Managing Insects on a Budget Tom A. Royer, Extension Entomologist 1 - - PowerPoint PPT Presentation

Managing Insects on a Budget

Tom A. Royer, Extension Entomologist Oklahoma No‐Till Conference, 2016

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“Utilizes all suitable pest management tactics…………..”

• Biological
• Cultural
• Host Plant Resistance
• Mechanical/Physical
• Host Plant Resistance
• Pesticides
• Regulatory

Should Pesticides be used in an IPM Program?

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Chemical Control (Using an Insecticide Economically)

• Follow LABEL recommendations for:
• Rate
• Frequency
• Coverage
• Use properly calibrated equipment designed to

deliver thorough coverage

• Spot treat only infested areas if possible
• Protect beneficial insects and limit run‐off

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Pest Management:

Decision Thresholds!

• Economic Injury Level (EIL)
• The break‐even point between the

cost of control and the loss in yield without control

• This must be measured in some way
• Not feasible for all pests

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Injury vs. Damage

• Injury: the effect of pest activities on host

physiology that is usually deleterious

• Centered on pest activities
• Damage: the measurable loss of host

value (yield, quality, aesthetics).

• Centered on crop and its response to

injury

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Calculating an Economic Injury Level

• Calculating Loss per Insect
• Not as easy as it might first seem
• Different insects, different types of injury
• Difference in crop susceptibility (variety,

growth stage)

• Can be obtained by:
• Crude field observations
• Simulated damage
• Experimentation with various insect

numbers at various crop growth stages

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How is an EIL Developed?

• Value of Crop is known
• Absolute pest numbers are related to

injury

• Injury is related to yield loss
• Effectiveness of control is measured

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The Economic Injury Level (EIL)

• Economic Injury Level – defines the break‐even point at

which the cost of control ($) equals the loss in yield ($) if the pest is not controlled

EIL =__C__ VIDK

C = Cost of control V = Value of commodity I = Physical injury/pest unit D = Loss/unit of physical injury K = Loss prevented by control

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Pest Management:

Decision Thresholds!

• Economic (Treatment)Threshold (ET)
• The pest density at which management

action should be taken to prevent an increasing pest population from reaching the economic‐injury level

• Not feasible for all pests (plant diseases,

weeds)

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Economic Threshold (ET)

• Is also called the ”action threshold”; it is

a pest population level or a damage threshold that allows a grower to control the pest before it exceeds the EIL.

• It can be fixed, or calculated:
• ET=EIL*C where C = a factor of

population increase over unit of time

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How is an ET Developed?

• Sampling method is selected for accurately

estimating pest numbers or injury level (index)

• Sample method is related to absolute pest

levels

• ET is set below the EIL, used as a prediction, or

trigger

• ET = EIL x Time Factor (fixed or predictive)
• Fixed = x % below threshold to provide time to treat
• Descriptive = EIL x C‐x where C = factor of increase per

unit time

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How is an ET Set?

• Thresholds are set for efficient (economic)

application of corrective pesticide applications

• They can be adjusted based on insect biology

(change in temperature, crop stage)

• Example: Greenbug thresholds are different

for January vs October, because greenbugs can multiply much faster in Oct.

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Using an Economic Threshold

5 10 15 20 25 30 35 40 1 4 7 10 13 16 20 23 26 29

Days Aphids per Tiller

Aphids Untreated EIL ET

Spray Decide

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Using an Economic Threshold

5 10 15 20 25 30 35 40 1 4 7 10 13 16 20 23 26 29

Days Aphids per Tiller

Aphids Treated EIL ET

Spray Decide

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Using an Economic Threshold

Pest resurgence

5 10 15 20 25 30 35 40 1 4 7 10 13 16 20 23 26 29

Days Aphids per Tiller

Aphids Treated EIL ET

Spray Decide Spray Decide

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Using an Economic Threshold

Pest resurgence

5 10 15 20 25 30 35 40 1 4 7 10 13 16 20 23 26 29

Days Aphids per Tiller

Aphids Treated EIL ET

Spray Decide Spray Decide

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Updated Expert Systems

Cereal Aphid and Sorghum Headworm

http://entoplp.okstate.edu/gbweb/index3.htm

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http://entoplp.okstate.edu/shwweb/index.htm

Updated Expert Systems

Cereal Aphid and Sorghum Headworm

• Cereal Aphid Expert System:
• A computer program located at

http://www.pswcrl.ars.usda.gov/gbweb/index.htm

• Developed by USDA ARS, SST Development Group and

OSU.

• Includes a calculator for determining economic thresholds for

greenbug infestations

• Sorghum Headworm Decision Support System
• A computer program located at

http://entoplp.okstate.edu/shwweb/index.htm

• Developed jointly by USDA, Oklahoma State, Texas A&M

and West Texas A&M University

• Includes a calculator for determining economic thresholds for

headworm infestations

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How does “Glance ‘n Go” Sampling for Greenbugs Work?

• Record counts of

infested tillers, i.e. that have one or more greenbugs and or mummies on a Glance ‘n Go form, which is based

• n the time of year, and

the pre‐determined economic threshold.

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Sorghum Headworm Sampling

• Record counts of

medium and large headworms collected in a shake bucket which is based on a pre‐ determined economic threshold

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myFields Economics

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Oklahoma State University

Managing Insects on a Budget

• Thanks!
• Kris Giles, Norm Elliott,

Ali Zarrabi, Jason Warren

• Oklahoma Wheat

Commission

• Great Plains Oilseed

Association

• Oklahoma Canola

Commission

• Oklahoma Cooperative

Extension Service and the Agricultural Experiment Station

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Should Pesticides be used in an IPM Program?

• Pesticides can to be used in an IPM program, however
• nly as a last resort and of course in a manner that is

legal.

• Pesticides are to be used when there is no risk of

environmental damage or when benefits outweigh the

• risks. Use pesticides only when other control practices

aren’t available, economical or practical.

• Must monitor pest populations in the field.
• Identify the pest
• Compare pest population and the economic threshold
• Life stage susceptible to pesticide?
• Crop stage and preventable loss.

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