Registration Decision for the New Active Ingredient 

California Red Scale Pheromone 

PC Code 017705 
Summary 

This document announces that the Environmental Protection Agency (EPA) has completed its 

initial evaluation of the proposed new biochemical pheromone California Red Scale (CRS) 

Pheromone and has concluded that it meets the regulatory and safety standards under the Federal 

Insecticide, Fungicide and Rodenticide Act (FlFRA). 

California Red Scale is a major pest to citrus crops; and CRS populations have increased 

dramatically over the last few years due to warmer winters and reduced winter mortality. 

California Red Scale infestations have been historically treated with conventional pesticides; 

however, the pest is developing resistance to many of these conventional treatments, which are 

relatively more toxic than this biochemical pheromone. It is for these reasons that EPA is 

expediting this registration of California Red Scale Pheromone. The Agency normally has a 15-

day public comment period on its proposed registration decision as part of its Public 

Participation Process. For California Red Scale, we are issuing the final decision and taking 

public comment subsequently. However, if the Agency receives substantive comments, EPA will 

address those comments, revise this decision appropriately, and re-issue a final decision 

memorandum. The Agency will also include a term in the registration notice, requiring the 

registrant to submit revised labeling consistent with EPA recommendations that may result from 

any substantive comments received during the Public Participation Process. If no comments are 

received, the Agency will note that and affirm this decision document as our final decision and 

the registration will stand unchanged. 

Two products are being registered under Section 3(c)(5) of FIFRA: a Manufacturing-use Product 

(MP), CheckMate CRS Teclmical Pheromone; and an End-use Product (EP), CheckMate CRS. 

The registrant for these products is Suterra, LLC. The new active ingredient will be used as a 

mating disruptor for California Red Scale (Aonidie!la auranti) in citrus crops and other orchards 

where California Red Scale are present. 

The new active ingredient California Red Scale Pheromone, chemically known as (3S, 6R) (3S, 

6S)-3-Methyl-6-isopropenyl-9-decen-l-yl acetate, is a technical grade synthetic arthropod 

pheromone. This pheromone is structurally identical to and mimics a naturally occurring 

pheromone produced by the female California Red Scale to attract the males for mating. 

California Red Scale Pheromone is intended for use in polymeric dispensers to disrupt the 

normal mating cycle of California Red Scale in orchards. The dispensers are typically deployed 

shortly before the males actively take (generational) flight. Mating disruption results when adult 

males, having only about six hours to mate before dying, are attracted to the pesticide product in 

the tree tops, and the distraction reduces the chance of their locating actual females, which are 

immobile. Applications are infrequent because they correlate directly with California Red Scale 

mating cycles, which normally occur just once a year. The pheromone will be applied at an 

effective rate of 12.6 g/acre/year (180 dispensers/acre/year); and the concentration of California 

Red Scale Pheromone resembles naturally-occurring background levels. Like most pheromones, 

California Red Scale Pheromone biodegrades rapidl y. 

As an arthropod pheromone applied via dispenser at low application rates, California Red Scale 

Pheromone is exempt from the requirement of a tolerance. Per 40 CFR § 180.11 24, arthropod 

pheromones are exempt when used in retrievable polymeric dispensers and when applied to 

growing crops at rates below 150 grams/acre/year. 

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The Biopesticides and Pollution Prevention Division (BPPD) has reviewed the data required to 

support the registration of this arthropod pheromone, under Section 3(c)(5) of the Federal 

Insecticide, Fungicide and Rodenticide Act (FIFRA). Data requirements for arthropod 

pheromones are reduced when the pheromone is to be applied in retrievable polymeric 

dispensers and when application rates are below 150 grams/acre/year. All product chemistry data 

requirements for CRS Pheromone were satisfied by acceptable guideline studi es. Acute toxicity 

data requirements were satisfied by guideline studies; all other human health data requirements 

were satisfied through rationales. Nontarget organism data requirements are not required for 

arthropod pheromones per 40 C.F .R. § 158.2060(a)(2). 

Background 

California Red Scale Pheromone is a we11-known arthropod pheromone with a history of use as a 

biochemical active ingredient. The active ingredient is a synthetic compound that is identical in 

structure and function to a natura11y occurring substance of insect origin and functions by a nontoxic mode of action on its target pest. Therefore, this compound has been classified as a 

biochemical pesticide. This Decision Document marks the second time that this active ingredient 

has been assessed and approved for pesticidal use. 

On September 9, 2002, EPA received an application from HBB Partnership to register two 

products containing California Red Scale Pheromone. On August 11,2004, EPA published a 

notice in the Federal Register announcing receipt of those Section 3 applications (69 FR 48867). 

No comments were received regarding that notice. The products were registered on March 10, 

2005. However, on July 24, 2009, EPA announced cancellation of those products due to nonpayment of fees (74 FR 36699). 

On March 16, 2016, EPA announced receipt of a Section 3 application from Suterra LLC to 

register two new products- CheckMate CRS Technical Pheromone and CheckMate CRSreviving the active ingredient California Red Scale Pheromone (Volume 81, Number 51, FR 

page numbers 14103- 14 104). A copy ofthat notice is available in Docket ID Number EPA-HQOPP-2016-0095 via http://www.regulations.gov. No substantive comments were submitted in 

response to the announcement. 

Evaluation 

In evaluating a pesticide registration application, the EPA assesses a wide variety of pesticidespecific information including where and how the pesticide is used, environn1ental fate (i.e., 

what happens to the pesticide once it's applied), and toxicity studies (i. e., effects on humans and 

other nontarget organisms) to determine the li kelihood of adverse effects (i.e., risk) from 

exposures associated with the proposed use of the product. Risk assessments are developed to 

evaluate the environmental fate of the compound as well as how it might affect a wide range of 

nontarget organisms including humans and terrestrial and aquatic wildlife (plants and animals). 

On the basis of these assessments, EPA evaluates and approves language for each pesticide label 

to ensure the directions for use and safety measures are appropriate to mitigate potential risk. In 

this way, the pesticide's label helps to communicate essential limitations and mitigations that are 

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necessary for public safety. It is a FIFRA violation to use a pesticide in a way that is inconsistent 

with the label. 

The human health and environmental risk assessments supporting this decision as well as the 

product labeling can be found in the regulatory docket (Document ID: EPA-HQ-OPP-20 16-

0095). 

Assessment of Risk to Human Health 

EPA requires a wide range of studies in order to assess a pesticide. For California Red Scale 

Pheromone, the database of studies and information supporting the assessment of risk to human 

health is sufficient to support registration of this non-food use pheromone. There is ample 

information indicating that the use of California Red Scale Pheromone will not result in any 

meaningful new exposure, and that, exposure notwithstanding, the compound is virtually 

nontoxic and does not pose a risk through any route of exposure. 

With regard to the Tier I Acute Toxicity data requirements, guideline studies were submitted in 

support of all those data requirements, except for Acute Inhalation and Skin Sensitization, which 

were waived. In the acute oral toxicity study, the acute oral LDso value was determined to be 

greater than the dose rate of 5000 mglkg; and no mortality occurred as part of the study. 

California Red Scale Pheromone is Toxicity Category IV for acute oral toxicity. A study for 

acute dermal toxicity established an LDso >5050 mg/kg; and is Toxicity Category lV. There was 

no observed dermal irritation throughout the study. A study for acute eye irritation determined 

that California Red Scale Pheromone was a mild irritant. No irritation was observed by Day l 0. 

In the acute dermal irritation study, no irritation was observed; and the pheromone was assigned 

a Toxicity Category IV. With regard to acute inhalation and skin sensitization, the data 

requirements were waived based on the following: California Red Scale Pheromone 

demonstrates low acute toxicity in the studies conducted; there is minimal pulmonary exposure 

potential; the compound has low vapor pressure; there have been no reported adverse effects in 

California Red Scale habitat; and minimal exposure is expected due to the pheromone's use in 

dispensers, from which the pheromone is released in very small quantities. Altogether, California 

Red Scale Pheromone exposures are expected to be minimal and the pheromone is considered 

virtually nontoxic for acute toxicity. 

The human health data requirements for subchronic toxicity, developmental toxicity and 

mutagenicity were waived. The rationales for the waiver request included the following 

information: 1) California Red Scale Pheromone has a low acute toxicity profile; 2) there is low 

exposure to California Red Scale Pheromone when it is applied in slow-release polymeric 

dispensers; 3) exposure to California Red Scale Pheromone approximates the naturally 

occurring pheromone concentration produced by California Red Scale females, to which humans 

are already exposed without known hazard; and 4) California Red Scale Pheromone has a 

nontoxic mode of action, which is target-pest specific. 

With specific regard to the subchronic toxicity data requirements, the data requirement is 

qualified for biopesticides; and these data can be waived when the use pattern of the product 

precludes the potential for long tern1 or repetitive exposure to the pheromone. In this case, lack 

of exposure is supported by the fact that the California Red Scale Pheromone will be formulated 

exclusively into polymeric dispensers that present minimal risk from exposure to humans or 

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nontarget organisms. The application rates of these arthropod pheromone dispensers are by 

necessity low because their activity on the target pest depends on their olfactory receptors being 

tuned to naturally occurring background levels, to which we are already exposed. Furthermore, 

the effective application rate of California Red Scale Pheromone at 12.6 gram/acre/year is an 

order of measure lower than the allowable maximum rate of 150 gram/acre/year, and does not 

constitute significant exposure. Accordingly, risks to applicators, mixers, loaders, and 

bystanders, from long term, repetitive exposure to California Red Scale Pheromone is negligible 

or unlikely; and the rationales supporting the waiver request are thereby further supported. 

Lastly, EPA has not found California Red Scale Pheromone to share a common mechanism of 

toxicity with any other substances. In addition, California Red Scale Pheromone does not appear 

to produce a toxic metabolite produced by other substances. 

Given the demonstrated lack of adverse effects on humans, a qualitative assessment of California 

Red Scale Pheromone is considered sufficient. Humans are rarely exposed to this nontoxic 

pheromone; and there have been no observed or reported adverse effects on humans who are 

regularly present in and around California Red Scale habitat. The active ingredient will be used 

at low rates in agricultural settings, and its use will result in concentrations resembling natural 

background levels. Also, the EP will only be used once a season. Due to the infrequent 

applications, low application rate, and high biodegradability, the pesticidal use of California Red 

Scale Pheromone is not anticipated to contribute significantly to human exposure beyond 

existing (but temporal) background levels. 

Assessment of Ecological Risk 

According to 40 CFR I 58.2060(a)(2), arthropod pheromones when applied at up to a maximum 

use rate of 150 grams active ingredient/acre/year, and that are not expected to be available to 

avian species, are not required to provide nontarget toxicity and environmental fate data. 

California Red Scale Pheromone is a synthetic arthropod pheromone that is structurally similar 

to and mimics the pheromone produced by the female California Red Scale. The pheromone acts 

specifically on male California Red Scale and has a non-toxic mode of action. California Red 

Scale Pheromone will be applied via retrievable polymeric dispensers at an effective rate of 12.6 

g/acre/year. Because the polymeric dispensers preclude avian exposure, no significant amount of 

California Red Scale Pheromone is expected to be available to avian species. 

Endangered/Threatened Species 

With regard to (all) arthropod pheromones, the Agency has concluded a No Effect for 

endangered or threatened species and designated critical habitat. Foremost, arthropod 

pheromones have a nontoxic mode of action and are highly specific to target pests. As attractants 

and confusants, no mortality is associated with these compounds; and these unique 

semiochemical compounds only react with the highly attuned sensors of the target species. 

Secondly, no significant exposures are anticipated with arthropod pheromone use. Applications 

rates are low; and they resemble naturally occurring background levels. Moreover, arthropod 

pheromones are highly volatile and biodegradable; and as a result, do not persist in either 

terrestrial or aquatic habitats. Finally, arthropod pheromones are virtually nontoxic; and there 

have been no known effects associated with our natural exposure to these compounds. 

Altogether, it is for these reasons that arthropod pheromones are both exempt from any nontarget 

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organism data requirements and that the use of arthropod pheromones are deemed to have no 

effect on threatened and endangered species. 

Alternatives 

Organophosphates, carbamates, pyriproxyfen, buprofezin, spirotetramat and horticultural oils 

(primarily mineral oils) are all used to combat California Red Scale infestations. These 

conventional active ingredients all have a more toxic profile than California Red Scale 

Pheromone and their use would likely be diminished with this registration. Notably, the toxic 

profiles of the organophosphate chlorpyrifos and the carbamate carbaryl have been subject to 

special consideration by the Agency due to their toxicity. Additionally, the insect growth 

regulators, pyriproxyfen and buprofezin, and the lipid synthesis inhibitor spirotetramat all have 

systemic modes of action associated with nontarget effects. And with regard to the horticultural 

oils, many of those active ingredients contain petroleum distillates and can have phytotoxic 

effects. The use of California Red Scale Pheromone as an additional tool to combat California 

Red Scale infestations offers substantial benefits by potentially reducing the use of more toxic 

alternatives. 

Benefits 

California Red Scale is a major pest to citrus crops and is typically controlled through the use of 

conventional insecticides. For the past several years, California citrus growers have experienced 

reduced efficacy of these conventional insecticides due to growing pesticide resistance. At the 

same time, California Red Scale populations have increased because wanner winters have 

reduced winter mortality and enabled the growth of more generations. Unfortunately, in response 

to these conditions, growers have had to use more of these conventional insecticides to control 

California Red Scale over the past few years. By registering California Red Scale Pheromone, 

growers will have another effective tool to control California Red Scale, forestalling resistance 

and reducing the number of conventional pesticide applications. And as discussed, these 

conventional pesticides generally have a more toxic profile and the reduction of their use will 

directly benefit both humans and nontarget organisms. Conversely, California Red Scale 

Pheromone is virtually nontoxic and is applied at a very low rate, at concentrations that resemble 

naturally occurring background levels. Secondarily, it should be noted that many conventional 

insecticides are also toxic to the natural enemies of California Red Scale, such as wasps and 

beetles, while California Red Scale Pheromone is specific to California Red Scale. And thus, by 

reducing the use of these conventional insecticides, the use of California Red Scale Pheromone 

re-opens this natural avenue of control, allowing for additional control beyond the mating 

disruption. Finally, California Red Scale Pheromone propitiously offers another tool at a time 

when California Red Scale are developing resistance to many conventional insecticides. In short, 

the use of California Red Scale Pheromone will allow growers another effective tool to control 

California Red Scale, reducing the number of more harmful conventional insecticide 

applications. 

Public Comments 

On March 16, 2016, EPA announced receipt of a Section 3 application to register two new 

products - CheckMate CRS Technical Pheromone and CheckMate CRS - containing the new 

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active ingredient California Red Scale Pheromone (Volume 81, Number 51 , FR page numbers 

14103- 14104). A copy of that notice is available in Docket ID Number EPA-HQ-OPP-2016-

0095 via http://www.regulations.gov. No substantive comments were submitted in response to 

the announcement. 

Regulatory Decision 

The California Red Scale Pheromone database is considered to be complete. The use of this new 

active ingredient in polymeric dispensers, at rates well below 150 mg/acre/year, are well 

supported by this database. In considering the assessed risk to human health and the 

environment, the Agency concludes that California Red Scale Pheromone meets the regulatory 

standard under the Federal Insecticide, Fungicide and Rodenticide Act (FIFRA). There are no 

outstanding data requirements for this biochemical. Therefore, the EPA is granting the 

unconditional registration of the new active ingredient California Red Scale Pheromone under 

Section 3(c)(5) of FIFRA. 

Two products will be registered- a Manufacturing-use Product, CheckMate CRS Technical 

Pheromone; and an End-use Product, CheckMate CRS. The End-use Product is applied as a 

retrievable polymeric dispenser, and is intended for use in orchards where California Red Scale 

are present, which are primarily citrus orchards. California Red Scale Pheromone mimics the 

natural pheromone emitted by the female California Red Scale. Mating disruption results when 

adult males, having only about six hours to mate before dying, are attracted to the pesticide 

product in the tree tops. This distraction reduces the chance of their locating actual females 

(which are immobile) with which to mate. Applications of the dispensers can be made any time 

prior to crop harvest. The pheromone will only affect adult California Red Scale males and has 

no effect on females or eggs. The application rate is 12.6 grams of active ingredient/acre and 

cannot exceed 150 grams active ingredient/acre/year. 

Due to the compelling need for a new tool to combat California Red Scale and the substantial 

benefits conferred by California Red Scale Pheromone, the registration of this new active 

ingredient is being issued concurrent with EPA's Pub I ic Participation Process. While the final 

decision on registration typically allows a 15-day comment period on the complete risk 

assessment prior to issuing the decision, the Agency believes that it is in the best interest of the 

public and the environment to issue the registration of California Red Scale Pheromone without 

delay. Notably, this active ingredient was previously registered until recently; and it was not 

associated with any known hazard. Moreover, this most recent risk assessment for California 

Red Scale Pheromone only affirms its negligible toxicity. Finally, it is noted that the Federal 

Register comment period for California Red Scale recently ended on April 15, 2016 without 

substantive comment, and that any substantive comments received through this additional 

comment period will still be addressed in a response for the record. 

The human health and ecological risk assessments supporting this decision as well as the draft 

labeling can be found in the regulatory docket (Docket ID EPA-HQ-OPP-20 16-0095). 

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