Pesticides
Pesticides
Pests• Any organism
that:
1. competes with us for food
2. Invades lawns and gardens
3. Destroys wood in houses
4. Spreads disease
5. A nuisance
Pea Aphids
Gypsy Moth Caterpillar
Emerald Ash Borer
Pesticides
• Kill pests (undesirable orgs)
• Insecticides: kills insects
• Herbicides: kills weeds• Fungicides: kills
fungus• Nematocides: kills
worms• Rodenticides: kills
rodents
RoundUp: Herbicide
Raid: Insecticide
D-Con: Rodenticide
Type: Chlorinated Hydrocarbons
• DDT• Paul Muller
discovered insecticide. Won Nobel Prize in 1948.
• Killed everything ranoff into water (fish).
• Bioaccumulation: fat soluble.
DDT Effects• Slow degradation..DDT interfered with Ca+
uptakes in birds laid weak shells.
Both Fish
Eaters!
Broken eggs led
to decrease in pop. size!
DDT Side Notes
• Neurotoxin: opens insect Na+ channels spasms/death.
• Resistant mutants
Human Effects
• Genotoxicity Carcinogen?
• Endocrine disruption
• Diabetes
• Miscarriages
Locally!• Montrose Chemical on
Normandy in Carson
• Dumped into sewers emptied into White Point Palos Verdes
• White croaker fish!
• Daily breeze 2008: seals higher concentrations of DDT
Rachel Carson: Silent Spring
• 1960’s• Showed effects of
biomagnification and bioamplification of DDT.
• Showed public the effects of env. pollution.
Type: Organophosphates
• Malathion: Insecticide
• Used to combat Med. fruit fly in CA. Sprayed in San Bernardino.
• Treats head lice and scabies!
Med Fly
Why Use Pesticides?
1) Saves lives. Ex: Malaria: a protozoan parasite infects RBCs. Passed on by mosquitoes.
• Kills 1-3 mill/yr.• Found in humid
areas.
Malaria
Why Use Pesticides?
• 2) Increases food supplies
• 3) Increase money profits for farmers.
Case Study: Myxomatosis
• Virus introduced to rabbits in Australia.
• Pops went from 600-100 mill.
• Now, only 50% effective.
• Intro’d another virus in ‘96
Why Use Pesticides?
4) Work faster and better than alternatives.
You Can Then Eat the Dead
Bugs!
Negatives
• 1) Pesticide Treadmill: All pests that are not killed reproduce make resistance offpsring.
• Now, farmer has to use more pesticide or switch to another brand.
Negatives
• 2) Toxic to Non-target species
• Pesticides do not stay put (rain/wind runoff).
• Affects ALL orgs of ecosystem.
Red-Tailed Hawk
CA King Snake
Negatives
• 3) Human Sickness• Acute (short-term) exposure: bleeding,
vomiting. • Chronic (long-term) exposure: nerve
problems, brain damage, cancer, birth defects.
Pesticide Regulation
• Federal Insecticide, Fungicide, and Rodenticide Act (FIFRA), 1947.
• All pesticide use must be approved 1st by the EPA.
• Pesticide makers must test for toxicity.
Integrated Pest Management
• Using a combo of pest control strategies: chemicals and alternatives.
+
Alternatives to Pesticides
• 1) Introduce natural predators of bug: ex: ladybug and aphid
• 2) Put up smells that attract bugs away from crops (pheromones)
• 3) Spray boiling H2O
Chrysanthemums
Alternatives
• 4) Genetically modify plants to be resistant to pests (GMO’s)
Frost-Resistant Strawberries (from fish gene)?
BroccoflowerTangelo: grapefruit
and tangerine
Case Study: BT Insecticide Gene
• BT = protein found in natural soil bacteria, Bacillus thuringensis.
• Disrupts guts of insects
• Not toxic to humans or animals
• BT gene placed in corn to protect against corn borer.
BT gene placed in corn to protect against corn borer
Broccoflower
Tangelo = Tang. And Grapefruit
Advantages of GMO’s
• Less pesticides are used
• Higher nutritional content
• Possible vaccine delivery
• Less water used (on irrigation)
• Less inorganic fertilizers are used
• Enough food to feed the world!
Disadvantages of GMO’s
• Cross pollination with wild species reduces biodiversity
• Emergence of superbugs
• Fear of unknown allergens
• Centralized control of food production
• Poor farmers can’t afford GM patented seeds