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.

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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

General Equilibrium Position

GEP

0 Time

0 Time

EIL GEP

0 Time

EIL ET GEP

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 O 1 2 4 Yield Manag. cost Net returns Total returns 10 0 100 8 0 80 6 60 100 80 60 Experiment with management action O 1 2 4 11 10 9 20 20 20 90 80 70 110 100 90

economic losses no losses benefit > cost

EIL ET

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 / m 2 4) # adult insects or larvae/sweep

Thrips Beet Webworm Clover cutworm

Examples of ET

Barley, Oats Red Clover Canola Canola, Mustard, Flax Cereals 7 - 8 thrips/stem prior to head emergence 50 - 80 thrips per flower head 20 - 30 larvae/m 2 20 - 30 larvae/m 2 3 - 4 larvae/m 2 Cutworms Diamondback moth Oilseeds Pea Canola, Mustard 25 to 30 per cent stand reduction 2-3 larvae /m 2 in the top 7 cm (3 in.) of soil 100 - 150 larvae/m 2 in immature and flowering fields 200 - 300 larvae/m 2 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 Commodity Yield-Pest Relationship Direct Marketable Simple Indirect Non-Marketable Complex Pest Status Any Pest Group Farmer Tolerance Usually Key Pest Insects & Pathogens Low Any 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?

No Apply Insecticide 2 if neccessary Yes Apply Insecticide 2

• 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.