Pesticides and Pest Control

Key Concepts  Types and characteristics of pesticides  Pros and cons of using pesticides  Pesticide regulation in the US  Alternatives to chemical pesticides

Pests  Compete with humans for food  Invade lawns and gardens  Destroy wood in houses  Spread disease  Are a nuisance  May be controlled by natural enemies 50-90% of pests are controlled this way  May be controlled by natural enemies 50-90% of pests are controlled this way

Pesticides: Types  Insecticides-kills insects  Herbicides-kills weeds  Fungicides-kills fungus  Rodenticides-kills rodents  Nematocides-kills worms

First Generation Pesticides  Primarily natural substances  Sulfur, lead, arsenic, mercury  Plant extracts: nicotine, pyrethrum  Plant extracts are degradable

Second Generation Pesticides  Primarily synthetic organic compounds  630 biologically-active compounds  Broad-spectrum agents-toxic to many species  Broad-spectrum agents-toxic to many species  Narrow-spectrum agents-effective on Only a few select species  Narrow-spectrum agents-effective on Only a few select species  Target species-1 species  Nontarget species

Case for Pesticide Use  Save human lives  Increase supplies and lower cost of food  Work better and long shelf lives  Health risks may be insignificant compared to benefits  Newer pesticides are becoming safer  New pesticides are used at lower rates

Characteristics of an Ideal Pesticide  Kill only target pests  Harm no other species  Break down quickly and naturally  Not cause genetic resistance  Be more cost-effective than doing nothing

The Case Against Pesticides  Genetic resistance:5-10 years insects, more slowly In plants currently have resistance  Genetic resistance:5-10 years insects, more slowly In plants currently have resistance  Can kill non-target and natural control species  Can cause an increase in other pest species  The pesticide treadmill  Pesticides do not stay put: 2-5% remain  Can harm wildlife-DDT birds, runoff kills fish  Potential human health threats

The Pesticide Treadmill When a pesticide doesn’t work then 1.Apply more often 2.Apply larger doses 3.Use new chemical This is harmful because insect population is larger and crop production is down Costs 4-6 billion dollars per year

Pesticide Regulation in the United States  Federal Insecticide, Fungicide, and Rodenticide Act (FIFRA)- all commercial pesticides must be approved by EPA  Tolerance levels-determined by EPA  EPA Evaluation of chemicals- doesn’t have To be complete before license is granted  EPA Evaluation of chemicals- doesn’t have To be complete before license is granted  Inadequate and poorly enforced  Food Quality Protection Act (FQPA)

Other Ways to Control Pests  Economic threshold  Adjusting cultivation practices: crop rotation  Use genetically-resistant plants: GMO’s  Biological pest control: Bring in predators  Biopesticides: Botanicals or Microbes  Ionizing radiation

Insect Control Genetic Engineering Sterilize males so Ineffective when mate Ex) Screw worm fly, Tetsie fly High cost and large Number to be effective Ionizing Radiation Irradiated foods: exposing to lose dose of radiation delays sprouting, kills pests, and extends shelf life Food itself is NOT radioactive Ionizing Radiation Irradiated foods: exposing to lose dose of radiation delays sprouting, kills pests, and extends shelf life Food itself is NOT radioactive

Integrated Pest Management  Ecological system approach  Reduce pest populations to economic threshold but doesn’t eradicate them  Field monitoring of pest populations  Use of biological agents  Chemical pesticides are last resort  Increases production while lowering costs

Effects of IPM