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.