UNITED
STATES
ENVIRONMENTAL
PROTECTION
AGENCY
WASHINGTON,
D.
C.
20460
April
13,
2006
OFFICE
OF
PREVENTION
PESTICIDES
AND
TOXIC
SUBSTANCES
Memorandum
SUBJECT:
Biological
and
Economic
Analysis
of
Dichlorvos
for
Bulk
Stored
Commodities
FROM:
Don
Atwood,
Entomologist
Biological
Analysis
Branch
Biological
and
Economic
Analysis
Division
(
7503C)

THRU:
Arnet
Jones,
Chief
Biological
Analysis
Branch
Tim
Kiely,
Acting
Chief
Economic
Analysis
Branch
Biological
and
Economic
Analysis
Division
(
7503C)

TO:
Dayton
Eckerson/
Eric
Olson,
Chemical
Review
Manager
Reregistration
Branch
1
Special
Review
and
Reregistration
Division
(
7508C)

PRP
REVIEW
DATE:
March
31,
2006
SUMMARY
Dichlorvos
use
for
bulk
stored
commodities
is
minor.
Usage
is
recommended
by
numerous
states
to
control
the
Indian
meal
moth.
While
dichlorvos
usage
is
recommended
for
onfarm
storage,
surveys
conducted
by
the
USDA
since
1999
indicate
no
usage
at
off­
farm
storage
facilities.
This
indicates
that
any
impact
would
be
at
the
on­
farm
storage
level.
USDA
in
1990,
the
most
recent
available
data,
indicated
that
5%
of
storage
facilities
were
using
dichlorvos
for
insect
control.
However,
there
are
other
insecticides
including
diatomaceous
earth,
Bacillus
thuringiensis,
and
pirimiphos­
methyl
which
could
be
used
as
top
dressing
in
the
absence
of
dichlorvos.
BEAD
concludes
negligible
biological
and
economic
impact
in
the
absence
of
dichlorvos
due
to
the
limited
usage
and
availability
of
alternatives.
2
I.
SCOPE
AND
LIMITATIONS
OF
ASSESSMENT
The
scope
of
this
assessment
is
at
the
national
level.
This
mitigation
scenario
is
in
response
to
the
health
risks
identified
by
the
Health
Effects
Division
of
the
Office
of
Pesticide
Programs
for
applicators
in
mushroom
houses.

There
are
limits
to
this
assessment.
The
primary
limit
is
the
lack
of
available
data
associated
with
usage
of
dichlorvos
on
bulk
stored
commodities.
In
addition,
due
to
time
constraints
and
the
diverse
number
of
crops
which
can
be
considered
bulk
stotage
commodities,
emphasis
of
this
assessment
is
placed
on
small
grain
crops.
The
assessment
relies
primarily
upon
state
insecticide
recommendations
for
stored
grain
insect
control.
In
the
absence
of
efficacy
data
for
dichlorvos
alternatives,
this
assessment
assumes
that
alternatives
as
recommended
by
the
states
can
provide
efficacy
equivalent
to
dichlorvos.

II.
BULK
STORED
COMMODITES
Bulk
stored
commodity
storage
is
common
in
the
US.
Bulk
stored
commodities
include
small
grains
(
wheat,
oats,
grain
sorghum,
barley,
and
rye),
corn,
and
peanuts.
Table
1
provides
production
information
for
bulk
stored
commodities
in
2001.

Table
1.
Production,
Supply,
Use
and
Stocks
of
Bulk
Stored
Commodities
in
2001.
a
Crop
Production
(
1,000
bushels)
Total
Supplyb
(
1,000
bushels)
Total
Usec
(
1,000
bushels)
Stocks
(
1,000
bushels)

Wheat
1,958,000
2,929,000
2,258,000
671,000
Rye
6,971
12,161
10,971
1,190
Corn
9,506,840
11,416,000
9,870,000
1,546,000
Oats
117,000
290,000
227,000
62,000
Barley
250,000
381,000
297,000
84,000
Sorghum
515,000
556,000
505,000
51,000
a
2002
Agricultural
Statistic,
USDA/
NASS
b
Includes
2001
production,
beginning
stocks,
and
imports.
c
Includes
2001
exports.

Bulk
storage
of
commodities
occurs
either
on­
farm
or
off­
farm.
However,
site
of
storage
is
fluid
and
can
vary
according
to
storage
availability
and
market
demands.
Table
2
provides
a
break
down
of
bulk
stored
commodities,
small
grains,
in
relation
to
storage
site
(
on
or
off
farm).
3
Table
2.
Bulk
Stored
Commodity
Stocks
On
and
Off
Farm
in
2001.
a
Crop
On
farm
(
1,000
bushels)
b
Off
farm
(
1,000
bushels)
b
%
Stored
On
Farm
Wheat
517,890
1,105,485
31.9%

Rye
NA
NA
NA
Corn
5,275,000
2,989,257
63.8%

Oats
58,100
56,120
50.9%

Barley
92,400
102,589
47.4%

Sorghum
72,400
240,937
23.1%

a
2002
Agricultural
Statistic,
USDA/
NASS
b
As
of
Dec
31
2001
III.
BULK
STORAGE
COMMODITIES
DICHLORVOS
USEAGE
Examination
of
USDA
postharvest
insecticide
application
surveys
for
bulk
stored
commodities
from
1999
to
2002
indicates
no
dichlorvos
usage.
However,
it
must
be
considered
that
the
postharvest
usage
as
presented
by
the
USDA
represent
off­
site
storage
and
does
not
include
on­
farm
storage
of
these
commodities.
In
1990,
AMVAC
Chemical
Corporation
indicated
that
bulk
commodity
use
accounted
for
approximately
7%
of
the
total
pounds
of
dichlorvos
produced.
It
is
assumed
that
the
bulk
of
dichlorvos
usage
for
stored
bulk
commodities
is
for
on
farm
use.
The
last
available
data,
USDA
1990,
estimated
that
approximately
5%
of
grain
storage
bins
are
treated
with
dichlorvos
strips.

IV.
TARGET
PESTS
FOR
BULK
STORED
COMMODITIES
Dichlorvos
is
registered
to
control
a
number
of
insects
which
infest
bulk
stored
commodities.
It
is
primarily
used
as
a
surface
treatement
to
prevent
insects
from
entering
the
grain
from
the
outside.
Pests
for
which
dichlorvos
is
registered
include;
Indian
meal
moth,
almond
moth,
Angoumois
grain
moth,
cigarette
beetle,
confused
flour
beetle,
flat
grain
beetle,
granary
weevil,
and
the
sawtoothed
grain
beetle.
However,
dichlorvos
is
generally
only
recommended
by
the
states
for
control
of
flying
insects.
The
primary
pest
which
is
recommended
for
control
with
dichlorvos
is
the
Indian
meal
moth.
The
Indian
meal
moth
is
one
of
the
most
troublesome
pests
of
stored
grains.
This
pest
and
will
infest
almost
any
kind
of
grain
or
milled
products.
However,
this
pest
rarely
causes
damaged
kernels
or
grain
discounts
at
time
of
sale.
However,
larvae
may
completely
web
over
the
grain
surface
and
thus
prevent
proper
air
movement
for
aeration
and
fumigation,
causing
surface
grain
moisture
accumulation
and
"
top
crusting".
Indian
meal
moth
cotaminate
grain
with
frass,
cast
exoskeletons,
and
silk.
Female
moths
deposit
60
to
300
egss,
singly
or
in
groups
either
4
on
or
within
the
upper
grain
mass.
The
life
cycle
from
egg
to
adult
takes
6­
8
weeks
and
there
are
usually
4
to
6
generations
per
year
depending
upon
the
food
supply
and
temperature
conditions.
Dichlorvos
is
used
as
a
surface
treatment
to
control
Indian
meal
moth
in
stored
grain.
Dichlorvos
impregnated
strips
are
hung
in
the
open
space
of
the
grain
storage
bin.
Strips
are
placed
at
a
rate
of
1
strip
per
1,000
cubic
feet
of
air
space
and
are
generally
effective
for
up
to
3
months.
Replacement
of
strips
is
dependent
up
season
and
amount
of
air
transfer
in
the
open
spaces.
Dichlorvos
is
not
usually
effective
against
larval
stages
located
below
the
grain
surface
and
should
be
used
in
conjuction
with
an
insecticide
application
to
the
top
of
the
leveled
grain
mass.
In
addition,
effective
control
should
include
residual
surface
spraying
or
fumigation
of
empty
bins
prior
to
storage.

V.
ALTERNATIVE
CONTROL
A.
INSECTICIDE
ALTERNATIVES
­
Alternative
insecticides
are
available
to
control
the
Indian
meal
moth
in
bulk
stored
commodities.
Insecticides
may
be
applied
directly
to
the
grain
when
binning
or
as
a
top
coat
after
leveling
the
grain.
Alternative
insecticides
for
use
as
a
top
dressing
to
control
flying
insets
in
stored
grains
are
listed
in
Table
3.
Direct
grain
application
is
not
discussed
as
it
not
a
direct
replacement
for
dichlorvos
against
the
Indian
meal
moth.

Table
3.
Alternative
insecticides
to
dichlorvos
as
a
top
treatment
for
bulk
stored
commodities.

Insecticide
Commodity
Comments/
Restrictions
Bacillus
thuringiensis
Corn,
oats,
rye,
wheat,
barley,
sorghum,
soybeans,
sunflowers
Evidence
of
Indian
meal
moth
resistance
within
3
generations
so
use
should
be
in
conjunction
with
other
management
practices
and
should
not
be
used
excessively
at
any
one
location.

pirimiphos­
methyl
corn,
sorghum
Effective
on
all
stored
grain
insects
but
is
not
labeled
for
small
grains
diatomaceous
earth
corn,
wheat,
sorghum,
soybeans,
oats,
rye,
barley
Grain
buyers
reluctant
to
purchase
treated
grain
due
to
possible
lower
grade,
reduced
flowability,
reduced
test
weight
,
increased
wear
on
equipment,
and
worker
respiratory
issues.

Methoprene
corn,
wheat,
sorhum,
oats,
rye,
barley,
rice,
peanuts
Only
controls
immatures
(
IGR).
Should
be
used
in
conjunction
with
an
adulticide.

B.
BIOLOGICAL
CONTROL
­
No
effective
biological
control
agents
are
available
at
this
time.
5
C.
CULTURAL
CONTROL
­
Sanitation
and
grain
management
are
important
parts
of
bulk
stored
commodity
insect
control.
Insecticides
and
fumigants
should
be
considered
as
supplements
to
sound
storage
and
not
as
replacements.
Thorough
cleaning
of
grain
residues
from
bins
and
areas
around
the
bins
will
remove
residues
that
are
the
main
source
of
insect
infestations
for
farm
stored
grain.
Good
grain
condition
will
also
reduce
or
eliminate
insect
problems
for
long
term
storage.
Stored
grain
moisture
should
be
14%
or
less
and
temperature
of
the
stored
grain
mass
should
be
within
20
°
F
of
the
average
outside
air
temperature.
Proper
grain
aeration
to
cool
grain
can
prevent
insect
feeding
and
reproduction.

VI.
BIOLOGICAL
IMPORTANCE
OF
DICHLORVOS
FOR
BULK
STORKED
COMMODITIES
As
there
is
limited
usage
of
dichlorvos,
alternative
insecticides
are
available,
and
the
nature
of
the
pest
damage,
BEAD
concludes
that
negligible
biological
impact
would
occur
in
the
absence
of
dichlorvos.
Use
of
alternative
insecticides
in
conjunction
with
good
storage
practices
should
provide
acceptable
control.

VII.
ECONOMIC
IMPORTANCE
OF
DICHLORVOS
FOR
BULK
STORED
COMMODITIES
The
availability
of
efficacious
alternatives
and
limited
usage
of
dichlorvos
on
bulk
stored
commodites
(<
5%
in
1990)
render
negligible
economic
impact
without
dichlorvos.

VIII.
REFERENCES
1.
Agricultural
Statistics.
2002.
USDA/
NASS.
http://
www.
usda.
gov/
nass/
pubs/
agr02/
acro02.
htm
2.
Agricultural
Chemical
Usage
­
Postharvest
Applications
­
Corn
and
Wheat.
1999.
USDA/
NASS.
http://
usda.
mannlib.
cornell.
edu/
reports/
nassr/
other/
pcu­
bb/
agch0399.
pdf
3.
Agricultural
Chemical
Usage
­
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Applications
­
Wheat.
2002.
USDA/
NASS.
http://
usda.
mannlib.
cornell.
edu/
reports/
nassr/
other/
pcu­
bb/
agcp0302.
pdf
4.
Agricultural
Chemical
Usage
­
Postharvest
Applications
­
Peanuts,
Rice
and
Sorghum.
2001.
USDA/
NASS.
http://
usda.
mannlib.
cornell.
edu/
reports/
nassr/
other/
pcu­
bb/
agch0301.
pdf
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66­
W.
http://
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edu/
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ext/
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E­
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pdf
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http://
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ifas.
ufl.
edu/
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IG103
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Field
Crop
Insect
Management
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­
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2002.
North
Dakota
State
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E­
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nodak.
edu/
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entupdates/
icg02pdf/
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pdf
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