Ellsworth/UA

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

Ellsworth/UA

World Distribution of Outbreaks of B. tabaci

Arizona

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State of Arizona, U.S.A.

Maricopa Agricultural Center (~350 m)

Yuma Agricultural Center (~50 m)

Majority of cotton production in AZ

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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

• 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.

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15 cents/lb

DSW 31-3/35 minus NNYCElate

1980’s1992 – 1993

1994 – 1995

late 1990’s

*0¢

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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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Whitefly Pink bollworm Lygus bugs Other

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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.

199019911992199319941995199619971998199920000

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Whitefly Pink bollworm Lygus bugs Other

IGRs, Bt cotton, & AZ IPM Plan introduced

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Whitefly IPM……depends on 3 basic keys

1

2

3

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Avoidance

1

…all practices that serve to prevent or

maintain pests below economic levels.

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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...

1

2

3…we depend on the top two levels of the pyramid

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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

Count adults first

5th leaf

Locate between main veins

“Quarter-sized” disk

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

• Timing Stage II & III

conventional sprays57% of leaves infested with 3 or more adults

Number of leaves infested with 3 or more adults

Percent infested leaves

Average per leaf

1 3.4 0.32 6.7 0.63 10 0.84 13 1.05 17 1.36 20 1.57 23 1.88 27 2.19 30 2.3

10 33 2.611 37 2.912 40 3.213 43 3.614 47 3.915 50 4.316 53 4.717 57 5.118 60 5.519 63 6.020 67 6.521 70 7.122 73 7.723 77 8.424 80 9.225 83 10.226 87 11.327 90 12.828 93 14.929 97 18.430 100 34.9

A D U L T S

Number of disks infested with large

nymphs

Percent infested disks

Average per disk

8 26 0.512 40 1.016 52 1.5

N Y M P H S

4040

4040

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Selective & Effective Chemistry…the insect growth regulators sit at the center of our pyramid.

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Egg

Crawler

2nd 3rd

4th, “pupa”

AdultKnack®Knack®

Applaud™Applaud™

Major Major

Points of Points of

Insect Insect

Growth Growth

RegulationRegulation

buprofezin

pyriproxyfen

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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

bbiioollooggiiccaalliinnsseeccttiiccee

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Bioresidual via natural mortality extends the effectiveness of IGRs, while conventional sprays kill

natural enemies & require repeated sprays.

… commercial-scale studies are shown for two years here...

One IGR spray lasts ONLY 14 days chemically

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IGRs

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IGRs v. Conventional Chemistry

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IGRs

Conventional

1999 1997

… 3 conventional sprays, or just 1 IGR spray needed in 1999.

chemical residual

chemical residual

… 4 conventional sprays vs. just 1 IGR spray in 1997.

UTC

UTC

threshold

bioresidualbioresidual bioresidualbioresidual7–8 weeks

~6 weeks

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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,

• Arizona Crop Information Site (ACIS), at

• http://ag.arizona.edu/crops

ACIS