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 disease-

resistant 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 broad-spectrum 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 non-target 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