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Ecological Selectivity

Ecological Selectivity. Differential mortality based on pesticide use Formulation (e.g. granules result in more mortality on soil pests than on foliar NE’s) Placement (e.g. spot sprays, seed treatments, wicks, in-furrow).

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Ecological Selectivity

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  1. Ecological Selectivity • Differential mortality based on pesticide use • Formulation (e.g. granules result in more mortality on soil pests than on foliar NE’s) • Placement (e.g. spot sprays, seed treatments, wicks, in-furrow). • Timing (e.g. pre vs. post-emergent applications, diurnal timing for bees) • Dosage – Reduced dosage usually used in conjunction with one of those above

  2. Uses of Selectivity in IPM • Mammalian toxicity of decreasing significance except in urban/structural IPM • Insecticides – Physiological selectivity favored (target & non-target intermingled) • Herbicides – Historically favored ecological selectivity • Bactericides/Fungicides – Non-selective pesticides usually favored.

  3. Types of Pesticides Your book identifies two kinds (pp. 250 – 257) • Traditional Toxic Chemicals • Inorganic • Organic (Synthetic) • Biopesticides (= Biorational Pesticides) • Living Systems (Microbial pesticides) • Fermentation Products • Botanical Pesticides • Transgenic (Plant Incorporated Pesticides) – cover under host plant resistance

  4. What are Reduced Risk Pesticides? • Any pesticide that meets any of the following criteria: • Reduce human health risk • Reduce risk to non-target organisms • Reduce environmental contamination • Enhance IPM adoption • All ingredients of a pesticide must meet these criteria • Can include traditional or biorational • Reduced risk pesticides have greatly reduced regulatory burdens: incentive to manufacturers & farmers

  5. Growth in the use of Reduced Risk Pesticides in California: 1990 - 1998 Tons Applied (Thousands) Acres Treated (Thousands)

  6. Pay particular attention to the following sections: An exam question is likely from each of these • Chemical Relationships: pp 262 – 264 • Modes of Action: pp 264 – 266 • Application Technology: 270 – 280 • Pesticide Label: 303 - 306

  7. Pesticide Interactions Book has these three categories, mostly discussed as antagonistic interactions. • Formulation Incompatibility • Altered Crop Tolerance • Alteration of Efficacy

  8. More Thoughts on Interactions • Additive Effects – Most Common: • Different pesticides with the same formulation but targeting different pests. • Synergistic Effects – pesticides used in combination are more effective than when used alone: Two types: • Biochemical • Ecological • Antagonistic Interactions • Formulation–based = “Incompatibility” • Biological = “Pesticide Antagonism”

  9. Resistance, Resurgence, and Replacement Chapter 12 – pp. 314 – 335 Three different ecological responses of pests to pesticides in this chapter: • Resistance – Pest susceptibility to pesticide decreases over time. • Resurgence – Pest population increases dramatically following pesticide • Replacement – One pest is replaced by another. We’ll take them in reverse order

  10. Pest Replacement • Mostly a problem with arthropods and weeds • Tends to be more reversible with arthropods • Note Fig. 12-7

  11. Resurgence • Mostly documented with insect pests • Mostly associated with indirect, secondary/minor pests for several reasons. • Key pests are watched too closely to resurge • Direct pests are mainly late-season pests & there isn’t time to resurge • Pest must be held at least partially in check by some agent that is affected by the pesticide • Note Fig. 12-6 in book.

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