Chapter 22

SACCONE POWERPOINT

Chapter 22

The Pesticide Dilemma

http://smccd.net/accounts/snitovsky/bio215/Labs/bioins.html

SACCONE POWERPOINT

Pesticides• PesticidesPesticides: toxic chemicals used to control : toxic chemicals used to control

pests (weeds, rodents, insects, bacteria, pests (weeds, rodents, insects, bacteria, fungi…)fungi…)

• Herbicides Herbicides weeds weeds

• Rodenticides Rodenticides rats, mice, moles, voles rats, mice, moles, voles

• Insecticides Insecticides insects, arachnids insects, arachnids

• Fungicides Fungicides fungi, molds, yeasts fungi, molds, yeastshttp://www.epa.gov/ebtpages/pollchemicals.html

http://www.epa.gov/ebtpages/pollchemicals.html

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Narrow-Spectrum

• These pesticides would kill only the target These pesticides would kill only the target organism. organism.

• It would biodegrade into C, H, & O. It would biodegrade into C, H, & O.

• It also would not move throughout the It also would not move throughout the environment.environment.

• However this “perfect pesticide” However this “perfect pesticide” does notdoes not exist. exist.

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Broad-Spectrum

• These pesticides kill a These pesticides kill a wide varietywide variety of organisms, of organisms, including including beneficial onesbeneficial ones..

• They They do not readily break downdo not readily break down but they turn but they turn into secondary pollutants.into secondary pollutants.

• They also They also move easilymove easily through ecosystems & through ecosystems & biomes (mobile).biomes (mobile).

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Pesticides• 11stst Generation Pesticides Generation Pesticides: produced prior to 1940 : produced prior to 1940

(before synthetics) & include inorganics, (before synthetics) & include inorganics, organics, & botanicals.organics, & botanicals.

• Botanicals are plant derived pesticides that are Botanicals are plant derived pesticides that are produced as a natural plant defense. produced as a natural plant defense.

• Ex: nicotine (tobacco), pyrethrin Ex: nicotine (tobacco), pyrethrin (chrysanthemum), rotenone (Derris plant)(chrysanthemum), rotenone (Derris plant)

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Pesticides

22ndnd Generation Pesticides: Generation Pesticides: synthetic (man-made) synthetic (man-made) pesticides mostly used after the 1940’s.pesticides mostly used after the 1940’s.

Ex: Ex: DDTDDT ddichloro-ichloro-ddiphenyl-iphenyl-ttrichloroethane was richloroethane was the first of the 2the first of the 2ndnd generation pesticides (1939). generation pesticides (1939).

http://www.epa.gov/pesticides/about/types.htm

Major Groups of Insecticides• Chlorinated hydrocarbonsChlorinated hydrocarbons: Organic compounds : Organic compounds

that contain Cl. that contain Cl.

• These are mostly broad-spectrum pesticides. These are mostly broad-spectrum pesticides. Slow degradation & remain in the environment Slow degradation & remain in the environment & within organisms.& within organisms.

• Still in use; endosulfan, lindane, & methoxychlor.Still in use; endosulfan, lindane, & methoxychlor.

• 1963 author Rachel Carson brought pesticides to 1963 author Rachel Carson brought pesticides to the public attention in Silent Spring.the public attention in Silent Spring.

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Major Groups of InsecticidesMajor Groups of Insecticides

• OrganophosphatesOrganophosphates: These contain phosphates & : These contain phosphates & were developed based upon nerve gas..; These are were developed based upon nerve gas..; These are more poisonous than other insecticides. They are more poisonous than other insecticides. They are toxic to birds, bees, & aquatic organisms.toxic to birds, bees, & aquatic organisms.

• These don’t persist in the environment as long as These don’t persist in the environment as long as the Hydrocarbons. Have replaced commercial use the Hydrocarbons. Have replaced commercial use of hydrocarbons.of hydrocarbons.

• Ex: Methamidophos, dimethoate, & malathion.Ex: Methamidophos, dimethoate, & malathion.

http://www.crisny.org/not-for-profit/nycap/mosquitopaper.htm

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Major Groups of Insecticides

CarbamatesCarbamates: derived from carbamic acid. Are : derived from carbamic acid. Are broad-spectrum pesticides. Not as toxic to broad-spectrum pesticides. Not as toxic to mammals as organophosphates.mammals as organophosphates.

Ex: carbaryl & aldicarbEx: carbaryl & aldicarb

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• NonselectiveNonselective: Kill all vegetation.: Kill all vegetation.

• Selective herbicidesSelective herbicides: kill only certain types.: kill only certain types.

A) A) Broad-leaf herbicidesBroad-leaf herbicides: Kill broad-leafed plant but no : Kill broad-leafed plant but no grasses.grasses.

B) B) Grass HerbicidesGrass Herbicides: kill grass but safe for most other plants.: kill grass but safe for most other plants.

Major Groups of HerbicidesMajor Groups of Herbicides

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Use of Herbicides in Vietnam Use of Herbicides in Vietnam

Use of Herbicides in Vietnam • 12 million gallons of herbicides 12 million gallons of herbicides to expose hiding to expose hiding

places & destroy crops of Vietcong.places & destroy crops of Vietcong.

Agent White, Agent White, Agent BlueAgent Blue, and , and Agent OrangeAgent Orange..

• Agent Orange is made of:Agent Orange is made of:

(2,4,-D) 2,4 dichlorophenooxyacetic acid &(2,4,-D) 2,4 dichlorophenooxyacetic acid &

(2,4,5-T) 2,4,5 trichlorophenooxyacetic acid(2,4,5-T) 2,4,5 trichlorophenooxyacetic acid

as well as as well as dioxins.dioxins.

Birth defects, stillbirths, cancer in VietnamBirth defects, stillbirths, cancer in Vietnam

Agent orange Syndrome in Vietnam Vets.Agent orange Syndrome in Vietnam Vets.

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Benefits of PesticidesBenefits of Pesticides

• Disease control (malaria, west Nile)Disease control (malaria, west Nile)

• Crop protection (increase yields)Crop protection (increase yields)

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Problems with PesticidesProblems with Pesticides• Genetic resistanceGenetic resistance

• Imbalance in the ecosystemImbalance in the ecosystem

• Persistence of pesticidesPersistence of pesticides

• Bioaccumulation in organismsBioaccumulation in organisms

• Biological magnification in food webBiological magnification in food web

• Mobility in the environmentMobility in the environment

• Risks to human health (short-term & long-term)Risks to human health (short-term & long-term)

Problems with PesticidesProblems with Pesticides• Genetic resistanceGenetic resistance: inherited characteristics : inherited characteristics

(natural selection) that decrease the effect (natural selection) that decrease the effect of the pesticide on the pest.of the pesticide on the pest.

• Resistance ManagementResistance Management: a technique : a technique employed to delay the evolution of genetic employed to delay the evolution of genetic resistance in a population to maximize the resistance in a population to maximize the effectiveness of a pesticide.effectiveness of a pesticide.

http://www.cdc.gov/mmwr/preview/mmwrhtml/mm5233a4.htmMethicillin-Resistant Methicillin-Resistant Staphylococcus aureusStaphylococcus aureus Infections Infections

Problems with PesticidesProblems with Pesticides• ImbalanceImbalance in the ecosystem in the ecosystem

http://www.indiana.edu/~bradwood/eagles/ddt2.htm

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Problems with PesticidesProblems with Pesticides

DDE (dichlorodiphenyldichloroethylene) and DDE (dichlorodiphenyldichloroethylene) and DDD (dichlorodiphenyldichloroethane) are chemicals DDD (dichlorodiphenyldichloroethane) are chemicals similar to DDT that contaminate commercial DDT similar to DDT that contaminate commercial DDT preparations.preparations.

DDE has no commercial use. DDT DDE has no commercial use. DDT Eagles Eagles DDE DDE

DDD was also used to kill pests, but its use has also been DDD was also used to kill pests, but its use has also been banned. One form of DDD has been used medically to treat banned. One form of DDD has been used medically to treat cancer of the adrenal gland.cancer of the adrenal gland.

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ImbalanceImbalance in the ecosystem in the ecosystem


• PersistencePersistence: resistance to degradation : resistance to degradation into less toxic forms.into less toxic forms.

http://www.epa.gov/pbt/pubs/accomp99.htm

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Bioaccumulation


• BioaccumulationBioaccumulation: the build up of a persistent : the build up of a persistent chemical (pesticide)within an organism.chemical (pesticide)within an organism.

• Biological magnification: Biological magnification: an increase in the an increase in the chemical (pesticide) concentration of a pollutant chemical (pesticide) concentration of a pollutant as it passes through successive trophic levels of as it passes through successive trophic levels of a food web.a food web.

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• MobilityMobility in the environment in the environment

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Pesticide MobilityPesticide Mobility in the environment in the environment


Risks to human health Risks to human health Short-term:Short-term:

Poisoning & irritationPoisoning & irritation

Long-term:Long-term:

CancersCancers

Endocrine disruptionEndocrine disruption

Mental/physical retardationMental/physical retardation

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Solutions to the Pesticide DilemmaSolutions to the Pesticide Dilemma• Using cultivation to control pestsUsing cultivation to control pests

• Biological controlsBiological controls

• Pheromones & hormonesPheromones & hormones

• Genetic controlsGenetic controls

• Bt & its potential & problemsBt & its potential & problems

• QuarantineQuarantine

• Integrated Pest ManagementIntegrated Pest Management

• Irradiating FoodsIrradiating Foods

Solutions to the Pesticide Dilemma• Using Using cultivationcultivation to control pests to control pests

Aphid infestation of Wheat & BarleyAphid infestation of Wheat & Barley

•Infestation was stopped by a local Infestation was stopped by a local resistant variety of these plants (not resistant variety of these plants (not a monoculture.)a monoculture.)

Solutions to the Pesticide Dilemma• Biological controlsBiological controls: utilizes naturally : utilizes naturally

occurring disease organisms, parasites,, occurring disease organisms, parasites,, or predators to control pests.or predators to control pests.

• Sterile Male techniqueSterile Male technique: reduces : reduces population by “tricking” the females into population by “tricking” the females into thinking their eggs have been fertilized thinking their eggs have been fertilized (sterile male can’t)(sterile male can’t)

biological controlsbiological controls

• Aphids and Ladybeetles

www.ces.ncsu.edu/.../notes/ Fruits/NoteS-1.html

www.eap.mcgill.ca/Publications/ EAP53.htm

biological controlsbiological controls

Solutions to the Pesticide Dilemma

• HormonesHormones: chemical : chemical messengers produced by messengers produced by organisms. organisms.

• PheromonesPheromones: : reproductive hormones reproductive hormones used to lure in the used to lure in the opposite sex.opposite sex.

• Both are used to lure Both are used to lure pests into traps or to pests into traps or to confuse pests to prevent confuse pests to prevent mating.mating.


Scientists will use pheromones to kill sea lamprey


• Genetic controlsGenetic controls: using genetic variation to : using genetic variation to produce species that are resistant to pests.produce species that are resistant to pests.

• Selective breeding (genetic diversity)Selective breeding (genetic diversity)

OrOr

• Genetic engineeringGenetic engineering: the ability to take one : the ability to take one gene from an organism & place it into an gene from an organism & place it into an unrelated organism where it is expressed.unrelated organism where it is expressed.


http://www.bt.ucsd.edu/crop_refuge.html

• Case in Point: Bt, Its Potential & Problems


• QuarantineQuarantine: restricting the importation of : restricting the importation of exotic plant & animal material that might exotic plant & animal material that might harbor pests.harbor pests.

SolutionsSolutions to the to the Pesticide DilemmaPesticide Dilemma

• Integrated Pest Integrated Pest ManagementManagement

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Solutions to the Pesticide Dilemma• Irradiating Foods:

http://www.storewars.org/flash/index.html

Irradiating FoodsIrradiating Foods

www.ext.vt.edu/pubs/foods/ 458-300/458-300.html

Pesticide Dilemma: Pesticide Dilemma: Laws, Laws, LawsLaws, Laws, Laws• FDCA Food, Drug, and Cosmetics ActFDCA Food, Drug, and Cosmetics Act: :

enacted in 1938 it recognized the need to regulate pesticides in enacted in 1938 it recognized the need to regulate pesticides in food (no means for regulation)food (no means for regulation)

The Miller AmendmentThe Miller Amendment: passed in 1954, required : passed in 1954, required standards for levels of pesticides in food (acceptable standards for levels of pesticides in food (acceptable & unacceptable) Who decides? Criteria?& unacceptable) Who decides? Criteria?

The Delaney ClauseThe Delaney Clause: 1958, no known carcinogens (lab : 1958, no known carcinogens (lab animals or humans) would be permitted in animals or humans) would be permitted in processed processed foodsfoods. (based upon 1978 standards) Prior?. (based upon 1978 standards) Prior?

Pesticide Dilemma: Pesticide Dilemma: Laws, Laws, LawsLaws, Laws, Laws

• FIFRA: Federal Insecticide, Fungicide, & FIFRA: Federal Insecticide, Fungicide, & Rodenticide Act: Rodenticide Act:

1947, required testing & registration of the active 1947, required testing & registration of the active ingredients of pesticides. 1988 version targeted ingredients of pesticides. 1988 version targeted older pesticides and new for EDolder pesticides and new for ED5050 and LD and LD5050

testing. testing.


• The Food quality Protection ActThe Food quality Protection Act: :

1996, amended both the FDCA and the FIFRA.1996, amended both the FDCA and the FIFRA.Set pesticide residue limits.Set pesticide residue limits.

Revised Revised The Delaney ClauseThe Delaney Clause to include raw & to include raw & processed foodsprocessed foods. .


• Stockholm Convention on Persistent Organic Stockholm Convention on Persistent Organic Pollutants:Pollutants: eliminate the production and use of eliminate the production and use of P.O.P’s (P.O.P’s (ppersistent ersistent oorganic rganic ppesticides).esticides).

• DDT falls into this category but DDT falls into this category but will still be used will still be used BY SOMEBY SOME..

ExternalExternal

ExternalExternal

InternalInternal

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Gene Splicing

GENE for Nicotine production

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Biotechnology

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Biotechnology

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Biotechnology

Each bacterial cell can now make nicotine.

Each bacterial cell has the gene for making

nicotine.

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Chapter 22