please read carefully ..
Biology 140
Instructor: Dr. Franklin Quarcoo
Office Location: 103 Morrison-Mayberry Hall
Phone: 727-8792
Office Hours: MWF 3.00 – 5.00 pm
Email: fquarcoo1@tuskegee.edu
- Pests (in Part 1)
- Pesticides
- Benefits (in Part 1)
- Problems (some in Part 1)
- Categories
- Chemical types
- Regulation of Pestitcides
- Alternatives to Pesticides
- Reducing Pesticide Exposure
- Effects on non-target species (in Part 1)
- Pesticide resistance and pest resurgence (in Part 1)
- Creation of new pests (in Part 1)
- Concentration in food chains
- Persistence and mobility in the environment
- Human health problems
- Bioaccumulation:
- Occurs in individual organisms.
- Many pesticides are fat-soluble.
- Small, harmless amounts of pesticide ingested .
- Pesticides bind with body fats (lipids).
- Pesticide not excreted or broken down.
- Over time pesticide builds up to high levels in body -- higher than what is in it’s food source = bioaccumulation.
- May or may not reach toxic levels..
- Biomagnification
- Occurs in food chains.
- Each organism in food chain concentrates pesticide in its body through bioaccumlation.
- Next organism up the food chain has more contaminated food; concentrates pesticide to a greater level.
- Concentration of pesticide in organisms increases as you move up the food chain = biomagnification.
- Top carnivores most susceptible to pesticide poisoning..
- DDT = dichloro-diphenyl-trichloroethane.
- 1874 -- first synthesized by Othmar Zeidler
- 1939 -- Paul Müller discovered insecticidal properties of DDT.
- 1943 -- DDT marketed as first commercial synthetic pesticide.
- Highly toxic to insects, but relatively non-toxic to humans.
- Heavily used in 1940s and 1950s on crops, livestock, homes and people.
- Very effective in controlling insect pests.
- 1948 -- Müller wins Nobel prize..
- DDT very persistent -- half life in soil of decades.
- Biomagnifies in food chains.
- High concentrations in top predator birds (eagles, hawks, falcons, pelicans).
- Inhibits deposition of calcium carbonate in eggshells.
- Thinner eggshells break easily -- reduced reproduction.
- Bald eagles reduced to about 400 pairs (lower 48 states).
- Peregrine falcons reduced to 120 birds (lower 48 states)..
DDT Use
- 1962 -- Rachel Carson wrote Silent Spring.
- Book described harmful effects of pesticides on environment, especially birds.
- Helped trigger start of environmental movement.
- 1972 -- DDT banned in U.S.
- Now banned world-wide for agricultural use.
- But still allowed for use for control of disease vectors in tropical countries (e.g. mosquitoes for malaria control)..
- Banning of DDT and other chlorinated hydrocarbons has led to recovery of populations of top predator birds.
- Peregrine falcons have recovered from 120 to 1400 birds (lower 48 states).
- Bald eagles have recovered from 400 to 9800 pairs (lower 48 states).
- Both birds were removed from the endangered species list in 1994..
DDT
- Some pesticides persist for decades before breaking down.
- Persistent pesticides move by wind, water and animals far from original application site.
- Pesticides tend to evaporate in warm areas and accumulate in polar regions.
- Inuits of northern Canada have highest levels of pesticide residues of any human population.
- Inuit breast milk contains 5 times as much pesticide residues as the breast milk of women from Canada’s industrial cities to the south..
ICA
- In the food chain: Plankton --> Fish --> Seal --> Killer Whale, the greatest concentration of pesticide residue is expected in the Killer Whale. This is due to the process of:
- (a) Bioaccumulation
- (b) Biomagnification
- (c) Biomass accumulation
- (d) Biopersistence and Mobility
- (e) Bioremediation
- In the food chain: Plankton --> Fish --> Seal --> Killer Whale, the greatest concentration of pesticide residue is expected in the Killer Whale. This is due to the process of:
- (a) Bioaccumulation
- (b) Biomagnification
- (c) Biomass accumulation
- (d) Biopersistence
- (e) Bioremediation
- Acute effects:
- Short-term illness.
- One or a few exposures (often accidental).
- High doses.
- Chronic effects:
- Long-term illness.
- Repeated exposure.
- Low-level doses.
- Cancer, sterility, birth defects, neurological problems, immune system problems, Parkinson’s disease..
- Acute poisoning (WHO and EPA):
- 3 million cases of acute poisoning per year (300,000 in U.S.).
- 18,000 deaths per year (25 in U.S.).
- Highest risk = agricultural workers, children.
- In U.S., 250,000 people per year become ill from household pesticides (bait boxes, pest strips, bug bombs, flea collars, pesticide pet shampoos, weed killers)..
- Chronic Poisoning:
- Hard to separate pesticides from other causes.
- Estimates of 2,000-10,000 premature deaths per year due to legal pesticide residues in food..
- Mothers who ate lake Michigan fish (high levels of PCBs) regularly had children with learning and attention problems (lower IQ scores, below average reading, poor memory).
- Missouri children from homes with “no-pest strips” had higher rates of leukemia and brain cancer than similar children from homes without “no-pest strips”..
- Foothill ranches:
- Low pesticide use.
- Valley ranches:
- High pesticide use.
- Valley children:
- Decreased memory, physical stamina, hand-eye coordination; greater irritability..
Low
Pesticide
Use
High
Pesticide
Use
- Insecticides kill insects
- Herbicides kill plants
- Fungicides kill fungi
- Rodenticides kill rodents
- Miticides kill mites
- Nematocides kill nematodes (roundworms)
- Inorganic
- Botanicals
- Chlorinated hydrocarbons (organochlorides)
- Organophosphates
- Carbamates
- Pyrethroids
- First pesticides:
- ~3000 BC -- Sumarians -- sulfur (insects, mites)
- ~500 BC -- China -- arsenic, mercury (body lice)
- ~1400 AD -- arsenic, lead, mercury applied to crops
- ~1920 -- most use discontinued due to increasing fatalities and poisonings.
- Currently-used inorganic insecticides:
- Boric acid (roaches).
- Lime sulfur (tree spray for bacteria, fungi, insects)..
- Extracted from plants.
- Plants’ natural defenses against insects.
- Commonly used before 1940 (when synthetic pesticides were first developed).
- Examples: pyrethrum (chrysanthemum), nicotene (tobacco), rotenone..
- Also called organochlorides.
- First synthetic pesticides.
- Kills by disrupting signal transmission along nerve cells.
- Widely used from 1940s into 1970s.
- Many now banned; few still used today.
- Toxicity to mammals: relatively low.
- Persistence: high (years); biomagnified in food chains.
- Examples: DDT, toxaphene, dieldrin, chlordane, lindane, mirex, paradichlorobenzene (mothballs)..
- Similar to nerve gas.
- Highly toxic, but short-lived.
- Kills by blocking signal transmission between nerve cells.
- Toxicity to mammals: high
- Persistence: low (days).
- Examples: malathion, parathion, diazinon..
- Kills by blocking signal transmission between nerve cells.
- Toxicity to mammals: moderate.
- Persistence: low (days).
- Examples: carbaryl (Sevin), aldicarb (Temik)..
- Synthetics based on pyrethrum (botanical).
- Fastest developing group.
- Very effective and safe.
- Kills by disrupting signal transmission along nerve cells.
- Toxicity to mammals: low.
- Persistence: low (days).
- Examples: allethrin (Raid), bifenthrin..
ICA
- The first group of synthetic pesticides that was widely used was:
- (a) Botanicals
- (b) Chlorinated hydrocarbons
- (c) Inorganic compounds
- (d) Organophosphates
- (e) Pyrethroids
- The first group of synthetic pesticides that was widely used was:
- (a) Botanicals
- (b) Chlorinated hydrocarbons
- (c) Inorganic compounds
- (d) Organophosphates
- (e) Pyrethroids
- Which group of insecticides has the highest toxicity to mammals?
- (a) Carbamates
- (b) Chlorinated hydrocarbons
- (c) Organophosphates
- (d) Pyrethroids
- Which group of insecticides has the highest toxicity to mammals?
- (a) Carbamates
- (b) Chlorinated hydrocarbons
- (c) Organophosphates
- (d) Pyrethroids