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How are economic thresholds established?. Pest Management Strategies Eradication – this is a strategy in which extensive efforts and costs are provided.

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Presentation on theme: "How are economic thresholds established?. Pest Management Strategies Eradication – this is a strategy in which extensive efforts and costs are provided."— Presentation transcript:

1 How are economic thresholds established?

2 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)

3 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

4 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.

5 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

6 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

7 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

8 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

9 IPM concept (1972) Integrated control. Pest management and Economic injury level. Environmental protection

10 Development of the concept Pierce, W. D. 1934: At what point does insect attack become damage?

11 Who came up with the damn idea?

12 Emphasized concerns regarding excessive and inappropriate uses of insecticides (4 R’s) -Resistance -Resurgence -Residue -Risk to human health & environment

13 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

14 General Equilibrium Position GEP Time Population density 0

15 GEP EIL Time Population density 0

16 GEP ET EIL Time Population density 0

17 Injury & Damage Damage: Measurable loss of host utility (quantity/quality/aesthetics). Injury: The effect of pest (insect) activities on host physiology that is usually deleterious. Certain level of injury may not produce damage or yield loss

18 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?

19 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

20 O124 O124 O124 Range of pest densities Experiment without management action Calculate yield and revenue

21 O124 O124 O124 Range of pest densities Experiment with management action Calculate yield and net revenue

22 O124O124 Experiment without management action Experiment with management action Yield Manag. cost Net returns 8 0 80 10 20 80 10 0 100 11 20 90 6 60 9 20 70 Total returns100 8060 110 10090

23 ET EIL Time Population density no losses benefit > cost cost > benefit economic losses

24 Factors affecting EIL

25 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

26 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


28 Examples of ET Thrips Barley, Oats 7 - 8 thrips/stem prior to head emergence Red Clover 50 - 80 thrips per flower head Beet WebwormCanola20 - 30 larvae/m 2 Clover cutwormCanola, Mustard, Flax20 - 30 larvae/m 2 Cutworms Cereals3 - 4 larvae/m 2 Oilseeds 25 to 30 per cent stand reduction Pea 2-3 larvae /m 2 in the top 7 cm (3 in.) of soil Diamondback mothCanola, Mustard 100 - 150 larvae/m 2 in immature and flowering fields 200 - 300 larvae/m 2 in podded canola fields

29 Classification of pests on the basis of ET Non-economic pest

30 Occasional pest

31 Perennial pest

32 Severe pest

33 Direct & Indirect Pests Comparison of Direct and Indirect Pests CharacteristicDirectIndirect CommodityMarketableNon-Marketable Yield-Pest Relationship SimpleComplex Pest StatusUsually Key PestAny Pest Group Insects & Pathogens Any Farmer ToleranceLowHigher


35 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?

36 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

37 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

38 Strategy vs. Program (Strategic Plan) Strategy Pest Management Program

39 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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