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