Integrated Management of
Whiteflies in Arizona
Peter C. Ellsworth, Ph.D.
IPM Specialist, University of Arizona
Maricopa, AZ, USA
&
Steve Naranjo, Ph.D.
Research Scientist, USDA-ARS, WCRL
Phoenix, AZ, USA
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World Distribution of
Outbreaks of B. tabaci
Arizona
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State of Arizona, U.S.A.
Maricopa
Agricultural
Center (~350 m)
Majority of cotton
production in AZ
Yuma
Agricultural
Center (~50 m)
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Impact of SWF on Arizona
• Whiteflies (biotype B) invaded
Arizona in the early 1990s.
• Losses to the agricultural
industry were catastrophic.
• Honeydew excreted by SWF
caused sticky cotton that
could not be sold at a premium
price after outbreaks in 1992 &
1995.
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AZ Lint Lost Value
15
1994 –
1995
cents/lb
late
1980’s
10
DSW 31-3/35 minus NNYCE
late
1990’s
1992 –
1993
5
0¢
0
*
12/17/99
6/18/99
12/18/98
6/19/98
12/19/97
6/20/97
12/20/96
6/21/96
12/22/95
6/23/95
12/23/94
6/24/94
12/24/93
6/25/93
12/25/92
6/26/92
12/27/91
6/28/91
12/28/2090
6/29/2090
12/29/2089
6/30/2089
12/30/2088
7/1/2088
• In the late 1980s, AZ enjoyed a premium for its
cotton lint relative to New York Futures.
• The 1992 & 1995 outbreaks led to depressed
prices for AZ lint, a loss that we continue to
endure in spite of clean cotton.
1/1/2088
-10
7/3/2087
1/2/2087
-5
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Pest Trends in Arizona (1990-2000)
• The 1995 outbreak led to a 25-yr high in foliar insecticide
use in cotton.
• There was a major shift in insecticide use in 1996...
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Arizona IPM Plan Introduced
• …due to the introduction of insect growth regulators, Bt
cotton, and the Arizona IPM plan.
• 1999 was a 25-yr low in foliar insecticide use in cotton.
IGRs, Bt cotton,
& AZ IPM Plan
introduced
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Whitefly IPM…
…depends on 3 basic keys
3
2
1
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Avoidance
…all practices that
serve to prevent or
maintain pests below
economic levels.
1
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Crop Management
…some factors lead to
increased SWF
numbers, such as
water-stress, excess N,
or hairy-leafed cultivars
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Exploitation of Pest
Biology & Ecology …knowing your
“enemy” will help guide
prevention efforts, such
as specific information
on how SWFs are dying
& the role of natural
enemies
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Area-Wide Impact
…is needed for this
mobile & polyphagous
pest & includes
elements of
cooperation, source
reduction & attention to
SWF movement...
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Areawide Impact
…also depends on
stable systems of
management to be in
place for all sensitive
crops in order to
reduce area-wide
pressure.
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When SWF are damaging...
3
…we depend on the top
two levels of the
pyramid
2
1
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Sampling
…sits atop
the pyramid
& serves all
layers of
management.
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Sampling (~ 7 min. / field)
• Locate 5th leaf (below terminal)
• Score as infested with adults when…
3 or more adults present
• Examine quarter-sized leaf disk
• Score as infested with nymph when…
1 or more LARGE nymphs present
• Tally up 30 leaves & 30 leaf disks
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Field Sampling for Nymphs
Locate between
main veins
“Quartersized” disk
Count adults first
5th leaf
Large nymphs
Presence / Absence count
on 30 leaves
Determine
% infested
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Action Thresholds
…with sampling, can
be used to precisely
time sprays with
IGRs (Stage I) &
other insecticides
(Stage II & III).
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Whitefly Thresholds
• Timing of IGRs (Stage I)
40% of leaves infested
with 3 or more adults
40% of disks infested with
1 or more large nymphs
40
N Y M P H S
• Timing Stage II & III
conventional sprays
57% of leaves infested
with 3 or more adults
A D U L T S
Number of leaves Percent
infested with 3 infested Average
or more adults
leaves per leaf
1
3.4
0.3
2
6.7
0.6
3
10
0.8
4
13
1.0
5
17
1.3
6
20
1.5
7
23
1.8
8
27
2.1
9
30
2.3
10
33
2.6
11
37
2.9
12
40
3.2
13
43
3.6
14
47
3.9
15
50
4.3
16
53
4.7
17
57
5.1
18
60
5.5
19
63
6.0
20
67
6.5
21
70
7.1
22
73
7.7
23
77
8.4
24
80
9.2
25
83
10.2
26
87
11.3
27
90
12.8
28
93
14.9
29
97
18.4
30
100
34.9
Number of disks
infested with large
nymphs
8
12
16
Percent
infested Average
disks
per disk
26
0.5
40
1.0
52
1.5
40
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Selective & Effective Chemistry
…the insect growth
regulators sit at the
center of our
pyramid.
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Major
Points of
Insect
Growth
Regulation
pyriproxyfen
Knack®
Adult
4th,
“pupa”
Egg
Crawler
2nd 3rd
™
Applaud
buprofezin
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IGRs & Natural Enemy
Conservation
…demonstrate the
interaction between
levels of the pyramid to
produce “bioresidual”...
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What is “Bioresidual”?
Overall killing power of an
insect control technology
including the direct effects
of the technology (i.e.,
chemical residual) PLUS
the associated natural
biological mortality.
Ellsworth & Martinez-Carrillo, 2001
b
i
o
l
o
g
i
c
a
l
i
n
s
e
c
t
i
c
e
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IGRs v. Conventional Chemistry
Large Nymphs per disk
Bioresidual via natural mortality
extends the
… 4 conventional
… commercial-scale
Onejust
IGR1 spray
lastswhile
ONLYconventional
14 days
chemically
effectiveness
of IGRs,
sprays
kill for
sprays
vs.
IGR
…
3 conventional
studies
are
shown
natural enemies & require repeated
sprays.
spray in 1997.
sprays,
or just
1 IGR
two years
here...
1999
1997 spray needed in 1999.
Conventional
IGRs
5
U
chemical
residual
4
Conventional
IGRs
7–8 weeks
chemical
residual
U
bioresidual
3
UTC
U
~6 weeks
U
UTC
U
bioresidual
U
K
A
C
U
K
U
U
threshold
2
C
U
K
C
K U
C
A
A
U
1
0
C
U
K
A
Jun
U
C
A
K
U
C
A
K
Jul
U
C
A
K
C
A
A
U
K
K
A
A
K
C
A
Aug
K
A
U
U
C
A
A
C
A
C
K
K
C
A
K
Sep
K
A C
U
K
C
A
U
K
C
C
C
A
U
K
Jun
A
U
K
C
A
C
U
K
Jul
K
C
K
C
A
A
Aug
A
C
K
A
C
K
U
K
A
C
Sep
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Recommended Strategy
1) Use IGRs first (1 use each only)
40% infested leaves AND
40% infested disks
2) Use IGRs without mixing with other
chemicals (if possible)
don’t waste the bioresidual
3) Delay the use of follow-up sprays
for 14–21 days
i.e., at least 1 generation of whiteflies
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Resistance Management
…is a shared
responsibility to ensure
efficacy of our valuable
chemistry. All chemistry
falls into 1 of 3 stages...
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Three Stage Strategy
• Stage I: Use IGR of choice when counts
exceed threshold
– Follow-up with alternate IGR, if needed
– Use each no more than once
• Stage II: Use Stage II (non-pyrethroid)
materials at least once before Stage III
materials
– Do not use foliar neonicotinoids in multi-crop
communities or more than twice in cotton areas
• Stage III: Reserve use of pyrethroid mixtures
until end of season, and no more than twice
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Conclusions (1)
• With the adoption of the AZ IPM plan, SWF sprays
have been reduced by 71% to around 1 spray per
season, and growers have saved over $100
million in control costs and yield savings in the
last 5 years.
• The AZ IPM plan depends on multiple elements of
“Sampling” & “Effective Chemical Use” built on a
foundation of “Avoidance”.
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Conclusions (2)
• Six years of success have been based on
research-based guidelines for sampling & thresholds,
access to powerful & selective IGRs with proven
guidelines for their use,
the extended suppressive interval, known as
“bioresidual”, which maximizes natural mortality factors
of the SWF & creates area-wide benefits, and
an organized & comprehensive educational campaign
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Information
• All University of Arizona
crop production & crop
protection information is
available on our web site,
A
C
I
S
• Arizona Crop Information
Site (ACIS), at
• http://ag.arizona.edu/crops
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