Transcript PEST CONTROL

PEST CONTROL
Green Revolution
• Dramatically increased agricultural production
brought about by “miracle” strains of grain
• Usually requires high inputs of water, plant
nutrients and pesticides
• Typically yield more than other varieties if
given optimum conditions but under
suboptimum conditions they usually do worse
than traditional varieties
Genetic Engineering
• Involves removing genetic material from one
organism and splicing it into the chromosomes
of another
• Has potential to greatly increase quantity and
quality of food supply
• Could, however, create superweeds or reduce
native biodiversity
First Generation Pesticides
• Mainly natural substances, chemicals
borrowed from plants that had been
defending themselves from insects for eons
• Used up to the early 1900s until synthetic
chemicals were produced (second generation
pesticides)
Pests and Pesticides
• Biological Pests:
– Organisms that reduce the availability, quality or
value of resources useful to humans
• Pesticide:
– Chemical that kills pests
• Biocide:
– Broad-spectrum pesticide that kills a wide range
of living organisms
– EX. Fumigants, such as ethylene dibromide, used
to protect stored grain
Pests and Pesticides
• The following are narrower spectrum agents
that attack a specific type of pest.
• Herbicides: Kill plants
• Insecticides: Kill insects
• Fungicides: Kill fungi
• Rodenticides: kill rodents
• Can also be defined by method of dispersal
(fumigation) or their mode of action (ovicide)
Pesticide Types
• Inorganic Pesticides: include compounds of
arsenic, sulfur, copper, lead and mercury
– Broad-spectrum, highly toxic, long lasting
• Natural Organic Pesticides (botanicals):
extracted from plants
• Fumigants: small molecules that gasify easily
and penetrate rapidly into a variety of
materials
Pesticide Types
• Chlorinated hydrocarbons: synthetic organic
insecticides that inhibit nerve membrane ion
transport and block nerve signal transmission
• Organophosphates: reacts with the central
nervous system
• Carbamates: effect nervous system of pests
more water soluble than chlorinated
hydrocarbons
• Microbial Agents and Biological Controls: living
organisms or toxins derived from them used in
place of pesticides
Pesticide Benefits
• Important weapons in competition for food
and shelter and to protect us from diseases
and predators
• Help control diseases by killing the vectors
that transmit the diseases
• Help protect crops by killing weeds, insects,
etc.
Pesticide Problems
• Often kill nontarget species
• Pest resurgence occurs: rebound of pest
populations due to acquired resistance to
pesticides
• Pesticide Treadmill: occurs: a need for
constantly increasing doses or new pesticides
to prevent pest resurgence
• Secondary Pest Outbreak: organisms that
were not originally a pest become pests
Alternatives to Current Pesticide Uses
• Biological Controls:
– Use of natural predators, pathogens or
competitors to regulate pest populations
• Insect Birth Control:
– Lab raised males are sterilized then released into
the pest population
Alternatives to Current Pesticide Uses
• Cultivation practices/Behavioral changes:
– Rotate types of crops planted, adjusting plant
times, planting trap crops
• Genetic Engineering:
– Speeds up the development of pest- and diseaseresistant crop strains
Alternatives to Current Pesticide Uses
• Sex Attractants:
– Use of pheromones to lure and trap the pest
• Hormones:
– Disrupt an insect’s normal life cycle causing the
insect to fail to reach maturity and reproduce
Alternatives to Current Pesticide Uses
• Spraying Insects with Hot Water:
– Worked well on cotton, alfalfa and potato fields
and in citrus groves n Florida
• Exposing Food with high-energy Gamma
Radiation:
– Such food irradiation extends food shelf life and
kills insects, parasitic worms and bacteria
Ideal Pesticide
• Kills only target pest
• Harm no other species
• Disappear or break down into something
harmless after doing its job
• Not cause genetic resistance in target organisms
• Be more cost effective than doing nothing
Alternatives to Current Pesticide Uses
• Integrated Pest Management (IPM)
– An ecologically based pest-control strategy that
relies on natural mortality factors, such as natural
enemies, weather, cultural control methods and
carefully applied doses of pesticides
– Doesn’t give up pesticide use but tries to minimize
the use, use as a last resort and avoid broadspectrum pesticides
Regulating Pesticide Exposure
• The EPA regulates the sale and use of pesticides
under the Federal Insecticide, Fungicide and
Rodenticide Act (FIFRA), which mandates the
registration of all pesticide products
– Regulates all pesticides, reviews can take several years,
most pesticides not use by the public
• The EPA determines which pesticides will not pose
significant risks to human health or the environment
• The EPA sets “tolerance levels” in food under the
Federal Food, Drug and Cosmetic Act (FFDCA)
Regulating Pesticide Exposure
• The FDA and USDA enforce pesticide use and
tolerance levels set by the EPA
• The FDA and USDA can seize and destroy food
shipments found to contain pesticide residues
in violation of limits set by the EPA
Food Quality Protection Act
• Emphasizes the protection of infants and
children in reference to pesticide residue in
food
• FQPA requires a new safety standard –
reasonable certainty of no harm – that must
be applied to all pesticides used on food
commodities
DDT
• Dichlorodiphyenyl trichloroethane
• First synthesized chlorinated organic pesticide
• Appeared to have low toxicity and was broad
spectrum
• Did not break down so it did not have to be
reapplied often
• Was water-insoluble (didn’t get washed away)
and was inexpensive
• Crop production increased, mosquitoes
decreased
DDT
• Rachel Carson published Silent Spring in1962
that made connection between DDT and nontarget organisms by
– Direct toxicity
– Indirect toxicity (persistence in
environment)—biomagnification and
bioaccumulaiton
DDT
• Used as an insecticide
• Has been found in regions not used because
chemicals can circulate in the biosphere