Economic injury level

Report
How are economic thresholds
established?
Pest Management Strategies
•
Eradication – this is a strategy in which extensive efforts and costs are
provided in the short term to completely remove the pest and therefore
provide unhindered produce development in future periods;
•
Prophylaxis – this is a strategy of insurance, in which pest controls are
applied systematically, periodically and generally preventively regardless
of the pest population;
• Containment – the intention is to ensure the pest population stays below a
specific level. The producer in this situation accepts some loss of yield (and
therefore revenue) and controls the pest when it is cost-effective to do so.
Cousens (1987)
History of Pest Management
• Synthetic Pesticide Era--1939 to ?????
Prior to this time, insecticides were formulated from
petroleum, coal tar distillates, plants or inorganic compounds
1930's
trend toward synthesizing new compounds
DDT
- synthesized by a German graduate student 1873
- Paul Muller, (Swiss) discovers insecticidal activity
- saves many soldiers' lives during WWII (body lice - typhus)
- such an impact on human health -- Muller wins 1948 Nobel prize in medicine
More soldiers were lost in WWII due to mosquito-borne disease than in
battle.
• During WWII both the Germans and the Allies working on the
development of organophosphates as nerve gases. They
discover the insecticidal properties of these chemicals
• After WWII development of other chlorinated hydrocarbons
and organophosphates as pesticides
• 1950's early 60's
• "The Green Revolution"
- synthetic pesticides and fertilizers the answer to world
hunger!!
- trend away from understanding pest phenology, density or
damage potential and toward pure chemical approach
• 1962
• Silent Spring
- Adverse effects on wildlife, water quality, human health?
- DDT found in milk and foods (biomagnification)
- Resistance of pests to pesticides
Response to book leads eventually to public policy changes in
1970's
• 1970's
USDA creates nationwide IPM Program in Land Grant
Universities
EPA created & given jurisdiction over pesticide registration &
regulation
• 1980's
Increase in IPM research
IPM concept (1972)
• Integrated control.
• Pest management and Economic injury level.
• Environmental protection
Development of the concept
Pierce, W. D. 1934:
At what point does insect attack become
damage?
Who came up with the damn idea?
• Emphasized concerns regarding excessive and inappropriate
uses of insecticides (4 R’s)
- Resistance
- Resurgence
- Residue
- Risk to human health & environment
Integrated control—the conceptual
foundation of all modern days IPM programs
Sophisticated idea of pest control predicted on the complementary action of
chemical and biological control
4 basic elements:
-
Threshold for determining the need for control
Sampling to determine critical densities
Understanding and conserving bio-control capacity of system
Use of selective insecticides when needed
Population density
General Equilibrium Position
GEP
0
Time
Population density
EIL
GEP
0
Time
Population density
EIL
ET
GEP
0
Time
Injury & Damage
Injury: The effect of pest (insect) activities on host physiology that is
usually deleterious.
Damage: Measurable loss of host utility (quantity/quality/aesthetics).
Certain level of injury may not produce damage or yield loss
Damage boundary: The level of injury (number of
insects) at which damage occurs
Pierce, W. D. 1934:
At what point does insect attack become damage?
EIL & ET
• EIL= C/VIDK
EIL= number of injury equivalents per production unit (e.g. insects/ha)
C= cost of management activity ($/ha)
V= market value ($/kg)
I= injury units per insect per production unit (e.g. proportion
defoliation/(insect/ha)
D= damage per unit injury (e.g. kg reduction/ha)
K= proportionate reduction of the insect population
Pedigo et al. 1986
Range of pest
densities
O
1
2
4
O
1
2
4 O
Experiment without management action
Calculate yield and revenue
1
2
4
Range of pest
densities
O
1
2
4
O
1
2
Experiment with management action
Calculate yield and net revenue
4 O
1
2
4
Experiment
without
management
action
Experiment
with
management
action
O 1
2
Yield
10
8
Manag. cost
0
0
4
O 1
6
11
2
10
20 20
Net returns
100 80
60
Total returns
100 80
60
90
80
4
9
20
70
110 100 90
economic losses
benefit > cost
EIL
Population density
ET
no
losses
cost > benefit
Time
Factors affecting EIL
ET categories
• The economic threshold is simply the operational criteria for
administering pest control action (Higley and Pedigo, 1996)
• Simple threshold: ET is usually arbitrarily set to some
reasonable level below the EIL to allow sufficient time for
making the treatment decision and scheduling control activity
• Comprehensive threshold
How to express ETs?
1) % damage to leaves, plants, foliage, or
2) # of plants showing damage;
or # adults or larvae/stem / plant.
3) # adult insects or larvae / m2
4) # adult insects or larvae/sweep
Examples of ET
Barley, Oats
7 - 8 thrips/stem prior to
head emergence
Red Clover
50 - 80 thrips per flower
head
Beet Webworm
Canola
20 - 30 larvae/m2
Clover cutworm
Canola, Mustard, Flax
Cereals
20 - 30 larvae/m2
3 - 4 larvae/m2
Oilseeds
25 to 30 per cent stand
reduction
Pea
2-3 larvae /m2 in the top 7
cm (3 in.) of soil
Thrips
Cutworms
100 - 150 larvae/m2 in
immature and flowering
fields
Diamondback moth
Canola, Mustard
200 - 300 larvae/m2 in
podded canola fields
Classification of pests on the basis
of ET
Non-economic
pest
Occasional pest
Perennial pest
Severe pest
Direct & Indirect Pests
Comparison of Direct and Indirect Pests
Characteristic
Direct
Indirect
Commodity
Yield-Pest
Relationship
Marketable
Non-Marketable
Simple
Complex
Pest Status
Usually Key Pest
Any
Pest Group
Insects &
Pathogens
Any
Farmer Tolerance
Low
Higher
Limitations of EIL/ET
• Limited applications for medical pests, veterinary pests, &
pathogens
• Market value of human health and life?
• Variable market values
• Substantial background research to calculate injury per insect
and injury/plant response relationship
• Multiple pests?
• Environmental cost?
Present and future prospect
• Provides practical approach to pest related decision
making
• EILs for guilds of species with similar injuries i.e.
single EIL for complex of species
Two Basic Decision Categories in IPM
1. Tactical vs. Strategic
•
•
Tactics – Individual control options
Strategies – Combinations of Tactics
2. Preventative (Prophylactic) vs. Curative
(Therapeutic)
•
•
Preventative – Before pest is a threat
Curative – When pest is threatening
Strategy vs. Program (Strategic Plan)
Strategy
Pest Management Program
Implement
Tillage Tactic
Implement
Tillage Tactic
Conserve
Biological
Controls
Conserve
Biological
Controls
Weekly Count
Insect A
Caterpillars
Too Many
Caterpillars?
Apply
Insecticide 2
if neccessary
Yes
Apply
Insecticide 2
No
• 1990's
New genetically engineered Bt crops (corn, potatoes) come
into use
How will these fit into IPM programs?
• 2000 and beyond??
Pest management is always changing and we cannot predict
the future.

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