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Pesticide

a pesticide that kills a variety of organisms, not just the targeted organisms
to kill pests

All insecticides are pesticides but

but not all pesticides are insecticides

fungus pesticide

fungicide

mice/rat pesticide

rodenticide

plant/weed pesticide

herbicide

"Silent Spring"

by Rachel Carson
about contamination of environment-insecticides that would kill all the birds
brought about awareness of environmental issues (mainly about DDT)

2 kinds of insecticides

natural (botanicals) & synthetic

examples of natural insecticides

nicotine, pyrethrine (extract of a mum flower that paralyzes insect), rotenone (legune from India)

Types of synthetic insecticides

1. Organochlorine (chlorinated hydrocarbons)
2. organophosphorus
3. Carbamates

What gives the synthetic insecticide it's toxicity

the element i.e. chlorine, phosphorus, nitrogen...

1st generation pesticide

inorganic compounds and botanicals i.e. lead, mercury, nicotine and pyrethrine

2nd generation pesticide

synthetic poison i.e. DDT

Major Benefit of Pesticides

Crop Protection
oests eat and destroy 1/3 of world's crops
farmers save $3-$5 for every $1 they invest in pesticides

Chlorinated Hydrocarbons

high environmental resistance
low mammalian toxicity
fat soluble
biomagnifies

DDT is what kind of synthetic pesticide?

chlorinated hydrocarbons

The "Dirty Dozen" are what kind of pesticides?

organochlorine

Endrin

organochlorine manufactured in STL
part of the Dirty Dozen

Mirex

used to control fire ants
part of the Dirty Dozen

Reasons why we don't use organochlorine

1. Persistent in the environment
2. Fat soluble (concentrate in fat tissue of organisms-bioaccumulates and biomagnifies)
3. Universal poison (kills both good and bad insects)

bioaccumulation

accumulation of toxic substancewithin an organism
can cause biomagnification

biomagnification

accumulates more concentration as it moves up the food chain
i.e. peregrine falcons

Relationship between organochlorines and birds

organochlorine upsets the estrogen cycle of female birds and they have thin eggs shells that make them break easily
especially found in predator birds

Genetic resistance to insecticides (DDT)

prey have greatest reproductive capability, therefore they are more probable to have genetic resistance
predator gets a double dose from environment
prey is most likely to be genetically resistance

Number of species resistant to DDT in 1945

12

Number of species resistant to DDT in 1960

137 (65 ate our crops)

Number of species resistant to DDT in 1980

over 200

Number of species resistant to DDT in 2000

less than 100

DDT was banned in...

1973

Organophosphates

low environmental resistance
high mammalian toxicity
water soluble
doesnt biomagnify

What is the most poisonous insecticide for humans?

organophosphates

Why was organophosphates developed?

developed in WWII by American gov't as an agent for chemical warfare (nerve gas)

Sarin

organophosphorus gas used in Tokyo subway
given to Sudam Hussian by US

Parathion

organophosphorus liquid that is highly toxic

Malathion

organophosphorus substance sprayed over Dallas (1970) because of an outbreak of insefilitus that was carried by mosquitos

What is the least toxic of organophosphates

Malathion

Pros of organophosphates

effective
doesnt persist in environment
doesn't biomagnify

Cons of organophosphates

very toxic

Effects of organophosphates on humans

upsets message from nerve to brain
nervous twitching/uncontrollable nerve movements
caused dilated pupils

Carbamates are derived from

methyl isocyanate (MIC)
organic compounds that contain nitrogen

What is the newest class of synthetic insecticides?

Carbamates

Active chemicals in carbamates

nitrogen and carbon (CN)

Cyanide

carbamate used to use people on death row in TX

Most well-known carbamate

sevin (used on pets-low mammalian toxicity)

Carbamates

low->medium environmental resistance
medium mammalian toxicity
water soluble
very little to no biomagnification

Pesticide treadmill

cost of applying pesticide increases because they must be applied more frequently or in larger doses
effectiveness decreases because of increase in genetic resistance in pests

Resistance management

strategies for managing genetic resistance in order to maximize the period in which a pesticide is useful
delays the evolution of genetic resistance-refuge of untreated plants

Problems with Pesticides

Persistence, Bioaccumulation, Biomagnification, Mobility-do not stay where they are applied, move through soil, water, air

Short-term effects of Pesticides

handling food with pesticide residue
mild case: nausea, vomiting, headaches
severe case: damage to nervous system

Long term effects of Pesticides

cancer-lymphoma
breast cancer
sterility
miscarriage
birth defects
reduce immunity
potential connection to Parkinson's disease

**Synergism

the sum of pesticides produces an enhanced effect
i.e. mercury + heat=enhanced toxicity

**Antagonism

sum of pesticides produces a reduced effect
i.e. tetroculin (acne meds) can't be taken with dairy products because it reduces its affectiveness

Alternatives to Pesticides

1. Cultural Methods
2. Biological Control
3. Pheromones
4. Hormones
5. Reproductive Controls

Cultural Methods to control Pesticides

cultivating a crop to minimize insect attacks
plant crop in alternate years so insects can't build up in that area
interplant mixtures of plants (altering rows)
proper timing of planting, fertilizing, and irrigating
crop rotating

Biological control to control Pesticides

use of naturally occurring disease organisms, parasites or predators to control pests
must take care that introduced agent does not attack unintended hosts
i.e. parasites, lady bugs
i.e. using bacteria and viruses that only attack the insect eating the crops

Phermones to control Pesticides

sex attractant/insect attractants
used to lure pests to traps

Hormones

causes changes in organism
causes insect metamorphosis change
if applied at the wrong time in life cycle, insects can be killed off

Reproductive controls to control Pesticides

sterilization controls
i.e. sterilize male screw worm so it cannot reproduce and lay eggs on deer's open wounds
when screw worm was eradicated, the deer population went up

IPM

Integrated Pest Management
combination of pest control methods that keep pest population low without economic loss
conventional pesticides are used sparingly when other methods fail
uses the judicious use of pesticides

Manufacture and Use of Banned Pesticides

some US companies still make banned or seriously restricted pesticides (produce is exported)
may lead to the importation of food tainted with banned pesticides
global ban of persistent organic pollutants (POP's) Stockholm Convention of Persistent Organic Pollutants

Selective herbicides

kill only certain types of plants
can be classified to the type of plant they kill
-broad-leaf herbicides
-grass herbicides
i.e. 2,4-D; 2,4,5-T; Agent Orange

2,4-D

weed herbicide

2,4,5-T

herbicide for trees

Hochimen Trail

trail was covered with trees and virus
US went and sprayed with 2,4,5-T to kill trees and added 2,4_D to kill vines
-made 50/50 mixture called "Agent Orange"

Agent Orange

used to spray Hochimen Trial
effect on troops: cancer (carcinogenic), birth defects (teratogenic), genetic defects (mutagenic)

What caused harmful effects from Agent Orange?

contaminent in 2,4,5-T: Dioxin (TCDD)

TCDD

Dioxin; contaminant in Agent Orange

PCB

Polychlorinated Biphenyls
used in electrical transformers-now banned
have same environmental effect at DDT

PBB

PolyBrominated Byphenyls
flame retardent
used in baby clothing and baby blankets

MIC

methyl isocyanate

What is the building block of all carbamate insecticides?

MIC

Bhopal, India

1984; gives off cyanide has if mixed with water
killed 5,000 people

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