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Economic Thresholds for Pest Control: Understanding the Basics of EILs and ETs, Exercises of Pest Management

The LNM Institute of Information TechnologyPest Management

An overview of economic injury levels (eils) and action thresholds (ets) in pest control. It explains the concept of these thresholds, their calculation methods, and their advantages. The document also discusses the limitations of thresholds and mentions the flexibility and applicability of this approach in various situations.

Typology: Exercises

2012/2013

Uploaded on 08/31/2013

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jaee 🇮🇳

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Decision Making
• Have discussed the “Maximum Tolerable Level” but have not defined it.
• Several Points to Make:
– More than 1 “Level” is usually needed.
– There are many kinds of such levels (cf. p. 200 – 201 in text for one list).
– “Action Levels” or “Thresholds” are one general method of decision making. We
will discuss the other one (Optimization) later.
• The leader in this field has been L. Pedigo. Be sure & read his article in
the “Reading Assignments”
The General Problem
We actually see this:
One problem is that we need to allow for management response time – The time
between when a control decision is made and when it takes effect
pf3
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pf5
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Partial preview of the text

Download Economic Thresholds for Pest Control: Understanding the Basics of EILs and ETs and more Exercises Pest Management in PDF only on Docsity!

Decision Making

  • Have discussed the “Maximum Tolerable Level” but have not defined it.
  • Several Points to Make:
    • More than 1 “Level” is usually needed.
    • There are many kinds of such levels (cf. p. 200 – 201 in text for one list).
    • “Action Levels” or “Thresholds” are one general method of decision making. We will discuss the other one (Optimization) later.
  • The leader in this field has been L. Pedigo. Be sure & read his article in the “Reading Assignments”

The General Problem

We actually see this:

One problem is that we need to allow for management response time – The time between when a control decision is made and when it takes effect

The other problem is uncertainty

Solution to both problems (mgmt response time & uncertainty) is

to create two levels

Quick Notes on EILs & ETs

  • ET is always < EIL
  • Units of ET & EIL are the same
    • Often pest density (absolute or relative)
    • Can also be injury (e.g. % defoliation)
    • Can also be implicit factors (e.g. leaf wetness)
  • EIL & ET are hard numbers calculated from equations

developed through field research.

  • It costs $50/A to apply a given control ( C )
  • A crop is worth $40/bushel ( V )
  • Leaf area equal to two leaves/row foot are eaten by each pest individual/plant ( I )
  • The loss of two leaves/row foot results in the loss of one bushel/A ( D )
  • Even if you apply the control, you will still lose 10 % of the crop ( K = 0.1, no units)

Example, Continued

Understanding the Units is Key

Here’s how the units balance

One of the principal advantages of EILs is their objectivity and scientific basis The principal source of subjectivity is in “Value”: Ex: Tree Crops & Gypsy Moth Some examples of EILs & their derivation.

  • EIL for Mexican Bean Beetle in Soybean – Details the

development of an EIL.

  • EILs for sorghum midge on sorghum – See Table 1 in the

middle of the article.

  • Common stalk borer in Nebraska corn
  • Sweet potato whitefly on cantaloupe
  • Note your text’s discussion of limitations of thresholds.

Advantages of Thresholds

  • Conceptually easy to understand makes them easy to implement/adopt. Can also be represented in many formats: single numbers, tables, charts.
  • Scientific basis to threshold criteria
  • Flexibility gives broad applicability
    • Can be applied to a variety of pests in many situations
    • Can utilize many variables as the action variable. Climatic variables often used for pathogens.
    • Have been extended to take into account many other issues. Examples include
      • Age distribution
      • Multiple controls (e.g. biocontrol)
      • Environmental Impacts (i.e. macroeconomic “C” values)
      • Risk

Closely read the remainder of this chapter

  • This is the only place where the following topics are discussed:
    • Use of field history
    • Field location & size
    • Monitoring climate
    • Use of computer/mathematical models
    • Aesthetic effects
    • Risk Assessment
    • Economics