MAY
06
2003
MEMORANDUM
SUBJECT:
Review
of
Insect
Resistance
Management
considerations
associated
with
Pioneer
and
Dow
Agroscience's
proposed
EUPs
for
Bacillus
thuringiensis
PS149B1
in
corn.
EPA
Reg.
Nos.
29964­
EUP­
L,
29964­
EUP­
U,
68467­
EUP­
I,
68467­
EUP­
T.
DP
Barcodes:
D288786,
D288789,
D288852,
D288855.
Cases:
067211,
067212,
065381,
065383.
Submission:
S630869,
S630878,
S631040,
S631056.
MRID#:
457904­
09,
­
10.

TO:
Mike
Mendelsohn,
Regulatory
Action
Leader
Microbial
Pesticides
Branch
Biopesticides
and
Pollution
Prevention
Division
(
7511C)

FROM:
Alan
Reynolds,
Entomologist
/
s/
Microbial
Pesticides
Branch
Biopesticides
and
Pollution
Prevention
Division
(
7511C)

THROUGH:
Sharlene
Matten,
Ph.
D.,
Biologist
/
s/
Alan
Reynolds
for/
Microbial
Pesticides
Branch
Biopesticides
and
Pollution
Prevention
Division
(
7511C)

ACTION
REQUESTED
AND
BACKGROUND
BPPD
has
been
asked
to
review
the
Insect
Resistance
Management
(
IRM)
considerations
with
the
proposed
Experimental
Use
Permits
(
EUP)
for
PS149B1
insect
control
protein
(
derived
from
Bacillus
thuringiensis
Cry34/
35
Ab1;
hereafter
referred
to
as
Cry34/
35
corn)
requested
by
Pioneer
(
EPA
Reg.
Nos.
29964­
EUP­
L
and
29964­
EUP­
U)
and
Dow
AgroSciences
(
EPA
Reg.
Nos.
68467­
EUP­
I
and
68467­
EUP­
T).
Each
company
is
proposing
to
test
two
separate
vectors:
17662
and
17658.
Cry34/
35
corn
is
targeted
against
western
corn
rootworm
(
Diabrotica
virgifera
virgifera,
WCRW)
and
northern
corn
rootworm
(
Diabrotica
berberi,
NCRW).

The
proposed
acreage
for
the
Pioneer
EUPs
is
623.9
(
29964­
EUP­
L)
and
622.4
(
29964­
EUP­
U),
planted
in
18
states
and
Puerto
Rico.
Each
of
the
two
proposed
Dow
EUPs
will
cover
393.5
acres
planted
in
15
states
and
Puerto
Rico.
The
total
acreage
for
all
four
EUPs
is
2033.3.
The
IRM
portion
of
the
submission
consists
of
a
"
Section
G"
(
Experimental
Protocol
for
each
EUP,
a
"
Trait
Durability"
plan
for
the
EUP
(
MRID#
457904­
09),
and
field
efficacy
data
(
MRID#
457904­
10).
2
CONCLUSIONS
AND
RECOMMENDATIONS
1.
For
the
EUPs,
a
specific
refuge
requirement
is
not
necessary.
The
threat
of
resistance
to
Cry34/
35
corn
should
be
minimal
for
the
EUPs
because:
1)
the
EUPs
are
for
limited
acreage
(
2033
total
acres);
2)
the
acreage
will
consist
of
small
plots
(
most
<
5
acres)
scattered
over
19
states
and
Puerto
Rico;
and
3)
the
EUPs
are
for
one
year
only.
However,
for
full
Section
3
registration
involving
larger
acreage,
structured
refuge
should
be
required
to
mitigate
the
potential
for
the
development
of
resistance.
Dow's
submitted
"
Trait
Durability"
plan
(
MRID#
457904­
09)
is
acceptable
for
the
EUPs.

2.
It
is
recommended
that
for
a
full
commercial
Section
3
registration
of
Cry34/
35
corn,
the
registrants
submit
an
Insect
Resistance
Management
(
IRM)
plan
that
fully
addresses
all
pertinent
topics:
refuge
(
size,
proximity,
and
structure),
dose,
IRM
research,
cross
resistance,
monitoring,
remedial
action,
grower
education,
and
compliance.

3.
The
IRM­
related
experimental
objectives
for
the
EUPs
as
proposed
by
Dow
in
their
"
Trait
Durability"
plan
are
acceptable.
The
areas
of
study
include:
model
sensitivity
analyses,
dose
evaluation,
pest
biology
(
larval
movement),
monitoring
(
susceptibility
analysis
and
determining
levels
of
"
unexpected
damage"),
grower
education,
and
compatibility
with
existing
corn
refuge
strategies.
However,
the
"
Section
G"
(
proposed
experimental
program)
reports
do
not
describe
these
objectives
(
other
than
dose
investigation),
so
it
is
unclear
exactly
what
IRM
research
will
be
undertaken.

4.
Field
efficacy
data
submitted
by
Dow
(
MRID#
457904­
10)
showed
that
Cry34/
35
corn
significantly
reduced
root
damage
versus
non­
transgenic
corn
(
determined
with
the
Iowa
State
Linear
Scale).
Root
ratings
for
Cry34/
35
corn
were
0.07
to
0.18
(
indicating
7
­
18%
of
one
root
node
eaten
­
very
minor
feeding
damage)
while
the
non­
transgenic
corn
ratings
were
1.22
to
1.28
(
indicating
1.22
­
1.28
root
nodes
eaten).

INSECT
RESISTANCE
MANAGEMENT
The
details
of
the
IRM
strategy
and
research
goals
for
the
EUPs
were
contained
in
a
report
("
Trait
Durability
and
Experimental
Use
of
Transgenic
Maize
Expressing
the
Insecticidal
Crystalline
Proteins
Cry34Ab1
and
Cry35Ab1")
(
MRID#
457904­
09)
submitted
by
Dow
and
in
the
Proposed
Experimental
Program
("
Section
G")
for
each
EUP.
It
is
noted
that
the
"
Section
G"
reports
submitted
by
both
Dow
and
Pioneer
describe
the
same
IRM
objectives.

Dow's
"
Trait
Durability"
submission
argues
that
selection
pressure
for
resistance
to
Cry34/
35
corn
should
be
insignificant
for
the
experimental
period.
The
reviewers
agree
with
this
assessment,
given
that
the
EUP
is
for
one
year
and
will
involve
limited
acreage
in
small
plots.
The
total
acreage
for
all
four
EUPs
is
2033.3,
planted
across
19
states
and
Puerto
Rico.
Most
of
the
3
experimental
plots
will
be
less
than
five
acres
(
the
largest
plots
will
be
40
acres).
In
addition,
plots
will
be
surrounded
by
border
rows
of
corn,
which
will
serve
as
de
facto
refuge.
After
harvest,
plots
will
be
demarcated
and
monitored
for
volunteer
corn.

Considering
these
factors,
a
refuge
plan
should
not
be
necessary
for
the
EUPs.
However,
for
full
FIFRA
Section
3
registration
or
larger
acreage
requests,
structured
refuge
should
be
required
to
mitigate
the
potential
for
the
development
of
resistance.
A
full
IRM
plan
should
be
submitted
with
a
Section
3
registration
request
to
address
the
following
areas:
refuge
(
size,
proximity,
and
structure),
dose,
IRM
research,
cross
resistance,
monitoring,
remedial
action,
grower
education,
and
compliance.

The
August
27­
29,
2002
SAP
addressed
IRM
for
CRW­
protected
transgenic
corn.
Although
the
meeting
was
held
in
the
context
of
MON
863
(
a
Monsanto­
registered
hybrid),
much
of
the
discussion
was
relevant
to
general
CRW
IRM.
Dow
and
Pioneer
should
address/
incorporate
the
August
2002
SAP
report
recommendations
on
CRW
IRM
as
appropriate
for
Cry34/
35
corn.

As
part
of
the
experimental
program
for
the
EUPs,
Dow
has
proposed
to
conduct
research
on
a
number
of
IRM­
related
topics
(
detailed
Dow's
"
Trait
Durability"
plan).
The
major
areas
of
research
include:
model
sensitivity
analyses,
dose
evaluation,
pest
biology
(
larval
movement),
monitoring
(
susceptibility
analysis
and
determining
levels
of
"
unexpected
damage"),
grower
education,
and
compatibility
with
existing
corn
refuge
strategies.
These
research
topics
should
aid
the
registrants
in
developing
a
sound
IRM
plan
for
Cry34/
35
corn.
However,
it
is
noted
that
the
"
Section
G"
(
proposed
experimental
program)
reports
for
each
EUP
indicate
that
IRM
research
will
focus
only
on
investigation
of
dose
(
other
research
areas
are
not
described).
It
is
unclear
from
the
Section
G
reports
whether
the
other
research
topics
described
in
the
"
Trait
Durability"
study
will
investigated
as
part
of
the
EUPs.

Separate
from
their
EUP
submission,
Dow
has
provided
details
of
their
plan
to
evaluate
high
dose
with
Cry34/
35
corn
(
described
in
a
confidential
handout
from
Dow
and
personal
communication
with
N.
Storer).
The
reviewers
have
evaluated
this
plan
and
agree
with
Dow's
approach
for
assessing
dose
in
Cry34/
35
corn.

FIELD
EFFICACY
OF
CRY34/
35
CORN
As
part
of
their
submission,
Dow
has
submitted
the
data
from
a
field
efficacy
study
to
evaluate
the
performance
of
Cry34/
35
corn
(
MRID#
457904­
10).
Efficacy
was
evaluated
for
six
events
­
three
from
vector
17662
(
68467­
EUP­
T)
and
two
from
vector
17658
(
68467­
EUP­
I).
The
other
tested
event
is
not
part
of
the
proposed
EUPs.

The
study
was
conducted
in
two
locations
(
York,
Nebraska
and
Rochelle,
Illinois)
during
the
2002
growing
season.
Plots
of
Cry34/
35
and
control
(
non­
transgenic)
corn
were
artificially
infested
with
500
(
Rochelle)
or
1000
(
York)
WCRW
eggs.
After
the
larvae
were
given
sufficient
time
to
pupate,
the
roots
were
unearthed
and
assessed
for
rootworm
feeding
damage
using
the
4
Iowa
State
Linear
Scale
(
Oleson
1998).
The
Linear
Scale
assigns
a
numerical
score
to
each
plant's
root
system:
whole
numbers
indicate
full
root
nodes
eaten
and
decimals
indicate
the
percentage
of
a
single
node
eaten
(
e.
g.
1.25
would
indicate
one
complete
node
and
25%
of
another
node
eaten).

The
results
showed
that
Cry34/
35
corn
sustained
very
little
feeding
damage:
root
scores
were
0.07
­
0.18
(
7
to
18%
of
one
node
eaten)
with
no
significant
difference
between
the
six
tested
events.
Control
plant
root
scores
were
1.22
­
1.28
(
one
full
node
and
22
to
28%
of
a
second
node
eaten),
which
was
significantly
greater
feeding
damage
than
experienced
by
the
Cry34/
35
corn,
despite
reported
"
moderate"
insect
pressure
from
the
artificial
infestation.
Given
these
results,
Cry34/
35
corn
should
be
effective
in
preventing
damage
from
rootworm
feeding.

Reference:

Oleson,
1998.
Linear
scale
for
evaluating
corn
rootworm
larval
injury.
Poster
presentation
given
at
the
Annual
Meeting
of
the
Entomological
Society
of
America.
