTA 

Region 10

Lokern Clay, Site 

S3 (Heavy)

Nectar, 

Pre-App

0.76 -3 1.2

<1

<1

<1

<1

<1

1.5

1.2

Average

1.4

NT004 Kings County, 

CA NAFTA 

Region 10 2010

Houser Clay, Site 

S4 (Heavy) 

Nectar, 

Pre-App

0.25 -2 2.2

2.1

<1

<1

<1

<1

2.5

2.4

Average

2.5

NT005 Kings County, 

CA NAFTA 

Region 10 2010

Tulare Clay, Site 

S5 (Heavy)

Nectar, 

Pre-App

0.47 -2 4.0

3.8

<1

<1

<1

<1

4.3

4.1

Average

4.2

Leaves Pre-Application Residue (ppb) a

NT001 Kern County, 

CA NAFTA 

Region 10

Buttonwillow

Clay, Site S1 

(Heavy)

Leaves, 

Pre-App

0.72 -7 4.8

5.3

<2

2.1

<2

<2

7.8

8.5

Average

0.0082

NT002 Kern County, 

CA NAFTA 

Region 10 2010

Lokern Clay, Site 

S2 (Heavy)

Leaves, 

Pre-App

0.76 -3 11.4

9.4

3.0

2.7

<2

<2

16

13

Average

14

NT003 Kern County, 

CA NAFTA

Region 10

Lokern Clay, Site 

S3 (Heavy)

Leaves, 

Pre-App

0.76 -3 <2

3.7

<2

<2

<2

<2

3.3

5.3

Average

4.3

NT004 Kings County, 

CA NAFTA 

Region 10 2010

Houser Clay, Site 

S4 (Heavy) 

Leaves, 

Pre-App

0.25 -2 16.3

17.8

3.1

3.0

<2

<2

21

22

Average

21
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Trial Identification

Location (City, State, 

Region)

Plot Name

Commodity

Rate, lb a.i./A

(2008 and 2009)b

Residue Sample Collection 

DAT (Days after 2010 

Tratement)c

Imidacloprid Residue (ppb)

5-Hydroxy Imidacloprid 

Residue (ppb)

Imidacloprid Olefin Residue 

(ppb)

Total Imidacloprid Residue 

(ppb)

NT005 Kings County, 

CA NAFTA 

Region 10 2010

Tulare Clay, Site 

S5 (Heavy)

Leaves, 

Pre-App

0.47 -2 22.2

18.6

2.2

<2

<2

<2

25

21

Average

23

a See Appendix 4 of the study report for analytical data summaries and refined data used to prepare this summary. 

Total imidacloprid is the sum of imidacloprid, 5-hydroxy imidacloprid, and imidacloprid olefin. b The rate reported is the total imidacloprid applied during the 2008 and 2009 growing seasons. See section 2.0 of 

this report for further detail regarding historical imidacloprid applications to these sites.

c DAT= Days after Treatment. Negative value indicates that samples were collected prior to the 2010 application of 

Provado 1.6F.

*Table 8A in study report.

Table 5B. Imidacloprid Residue Data from 2010 Post-Application Cotton. * Trial Identification Location (City, State, Region) Plot Name Commodity 2010 Total Seasonal Rate, lb a.i./A (fl oz FP/A)

b

Residue Sample Collection 

(DAT)

c

Imidacloprid Residue (ppb)

5-Hydroxy Imidacloprid 

Residue (ppb)

Imidacloprid Olefin Residue 

(ppb)

Total Imidacloprid Residue 

(ppb)

Nectar Post-Application Residue (ppb) a

NT001 Kern County, 

CA NAFTA 

Region 10

Buttonwillow

Clay, Site S1 

(Heavy)

Nectar, 

Post-App

0.063

(5.0)

6 14

18.1

<1

1.0

<1

<1

15

20

Average

16

NT002 Kern County, 

CA NAFTA 

Region 10 2010

Lokern Clay, Site 

S2 (Heavy)

Nectar, 

Post-App

0.063

(5.0)

6 17.5

11.9

<1

<1

<1

<1

19

13

Average

16

NT003 Kern County, 

CA NAFTA 

Region 10

Lokern Clay, Site 

S3 (Heavy)

Nectar, 

Post-App

0.063

(5.0)

6 20.5

14.8

1.2

<1

<1

<1

22

16

Average

19

NT004 Kings County, 

CA NAFTA 

Region 10 2010

Houser Clay, Site 

S4 (Heavy) 

Nectar, 

Post-App

0.063

(5.0)

6 31.7

42

1.5

2.1

<1

<1

34

45

Average

0.039
MRID 49103301 CDPR IMI Cotton (2011)

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Trial Identification

Location (City, State, Region)

Plot Name

Commodity

2010 Total Seasonal Rate,

lb a.i./A (fl oz FP/A)

b

Residue Sample Collection 

(DAT)

c

Imidacloprid Residue (ppb)

5-Hydroxy Imidacloprid 

Residue (ppb)

Imidacloprid Olefin Residue 

(ppb)

Total Imidacloprid Residue 

(ppb)

NT005 Kings County, 

CA NAFTA 

Region 10 2010

Tulare Clay, Site 

S5 (Heavy)

Nectar, 

Post-App

0.063

(5.0)

6 42.8

61.5

2.4

3.4

<1

<1

46

66

Average

56

Leave Post-Application Residue (ppb) a

NT001 Kern County, 

CA NAFTA 

Region 10

Buttonwillow

Clay, Site S1 

(Heavy)

Leaves, 

Post-App

0.063

(5.0)

6 135

269

14.5

24.1

2.9

4.3

150

300

Average

230

NT002 Kern County, 

CA NAFTA 

Region 10 2010

Lokern Clay, Site 

S2 (Heavy)

Leaves, 

Post-App

0.063

(5.0)

6 243

273

50.1

42.2

10.1

8.6

300

320

Average

310

NT003 Kern County, 

CA NAFTA 

Region 10

Lokern Clay, Site 

S3 (Heavy)

Leaves, 

Post-App

0.063

(5.0)

6 231

341

42.7

43.7

9.4

10.8

280

400

Average

340

NT004 Kings County, 

CA NAFTA 

Region 10 2010

Houser Clay, Site 

S4 (Heavy) 

Leaves, 

Post-App

0.063

(5.0)

6 1540

1820

55.4

55.9

14.6

13.4

1600

1900

Average

1700

NT005 Kings County, 

CA NAFTA 

Region 10 2010

Tulare Clay, Site 

S5 (Heavy)

Leaves, 

Post-App

0.063

(5.0)

6 792

1460

63.1

95.2

17.1

25.7

870

1600

Average

1200 a See Appendix 4 of the study report for analytical data summanes and refined data used to prepare th1s summary. 

Total imidacloprid is the sum of imidacloprid, 5-hydroxy imidacloprid, and imidacloprid olefin. b Total Seasonal Rate (lb ai/A) = Provado 1.6 F foliar application to cotton in 2010. The rate of the formulated 

product applied (fl oz FP/A) is indicated in parenthesis. See section 2.0 of this report for further detail regarding 

historical imidacloprid applications to these sites.

c DAT = Days after Treatment. Samples were collected 5 to 6 days following the 2010 application of

Provado 1.6 F.

*Table 8B in study report. 

7. STUDY VALIDITY/CLASSIFICATION AND STUDY LIMITATIONS 

Classification/Utility for Bee Risk Assessment. This study is classified as SUPPLEMENTAL because the 

application rate is far below the maximum annual application rate (so this is not a worst case scenario). 

The 2010 application rate of 0.063 lbs. a.i./acre, represents the highest allowable single foliar

application rate, but it does not represent the maximum foliar rate per season, resulting from 5 

applications, of 0.31 lbs./acre/season. The study also does not represent the maximum amount of 

imidacloprid allowable per season on cotton, which is 0.5 lbs./acre/season. The submitted data provides
MRID 49103301 CDPR IMI Cotton (2011)

12

information on potential residues in nectar from a single foliar application. However, the residues do not

represent cotton treated at the highest label rate possible in accordance with the label. The study

provides data that does not meet all of DPR’s reevaluation data requirements for cotton. Data from a 

worst case imidacloprid application scenario (including soil applications) at the maximum seasonal rate 

allowed by imidacloprid product labels is still needed.

Temporal Variability in Residues. Samples were collected 2-7 days before and 6 days after the aerial 

application in 2010 but a decline in residues was not recorded because only one time point was sampled 

after application. This study was not designed for temporal analysis of declining concentrations, but 

rather, to provide a snapshot of residue concentrations during flowering.

Spatial Variability in Residues. All five sites were in Kern and Kings County in the Southern Central 

Valley (i.e., San Joaquin Valley) of California. All of the sites had similar climatic conditions. All five sites 

had soil with fine (heavy) texture. Medium and coarse soils were not included in this study.

Pesticide Carryover. The extent to which prior year applications of imidacloprid contributed to year-toyear carryover was not analyzed by the study authors.

Additionally, if the data is to be used as part of a risk assessment, then the data should be re-analyzed 

taking the following uncertainties into consideration: (1) One of the five sites had two chemigation 

applications in 2009 but no application at all in 2008 (NT004); and (2) This study did not distinguish 

between floral and extra-floral nectar.

8. CONCLUSION

This report provides data for residues of total imidacloprid in five cotton trials conducted in clay soils 

(soil classification: heavy). All plots had received prior applications (2008 and/or 2009) of imidaclopridcontaining products at rates ranging from 0.18 to 0.38 lb ai/A, and received a single application of 

Provado 1.6 F to cotton in 2010 at 0.063 lb imidacloprid/A (5.0 fl oz formulated product/A) during 

flowering (BBCH 61 to BBCH 67). The average total imidacloprid residue in nectar ranged from 1.4 ppb 

to 4.2 ppb prior to the 2010 aerial application. Then, six days after application, the average total 

imidacloprid residue in nectar ranged from 16 ppb to 56 ppb. The study does not represent the 

maximum amount of imidacloprid allowable per season on cotton and thus this study is found to be 

supplemental.

9. REFERENCES

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

 Bayer CropScience Report No. M0-03-006885, M-1 05510-01-1.

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 14 200 0804. 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 lmidacloprid in Bee
MRID 49103301 CDPR IMI Cotton (2011)

13

 Relevant Matrices Using LC/MS/MS. Bayer Report No. NT-005-P1 0-01.

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. MR-853/98.

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

 pesticide residues in human health food exposure assessments. EPA Docket

 #OPP-00570A