Greenbug Expert System and “Glance ‘N Go”
Sampling for Cereal Aphids: Results of Field
Testing
Tom A. Royer
Department
of
Entomology
&
Plant Pathology
Oklahoma State University
What is the Cereal Aphid Pest
Management Expert System?
A computer program located at
http://entoplp.okstate.edu/gbweb/index.htm
Developed by USDA ARS, SST Development Group
and OSU.
It has several elements:



1.
2.
3.
4.
5.
Information on cereal aphids (UPDATED July 2005)
A calculator for determining economic thresholds for greenbug
infestations.
A natural enemy module (UPDATED July 2005)
A pesticide information module. (UPDATED July 2005)
A set of sampling plans for each economic threshold
(UPDATED June 2004)
Oklahoma State University
Objectives for Developing Greenbug
Expert System In Winter Wheat




Establish a treatment threshold based upon accurate
Economic Injury Levels (EILs) for cereal aphids in
different wheat production systems (dual purpose, grain
only, forage?).
Create a simple, accurate sampling strategy that reflects
differences in aphid distribution patterns, crop
susceptibility and natural enemy activity (Glance ‘n Go).
Develop an educational tool with information on natural
enemies, pesticide selection and aphid biology.
Develop a flexible system that could be expanded as
additional information became available and/or interface
with real-time weather data.
Oklahoma State University
Why Is This System Needed?




Past recommendations for managing greenbugs
were not determined from research-based
damage relationships for grain or forage yield.
No recommendations on managing BCOA.
Consideration of natural enemy activity was
rudimentary
No consideration of production system (grain vs.
dual purpose vs. forage).
Oklahoma State University
How Were These Tools Developed?



Greenbug: Treatment Thresholds based on an
Economic Injury Level and a temperature-based
greenbug development rate (Kindler et al 2003).
Aphid Mummy decision tool built into system Giles
et al 2004).
BCOA: “Research in progress, but will soon be
incorporated into new recommendations”
Oklahoma State University
What is a Treatment Threshold
(also known as an Economic Threshold)
• A Treatment Threshold is based upon an
existing Economic Injury Level (Kindler
et al. 2003) and a sampling method
(Giles et al 2000) that can effectively
estimate pest numbers in a time-efficient
manner.
Oklahoma State University
Using an Economic Injury Level
Economic Injury Levels account for:
• Cost of control
• Value of commodity
• Yield loss/pest unit
• Loss prevented by control
Oklahoma State University
Aphids per Tiller
A Treatment Threshold or Economic
Threshold (ET) is a Decision Tool
40
35
30
25
EIL
ET
Aphids Untreated
20
15
10
5
0
Spray
Decide
0
1
4
7
10 13 16 20 23 26 29
Days
Oklahoma State University
Aphids per Tiller
A Treatment Threshold or Economic
Threshold (ET) is a Decision Tool
40
35
30
25
EIL
ET
Aphids Treated
20
15
10
5
0
Spray
Decide
0
1
4
7
10 13 16 20 23 26 29
Days
Oklahoma State University
What Does the Greenbug Expert
System Provide?

It is capable
of using
weather data
to calculate
treatment
thresholds
based upon
the time of
year
Oklahoma State University
What Does the Greenbug Expert
System Provide?

It allows a
producer to
play the
“what If”
game with
pesticide
costs,
market
values
Oklahoma State University
What Does the Greenbug Expert
System Provide?

It has a full
complement of
treatment
threshold forms
that can be
printed off to
serve as a
permanent
record of the
sampling results
Oklahoma State University
What Does the Greenbug Expert
System Provide?
Aphid Biology

It has other
educational
modules
that can be
used:
Natural
Enemies
Insecticide Selector
Oklahoma State University
What Does the Greenbug Expert
System Provide?

It is readily
adaptable to
new results
once they
become
available.
Oklahoma State University
What is “Glance ‘n Go” Sampling ?


Presence/Absence Sampling: A sampling plan
that estimates greenbug numbers without
actually counting them, by counting infested
tillers (GLANCE).
Sequential Sampling

Allows you to make treatment decisions “On The GO”
You take only as many samples as needed to make a
decision. Some fields may require only a very few
samples, so you can move on to the next field.
Oklahoma State University
Sampling for Aphids in Wheat
Past Guidelines for Greenbug




Wait for evidence of injury
(yellow spots etc in field)
Examine 1 foot of row in at
least 5 locations per field
Avoid field edges
Take more samples in fields
greater than 80 acres
Oklahoma State University
Development of Glance ‘n Go for
Greenbugs



Developed Glance ‘n Go sampling plan, with
statistical probabilities using 100 fields in
Oklahoma.
Actively sought input from from County
Extension Educators, and crop consultants to
make it as usable as possible.
We are administering a tool to try and measure
impact and adoption of this method over 3-5
years.
Oklahoma State University
How does “Glance ‘n Go” Sampling for
Greenbugs Work?

Examine 15 90 individual
tillers, collecting
3 samples per
stop
Oklahoma State University
How does “Glance ‘n Go” Sampling for
Greenbugs Work?

Record counts of
infested tillers, i.e.
that have one or
more greenbugs on a
Glance ‘n Go form,
which is based on the
time of year, and the
pre-determined
economic threshold.
Oklahoma State University
How does “Glance ‘n Go” Sampling for
Greenbugs Work?

Example of a Decision to Treat
Oklahoma State University
How does “Glance ‘n Go” Sampling for
Greenbugs Work?

Example of a Decision to Not Treat.
Oklahoma State University
How does “Glance ‘n Go” Sampling for
Greenbugs Work?

Example of a Decision to Not Treat.
Oklahoma State University
How does “Glance ‘n Go” Sampling for
Greenbugs Work?

Example of a No-Decision
Oklahoma State University
Why Does the Time of Year matter for
“Glance ‘n Go” Sampling ?



Patterns of infestation vary
from year to year.
Fall infestations normally
occur from colonization of
winged adults
Spring infestations often
develop from overwintering
aphids that were already in
the wheat field
Oklahoma State University
Greenbug Distribution Patterns in
Winter Wheat in Oklahoma
Spring
Infestation
6 greenbugs/tiller
100
% Infested Tillers
90
80
70
60
50
Fall
Infestation
6 greenbugs/tiller
40
30
20
10
0
0
1
2
3
4
5
6
7
8
# Aphids/Tiller
9
10
Greenbug Distribution Patterns in
Winter Wheat in Oklahoma
Why Doesn’t the Size of the Wheat Plant
matter for “Glance ‘n Go” Sampling ?

AFTER the wheat
reaches the 4 leaf
stage, our research
showed that greenbugs
reduced yield in a
consistent manner,
regardless of the size of
the plant.
Oklahoma State University
New Promises?

Build in assessment of Bird cherry oat aphid into
decision system.

Develop similar system for Russian wheat aphid.

Understand the economics of forage reductions by fall
aphid infestations.
Oklahoma State University
Team Approach to Cereal Aphid
Management


USDA-ARS Laboratory Scientists:

Dr. Norm Elliott -Biological control, Area-wide management

Dr. Dean Kindler-Host range, developmental biology

Dr. Dave Porter - Host plant Resistance
OSU

Dr. Kristopher Giles - Biological control, integrated management
of cereal aphids

Dr. Eugene Krenzer - Wheat production

Dr. Robert Hunger - BYDV management

Dr. Tom Peeper - Chemical weed control.
Oklahoma State University
Greenbug Expert System and “Glance N’ Go”
Sampling for Cereal Aphids in Winter Wheat
Tom A. Royer
Department
of
Entomology
&
Plant Pathology
Oklahoma State University