pesticides - willis' sciencewillisscience.com/.../docs/pesticides.339111701.pdf ·...

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

• Ex: DDT!

• Paul Muller

discovered. Won

Nobel Prize in

1948.

• Killed everything

ranoff to H2O

(fish).

• Bioaccumulation

: fat soluble.

DDT Effects• Slow degradation..DDT interfered with Ca+

uptakes in birds laid weak shells.

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

1962; Showed effects of

biomagnification of

DDT.

Type: Organophosphates

• Ex: Malathion: Insecticide

• Combat Med. fruit fly in CA. Sprayed in San Bernardino.

• Treats head lice and scabies!

Why Use Pesticides?1) Saves lives.

Ex: Malaria!

Why Use Pesticides?2) Increases food supplies

3) Increase money profits for farmers.

Case Study: Myxomatosis

• Virus as a

pesticide,

rabbits,

Australia.

• Pops went from

600-100 mill.

• Now, only 50%

effective.

Why Not Use Pesticides?

• 1) Pesticide

Treadmill: All

pests that are not

killed reproduce

make

resistance

offspring more

pesticide usage.

2) Toxic to Non-target species

• Pesticides do not stay put (rain/wind runoff).

Why Not Use Pesticides?

3) Human Sickness

• Acute (short-term) exposure: bleeding, vomiting.

• Chronic (long-term) exposure: nerve problems, brain damage, cancer, birth defects.

Why Not Use Pesticides?

Pesticide Regulation

Federal Insecticide,

Fungicide, and Rodenticide Act (FIFRA), 1947.

• All pesticide use must be approved

1st by EPA.

• Pesticide makers must test for

toxicity.

Integrated Pest Management

• Using a combo of pest control

strategies: chemicals and

alternatives.

Alternatives

1) Introduce natural predators of bug:

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