REX MESSING

Chapter 10: Pest Control

Pests and Pesticides

A pest is something or someone that annoys us, detracts from some resource that we value, or interferes with a pursuit that we enjoy

Biological pest- organisms that reduce the availability, quality, or value of resource useful to humans

Based partly on perspective A mosquito annoys us but is a good food source for bats and birds Dandelions are considered weeds in the western hemisphere, but

in some countries they are grown as a crop 100 plants, animals, fungi, and microbes cause 90% of all crop

damage world wide Insects are considered to be the most frequent pest because they

are ｾ of all species on earth Most tend to be generalist that reproduce rapidly and migrate

quickly

Pesticides

Pesticide- is a chemical that kills pestsNot always toxic, some prevent developmentOther approaches to pest control are burning

crop residues or draining wetlands to eliminate breeding sites

Biocide- a broad-spectrum pesticide that kills a wide range of living organisms

Herbicides- Kill plantsInsecticides- Kill insectsFungicides- Kill fungi

Ancient Approaches

Every culture has been known to use salt, smoke, or insect repelling plants to keep away pests or preserve foods

Sumerians used sulfur 5000 years agoChinese used mercury and arsenic 2500

years agoAlcohol from fermentation to prevent growth

of organisms that would spoil food

Modern Pesticides

DDT 1939 Swiss chemist Paul Muller created dichloro-diphenyl-

trichloroethane Very lethal for wide range of insects Began to have bad affects on wildlife Rachel Carson’s Silent Spring EPA estimates that 5.3 billion pounds of pesticides are used per

year About half is chlorine and hypochlorites for water purification Next largest category is conventional pesticides such as

insecticides, herbicides, and fungicides 80% of all conventional pesticides are used for food storage of

shipping According to CropLife America, 90 million ha of crops are treated

with herbicides a year

Percentage of Pesticides used in the United States

6.40%

49.10%

23.30%

6.20%

15.10%

Specialty biocidesChlorine/HypochloritesConventional pesticides Other (sulfure, petroleum)Wood preservatives

Types of Pesticides

Defined by chemical culture Inorganic pesticide- include compounds of arsenic, sulfur, copper, lead, and

mercury Generally highly toxic and basically last forever Natural organic Pesticides- or “Botanicals,” generally are extracted from plants Ex. Nicotine, Rotenone, Turpentine Fumigants- small molecules that gasify easily and penetrate rapidly into a variety of

materials Ex. carbon tetrachloride, carbon disulfide, or ethylene dichloride Chlorinated hydrocarbons- organochlorines that are synthetic organic insecticide

that inhibit nerve membrane ion transport and block nerve signal transmission Ex. DDT, chlordane, aldrin, dieldrin, toxaphene Organophosphates- they inhibit cholinesterase, an enzyme essential for removing

excess neurotransmitter from synapse in the peripheral nervous system Ex. parathion, malathion, dichlorvos, chlorphyrifose Carbamates- are extremely toxic to bees, but lack environmental persistence Ex. Urethanes, mirex Micro Agents- are living organisms or toxins derived from them used in place of

pesticides

Benefits of Pesticides

Controlling insect borne diseases:insects and ticks numerous pathogens and parasitesmalaria: DDT saved 50 million over 50 yearsyellow fever, Encephalitis, West Nile, sleeping sicknessWithout pesticides, we may lose two-thirds of

conventional cropsestimated that farmers save 3-5 dollars for for every $1

spent on pesticidesCropLife America estimates that $21 billion dollars lost

in food productionReduced up to 67%70 million additional laborers to remove weeds by hand

Pesticide Problems

Often poison nontarget species:Estimated that 90% of pesticides used never reach intended

targetPest Resurgence- the idea of creating a population of

pesticide resistant offspring through breeding1000 insect species and 550 weeds have developed chemical

resistancePesticicde Treadmill- constantly try newer and more toxic

chemicals in an attempt to stay ahead of the pestsTough because some genetically resistant genes are passed

between species before a species is ever exposed to a pesticide

Ex. 50 to 60 types of malaria carrying mosquito species are resistant to DDT because of widespread usage

Problems Cont.

Misusage can create new pests: Broad spectrum pesticides are eliminating the lower number of

beneficial predators Ex. Wasps, ladybugs, praying mantises Relying on pesticides overtakes traditional farming methods such

as mixed crops, or rotation regimes Effective pesticides are stable, highly soluble, and highly toxic,

making them the biggest nightmare Traces of pesticides are found many years later in areas that were

not treated with pesticides Persistent Organic Pollutants (POPs)- are so long-lasting and

so dangerous that they have been banned in 127 countries Dirty dozen: aldrin, clordane, dieldrin, DDT, endrin,

hexachlorobenzene, neptachlor, mirex, toaphene, polychlorinated biphenyls (PCBs), dioxins, and furans

Human Health Affects

Two categories: Acute effects such poisoning and illnesses caused by relatively

high doses and accidental exposure Chronic effects suspected to include cancer, birth defects,

immunological problems and other chronic degenerative diseases 25 million suffer pesticide poisoning and 20 thousand die each

year from pesticide poisoning related diseases Two thirds of the results came from occupational exposure

through usage without proper warning or protective clothing Hard to document specific cases for chronic affects of pesticide

exposure but evidence shows problems Lower IQs, trouble focusing Ex. California children 3 times as likely to have acute

lymphocytic leukemia when living in a once fumigated home

Alternatives to Current Pesticide Uses

Improved management programs can cut pesticide use 50 to 90% without lowering crop production

Different Solutions

Crop rotation can keep pest populations from building up

Mechanical cultivation can substitute herbicidesFlooding fields before planting or burning crop

residues and replanting with a cover crop can suppress both weed and insect pests

Habitat diversification prevents soil erosion and provides perch areas for nesting birds that eat pests

Planting at different times and at different locations to avoid pests is another method

Monoculture fieldsTillage is effective at certain times of the year

Organisms That can Help with Pest Control

Predators can control many pest cheaper and safer than broad-spectrum synthetic chemicals

Naturally occurring bacterium that kills larvae but is harmless to mammals

Ducks, chickens, geese, and other large species are used to rid fields of insects and pests

Herbivorous insects have been used for weed controlSome plants produce natural pesticides or repellentsGenetics and bioengineering (GMOs) can help the

fight against pestsUse hormones that upset development or sex

attractants to bait traps containing toxic pesticides

Integrated Pest Management

Integrated Pest Management (IPM)- is a flexible, ecologically based pest control strategy that is applied at specific times and aimed at specific crops and pests

Often uses mechanical cultivation and techniques such as vacuuming bugs off crops as an alternative to chemical application

Tries to use minimum amount and avoids broad-spectrum pesticides Encourages plant defenses and diversity of beneficial organisms Trap crops Economic Thresholds- the point at which potential economic damage justifies pest

control expenditures, and precise time, type, and method of pesticide application is critical in IPM

Considered widely affective in the US and world wide Exposure 2.4 million metric tons of pesticides used in US every year contain 600 active

ingredients 1200 presumably inactive carriers, solvents, preservatives, and other ingredients in

about 25000 commercial products Less that 10% of active pesticide ingredients have received full tests Of 321 pesticides screened so far, 146 are probably human carcinogens 40 have been banned since 1972

Who Regulates Pesticides?

3 federal agencies: EPA: Environmental Protection Agency Regulates sale and use of pesticides under the Federal

Insecticide, Fungicide, and Rodenticide Act (FIFRA) EPA determines which pesticides are the biggest risk Also sets levels of pesticides that may remain in in foods FDA: the Food and Drug Administration Enforce tolerance levels set by EPA Can seize and destroy any food shipment found to violate EPA

limits USDA: the Department of Agriculture Enforce tolerance levels set by EPA Can seize and destroy any food shipment found to violate EPA

limits

12 Most Contaminated Foods

1. Strawberries2. Bell Peppers3. Spinach4. Cherries (US)5. Peaches6. Cantaloupe (Mexican)7. Celery8. Apples9. Apricots10. Green Beans11. Grapes (Chilean)12. Cucumbers

Is Organic the Answer?

Many farmers and buyers have gone to organic to avoid pesticide consumption

More eco-friendly and leaves soil healthier Yields in organic plots are 20 percent less than conventional

fields Net returns for organic farming was higher than conventional

farming 56% less energy use on organic field Pest-eating predators found to be in greater abundance in

organic fields 400 times less erosion than conventional farming Less than 1% devoted to organic growing in US More popular in Europe with 18% in Liechtenstein and 11% in

Sweden

Organics Cont.

“100% organic” must be produced without hormones, antibiotics, pesticides, synthetic fertilizers, or genetic modifications

“Organic” means that at least 95% of the ingredients must be organic

“Made with organic ingredients” must contain at least 70% organic ingredients

Organic animals must be raised on organic feed, given access to the outdoors, given no steroidal growth hormones, and treated with antibiotics only to treat diseases

The Skeptics

People doubt organic growers can produce enough food within these definitions to feed everyone

They need chemical pesticides and large scale, chemical intensive farming to provide enough food for the portrayed world population

It is thought that we can only produce enough food to feed 2 to 3 billion people without pesticides or synthetic fertilizers

Potential health risks go along with eating organic food only

“Bacteria and parasites are also all-natural”

Protect Yourself

Wash and scrub all fruits an vegetablesPeel fruits and vegetables when possibleStore food carefully Cook or bake goods that you suspect to have

been treated with pesticides Trim fat from meat, chicken and fishDon’t pick and eat berries or other wild fruits

that grow on roadsidesGrow your own fruits and vegetablesAsk for organically grown food or shop at a

farmer’s market