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Principles of Pest Mgt. in the Urban Environment

Principles of Pest Mgt. in the Urban Environment. Insect control in agriculture is a huge business: a 10 billion dollar business! In agriculture, chemical control is still the most popular way to prevent and stop insect outbreaks and disease infections. . Control of the Gladiola Bulb Fly.

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Principles of Pest Mgt. in the Urban Environment

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  1. Principles of Pest Mgt. in the Urban Environment

  2. Insect control in agriculture is a huge business: a 10 billion dollar business! In agriculture, chemical control is still the most popular way to prevent and stop insect outbreaks and disease infections. Control of the Gladiola Bulb Fly The mortality quotient: Mq = (Fecundity)(Sex Ratio)-1 (Fecundity)(Sex Ratio) • Fecundity = Female lays 100 eggs • Sex Ratio = Females/Males + Females, e.g. collect 200 pupae and rear them to adults & 100 males and 100 females; S.R. = 0.5 • Mq = (100)(0.5) – 1 • (100)(0.5) = 0.98 So: 100 – 98 = 2 (1 male & 1 female)

  3. In other words, to stop an outbreak of the gladiola bulb fly in a commercial operation you would have to kill 98% of the population. Question: How do you know you have to control the bulb fly? How do you know you are about to have economic damage?

  4. By killing 98.0% of the population: Ec EcTh WSBW Time By killing 98.0% here, Pop. will level off.

  5. The point is that’s it’s expensive to establish and maintain gladiola bulbs – the bulbs are real valuable. Should they die

  6. The gladiola bulb fly is a direct pest -- feeds on the product you want to produce or sell (2)This seems true, but how do you know if it’s necessary to control the bulb fly? (3) You better start sampling to see if you are about to cross the economic threshold.

  7. Production costs of gladiola bulbs at the Skagit Valley Bulb Farm. • Equip. depreciation = 3.20/ac • Field labor = 14.00 • Cultural operations • -cultivation • - planting • - weeding • - fertilizing • - irrigation • - etc. = 220.00

  8. Bulb fly control = 80.00/ac Harvesting & Packaging = 32.00 Marketing = 10.00

  9. Eq. Depr. $ 3.20 per acre Field Labor 14.00 “ Cult. Oper. 220.00 “ Bulb Fly Prot. 80.00 “ Harvesting etc. 32.00 “ Marketing 10.00 “ Total Costs $359.20 per acre • Expected Production = 850.00 bushels/ac. • To make costs; sell at $ 0.423/bu. • i.e. (0.423)(850) = $ 359.20 • III. To make 100% profit you sell at = $ 0.846

  10. What if production is less than 850 lbs/bu.? Market price threshold Production Cost/bu. 100% Profit Max. Price 850 $ 0.423 0.846 ----- 800 0.449 0.898 ----- 750 0.479 0.958 +/- $1.50 700 0.513 1.026 +/- $1.50 650 0.553 1.066 ----- 600 0.599 1.198 ----- 550 0.653 1.306 ----- 500 0.718 1.436 -----

  11. Your taxes at work: results of research by WA State University. ca. 700 Study to determine pest level & subsequent seed production 850 650 Bu. viable bulbs/ac. 400 .01 .03 1.0 10.0 Bulb flies/bulb/plant

  12. 800 EcThresh. 750 EcD. 700 Bu. viable bulbs/acre 400 Low Bulb Worm Population High Mq = 98% 850

  13. So, by developing a monitoring scheme you know when to spray the problem.

  14. Yea, that’s all very good for a Skagit Valley farm, but what’s it mean for the urban park or garden?

  15. In urban horticulture we have to think in terms of the aesthetic threshold!

  16. The Aesthetic Threshold/ Action Threshold Basic question: Is this an eye sore? AestheticThreshold Avg.PestLevel PestNos. Years

  17. Economic damage thresholds & aesthetic damage thresholds: • Crops are grown for profit, so economic damage thresholds in agriculture are based on economic criteria; pest control is done when it will improve yield and provide increased revenue that exceeds the extra cost of pest control. • There are no formal Control Action Guidelines for pests on landscape trees and shrubs. Why? It’s difficult to define that damage level that would be intolerable, the Aesthetic Damage Threshold.

  18. The Aesthetic Threshold varies with the attitude and knowledge of people using the landscape or garden. May depend on: -Education level -Where the damage occurs (front yard, back yard etc.) -The kind of damage (galls, defoliation, potential weakening & death etc.)

  19. On the other hand, there are plenty of pest control businesses that would help you decide the question, “do I need to control pests in my garden or landscape?”

  20. So if you feel that the aesthetic quality of your landscaping is threatened, you must think of using an Integrated Pest Management (IPM) approach to the problem. :of IPM: What must I do to permanently lower the Avg.PestLevel? AeTh PestLevel Avg.PestLevel Weeks

  21. When it comes down to making the control decision, only you can set your Aesthetic Damage Threshold: only then do you act! IPM solutions!

  22. (1) Management components: - other varieties - biological control - cultural treatment -- mulching -- replanting (shade) -- fertilizing etc. IPM (2) Sometimes the pest gets out of hand and pesticides must be used, but in terms of a surgical strike. AeTh Avg.PopLevel NewAvg.PopLevel PestNos. (3) Monitor! Weeks

  23. “Here are some IPM guidelines or components you may try?”

  24. Monitoring Has this problem passed the AeTh?

  25. Since the intelligent and prudent use of pesticides is still considered in an IPM program, let’s learn a little about toxicology.

  26. (1) Generally, urban-horticultural operations that use pesticides do not deal with pesticide residues on food crops. Great deal of concern, however, about residues in water and in the air (problem of drift). (2) Nevertheless the public is terribly concerned about pesticides in general. (3) Accordingly, it’s good to know about how the public is protected from the use and misuse of pesticides. (4) These concerns come under the topic of toxicology & pesticide registration.

  27. An important concern with the use of pesticides is the residue problem: how much is left on plant. Mechanical loss (drift) % Residue left on target Normal losses due to: dilution, plant enzymes, evaporation Residues in protected places Days after treatment

  28. The toxicity of a pesticide is an innate property of a product to do damage. The toxicity of a pesticide is critical to determine the MAXIMUM ALLOWABLE RESIDUE ALLOWED ON A CROP.

  29. “It’s not the poison that will kill me, it’s the dose!”

  30. The toxicity tests are based on dose:response relationships. Tests use carefully bred lab rats, guinea pigs, rabbits & other animals. The rats: • used in statistically reasoned tests. • all the rats are statistically the same size and weight. • bred to respond uniformly as possible. This rat died in laboratory toxicity tests to make the use of pesticides safe when used by humans.

  31. The three main toxicity tests are: • Acute oral toxicity test • Subacute oral toxicity test • Chronic toxicity test

  32. The “Big - 3” Oral Toxicity Tests Acute Oral Toxicity -- To determine that dosage required to kill 50% of a test population of laboratory rats. Subacute Oral Toxicity -- To determine the maximum daily dose of a pesticide that lab rats survive. To determine the maximum daily dose without effects on lab rats, the no effect level (NOEL). To determine the nature of effects above the NOEL level. Chronic Oral Toxicity -- To determine effects of pesticides over the life span of lab rats - - often 2-3 generations of rats.

  33. Acute Toxicity Test • Test rats are fed log doses of the test-toxicant. • Either by feeding them individually or allowing them to feed to satiation • Most commonly the rats are force-fed via a tube.

  34. Administration of a pesticide to a rat via a tube

  35. Are We Safe?

  36. Pesticides and fertilizers are important chemicals used in urban horticulture. • The use of these chemicals in agriculture far exceeds urban use: farmers in the U.S. contribute about $12.5 billion to the chemical industry. Use of pesticides is a huge business! Big three: cotton, corn, soybeans. • But there are historical and enormous benefits.

  37. Percent of Consumer Income Spent On Food

  38. People • fed by one • farmer • Number of U.S. farms • (Millions) 1930 1950 1970 1990 2010

  39. It’s fair to say that chemicals have played a major role in freeing our people from farms for employment elsewhere. • For example: • one person working for a company producing Roundup™ • that person can do more for agriculture than 250 people with hoes -- why? • the herbicide can remove deep-rooted perennials which would only sprout again if their tops were clipped with a hoe, mower or cultivator • the herbicide kills the weeds entirely - - no re-treatment.

  40. This massive increase in agricultural production is known as the “Green Revolution.” This revolution came about: - fertilization technology - irrigation technology, e.g. drip technology - crop genetics - modern pesticides For example: what would the prevention of fungicides do the price of key food items?

  41. *These crops would be eliminated from U.S. markets without fungicide use

  42. Are we protected? I reiterate the reasons for why we are looking into this arena of Toxicology & Pesticides (1) Generally, urban-horticultural operations that use pesticides do not deal with pesticide residues on food crops. (2) Nevertheless the public is terribly concerned about pesticides in general. (3) Accordingly, it’s good to know about how the public is protected from the use and misuse of pesticides.

  43. 1 2 3 4 5 6 7 8 A test with 1,000 lab rats being force-fed a test chemical at 8-dosage levels – then repeated many times, i.e. many replicates: Acute Toxicity Test. % CumMortality Dosage Units Numbers Dying 25 2.5 75 10 150 25 250 50 250 75 150 90 75 97.5 25 99.99999

  44. Sigmoidal mortality response to increasing doses of a tested pesticide 100 90 80 70 60 50 % Mortality 40 Median lethal dose is 4 30 20 10 0 0 2 4 6 8 Dose

  45. The LD50 Concept 100 75 LD50 is that dose in mg/kg of body weight expected to kill 50% of a test population or rats. 50 % CumMortality 25 0 0 10 100 1000 log Doses

  46. See! Why the 50% mortality level? • You can compare the slopes of different pesticides and see: • - which is more toxic • - which has a heterogeneous or homogeneous response • 2. There is minimal statistical variation around the • 50% mortality reference point. • 3. By convention the 50% mortality point has been • STANDARDIZED as a way to express acute oral • toxicity.

  47. The LD50 Concept (A) 100 Uniform response to a really toxic pesticide (B) 75 50 % CumMortality (C) A less toxic pesticide but a heterogeneous response (scary) 25 0 0 10 100 1000 log Doses

  48. Least variation The LD100 (Prod.1) test (Prod.2) test (Prod.3) test 100 75 50 % CumMortality 25 0 0 10 100 1000 log Doses

  49. II I Toxicity categories based on LD50 Caution Caution Danger Poison Warning III IV 50-500 mg/kg 500-5000 mg/kg 50-500 mg/kg Oral LD50 50 mg/kg

  50. There also are dermal acute toxicity tests using ultra sensitive rabbits

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