1
UNITED
STATES
ENVIRONMENTAL
PROTECTION
AGENCY
WASHINGTON,
D.
C.
20460
OFFICE
OF
PREVENTION,
PESTICIDES
AND
TOXIC
SUBSTANCES
Memorandum
SUBJECT:
Benefits
assessment
for
methyl
parathion
use
on
soybeans
FROM:
William
Gross,
Entomologist
Herbicide
and
Insecticide
Branch
Timothy
Kiely,
Economist
Economic
Analysis
Branch
Biological
and
Economic
Analysis
Division
(
7503C)

THROUGH:
David
Brassard,
Senior
Entomologist
Arnet
Jones,
Chief
Herbicide
and
Insecticide
Branch
David
Widawsky,
Chief
Economic
Analysis
Branch
Biological
and
Economic
Analysis
Division
(
7503C)

TO:
Laura
Parsons,
Chemical
Review
Manager
Susan
Lewis,
Chief
Reregistration
Branch
Special
Review
and
Reregistration
Division
(
7508C)

Reviewed
by
BEAD
Peer
Review
Panel:,
2002
Summary
The
primary
use
of
methyl
parathion
on
soybeans
is
for
the
control
of
stink
bugs
(
Southern
green,
green,
and
brown).
It
is
applied
to
less
than
1%
of
the
soybean
acreage
for
the
control
of
these
and
other
minor
pests
on
soybeans.
Due
to
the
availability
of
a
number
of
effective
alternatives
to
methyl
parathion
on
2
soybeans
for
the
control
of
these
pests,
soybean
growers
are
not
expected
to
face
any
significant
impacts
if
methyl
parathion
were
not
available
for
use.

Background
of
U.
S.
Soybean
Production
An
average
of
73.5
million
acres
of
soybeans
are
planted
in
the
United
States
annually.
Production
is
limited
to
the
Eastern
and
Central
U.
S.
with
the
northern
states
in
these
regions
accounting
for
75%
of
total
U.
S.
production.
Total
U.
S.
soybean
production
was
nearly
2.8
billion
bushels
in
2000.
The
top
soybean
production
states
are
Illinois,
Iowa,
Indiana,
and
Minnesota,
which
together
account
for
more
than
50%
of
total
soybean
production.
Other
high
production
states
include
Ohio,
Missouri,
Nebraska
and
South
Dakota.

Insecticide
Usage
on
Soybeans
Organophosphate
insecticides
represent
approximately
42%
of
all
insecticide
usage
on
soybeans,
with
an
average
of
1.1
applications
per
season.
Analysis
of
OP
usage
was
conducted
for
two
regions:
Northern
U.
S.
(
IL,
IN,
IA,
KS,
KY,
MI,
MN,
MO,
NE,
NJ,
ND,
OH,
PA,
SD,
and
WI)
and
Southern
U.
S.
(
AL,
AR,
DE,
FL,
GA,
LA,
MD,
NC,
OK,
SC,
TN,
TX,
and
VA).
Insecticide
use
patterns
and
key
pests
vary
between
regions,
mainly
because
of
environmental
limitations
that
prevent
some
insect
pests
from
overwintering
in
the
northern
U.
S.
However,
some
tropical
insects
that
typically
infest
southern
grown
beans,
are
carried
to
northern
areas
by
prevailing
atmospheric
winds.
Typically
only
2.5%
of
all
soybean
acreage
is
treated
annually
with
insecticides.

According
to
USDA,
less
than
1%
of
the
U.
S.
soybean
acreage
is
treated
with
methyl
parathion
and
less
than
200,000
pounds
are
applied.
Historically,
its
use
has
occurred
in
Louisiana,
Arkansas,
Indiana,
Mississippi
and
Nebraska.

Methyl
Parathion
Use
on
Soybeans
Methyl
parathion
is
used
to
control
bean
leaf
beetle,
potato
leafhopper,
three­
cornered
alfalfa
hopper,
cabbage
looper,
soybean
looper,
corn
ear
worm
or
pod
worm,
beet
armyworm,
grasshoppers
and
stink
bugs.
Among
the
major
pests
for
which
methyl
parathion
is
used
control
are
stink
bugs:
Southern
green
,
(
Nazara
viridula),
green
stink
bug
(
Acrosternum
hilare
and
brown
stink
bug
(
Euschistus
servus).
Methyl
parathion
still
gives
good
control
of
the
former
species
of
stink
bugs;
however,
the
brown
stink
bug
is
showing
resistance
to
methyl
parathion
from
wheat
and
cotton
to
soybeans.
A
review
of
one
efficacy
study
suggest
that
acephate
is
as
effective
as
methyl
parathion.
According
to
the
study,
"
Insecticide
Evaluation
Against
Stink
Bugs
on
Soybeans
in
Louisiana",
stink
bug
pre­
treatment
densities
exceeded
Louisiana's
action
threshold
(
$
9
SB/
25
sweeps).
At
7
day
after
treatment,
acephate
and
methyl
parathion
had
significantly
fewer
brown
stink
bug
adults
than
untreated
plots.
However,
acephate
was
rated
more
effective
in
controlling
all
species
of
stink
bug.
3
According
to
Dr.
Gus
Lorenz,
extension
entomologist
with
the
University
of
Arkansas,
methyl
parathion
will
only
control
brown
stink
bug
on
the
day
of
application,
as
opposed
to
acephate
that
provides
good
residual
control.
4
Alternatives
to
Methyl
Parathion
Use
on
Soybeans
Acephate,
chlorpyrifos,
diazinon,
dimethoate,
disulfoton,
malathion
and
phorate
are
organophosphate
insecticides
used
to
control
insect
pests
on
soybeans.
Carbaryl,
carbofuran
and
methomyl
are
carbamate
insecticides
that
are
used
as
alternatives
to
methyl
parathion.
There
are
several
synthetic
pyrethroids,
including
esfenvalerate,
lambda­
cyhalothrin
and
tralomethrin,
to
name
a
few
that
control
soybean
pests.
However,
acephate
is
the
most
efficacious
chemical
against
the
methyl
parathion
resistant
brown
stink
bug,
and
causes
the
least
secondary
effects
on
parasites
and
predators
in
the
soybean
agri­
ecosystem.

Biological
Impacts
of
Extending
Restricted
Entry
Interval
Extending
the
restricted
entry
interval
(
REI)
on
soybeans
for
methyl
parathion
use
would
have
minimal
impacts,
in
that
very
little
hand­
weeding
or
irrigation
occurs
in
soybeans,
and
scouting,
which
occurs
more
often
in
soybean
fields,
is
exempt
under
the
worker
protection
standard.

Biological
Impacts
of
Further
Restricting
Methyl
Parathion
in
Soybean
Production
Due
to
the
availability
of
a
number
of
efficacious
alternatives
to
methyl
parathion
to
control
soybean
pests,
and
the
apparent
resistance
of
the
brown
stink
bug
to
methyl
parathion,
the
impacts
that
may
be
caused
by
further
restricting
the
use
of
methyl
parathion
on
soybeans
would
be
minimal.

Sources
USDA,
National
Agricultural
Statistics
Service.
Agricultural
Chemical
Usage,
Field
Crop
Summary,
1998­
2001.

USDA,
National
Agricultural
Statistics
Service.
Agricultural
Statistics,
2001.

Citations
B.
J.
Fitzpatrick
et
al
(
2001).
Evaluation
of
Insecticides
Against
Stink
Bug.
Arthropod
Management
Tests,
Volume
26,
(
F96).

Lorenz,
Gus
(
2002).
Comparison
of
Acephate
Versus
Methyl
Parathion.
Communication
to
Bill
Gross
