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Ms. Lois Rossi, 

Director, Registration Division 

Office of Pesticide Programs (7504P) 

U.S. Environmental Protection Agency 

Room S4900, One Potomac Yard 

2777 S. Crystal Drive 

Arlington, VA 22202

Subject: Spirotetramat; Re-instatement of Registration. 

 Response to EPA regarding the Decision on Bee Safety Label 

Language 

 (EPA Reg. No. 264-1049; EPA Reg. No. 264-1050). 

Dear Ms. Rossi: 

On July 13th, 2010, Meredith Laws confirmed that two changes regarding bee 

safety will be required by EPA to the existing labels of spirotetramat end-use 

products. These are: 

1. The deletion of the cucurbit vegetables (crop group 9) use, and; 

2. The modification of the bee safety statement for the citrus (crop group 10) 

use from the existing statement, viz: 

Do not apply this product within 10 days prior to bloom, during 

bloom, or until petal fall is complete. 

to: 

Do not apply until after petal-fall. 

Relative to the proposed modification of the bee safety statement for citrus, this 

language change raises confusion in light of the fact that EFED, in a document 

dated July 7th, 2010, clearly states that the existing label language for citrus and 

cucurbits are sufficient to mitigate the potential hazard to bees. 

We responded the afternoon of July 13th, 2010, that these requirements are 

scientifically unacceptable to Bayer CropScience given the fact that we have 

chronic bee field studies that show the safety of spirotetramat to bee colony 

health, even when applied during the bloom stage to melons [MRID# 47563303, 

Bayer CropScience 

2 T.W. Alexander Drive 

P. O. Box 12014 

Research Triangle Park,

 NC 27709 

Tel: 919 549-2000

Date:July 20, 2010
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47563302, 47563305, 47563306, 47563307, 47563308, 47563310, 47563311, and 

46904462], and citrus [MRID# 47563309 and 47563304]1

. Furthermore, the 

Asian Citrus Psyllid (“ACP”), a new pest (and vector of Huanglongbing, or citrus 

greening) of critical importance to the citrus industry, feeds exclusively on new 

growth and attacks trees during periods of flush, some of which occur prior to, or 

at, bloom time. In order to prevent ACP from transmitting the bacteria that causes 

citrus greening disease, it is necessary that new growth be continuously protected. 

We would now like to address the revised bee language proposed by EPA for the 

citrus crop group. This can be more easily expressed pictorially below: 

Scenario A: Existing Citrus Treatment Guidance relative to Bee Safety

Do not apply this product within 10 days2 prior to bloom, during 

bloom, or until petal fall is complete. 

 

1

 An additional two citrus study reports will be submitted to EPA before August, 2010, one of 

which (the citrus study undertaken in Florida in 2009) EPA was involved in the design and for 

which the interim results have been made available to the EPA. A summary of the results of these 

two studies can be found in Attachment 1 to this letter. 2

 The setting of the language restricting applications to 10-days prior to blossom emergence was 

intentionally based on the absence of larval effects noted in the tunnel test when application was 

made 10 days or more prior to flowering in Phacelia at 150 g ai/ha (refer to Attachment 2 for a 

detailed summary of this test). 
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Scenario B: EPA Proposed Citrus Treatment Guidance relative to Bee 

Safety

Do not apply until after petal-fall. 

Hopefully, these pictures portray the fact that citrus is not like deciduous crops, 

such as pome or stone fruit, tree nuts, etc. Being an evergreen crop and grown in 

subtropical environments, the treatment season has “no end”. Thus, the post-petal 

fall period runs full circle, from literal petal fall right up to when new blossom 

buds form. Bayer CropScience’s existing language defines a beginning and an 

end to the post-petal fall period that, in essence, defines an application restricted 

period, unlike the language that EPA is proposing. Consequently, the language 

proposed by EPA is likely to create confusion and difficulty with compliance. 

For instance, one could easily interpret that they would legally be able to treat the 

citrus crop right up until new blossom bud formation (Fig. 2) as the definition 

does not define a closure to the post-petal fall period. From our viewpoint, this 

interpretation would satisfy the needs we see in being able to effectively treat 

against ACP and other key pests; however, as a responsible company, we have 

concerns around the confusion that will play out in the States due to fact that the 

language is now open to interpretation. 

Last, Bayer CropScience is in the process of receiving input (which has/will be 

forwarded to EPA as well) from citrus commodity groups and other citrus experts 

who identify the need for Movento® pre-bloom in order to effectively manage 

ACP. You will find that these experts, both from California as well as Florida, 

provide opinions that are contrary to the one you received. 
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Relative to the proposal by EPA to delete the existing use for the cucurbit crop 

group, Bayer CropScience disagrees. The existing bee safety mitigation language 

on the existing label is the same as that for citrus, specifically: 

Do not apply this product within 10 days prior to bloom, during bloom, or 

until petal fall is complete

This language renders this use impractical due to the indeterminate nature of 

flowering for this crop (as well as for melons) and the need for pollinators to 

assure enhanced production. Accordingly, Bayer CropScience had already 

removed this use from their commercial label from the initial registration 

approval back in 2008, and has not - and does not intend - to market this use until 

such time as we can prove the safety of spirotetramat to bees active during 

blooming. To this end, Bayer CropScience had undertaken additional sub-chronic 

and chronic bee studies on melons, or surrogate crops, to evaluate the safety of 

spirotetramat to bees (and their colonies) at targeted label rates. To date, 9 studies 

have been conducted and submitted to EPA3

 with the intention of establishing that 

the precautionary bee safety language is unnecessary. 

Despite the set-back brought about by the lawsuit, it is still Bayer CropScience’s 

intention to pursue the removal of bee mitigation language on cucurbits as well as 

citrus as it continues to be our opinion, based on the scientific data, that this 

compound does not harm bees even when applied during bloom at the prescribed 

label rates for these crops, as shown by our scientific studies. 

In summary, we reiterate that the lawsuit brought by NRDC and the subsequent 

order by the Court to vacate the registrations of spirotetramat was based on an 

administrative (procedural) failure by EPA. We remind the Agency that Bayer 

CropScience, subsequent to the registration, has submitted multiple chronic bee 

field studies [MRID# 475633-00, with a follow-up letter, dated March 29, 2010; 

refer to Attachment 3] that support the safety to bees under the labeled use 

conditions, even including during bloom. Additional studies on citrus will be 

submitted shortly. The concerns raised by NRDC, and others, are based on Bayer 

CropScience’s own tunnel tests administered under elevated (exaggerated) dose 

rates that indicated the potential for spirotetramat to adversely affect bees; this is, 

in fact, the purpose of the tunnel tests. If anyone has data to suggest a different 

conclusion than what the extensive existing data set show, we’d be more than 

willing to review it openly. Otherwise, conjecture and opinion should remain just 

that. 

 

3

 The following studies on melons were submitted to the EPA in 2008 and again in March, 2010: 

MRID 47563303, 47563302, 47563305, 47563306, 47563307, 47563308, 47563310, 47563311, 

and 46904462. 
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If you have any questions, please contact me by phone at 919.549.2824 (or via email at: clive.halder@ bayercropscience.com). 

Yours Sincerely, 

Clive A. Halder, Ph.D. 

Director, Registrations, Insecticides, Fungicides and Seed Treatments 
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Attachment 1

Summary of Two Additional (Unsubmitted) Citrus Field Studies

Florida Study: 

The Asian citrus psyllid (ACP), Diaphorina citri, is the single greatest insect pest to the global 

citrus industry. Citrus growers have numerous options for controlling the ACP, however, most 

are not bee-safe. Movento® contains a new insecticidal active ingredient (a.i), spirotetramat, that 

controls ACP, however due to uncertainty about bee safety, its use is not currently allowed just 

prior to or during bloom, when it is most effective for ACP control. 

Bayer CropScience continues to investigate the potential effects of Movento® on western honey 

bee (Apis mellifera) brood and whole colonies when applied to citrus during bloom. Establishing 

the bee safety of Movento® during bloom will enable its use in order to control this important 

pest. Bayer CropScience in consultation with the National Honey Bee Advisory Board, the US 

Environmental Protection Agency (EPA), Florida Department of Agriculture and Consumer 

Services and the US Department of Agriculture (USDA), developed a protocol for a field study 

to monitor colony exposure and resulting effects from application of Movento® during bloom in 

citrus. Twelve colonies were placed at the edge of each of two citrus groves at the start of bloom 

in March 2009 and removed after bloom finished; one grove received a single application of 

Movento® at full citrus label rate of 0.16 lb ai/acre (175 g ai/ha) and the other received no 

treatments. Colonies were assessed for strength and health (i.e., adult and brood populations, 

food stores, pests, and diseases), and brood effects. Also, pollen, nectar, honey and wax samples 

were collected and analyzed for presence of residues of spirotetramat. After the conclusion of 

field work in Florida, the colonies were returned to a commercial beekeeping operation and 

transported to northern states for use in pollination of several crops where typical agricultural 

practices were followed with no imposed limitations. Follow-up assessments of the health of 

these colonies were performed during May in Pennsylvania after apple pollination, during June 

in Maine after blueberry pollination, and during October in Pennsylvania after late summer 

pumpkin pollination. 

Quantifiable residues of total Movento® residues (spirotetramat and the metabolite, 

spirotetramat-enol) were detected in bee-collected pollen and nectar for only a few weeks postapplication to blooming citrus. Highest individual detects were 3.52 ppm in whole blossoms, 

0.55 ppm in bee-collected pollen and 0.04 ppm in bee-collected nectar. No quantifiable residues 

of Movento® were present in samples of stored pollen and honey collected from the study hives 

during the remainder of the study, or in the citrus blossoms of the study trees collected the 

following year. Based on the low levels of residues, it appears there is a high degree of safety 

with Movento® use during citrus bloom. There were no significant differences between the 

control and treatment groups of hives for any colony strength and health measurements, and 

brood cohort success, during the in-citrus phase of the study. Both groups of hives started 

experiencing high losses of colonies between the blueberry pollination period and the fall colony 

assessments. Varroa mite and Nosema counts were high in both groups of hives throughout 

most of the study period, and deformed-wing condition accounted for almost one-third of intrahive mortality before leaving citrus. Hive monitoring and assessment results strongly suggest 
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that the primary causes of the high colony losses by fall, in both groups of hives, were Varroa 

destructor, Nosema spp., deformed-wing virus, queen issues (i.e. direct losses, failed 

replacement, poor performance), and multiple and various other pathogens and factors possibly 

to a lesser degree. 

Argentina Study

An extensive citrus field study was also performed in Argentina. The test item Spirotetramat OD 

150 was applied in flowering citrus orchards of approximately 2-3 ha size. There were 2 

treatment groups, each with 4 replicates. Treatment group 1 served as untreated control. The 

plots of treatment group 2 received 2 applications of 96 g a.s./ha/m canopy height in a spray 

interval of 14 days or 16 days, resulting in 2 applications of 278.4 g a.s./ha on plot 2, 240.0 g 

a.s./ha on plot 3, 230.4 g a.s./ha on plot 4, and 172.8 g a.s./ha on plot 8, respectively (differences 

in applications were based on canopy height). All plots were in approximately 3 km distance of 

each other. 

Three bee hives were set up on each plot. During the assessments, the bee colonies were 

observed for potential treatment-related effects on brood (eggs, unsealed brood – larvae, and 

sealed brood - pupae), as well as hive weight, colony strength, pollen and nectar/honey storage. 

Additionally, mortality in front of each hive was assessed for up to 6 days in 24 h intervals and 

thereafter in 48 h intervals after the applications. Citrus blossoms were collected and analyzed 

for spirotetramat residues. Concurrently, the number of foraging bees on the citrus blossoms was 

assessed. 

Citrus blossom residues measured after the first application ranged from 1.69-6.9 ppm (1 day 

after application) to 0.010-0.72 ppm (15 days after application). No effects on brood 

development (eggs, larvae, pupae) and abundance of adult honey bees were found. Also, there 

were no effects on foraging activity, mortality determined in front of the hives, hive weight 

development or the food storage behavior. 

These study reports are expected to be submitted to EPA very soon. However, summaries of the 

study findings from the US study have already been communicated to the Agency. 
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Attachment 2

Rationale behind Setting the 10-Day Period Prior to Blossom Emergence

For use in citrus, the following language is recommended until EPA has an opportunity to 

review all available bee safety data, “Do not apply this product within 10 days prior to 

bloom, during bloom, or until petal fall is complete.” The important agronomic reasons 

for why a pre-bloom application is needed were presented above. In addition, even under 

the conditions where mild and transient brood effects were noted (enclosed exposures), 

data submitted to EPA demonstrated that there were no effects on brood when the 

applications were made 10 days or more before flowering (MRID 47276901). 

Percentage of comb area covered by larval cells 

 (at X days after beginning of exposure) 

Crop, Treatment and 

Application Rate 

0 +4 +7 +15 +22 +28 

Phacelia, 

20 days prior to flowering 

spray rate: 150 g a.s./ha

10.8 15.0 10.0 5.0 19.2 23.3 

Phacelia, 

15 days prior to flowering, 

spray rate: 150 g a.s./ha

10.0 11.7 10.0 10.0 18.3 17.5 

Phacelia, 

10 days prior to flowering, 

spray rate: 150 g a.s./ha1

16.7 14.2 7.5 8.3 15.8 19.2 

Phacelia, 

5 days prior to flowering, 

spray rate: 150 g a.s./ha

12.5 0.8 1.7 3.5 12.5 12.5 

Phacelia, 

on flowering crop at bee 

flight 

spray rate: 150 g a.s./ha

16.7 2.5 5.0 4.2 7.5 11.7 

Phacelia, 

on flowering crop after bee 

flight (21:00), 

spray rate: 150 g a.s./ha

11.7 7.5 3.3 5.8 16.7 12.5 

Phacelia, 

Reference (Insegar); on 

flowering crop at bee flight 

(spray rate 150 g a.s./ha)

12.5 1.7 0.0 0.0 16.7 7.5 

Phacelia, untreated

13.3 21.7 16.7 8.3 19.2 13.3 

1

 No effect noted when application was made 10 days or more prior to flowering in 

Phacelia at 150 g ai/ha. 

It is also important to consider that residues measured in Phacelia are higher than those 

measured in citrus even when the Phacelia rate is lower, making this a worse-case 

comparison for bee safety in citrus. The Phacelia residue data were submitted to the 

EPA (MRID 47563310) and the citrus residue data are included in the new report on 

citrus and described above. 
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Measured residues 

Crop and rate Pollen Nectar 

Phacelia (100 g ai/ha) 2.1 - 6.1 ppm 0.20 - 0.31 ppm 

Citrus (175 g ai/ha) <0.01 - 0.55 ppm <0.01 - 0.04 ppm 
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Attachment 3

Summary of Honey Bee Studies Conducted with Spirotetramat versus label rate 

on target crop 

Table 1. Honey Bee Studies - Laboratory and Semi-field Tests 

MRID 

Number Study Title Study Description 

46904461 Acute Toxicity of BYI 08330 150 OD to the 

Honeybee Apis mellifera L. Under 

Laboratory Conditions 

Acute contact and oral toxicity to bees for 

formulation in the laboratory. Purpose of 

study was to identify hazard. 

46904449 Effects of BYI 08330 (Acute Contact and 

Oral) on Honey Bees (Apis mellifera L.) in 

the Laboratory 

Acute contact and oral toxicity to bees for 

active ingredient in the laboratory. Purpose 

of study was to identify hazard. 

46904469 Effects of BYI 08330 240 SC (Acute 

Contact and Oral) on Honey Bees (Apis 

mellifera L.) in the Laboratory. 

Acute contact and oral toxicity to bees for 

formulation in the laboratory. Purpose of 

study was to identify hazard. 

46904458 Assessment of the Side-Effects of BYI 

08330 OD 100 on the Honey Bee (Apis 

mellifera L.) in a Feeding Test 

Colony feeding test – pure sucrose solution 

at a concentration of 0.0144 % a.i. fed to 

colony. Purpose of study was to identify 

hazard. 

46904470 Assessment of the Side-Effects of BYI 

08330 SC 240 on the Honey Bee (Apis 

mellifera L.) in a Feeding Test. 

Colony feeding test – pure sucrose solution 

at a concentration of 0.0144 % a.i. fed to 

colony. Purpose of study was to identify 

hazard. 

46904459 Assessment of Side Effects of BYI 08330 

OD 100 on the Honey Bee (Apis mellifera

L.) in the Semi-Field 

Tunnel test with bees 

47276901 Summary of Orientating Research Tunnel 

Trials on Effects of Spirotetramat to Honey 

Bees According to EPPO 170: Evaluation of 

Brood Effect Endpoints. 

Summary of multiple agronomic 

development trials in tunnels with various 

crops and rates. 
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Table 2. Spiked Pollen Feeding Studies and Residue Measurements for Risk Assessment 

MRID 

Number Study Information Study Description Co

47563305 Determination of Effects of Spirotetramat in 

Spiked Pollen to Honeybee Brood under SemiField Conditions (Trial 2008). 

Spiked pollen feeding study with the target concentrations of 2, 10 and 20 mg/kg pollen. 

Field rate ncomparison residue asse

47563306 Determination of Effects of BYI 08330 in Spiked 

Pollen to Honeybee Brood under Semi-Field Conditions (Trial 2006). 

Spiked pollen feeding study with the target concentrations of 10, 2, 0.5, 0.2 and 0.05 mg a.s./kg pollen mg/kg pollen. 

Field rate ncomparison residue asse

47563307 Residues of Spirotetramat and its Metabolites in 

Blossom Samples of Melons after Spray Application in Spain. 

Melon

Residue study Application of 72 g as/ha or 288 g as/ha 

Melon crop and exagge(seasonal mapplied 

47563308 Residues of Spirotetramat and its Metabolites in 

Nectar and Pollen Samples of Melons after Spray Application (Tunnel Test) in Spain. 

Melon

Residue study Application of 288 g as/ha or 96 g as/ha 

Melon crop applied and ai/ha (seasoEU) applied 

47563309 Residues of Spirotetramat and its Metabolites in 

Citrus Blossoms after Spray Application in Spain. M/295276/01/1. 

Citrus

Residue study Two applications of 112.5 g ai/ha, citrus, Spain 

EU citrus rathan US citdue to apheight 

47563310 Residues of Spirotetramat and its Metabolites in 

Nectar and Pollen of Phacelia after Spray Application in Germany. 

Phacelia

Residue study Application of 100 g as/ha; 

Phacelia uscrop, rate hcrop rate (8

47563311 Residues of Spirotetramat and its Metabolites in 

Nectar and Pollen of Summer Oilseed Rape after Spray Application in Germany. 

Canola

Residue study Application of 100 g as/ha 

Canola crofield crop, field crop ra
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MRID 

Number Study Information Study Description Co

47563312 Residues of Spirotetramat and its Metabolites in 

Nectar and Pollen of Citrus after Spray Application in Spain. 

Citrus

Residue study Two applications of 112.5 g ai/ha 

Citrus rate aUS citrus rato applicatio

Table 3. Honey Bee Field Studies 

MRID 

Number Study Information Study Description Co

46904462 Assessment of Side Effects of Spirotetramat OD 

150 on the Honey Bee (Apis mellifera L.) in the Field 

Phacelia tanacetifolia. 

Two treatments: 4 × 72 g a.s./ha, two times before flowering and two times during flowering of the crop and foraging activity of the bees 2 × 96 g a.s./ha during flowering of the crop and foraging activity of the bees 

Phacelia uscrop, EU (exceeds US g ai/ha). 

47563302 Assessment of Effects of Spirotetramat OD 150 

on Honey Bee (Apis mellifera L.) Colonies under a Realistic Field Scenario in a Melon Crop in 2007 (non-GLP). 

Melon

Two treatment groups 4 applications of 72 g as/ha 4 applications of 88 g as/ha 

EU field crUS field cro

47563303 Assessment of Effects of Spirotetramat OD 150 

to Honey Bee (Apis mellifera) Colonies under a 

Realistic Field Scenario in a Melon Crop-GLP Trial 2008. 

Melon

Two treatment groups 4 applications of 75 g as/ha 2 applications of 88 g as/ha 

EU and US ai/ha) applie

47563304 Assessment of Side Effects of Spirotetramat OD Citrus EU citrus r
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MRID 

Number Study Information Study Description Co

150 on the Honey Bee (Apis mellifera L.) Applied to Citrus in the Field in Spain 

Application: 2 x 192 g as/ha citrus rate o