MRID 49090502 CDPR IMI Strawberry

1 Reference

Gould, T.; Dallstream, K.; Beedle, E. (2012) Determination of the Residues of Imidacloprid and its

Metabolites 5

- Hydroxy Imidacloprid and Imidacloprid Olefin in Bee Relevant Matrices Collected from

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

Successive Years . Project Number: EBTNL056/04, M/445207/01/2. Unpublished study prepared by

Bayer Cropscience LP and California Agricultura l Research Inc. 186p. MRID 49090502 , CDPR Study ID

268742 , Data Volume 51950

- 0812 , Tracking ID# 256590

1. STUDY INFORMATION

Chemical: Imidacloprid PC Code 129099

Test Material: 1) Admire Pro

2) Alias 4F Percent Active

Ingredient: 1) 42.8%

2) 40%

Study Type: Non

- G uideline field residue study to establish imidacloprid and metabolite levels

in blossoms, anthers, pollen and leaves from strawberry in site locations that

have been previously treated with imidacloprid at least once for two successive

years

.

Sponsor: Bayer CropScience

2T.W. Alexander Drive

Research Triangle Park, NC

USA 27709 Experiment Start and

End Date: September 2011

–

December 1 3 , 2012

Sponsor Study

ID: EBNTL056

- 04

Study Locations: Seven treated fields

sites within California

that consist of either

sand or loam soil. Study

Completion

Date: December 27, 2012

GLP Status: Non

- GLP; protocol reviewed by CDPR

. [CDPR study ID 260012 , Data Volume 51950

- 0791 , Tracking ID# 247269 ]

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

Blossom and leaf samples were collected from seven treated field sites in Santa Barbara County, California

to determine the residues of imidacloprid and its metabolites (5

- hydroxy imidacloprid and imidacloprid

olefin) in blossoms, anthers, pollen and leaves collected from strawberry plants grown at locations treated

with imi dacloprid at least once per year for two years. The site locations consisted of either a sand soil (3

sites, “light ” ) or a loam soil (4 sites, “medium”), which had all previous received applications of either Alias

4F or Admire Pro at a rate of 0.5 l b

. a

. i

. / acre in the prior year as well as an application of imidacloprid in

2010.MRID 49090502 CDPR IMI Strawberry

2 Duplicate composite samples of strawberry blossoms for direct analysis, strawberry blossoms for anther

samples, strawberry blossoms for pollen samples and strawberry leaves were collected at a BBCH ranging

from 61 to 69 (flowering) at each field site.

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. The individual analyte residues were summed to give a total

imidacloprid residue

.

4. STUDY VALIDITY

Guideline Followed: Non

- guideline study (protocol was reviewed by U.S. EPA/PMRA/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, Alias and

Unknown Formulations pH (24°C) 7.8

Description: U nknown Density (20°C) : 1.54 g/mL

CAS #: 138261

- 41

- 3 Solubility: 0.51 to 0.61 g/L

5A. S TUDY D ESIGN

Seven treated field sites in California representing two soil categories classified as either 'light,' generally

sand soil, or 'medium,' generally loam soil, were selected based on previous application(s) of

imidacloprid according to grower interviews. Classification of the soils was obtained from the Soil Survey

Geographic (SSURGO) Database provided by the Natural Resources Conservation S ervice. All test sites

had received applications of imidacloprid in the preceding years (2011, 2010).

The field sampling phase of this study occurred in September, 2011, and was not conducted under GLP.

The GLP experimental start date was August 22, 2012 ( leaf sample homogenization), and the

experimental end date was December 13, 2012 (last analysis). The field sampling phase of the study was

conducted by California Agricultural Research, Inc. (CAR).

The sampling of blossoms and leaves, as well as the separation of the pollen and anthers, were

performed at the test site. Homogenization of the leaves and blossoms for direct analysis from this

study were performed at the Bayer Research Park (BRP) located in Stilwell, KS. Sample analysis and

report prepara tion was performed at Bayer CropScience located in Research Triangle Park, NC. All raw

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

report under Notebook Number EBNTL056

- 04 at locations specified b y Bayer CropScience.

5B. A PPLICATION T IMING AND R ATESMRID 49090502 CDPR IMI Strawberry

3 In 2011, one application of either Alias 4F or Admire Pro was made to the soil at a rate of 0.5 lb

. a

. i ./acre

in each of the seven field sites. In 2010, one soil application of an imidacloprid product ( the subject

product s were not identified for four out of seven of the sites) was made at a rate of 0.5 lb

. a

. i ./acre in

each of the seven field sites. Method, timi ng or growth stage, and spray volume of these applications

were not reported by the study authors. Thus, it is uncertain when the sampling was conducted in

relation to the imidacloprid applications.

The test substance use pattern for imidacloprid in 2011 and 2010 for each site is described in Table 1 . All

site locations were in Santa Barbara county in California, NAFTA Region 10

. For the applications in 2011,

either Alias 4F or Admire Pro were applied at a rate of 0.5 lb ai/A.

Table 1. Study Use Pattern f or 2011 Application of Imidacloprid on Strawberry.

Trial

Identification Location Year End Use

Product a Timing/Grow

th Stage Spray

Volume b Rate (lb.

a.i./A) a

NT031

- 11ZA Santa

Maria, CA

Region 10 2011

2010 Alias 4F

Alias 4F Unknown

Unknown Unknown

Unknown 0.5

0.5

NT032

- 11ZA Santa

Maria, CA

Region 10 2011

2010 Alias 4F

Alias 4F Unknown

Unknown Unknown

Unknown 0.5

0.5

NT033

- 11ZA Santa

Maria, CA

Region 10 2011

2010 Alias 4F

Alias 4F Unknown

Unknown Unknown

Unknown 0.5

0.5

NT035

- 11ZA Santa

Maria, CA

Region 10 2011

2010 Alias 4F

Not Available c Unknown

Unknown Unknown

Unknown 0.5

0.5

NT037

- 11ZA Santa

Maria, CA

Region 10 2011

2010 Admire Pro

Not Available c Unknown

Unknown Unknown

Unknown 0.5

0.5

NT038

- 11ZA Santa

Maria, CA

Region 10 2011

2010 Admire Pro

Not Available c Unknown

Unknown Unknown

Unknown 0.5

0.5

NT039

- 11ZA Santa

Maria, CA

Region 10 2011

2010 Admire Pro

Not Available c Unknown

Unknown Unknown

Unknown 0.5

0.5

a imidacloprid use was obtained from verbal communications wi th the growers or pest control advisors.

b Rates and spray volumes that were provided in the application order/recommendation. See Appendix 2 of the

study report for field trial summary data.

c imidacloprid use was confirmed by the grower, but no documentation was available .

5C. S TUDY S ITE L OCATION AND C HARACTERISTICS

The trial site conditions including soil chara cteristics are listed in Table 2 . All sites used agronomic

practices typical for commercial production of strawberries. A chronological listing of significant study

dates is given in Appendix 1 of the study report

.MRID 49090502 CDPR IMI Strawberry

4 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 th e study.

Tem perature and precipitation data for each trial were obtained from the nearest National Climatic Data

Ce nter (NCDC) weather station

. Application, sampling and climatic data are located in Appendix 2 of the

study report

.

Table 2. Trial Site Conditions for Imidacloprid on Strawberry.

Trial

Identification Trial Location Soil Type a Rainfall (in) b Temperature

Range (°F) b

NT031

- 11ZA Santa Maria, CA

Region 10 Batteravia Loamy

Sand, Light 0.1 58

- 78

NT032

- 11ZA Santa Maria, CA

Region 10 Oceano Sand,

Light 0.1 58

- 78

NT033

- 11ZA Santa Maria, CA

Region 10 Batteravia Loamy

Sand, Light 0.1 58

- 78

NT035

- 11ZA Santa Maria, CA

Region 10 Sorento Sandy

Loam, Medium 0.1 58

- 78

NT037

- 11ZA Santa Maria, CA

Region 10 Sorrento Loam,

Medium 0.1 58

- 78

NT038

- 11ZA Santa Maria, CA

Region 10 Sorrento Loam,

Medium 0.1 58

- 78

NT039

- 11ZA Santa Maria, CA

Region 10 Sorento Sandy

Loam, Medium 0.1 58

- 78

a Classification of the soils was obtained from the Soil Survey Geographic (SSURGO) Database provided by the

Natural Resources Conservation Service.

b Data is for the interval of the month of sampling. Meteorological data were obtained from nearby government

weather stations.

5D. S AMPLE C OLLECTION

, H ANDLING

, P ROCESSING

At each sampling interval, duplicate samples of strawberry blossoms, strawberry blossoms for anther

samples, strawberry blossoms for pollen samples, and strawberry leaves were collected from the

treated sites during flowering.

Strawberry blossoms and leaves were placed into coolers with dry ice directly after sampling. Strawberry

blossoms for anther samples were processed by removing the anthers from the blossom with

tweezers/ small scissors and transferred to a sampling jar and frozen. Strawberry blossoms for pollen

samples were allowed to dr y overnight, and the pollen was removed by vacuum and frozen.

Untreated (control) blossom and leaf samples used for validation of the analytical method and for

transit stability samples were obtained from a nearby farm that was believed to have no r ecent

imidacloprid application.

All samples were placed in frozen storage at CAR Samples were shipped to BRP frozen via Agricultural

Chemicals Development Services (ACDS) and were placed in frozen storage upon receipt and remained

frozen throu ghout the storage period at BRP.MRID 49090502 CDPR IMI Strawberry

5 The anther and pollen samples, along with the transit stability samples, were shipped frozen to Bayer

CropScience, Research Triangle Park (RTP), NC, via ACDS. Homogenization of the leaf and blossom

samples was conducted at BRP and shipped f rozen via FedEx to RTP. During storage at RTP, the anther

and pollen samples, along with the transit stability samples, reached room temperature for

approximately three days due to freezer failure. 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. Samples were transferred to Bayer

CropScience, Research Triangle Park, NC, for analysis. Samples remained frozen at all times except

d uring preparation for analysis A summary of collection, shipment, and homogenization dates for the

trials is given in Appendix 1 of the study report

.

Additionally, freezer storage stability studies have indicated the imidacloprid residues are stable (<30%

decomposition) for 24 months (728 to 769 days) of freezer storage in the following representative crops:

an oilseed (cottonseed), a non

- oily grain (wheat), a leafy vegetable (lettuce), a root crop (potato), a tree

fruit (apple), and a fruiting vegetable ( tomato). 7

- 11

Demonstrated freezer stability in the transit stability samp les from this study, as well as stability

demonstrated in the above crops is representative of the freezer stability of imidacloprid residues to be

expected in the blossoms, anthers , pollen, and leaves collected in this study.

5E. A NALYTICAL M ETHODS

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

- hydroxy imidacloprid,

and imidacloprid olefin in strawberry blosso ms, anthers, pollen 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.

Samples of anthers, blossoms, leaves , and pollen were analyzed for residues of imid acloprid,

imidacloprid olefin, and imidacloprid 5

- hydroxy. For anthers, blossoms, and leaves , a sample was

extracted by blending samples with 2:1 acetonitrile/water (ACN/H 2 0). The mixture was amended with

MgS0 4 , NaCI, and isotopically labeled internal standards, mixed well, and centrifuged. An aliquot of the

supernatant was transferred to a 15

- mL centrifuge tube containing MgS0 4 and Bondesil

- PSA. The

contents of the tube were mixed well and centrifuged. About 1.2 ml of the supernatant was percolated

thr ough a C18 SPE cartridge (50 mg Bond Elut) into a 20x150mm culture tube. The eluate was

evaporated to dryness and the residue was reconstituted with 1:9 methanol/water (MeOH/H 2 0) for

analysis by high performance liquid chromatography/tandem mass spectromet ry (LC/MS/MS).

For pollen a sample was extracted by shaking with water for 10 min utes , adding ACN and shaking for an

additional 55 min utes . The mixture was amended with isotopically labeled internals standards, mixedMRID 49090502 CDPR IMI Strawberry

6 well and centrifuged. The supernatant was drawn off, evaporated to an aqueous remainder, amended

with water and applied to a Chern Elute cartridge (3

- ml). The analytes were extracted from the cartridge

with 3 x 5 ml of hexane/ethyl acetate (1:1 v/v). The eluate was evaporated to dryness and th e residue

was reconstituted with 1:9 methanol/water (MeOH/H 2 0) for analysis by 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 analyt e in the

standards (Appendix 3 of the study report )

.

The relative responses of imidacloprid, 5

- hydroxy imidacloprid, and imidacloprid olefin in solvent were

measured over the range of 3 ppb to 3 00 0 ppb for each analyte. The coefficients of determination (r 2 )

were calculated using linear regression analysis (Microsoft Excel 2010; Appendix 3 of the study report ).

The total imidacloprid residue is the sum of the individual measured residue valu es 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 ass igned 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.

Blossoms and leaves were collected from the control test site and were used for validation, LOD

determination, and concurrent recoveries. Commercially obtained bee pollen was also used for

validation and recovery. Because only small, untreated control samples of anthers and pol len were

generated in the field phase of this study, surrogate anther and pollen controls were used for validation,

LOD determination, and concurrent recoveries. Blossom validation LOD data was used for anthers while

the control strawberry blossoms were used for anther concurrent recoveries. Commercial bee pollen

was obtained fr om a local health food store and stored at room temperature. The bee pollen was used

without any preparation. The commercial pollen was used for pollen validation, LOD determination, and

for concurrent recoveries.

The method for determining imidacloprid, 5

- hydroxy imidacloprid, and imidacloprid olefin residues

in/on strawberry blossoms, anthers, pollen and leaves was validated by measuring the recovery of these

analytes from control matrices fortified at their respective LOQs.

Additional recoveries at hig her 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 performan ce.

5F. Q UALITY A SSURANCE R ESULTS

The responses of the LC/MS/MS system to imidacloprid, 5

- hydroxy imidacloprid, and imidacloprid olefin

were linear in solvent over the range of 3 ppb to 3 000 ppb for each analyte. The coefficients of

determination were > 0.99.

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

of the recoveries for each matrix were within the acceptable range of 70% to 120%, and the standardMRID 49090502 CDPR IMI Strawberry

7 deviation values were below 20%, except for 5

- hydroxy imidacloprid recovery from blossoms which had

a percent recovery standard deviation of 24%.

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 tot al 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 t 0.99 [where t 0.99 is the one

tailed 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.

The LOQs and LODs ar e summarized in the table below

.

Summary of LOQs and LODs

Matrix Analyte LOQ (ppb , parent equivalents) LOD (ppb , parent equivalents)

Strawberry

Blossom Imidacloprid 5.0 0. 87

5

- hydroxy Imidacloprid 5 .0 3.9

Imidacloprid olefin 5.0 1.3

Total Imidacloprid 5.0 3. 9

Strawberry

Anthers Imidacloprid 5.0 0. 87

5

- hydroxy Imidacloprid 5.0 3. 9

Imidacloprid olefin 5.0 1. 3

Total Imidacloprid 5.0 3

. 9

Strawberry

Pollen Imidacloprid 10 1

. 1

5

- hydroxy Imidacloprid 10 2.6

Imidacloprid olefin 10 2.2

Total Imidacloprid 10 2.6

Strawberry

Leaves Imidacloprid 10 2.2

5

- hydroxy Imidacloprid 10 3.0

Imidacloprid olefin 10 4.6

Total Imidacloprid 10 4.6

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

r eported as < 5 pp b for blossoms and anthers and < 10 ppb for leaves and pollen. In Appendix 3 of the

study report , any residue value that was below the LOD was reported as less than the LOD and

m easured residue values betwe en the LOQ and LOD are also provided.

6. RESULTS:

Summary statistics for concentration of total imidacloprid in strawberry blossoms, anthers, pollen and

leaves are contained in Table 3

. The individual analyte resid ues were summed to give a totalMRID 49090502 CDPR IMI Strawberry

8 i midacloprid residue. The study authors stated that when ind ividual analyte residue values were less

than the LOD, the residues were assigned a finite value of half the value of the respective LOD.

Table 3

. Magnitude of total imidacloprid residues in strawberry blossoms, anthers, pollen, and leaves.

Commodity Soil Texture

Category a Total Imidacloprid Residue Levels (ppb) b

N Min Max Highest

Avg

. Site

Residue Median Mean Standard

Deviation

Strawberry Blossoms Coarse 6 21 0 53 0 50 0 38 0 3 6 0 1 3 0

Strawberry Anthers Coarse 6 81 30 0 25 0 20 0 18 0 82

Strawberry Pollen Coarse 6 78 32 0 28 0 21 0 19 0 95

Strawberry Leaves Coarse 6 17 00 28 00 2 4 00 2 1 00 2 2 00 41 0

Strawberry Blossoms Medium 8 < 5 .0 31 18 6.4 9.4 9.1

Strawberry Anthers Medium 8 11 33 23 13 18 7

. 9

Strawberry Pollen Medium 8 < 10 .0 < 10 .0 < 10 .0 < 10 .0 < 10 .0 < 10 .0

Strawberry Leaves Medium 8 < 10 .0 18 17 11 11 < 10 .0

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 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 Dev iation is the standard deviation for a small population of “N” samples.

The total imidacloprid residue data for strawberry blossoms, anthers, pollen and leaves are provided in

Table 4

.

Table 4. Imidacloprid Residue Data from Strawberry.TrialIdentificationLocation (City, State,Region)Plot NameCommodityRate, lb a.i./AResidue Sample CollectionDAT (Days after 2010Imidacloprid Olefin Residue(ppb)5-Hydroxy ImidaclopridResidue (ppb)Imidacloprid Residue (ppb)Total Imidacloprid Residue(ppb)

Blossoms Residue (ppb) a

NT031

- 1ZA Santa Maria,

CA, Region 10 Sand 1 Blossom 0.5 NA 10

12 46

33 470

420 530

470

Average

500

NT032

- 1ZA Santa Maria,

CA, Region 10 Sand 2 Blossom 0.5 NA 8.7

8.2 31

27 340

350 380

380

Average

380MRID 49090502 CDPR IMI Strawberry

9TrialIdentificationLocation (City, State,Region)Plot NameCommodityRate, lb a.i./AResidue Sample CollectionDAT (Days after 2010Imidacloprid Olefin Residue(ppb)5-Hydroxy ImidaclopridResidue (ppb)Imidacloprid Residue (ppb)Total Imidacloprid Residue(ppb)

NT033

- 1ZA Santa Maria,

CA, Region 10 Sand 3 Blossom 0.5 NA 8.5

10 38

40 160

170 210

220

Average

220

NT035

- 1ZA Santa Maria,

CA, Region 10 Loam 1 Blossom 0.5 NA <5.0

<5.0 7.0

<5.0 22

<5.0 31

<5.0

Average

18

NT037

- 1ZA Santa Maria,

CA, Region 10 Loam 3 Blossom 0.5 NA <5.0

<5.0 7.4

<5.0 <5.0

<5.0 11

6.0

Average

8.6

NT038

- 1ZA Santa Maria,

CA, Region 10 Loam 4 Blossom 0.5 NA <5.0

<5.0 5.1

6.8 <5.0

<5.0 6.7

8.8

Average

7.7

NT039

- 1ZA Santa Maria,

CA, Region 10 Loam 5 Blossom 0.5 NA <5.0

<5.0 <5.0

<5.0 <5.0

<5.0 <5.0

<5.0

Average

<5.0

Anthers Residue (ppb) a

NT031

- 1ZA Santa Maria,

CA, Region 10 Sand 1 Anthers 0.5 NA 19

9.5 43

26 240

170 300

210

Average

250

NT032

- 1ZA Santa Maria,

CA, Region 10 Sand 2 Anthers 0.5 NA 7.5

9.5 24

35 160

180 190

220

Average

210

NT033

- 1ZA Santa Maria,

CA, Region 10 Sand 3 Anthers 0.5 NA 5.5

7.6 26

20 64

54 96

81

Average

89

NT035

- 1ZA Santa Maria,

CA, Region 10 Loam 1 Anthers 0.5 NA <5.0

<5.0 13

7.6 38

<5.0 19

11

Average

15

NT037

- 1ZA Santa Maria,

CA, Region 10 Loam 3 Anthers 0.5 NA <5.0

<5.0 13

22 <5.0

<5.0 14

25

Average

19

NT038

- 1ZA Santa Maria,

CA, Region 10 Loam 4 Anthers 0.5 NA <5.0

8.8 8.7

23 <5.0

<5.0 13

33

Average

23MRID 49090502 CDPR IMI Strawberry

10TrialIdentificationLocation (City, State,Region)Plot NameCommodityRate, lb a.i./AResidue Sample CollectionDAT (Days after 2010Imidacloprid Olefin Residue(ppb)5-Hydroxy ImidaclopridResidue (ppb)Imidacloprid Residue (ppb)Total Imidacloprid Residue(ppb)

NT039

- 1ZA Santa Maria,

CA, Region 10 Loam 5 Anthers 0.5 NA <5.0

<5.0 11

11 <5.0

<5.0 12

13

Average

13

Pollen Residue (ppb) a

NT031

- 1ZA Santa Maria,

CA, Region 10 Sand 1 Pollen 0.5 NA 17

14 42

33 260

200 320

250

Average

280

NT032

- 1ZA Santa Maria,

CA, Region 10 Sand 2 Pollen 0.5 NA 14

10 32

25 190

150 240

190

Average

210

NT033

- 1ZA Santa Maria,

CA, Region 10 Sand 3 Pollen 0.5 NA <10

<10 21

18 57

54 87

78

Average

83

NT035

- 1ZA Santa Maria,

CA, Region 10 Loam 1 Pollen 0.5 NA <10

<10 <10

<10 <10

<10 <10

<10

Average

<10

NT037

- 1ZA Santa Maria,

CA, Region 10 Loam 3 Pollen 0.5 NA <10

<10 <10

<10 <10

<10 < 10

<10

Average

<10

NT038

- 1ZA Santa Maria,

CA, Region 10 Loam 4 Pollen 0.5 NA <10

<10 <10

<10 <10

<10 <10

<10

Average

<10

Leaves Residue (ppb) a

NT031

- 1ZA Santa Maria,

CA, Region 10 Sand 1 Leaves 0.5 NA 14

17 50

64 1600

2200 1700

2300

Average

2000

NT032

- 1ZA Santa Maria,

CA, Region 10 Sand 2 Leaves 0.5 NA 27

18 53

48 2300

1900 2400

1900

Average

2200

NT033

- 1ZA Santa Maria,

CA, Region 10 Sand 3 Leaves 0.5 NA 42

25 100

70 2700

1800 2800

1900

Average

2400MRID 49090502 CDPR IMI Strawberry

11TrialIdentificationLocation (City, State,Region)Plot NameCommodityRate, lb a.i./AResidue Sample CollectionDAT (Days after 2010Imidacloprid Olefin Residue(ppb)5-Hydroxy ImidaclopridResidue (ppb)Imidacloprid Residue (ppb)Total Imidacloprid Residue(ppb)

NT035

- 1ZA Santa Maria,

CA, Region 10 Loam 1 Leaves 0.5 NA <10

<10 <10

<10 14

<10 18

16

Average

17

NT037

- 1ZA Santa Maria,

CA, Region 10 Loam 3 Leaves 0.5 NA <10

<10 <10

<10 <10

<10 <10

10

Average

<10

NT038

- 1ZA Santa Maria,

CA, Region 10 Loam 4 Leaves 0.5 NA <10

<10 <10

<10 <10

<10 12

13

Average

13

NT039

- 1ZA Santa Maria,

CA, Region 10 Loam 5 Leaves 0.5 NA <10

<10 <10

<10 <10

<10 <10

<10

Average

<10

a See Appendix 3 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 .

In coarse

- textured soils, mean residues of total imidacloprid were 360, 180, 190, and 2200 ppb in

blossoms, anthers, pollen, and leaves, respectively and, maximum residues were 530, 300, 320, and

2800 ppb in blossoms, anthers, pollen, and leaves respectively. In medium

- textured soils, mean residues

of total imidacloprid were 9.4, 18, <0.010 (LOQ), and 11 ppb in blossoms, anthers, pollen, and leaves,

respectively, and maximum resi dues were 31, 33, <0.010 (LOQ), and 18 ppb in blossoms, anthers, pollen,

and leaves respectively. Thus, in all matrices (blossoms, anthers, pollen, and leaves) mean

concentrations of total imidacloprid were approximately ten times higher in strawberries gr own in

coarse

- textured soil than in medium

- textured soil.

7. STUDY VALIDITY/ CLASSIFICATION AND STUDY LIMITATIONS

Classification/Utility for Bee Risk Assessment. The study is SUPPLEMENTAL for considering the level of

residues of imidacloprid in pollen after soil application in strawberry. The level of imidacloprid residues

appeared to be much higher in strawberries grown in coarse

- textured sandy soil than in medium

textured loamy soil. In sandy soil, soil application at 0.5 lb ai/A of imidacloprid for two consecutive years

resulted in maximum total imidacloprid residues of 320 ppb (mean ± SEM, 190 ± 95), 300 ppb (180±82),

530 ppb (360±130) and 2800 ppb (2200±410) respectively in strawberry pollen, anthers, blossoms and

leaves. Residues in strawberry nectar, another bee

- relevant matrix, were not measured. Another

concern is that the date of the last soil application was not provided, thus the duration from the soil

application to the collecti on of the samples could not be estimated.MRID 49090502 CDPR IMI Strawberry

12 Temporal Variability in Residues . This study was not designed to measure temporal variability in

residues. All samples were taken in 2011, within five days of each other. Thus, this study was designed

to analyze i midacloprid residues at a single time point. In addition, time of sampling in relation to the

imidacloprid applications, is unknown.

Spatial Variability in Residues. All seven sites for this strawberry study were located in Santa Maria, CA.

As expected, reported weather conditions (temperature and precipitation) were the same across all

seven sites. As a result of the close proximity of trial sites, this study provides very limited information

on how differences in environmental conditions across differen t areas of the US may affect

accumulation of total imidacloprid in bee

- relevant matrices. However, because there are different soil

types represented (3 sand soil sites and 4 loam soil sites), this study may offer insight to how soil type

may affect accumu lation of total imidacloprid in bee

- relevant matrices. In all matrices (blossoms,

anthers, pollen, and leaves) mean concentrations of total imidacloprid were higher in strawberries

grown in sandy soil than in loam soil.

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

taken in 2011, within five days of each other. This this study is designed to analyze imidacloprid residues

at a single time point.

8. CONCLUSION

Samples were obtained from 7 field sites where soil in 3 of the sites was classified as coarse

- textured

and the other 4 classified as medium

- textured. The cultivar of strawberry was not reported that was

grown in each field. Parent imidacloprid and 2 breakdown products, the 5

- Hdroxy and Olefin re sidues,

were measured. Concentrations were measured for whole blossoms, anthers and pollen separated from

the blossom, and leaves. Chemical analysis was conducted on samples stored for more than 1 year.

Samples were purported to store well over this period but storage data were only referenced and not

provided.

In coarse

- textured soils, mean residues of total imidacloprid were 360, 180, 190, and 2200 ppb in

blossoms, anthers, pollen, and leaves, respectively and, maximum residues were 530, 300, 320, and

28 00 ppb in blossoms, anthers, pollen, and leaves respectively. In medium

- textured soils, mean residues

of total imidacloprid were 9.4, 18, <0.010 (LOQ), and 11 ppb in blossoms, anthers, pollen, and leaves,

respectively, and maximum residues were 31, 33, <0. 010 (LOQ), and 18 ppb in blossoms, anthers, pollen,

and leaves respectively. Thus, in all matrices (blossoms, anthers, pollen, and leaves) mean

concentrations of total imidacloprid were approximately ten times higher in strawberries grown in

coarse

- texture d soil than in medium

- textured soil.

9. REFERENCES

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

Bayer CropScience Report No. M0

- 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.MRID 49090502 CDPR IMI Strawberry

13 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 201 0. An Analytical Method for the Determination of Residues of lmidacloprid

and its Metabolites lmidacloprid Olefin and 5

- Hydroxy lmidacloprid 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 Re sidues 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/MS Detection. 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.

7. Noland, P.A. 1992. lmidacloprid and metabolites

- freezer storage stability study in crops. Bayer

CropScience R eport No. 103237. MRID 42556135.

8. Noland, P.A. 1993. lmidacloprid and metabolites

- freezer storage stability study in crops. Bayer

CropScience Report No. 103237

- 1. MRID 42810311.26. Noland, P.A. 1994. lmidacloprid and

metabolites

- freezer storage stability study in crops. Bayer CropScience Report No. 103237

- 2.

MRID 43197203.

9. Lenz, C.A. 1993. Addendum 1. lmidacloprid and metabolites

- freezer storage stability study in

crops (what matrices, cottonseed, tomato, cauliflower, and lettuce). Bayer CropScience Rep ort

No. 103949

- 1. MRID 42810313.

10. Lenz, C.A. 1993. Addendum 2. lmidacloprid and metabolites

- freezer storage stability study in

crops (what matrices, cottonseed, tomato, cauliflower, and lettuce). Bayer CropScience Report

No. 103949

- 2. MRID 43197201.

11. Lenz, C.A. 1993. Addendum 3. lmidacloprid and metabolites

- freezer storage stability study in

crops (what matrices, cottonseed, tomato, cauliflower, and lettuce). Bayer CropScience Report

No. 103949

- 3. MRID 43487301.