Document ID: EPA-HQ-OPP-2004-0146-0005
Agency: epa
Document Type: Supporting & Related Material
Title: 
Posted Date: 2004-05-24T04:00Z

AGENCY
POSITION
PAPER
FOR
JUNE
2004
SAP
(
5/
04/
04)

The
Agency
has
reviewed
and
evaluated
the
product
characterization
data,
human
health
data,
ecological
toxicity
data,
and
insect
resistance
management
plan
for
the
Cry1F/
Cry1Ac
proteins
expressed
in
Widestrike
cotton,
and
the
data
to
support
continuation
of
the
95:
5
external,
unsprayed
structured
refuge
for
cotton
bollworm
resistance
management
for
Bollgard
cotton
and
Bollgard
II
cotton.
Following
is
a
brief
description
of
the
Agency&
rsquo;
s
position
based
on
the
scientific
findings.

The
mammalian
toxicity
data
submitted
for
WideStrike
cotton
includes
toxicity
testing
on
each
individual
Cry
protein
as
well
as
studies
with
the
combination
of
Cry1Ac
and
Cry1F.
All
the
tests
were
done
with
purified
protein
at
high
doses
approaching
the
limit
dose
values
for
acute
oral
toxicity.
Based
on
the
results
of
mammalian
toxicity
studies
and
product
characterization
data
for
the
Cry1F
and
Cry1Ac
proteins
expressed
in
WideStrike
cotton,
the
Agency&
rsquo;
s
risk
assessment
indicates
that
WideStrike
cotton
should
not
cause
adverse
effects
to
human
health.

Based
on
the
evaluation
of
the
submitted
limit
dose
testing
data
and
information
on
the
general
biology
of
Bt
Cry
proteins,
the
Agency&
rsquo;
s
ecological
risk
assessment
did
not
identify
any
adverse
effects
on
the
flora
and
fauna
of
the
cotton
agroecosystems
that
would
be
expected
from
the
cultivation
of
WideStrike
cotton.
Specific
data
were
reviewed
relating
to
aquatic
and
terrestrial
wildlife,
Cry
protein
fate
in
soils,
potential
effects
on
soil
biota
and
field
census
data
examining
the
effects
on
non­
target
foliar
insects,
and
endangered
or
threatened
species
hazard
assessment,
particularly
Lepidoptera
listed
as
threatened
or
endangered
by
the
United
States
Fish
and
Wildlife
Service.
The
submitted
studies
examined
the
effects
of
the
Cry1F
and
Cry1Ac
proteins
separately
and
in
combination
to
detect
any
possible
synergistic
effects.
No
synergistic
effects
or
increase
in
non­
target
host
range
as
a
result
of
stacking
were
identified.

WideStrike
cotton,
expressing
both
the
Cry1F
and
Cry1Ac
insecticidal
control
proteins,
is
intended
to
protect
cotton
from
feeding
by
three
key
lepidopteran
pests
of
cotton
in
their
respective
geographies:
tobacco
budworm
(
Heliothis
virescens,
TBW,
Lepidoptera:
Noctuidae)),
pink
bollworm
(
Pectinophora
gossypiella,
PBW,
Lepidoptera:
Gelechiidae),
and
cotton
bollworm
(
Helicoverpa
zea,
CBW,
Lepidoptera:
Noctuidae).
Dow
AgroSciences&
rsquo;
(
Dow&
rsquo;
s)
proposed
insect
resistance
management
(
IRM)
plan
for
WideStrike
proposes
the
following
refuge
options:

1.
5%
external
unsprayed
refuge
option.
Five
percent
of
the
cotton
fields
must
be
planted
to
non­
Bt
cotton
and
not
be
treated
with
any
lepidopteran­
control
technology.
The
refuge
must
be
at
least
150
ft.
wide
(
preferably
300
ft.)
and
within
½
mile
(
preferably
adjacent
or
within
1/
4
mile
or
closer)
of
the
Bt
cotton.

2.
20%
external
sprayable
refuge
option.
Twenty
percent
of
the
cotton
fields
must
be
planted
to
non­
Bt
cotton
and
may
be
treated
with
lepidopteran­
active
insecticides
(
or
other
control
technology)
except
for
microbial
Bt
formulations.
The
refuge
must
be
within
1
mile
(
preferably
within
½
mile
or
closer)
of
the
Bt
cotton
fields.

3.
5%
embedded
refuge
option
(
for
TBW
and
CBW).
Five
percent
of
a
cotton
field
(
or
fields)
must
be
planted
with
non­
Bt
cotton
as
a
block
within
a
single
field,
at
least
150
ft.
wide
(
preferably
300
ft.
wide)
or
single
field
blocks
within
a
one
mile
squared
field
unit.
The
refuge
may
be
treated
with
lepidopteran­
active
insecticides
(
or
other
control
technology)
only
if
the
entire
field
or
field
unit
is
treated
at
the
same
time.

4.
Embedded
(
in­
field
strip)
refuge
option
for
PBW.
One
single
row
of
a
non­
Bt
cotton
variety
must
be
planted
for
every
6
to
10
rows
of
Bt
cotton.
This
can
be
treated
with
lepidopteran­
active
insecticides
(
or
other
control
technology)
only
if
the
entire
field
is
treated
at
the
same
time.

5.
Community
refuge
option.
Farmers
can
combine
neighboring
fields
within
a
one­
mile
squared
field
unit
that
act
as
a
20%
sprayable
refuge
or
the
5%
unsprayed
refuge.
Participants
in
the
community
refuge
option
must
have
a
community
refuge
coordinator
and
appropriate
documentation
is
required.

Based
on
the
Agency&
rsquo;
s
analysis,
the
Dow
IRM
plan
is
appropriate
for
insect
resistance
management
to
the
Cry1F
and
Cry1Ac
proteins
expressed
in
WideStrike
cotton.
The
Dow
CBW
modeling
efforts
show
that
we
can
have
high
confidence
that
there
will
not
be
a
significant
change
in
population
fitness
of
CBW
on
WideStrike
cotton
in
a
15­
year
time
horizon
even
without
a
high
dose
for
either
Cry1Ac
or
Cry1F
and
incomplete
cross­
resistance
(
20
to
60%
maximum
shared
binding).
For
TBW,
the
addition
of
a
second
insecticidal
control
protein
(
ICP),
makes
the
20%
refuge
even
more
durable
than
for
a
single
ICP
expressed
at
a
high
dose
and
reduces
the
refuge
size
(
as
compared
to
a
single,
high
dose
ICP)
needed
for
the
same
level
of
protection
as
predicted
by
past
TBW
resistance
management
models
across
the
same
time
horizon.
For
PBW,
WideStrike
cotton
expresses
a
high
dose
of
Cry1Ac.
Cry1F
is
not
effective
against
PBW.
A
market
mix
of
different
Bt
cottons,
as
well
as
other
control
technologies,
further
reduces
the
expected
selection
pressure
for
resistance
against
the
Cry1F
and
Cry1Ac
proteins
expressed
in
WideStrike
cotton.

As
a
condition
of
the
Bollgard
®
cotton
and
Bollgard
®
II
cotton
registrations,
EPA
required
the
Monsanto
Company
conduct
CBW
alternate
host
research
studies
and
pyrethroid
overspray
studies
that
would
support
the
adequacy
of
the
5%
external,
unsprayed,
structured
refuge
for
CBW
resistance
management.
Based
on
the
Agency&
rsquo;
s
review
of
the
pyrethroid
overspray
studies,
pyrethroid
oversprays
in
Bollgard
cotton
fields
will
increase
the
level
of
control
of
CBW
and
delay
the
evolution
of
resistance.
The
Agency&
rsquo;
s
review
of
the
two­
year
alternate
host
studies
conducted
in
five
states
indicates
that
both
C3
and
C4
alternative
hosts
serve
as
unstructured
refugia.
CBW
moths
are
produced
on
alternative
hosts
in
sufficient
numbers
throughout
the
cotton
growing
season
(
synchronous)
to
mate
with
any
putative
resistant
CBW
moths
emerging
in
Bollgard
or
Bollgard
II
cotton
fields
and
dilute
resistance.
That
is,
the
susceptible
CBW
moths
coming
from
alternative
hosts
will
reduce
the
intensity
of
Cry1Ac
and
Cry2Ab2
resistance
selection
in
CBW
and
lower
the
likelihood
of
resistance
evolution.
Despite
the
limitations
EPA
has
identified
associated
with
the
Gustafson
et
al.
(
2001/
2004)
model,
both
the
pyrethroid
overspray
data
and
alternate
host
data
support
the
model&
rsquo;
s
predictions
that
it
will
take
many
times
longer
for
CBW
resistance
evolution
than
without
the
inclusion
of
these
parameters.
Other
data
regarding
CBW
reverse
migration
indicated
no
significant
impact
on
CBW
adaptation
to
Bt
corn
and
cotton.
Based
on
the
Agency&
rsquo;
s
analyses,
the
pyrethroid
overspray
studies
and
alternative
host
studies
support
the
continuation
of
the
5%
external,
unsprayed
structured
non­
Bt
(
Bacillus
thuringiensis)
cotton
refuge
for
CBW
resistance
management.
EPA
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Last
updated
on
Thursday,
May
27th,
2004
URL:
http://
www.
epa.
gov/
scipoly/
2004/
june/
positionpaper.
htm