UNITED STATES ENVIRONMENTAL PROTECTION AGENCY

WAS HINGTON D.C.• 20460

DEC 09 2010

OFFICE OF

CHEMICAL SAFETY AND

POLLUTION PREVENTIO N

MEMORANDUM

SUBJECT: BEAD Chemical Profile for Registration Review:Gamma-cyhalothrin

Jihad Alsadek J v t.-...(' If"

Science Information & Analysis Branch

FROM: Nikhil Mallampalli, Entomologist

Biological Analysis Branch

Elizabeth Hill, Economist

Economic Analysis Branch

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THRU:

Diann Sims, Chief J:&.l-"-,....~9--""-,,/

Science Information and Analysis Branch

Biological and Economic Analysis Division (7 503 P)

TO: Wilhelmina Livingston

Chemical Review Manager

Pesticide Reevaluation Division (7508P)

Peer Review Panel date: May 12,201 0

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Introduction

Gamma-cyhalothrin is in the class of chemistry known as synthetic pyrethroids. Their mode of

action, according to the Insecticide Resistance Action Committee (IRAC), is to act as sodium

channel modulators that result in neurotoxicity in the target insects. Pyrethroids are derived from

the chemical structure of pyrethrum, a chemical produced by chrysanthemum plants.

Gamma-cyhalothrin is a restricted-use, broad-spectrum, insecticide registered in the U.S. for

most major aphid, caterpillar and beetle pests on a wide variety of crops and non-agricultural

uses. "Gamma-cyhalothrin is a mirror isomer of lambda-cyhalothrin, the active ingredient in

"Warrior®" brand insecticide. The gamma isomer is reported to be approximately twice as

potent as the lambda isomer. Therefore, gamma-cyhalothrin is formulated with halfthe amount

of active ingredient and applied at similar rates per acre as Warrior®" (Boucher 2006).

This document follows a format recently developed by BEAD to convey usage information on

pesticides that are beginning to undergo registration review. The anticipated audience for this

paper consists ofthe team of EPA staff currently evaluating the registration status of gammacyhalothrin, and eventuall y the general public. This document builds upon the data already

provided in the "Usage and Label Use Data Packages" that are also provided to Registration

Review teams by BEAD.

PRIMARY USE SITES'

Gamma-cyhalothrin is registered on a wide range of crops (under the brand names Cobalt® and

Proaxis®, among others) as well as for the treatment of various non-agricultural settings (eating

establishments, feed mills, animal kennels, etc.). It also has a few labels for use as a postharvest

treatment for almonds, cherries, nectarines, and peaches. Crops for which it is registered include

tree fruit, vegetables, and row and field crops such as alfalfa, rice, soybean, and wheat.

The major use sites appear to be alfalfa, soybean, and winter wheat (see below for further

discussion ofthese and other crops).

COMMON FORMULATIONS AND APPL ICATIO N METHODS'

Fonnulations

Formulations include the following: microencapsulated, liquid, emulsifiable concentrate, readyto-use, impregnated collar-tag, pressurized liquid, and granular.

Application Methods

Gamma-cyhalothrin products are applied as crack and crevice and/or spot treatment , indoor

general surface treatment, indoor premise treatment, void treatment, contact and/or surface

treatment , spray, directed spray, perimeter treatment, broadcast, chemigation, high volume spray

1 Please refer to the LUIS report for a comprehensive list.

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(dilute), low volume spray (concentrate), outdoor treatment, outdoor premise treatment, animal

treatment (pour-on), animal treatment (ear tag), mound drench, soil treatment (Tebanding}, soil

in-furrow treatment, conservation tillage, mound treatment, band treatment, dip treatment, and

bark treatment.

GAMMA·CYHALOTHRIN USAGE

Agricultural Usage

Based on private market pesticide usage data from 2004·2008, the annual total agricultural usage

of gamma-c yhalothrin averaged approximately 6,000 pound s of active ingredient for 600,000

acres (GtK Kynetec, EPA proprietary data, 2004-2008). It is typically used at very low rates

(0.01-0.02 lbs a.iJA). Garnma-cyhalothrin was first registered March 31, 2004 (OPPIN) and

according to our usage data from 2004-2008, usage has been steadily increasing. Over the past

five years, usage has significantly increased for alfalfa, soybeans. and winter wheat.

• From 2004-2008. the largest markets in terms oftotal pounds of active ingredient applied

were soybeans (51%), alfalfa (14%), rice (8%), winter wheat (7%), apples (5%), and

cotton (4%) (GtK Kynetec, EPA proprietary data, 2004.2008). These are also the largest

markets in terms of acres treated.

Pounds AI

S1 ..

• So)beans

• A lfalfa o Rice

o Wheat, Winter

• A pple s

• Cotton

• 0'10,,,

AernTrnted

1,800.000.------ - - ------,

2004 2005 2006 2007 2006

Vear

. CollOn

.-

0

O Rice _ _

...... • So )Oe&nS

Page 3 0f 6
• According to the 2010 SLUA, the crops with the highest percent of crop treated were

apples and onions. Apples had an average and maximum percent crop treated of 5%,

while onions had an average of less than 2.5% crop treated and a maxim um of 5% crop

treated. Please refer to the Screening Level Usage Analysis (SLUA) for a complete listing

of crop PCT values.

• The states with the most agricultural usage in terms of "pounds ai applied" are

Minnesota, South Dakota, Mississippi, Iowa, Colorado, and New York. This order

slightly differs in comparison to agricultural usage in terms of "acres treated", as seen

below.

Pounds AI

• MINNESOTA

• SOUTH DAKOTA

o MISSISSIPPI

n IOWA

• COLORADO

a NEW YORK

• Other

• MINNESOTA

. IOVIIA

OSOUTH DAKOTA

OCOlORADO

. TEXAS

. NEW YORK

1,600,000

2004 2005 2006 2007 2008

Year

Non-Agricultural Usage

BEAD reviewed available non-agricultural sources but did not find any information on use of

gamma-cyhalothrin in or on non-agricultural use sites.

USE TRENDS

From 2004-2008, the largest markets in terms of total pounds of active ingredient applied were

soybeans, alfalfa, rice, winter wheat, apples, and cotton. The usage data for all ofthe crops listed

above were examined for trends. Pounds of gamma-cyhalothrin used on soybeans, alfalfa, and

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winter wheat increased substantially since registration, whereas pounds of gamma-cyhalothrin

overall used on rice, cotton, and apples fluctuated over the same period. See graph below.

Gemma Cyhalothrtn Use Trend : Top 6 Crops

16 .000 00 ..-- -_- --- - - -,

;;

•

1!,

.oo l---'=~

2004 2005 2006 2.007 2006

'CAPPIes

1_Q:ltton

;O Rce

(]WnterWheat

,

:P falfa

Scybea...

According to BEAD's Official Records Database, and RO's Section 18 database, there have

been no emergency exemption requests for gamma-cyhalothrin. There are also no formal

benefits assessment memoranda from BEAD for this insecticide.

Gamma-cyhalothrin is one ofthe recommended control options for a set ofsignificant pests in

the crops with the highest usage. In soybeans, it is recommended for control of soybean aphid,

Aphis g/ycines. This insect, introduced from China, was first detected in the U.S. in 2000, and

now occurs throughout the country's main soybean production regions. In addition to causing

yield losses in high infestations, this aphid can also transmit several plant viruses (Rice et al.,

2007).

While there are several other pyrethroids, as well as neonicotinoids and organophosphates,

mentioned in soybean aphid management recommendations from major production states (e.g.,

Iowa, Wisconsin), garnma-cyhalothrin use in this crop may have increased in recent years as

concern about this pest has grown among soybean farmers.

In alfalfa, gamma-cyhalothrin is one ofthe recommended options for control ofthe alfalfa

weevil, Hypera pastica. There are several other pyrethroids and organophosphates recommended

for this pest as well. In South Dakota, one ofthe states with high gamma-cyhalothrin usage,

grasshoppers of various species may also be a target of pyrethroid treatments (USDA 2001). In

winter wheat, major target pests for gamma-cyhalothrin appear to be the Russian wheat aphid

(Diuraphis noxia) and greenbug, Schizaphis graminum Rondani. The Russian wheat aphid is

another introduced invasive pest that is capable of plant disease transmission.

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It is worth noting that pyrethroid performance is enhanced in "cool temperatures" (Rice et al.

2007). Since the major use of gamma-cyhalothrin occurs in Midwestern states that generally

have cooler springs and falls, this aspect may be another factor in the popularity of this

insecticide in alfalfa, soybean, and winter wheat.

Data needs relevant to BEAD's fut ure work on gamma-cyhalothrin

Obtaining additional information on the following items would improve BEAD's assessment of

the importance of gamma-cyhalothrin as a pest management tool. This assessment is likely to be

required as part ofthe registration review ofthis pesticide.

l . For non-agricultural and post-harvest commodity uses, informati on on target pests,

quantity used, percent crop treated (or an equivalent measure), and treatment costs.

2. Confirmation ofthe major target pests for which gamma-cyhalothrin is used in

agricultural production.

3. Resistance reports for gamma-cyhalothrin in populations of important target pests.

4. For agricultural uses, worker activities that occur in treated fields at the typical time of

gamma-cyhalothrin applications.

REFERENCES

Boucher, J. 2006. New Vegetable Crop InsecticidelMiticidelMolluscides. Online article from the

University of Connecticut Cooperative Extension System. Available at:

http://\'.iV<i'W.hort.uconn.edwipm/veglhtms/2006 insecticid. htm.

GfK Kynetec, EPA proprietary data, 2004-2008

Rice, M., M. O'Neal, and P. Pedersen. 2007. Soybean Aphids in Iowa - 2007. Publication SP247 of the Iowa State University Extension Service . Available at

extension.agron.iastate.edulsoybean/documents/SP247Aphids07.pdf

USDA. 2001. Crop Profile for Alfalfa and Other Hay Production In South Dakota. Available at:

http://\'.iV<iw.ipmcenters.org/cropprofiles/CP fonn.cfrn.

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