Pest Management

Classes, Functions, Methods

Pests – 100 species cause 90% of damage

Any organism that interferes in some way with human welfare or activities

PROTECTING FOOD RESOURCES: PEST MANAGEMENT

Organisms found in nature (such as spiders) control populations of most pest species as part of the earth’s free ecological services.

Figure 13-27

Spiders kill far more insects than insecticides do

PROTECTING FOOD RESOURCES: PEST MANAGEMENT

We use chemicals to repel or kill pest organisms as plants have done for millions of years.

1600’s – nicotine from tobacco1800’s – pyrethrum from chrysanthemum flower

Chemists have developed hundreds of chemicals (pesticides) that can kill or repel pests.

Pesticides vary in their persistence.Each year > 250,000 people in the U.S. become ill from household pesticides.

PEST MANAGEMENT: Conventional chemical pesticides

25% - non agriculture use (lawns, golf courses, etc)Average lawn gets 10x more per acre than cropland

Figure 13-28

Classification of Pesticides

Specific Types:

Herbicides

A toxic chemical that kills plants

Insecticides

A toxic chemical that kills insects

Other PesticidesRodenticides

A toxic chemical that kills rodents

FungicidesA toxic chemical that kills fungi

NematicidesA toxic chemical that kills nematodes (roundworms)

AlgaecidesA toxic chemical that kills algae

BactericidesA toxic chemical that kills bacteria

PiscicidesA toxic chemical that kills fish (unwanted species)

Characteristics:Composed of compounds that retain their toxicity for long periods of time. They work their way up the food chain through animals and may accumulate in their fatty tissues and stay indefinitely.

Hard/Persistent Pesticides

DDT and many other chlorinated hydrocarbons.Examples

CharacteristicsReduced-risk pesticides. They are short-term and don’t harm the environment or man.

Soft Pesticides

soaps, oils, plant extracts, baking soda, and dish liquid.

Examples

Chemical Classes of Pesticides

Organochlorines (chlorides)

Hard/persistent Toxic in the long termNot very toxic in the short-termEx. DDT

OrganophosphatesSoft/not persistent Highly toxic in the short termThey require very specific safety equipment for application. Ex. Parathion

Carbamates

Soft/not persistentNot as toxic as the other twoMost of the over-the-counter pesticides. Ex. Sevin Dust

Historical Use of PesticidesNatural Pesticides – pyrethrins (from chrysanthemums); sulfur and garlic

Synthetic Pesticides – Used during and after WWII and today.

Benefits of Pesticide Usage

Disease Control

Save human lives Prevent insect-transmitted diseases, such as malaria (anapheles mosquito), bubonic plague (rat fleas), typhus (body lice & fleas), & sleeping sickness (tsetse fly).

Food ProductionIncrease food supplies and lower food costs. About 55% of the world’s food supply is lost to pests before (35%) and after (20%) harvest. These losses would be worse and food prices would rise.

Fiber Production

Crops such as cottonKills pests like the cotton boll weevil.

Efficiency When Compared to Alternatives

Pesticides control most pests quickly and at a reasonable cost.They have a long shelf lifeEasily shipped and appliedAre safe when handled properly. When genetic resistance occurs, farmers can use stronger doses or switch to other pesticides. Proponents feel they are safer than the alternative

Development of Safer Pesticidessuch as botanicals and micro-botanicalssafer to users and less damaging to the environment.Genetic engineering holds promise in developing pest-resistant crop strains. It is very expensive to develop these, so they are only doing it for large-market crops like wheat, corn, and soybeans.

Problems Associated with Pesticide Usage

Genetic Resistance

Pesticide use accelerates development of resistant organisms

Pests breed quickly

Creates pesticide “treadmill” - having to use more pesticides that will continue to have less effect

SuperbugsGenetic resistance to pesticides. Insects breed rapidly; within 5-10 years (sooner in tropics) they can develop immunity to pesticides and come back stronger than before. Weeds and plant-disease organisms also become resistant. 520 insect and mite species, 273 weed species, 150 plant diseases, and 10 rodent species (mostly rats) have developed genetic resistance to pesticides. At least 17 insect pest species are resistant to all major classes of insecticides

SuperpestsSuperpests are resistant to pesticides.Superpests like the silver whitefly (left) challenge farmers as they cause > $200 million per year in U.S. crop losses.

Figure 13-29

Case Study: Growing Germ Resistance to Antibiotics

Rabidly producing infectious bacteria are becoming genetically resistant to widely used antibiotics due to:

Genetic resistance: Spread of bacteria around the globe by humans, overuse of pesticides which produce pesticide resistant insects that carry bacteria.Overuse of antibiotics: A 2000 study found that half of the antibiotics used to treat humans were prescribed unnecessarily.

Formation of New PestsTurning of minor pest into major pests.The natural predators, parasites, & competitors of a pest may be killed by a pesticide it allows the pest population to rebound. EX. DDT to control insect pests on lemon trees caused an outbreak of a scale insect (a sucking insect that attacks plants) that had not been a problem.

Impact on Non-target OrganismsPesticides don’t stay put.The USDA says that only 2% of the insecticides from aerial or ground spraying actually reaches the target pestsOnly 5% of herbicides applied to crops reaches the target weeds. They end up in the environment

Food/Water ContaminationPesticides run off into our water as we spray for bugs & stay on our food.Example: cyanide in apple seedsCan harm wildlife and threaten human health

PersistenceMany pesticides stay in the environment for a very long time. Ex. Biomagnification of DDTIncrease severity higher up in the food chain.

Bioaccumulation/BiomagnificationIncrease in the concentration of a chemical in specific organs or tissues at a level higher than normal. Stored in body fat and can be passed along to offspring.Usually a concern to organisms higher on the food chain.

Case Study: Minamata, JapanMental impairments, birth defects, and deaths were caused by mercury.The mercury dumped in Minamata Bay by a factory entered humans through their diet of fish.

Pesticide Poisoning (Toxicity)Short-term exposure to high levels of pesticides can result in harm to organs and even death (Acute)Long-term exposure to lower levels of pesticides can cause cancer. (Chronic) Children are at a greater risk than adults.

SymptomsNausea, vomiting, and headaches.More serious can result in damage to the nervous system & other body organs.

Pesticide Poisoning

The W.H.O. estimates that more than 3 million people are poisoned by pesticides each year, & about 220,000 die.

Examples

CarcinogenNational Cancer Institute

Pesticides have been shown to cause lymphomas, leukemia, brain, lung, and testicular cancers. The issue of whether certain pesticides cause breast cancer remains unresolvedResearchers have noted a correlation between a high level of pesticides in the breast's fatty tissue and cancer.

Label RequirementsThe brand name The ingredient statementThe percentage or amount of active ingredient(s) by weightThe net contents of the containerThe name and address of the manufacturerRegistration and establishment numbersHarvesting and/or grazing restrictions

Signal words and symbolsPrecautionary statementStatement of practical treatmentEnvironmental hazard statementClassification statementDirections for useRe-entry statement Storage and disposal statement.

How Pesticides Function

LD-50 (Median Lethal Dose)

The LD-50 is the amount of pesticide it will take, in one dose, to kill ½ of all the target organisms (usually rats & mice). Use of dose-response analysis exposes organisms to different concentrations of toxins.Threshold dose occurs once there is a negative effect

Nervous SystemSome interfere with the nervous system, cause uncontrollable muscle twitching or paralysis.Some are nervous system poisons. Ex. Spectracide, Nicotine, DDT, Dursban, & Diazinon.

Photosynthesis

Some pesticides inhibit photosynthesis and prevent chlorophyll formation. Ex. Stampede, Pyrazon.

SmotheringThe vapors kill the pest by suffocating the animal. Soap can smother soft bodies of insects. Ex. flea collars, pest strip, and soap.

DehydrationDehydration uses the fossilized remains of tiny, one-celled organisms called diatoms. It kills insects by scratching their wax outer covering and causing them to dehydrate. This is a soft pesticide.

Inhibition of Blood Clotting

Other types of pesticides cause animals (especially rats) to bleed to death by preventing their blood from clotting.

The Ideal Pesticide

The ideal pest-killing chemical has these qualities:

Kill only target pest.Not cause genetic resistance in the target organism.Disappear or break down into harmless chemicals after doing its job.Be more cost-effective than doing nothing.

The Perfect PesticideCharacteristics: The ideal pesticide would kill only the organism for which it was intended to harm, and not any other species. It would be broken down by natural chemical decomposition or by biological organisms.Example: The perfect pesticide would break down into safe materials such as water, carbon dioxide, and oxygen. It would stay exactly where it was put and not move around in the environment. There is no such thing!

EPAThe EPA & USDA & FDA are responsible for the overseeing the laws.

Pesticides and the Law

ResearchPesticide companies must use 3 methods to determine pesticides health threats:

Case Reports – (made to physicians) about people suffering from adverse health effectsLaboratory Investigations – (usually on animals) to determine toxicity, residence time, what parts of the body are affected and how the harm takes place.Epidemiology – (in populations of humans exposed) used to find why some people get sick while others do not

Days to Harvest

The last day you can spray crops before you harvest them for human consumption.

RestrictionsThe EPA sets a tolerance level specifying the amount of toxic pesticide residue that can legally remain on the crop when the consumer eats it.

FFDCA

Federal Food, Drug, and Cosmetic ActStrengthened in 1996 Sets pesticide tolerance levels

FIFRAThe Federal Insecticide, Fungicide & Rodenticide ActIt was first established in 1947 & revised as recently as 1996. States what must be on a pesticide label & requires registration of all pesticides.

Label Requirementsthe brand name the ingredient statementthe percentage or amount of active ingredient(s) by weightthe net contents of the containerthe name and address of the manufacturerRegistration and establishment numbersSignal words and symbolsPrecautionary statementStatement of practical treatmentEnvironmental hazard statementClassification statementDirections for useRe-entry statement Harvesting and/or grazing restrictionsStorage and disposal statement.

FQPA

Food Quality Protection ActEstablished in 1996 Amends both FIFRA and FFDCA.

Problems with enforcement

• Lack of time and money to test all compounds• Inadequate enforcement• Pre-1972 pesticides don’t have as strict

standards• Banned or unregistered pesticides can be

shipped to other countries• Imported food may have unsafe levels of

pesticide residue

Time

Rachel Carson lived from 1907 to 1964. She published her famous work Silent Spring in 1962.

Rachel Carson

Contributions“Pesticide sprays, dusts, and aerosols are now applied almost universally to farms, gardens, forests, and homes - non selective chemicals that have the power to kill every insect, the good and the bad, to still the song of birds and the leaping of fish in the streams, to coat the leaves with a deadly film and to linger on soil - all this though the intended target may be only a few weeds or insects. Can anyone believe . . .

Contributions

. . . it is possible to lay down such a barrage of poisons on the surface of the earth without making it unfit for life? They should not be called insecticides, but biocides.” Silent Spring heightened public awareness and concern about the dangers of uncontrolled use of DDT and other pesticides, including poisoning wildlife and contaminating human food supplies.

Fig. 13-30, p. 299

What Can You Do?

Reducing Exposure to Pesticides

• Grow some of your food using organic methods.

• Buy organic food.

• Wash and scrub all fresh fruits, vegetables, and wild foods you pick.

• Eat less or no meat.

• Trim the fat from meat.

Definition:A limited use of pesticides along with other practices.Important as a form of pollution prevention – reduces risk to wildlife and humans

Integrated Pest Management (IPM)

Other Ways to Control PestsThere are cultivation, biological, and ecological alternatives to conventional chemical pesticides.

Fool the pest through cultivation practices.Provide homes for the pest enemies.Implant genetic resistance.Bring in natural enemies.Use pheromones to lure pests into traps.Use hormones to disrupt life cycles.

Integrated Pest Management

Intercropping: peas and corn

Integrated pest management (IPM) describes pest control practices where each crop and its pests are evaluated as part of an ecological system. A program is developed that includes crop management(e.g. intercropping or polyculture where multiple types of plants are planted together), and biological and chemical controls.

The aim is not to eradicate pestpopulations, but to reduce cropdamage to an economicallytolerable level.

An increasing number of pestcontrol experts and farmersbelieve IPM is the best way tocontrol crop pests because of the many different methods that are used.

IPM involves several phases. Crop management and monitoring of pest levels are ongoing. When crop damage becomes unacceptable, farmers implement the following control measures in sequence and with the proper timing.

Stage 1: Cultivation controls, such as hand weeding and vacuuming crops to remove insect pests.Stage 2: Biological controls, such as pheromone traps, and natural predators, parasites, and disease organisms.Stage 3: Targeted pesticide use (chemical controls), mostly based on natural insecticides. Different chemicals are used to slow the development of resistance.

Stages in IPM

Cer

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Cen

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AFC

Hand weeding

Pheromone trap

Cultural Methods

Physical

This includes rotating between different crops, selecting pest-resistant varieties, planting pest-free rootstock, and vacuuming up harmful bugs.                               

Traditional “EcoFarmer”Each crop is evaluated as parts of an ecological system. A control program is developed that includes a mix of cultivation, biological, and chemical methods applied in proper sequence with the proper timing.

Biological Methods

Other Ways to Control Pests

Biological pest control: Wasp parasitizing a gypsy moth caterpillar.

Figure 13-31

Predators/Parasites

Using natural predators & parasites to control population of pests.

Biological control (biocontrol) is a management tool for controlling pests using parasites, predators, disease organisms.Control agents with a botanical or microbial origin (e.g. Bt toxin) are classified as biopesticides.Biological control is an important part of IPM but it is not risk free. Some biocontrol agents may even become pests themselves attacking beneficial species. The cane toad (right) was introduced to Australia to control gray cane beetle and is now a major threat to native wildlife by displacing native species.

Biological Pest Control

Phot

o: Ia

n Sm

ith

Ladybugs are voracious predators of aphids

Cane toad

Diseases

Using disease organisms (bacteria and viruses) to control pests.

Natural Repellants

Garlic, sulfur, pyrethrins (from chrysanthemums) to help control pests.

                                              

                                                                               

         

Microbials

Used for insect wars, especially by organic farmers.EX. The Bacillus thruingensis (Bt) toxin is a registered pesticide sold commercially as a dry powder. Each of the thousands of strains of this common soil bacteria kills a specific pest.

Timing of Application

Adjusting planting times so that major insect pests either starve or get eaten by their natural predators.

Type of Crops

Switching from vulnerable monocultures to intercroping, agroforestry, and polyculture, which use plant diversity to reduce losses to pests.

Photodegradable Plastics

Using plastic that degrades slowly in sunlight to keep weeds from sprouting between crops.

PheromonesSynthesized bug sex attractant used to lure pests into traps or attract their predators.

Genetic MethodsGMO- Genetically Modified

Organism

Can be controversial Banned in Europe

Genetically Modified

The process of making a genetically modified organism.

‣Genetically modified organisms (GMOs) or genetically modified foods (GMFs) have

environmental advantages:Higher yields per acre and thus less land is

needed.

Permits low tillage which reduces soil erosion, energy consumption and water loss.

Lower fertilizer requirement, drought, disease, frost, salinity and pest resistance.

‣Disadvantages:Resistance may impact beneficial insects

Native plant diversity impacted

Higher yields require higher inputs of herbicides and pesticides

Lower genetic variability

Other Ways to Control Pests

Genetic engineering can be used to develop pest and disease resistant crop strains.

Both tomato plants were exposed to destructive caterpillars. The genetically altered plant (right) shows little damage.

Figure 13-32

Resistant CropsPlants and animals that are resistant to certain pest insects, fungi, and diseases can be developed.This can take 10 to 20 years. Genetic engineering is now helping to speed up this process through the development of transgenic crops.

SterilizationMales of some insect species can be raised in the laboratory, sterilized by radiation or chemicals, and released into an infested area to mate unsuccessfully with fertile wild females. Males are sterilized rather than females because the male insects mate several times, whereas the females only mate once.

Sterilization: Screw wormFly lays flesh eating maggots in wounds of animals…really gross!modern cattle industry provided many thousands of cows as potential hosts for the fly serious outbreak in the southern US in 1934 resulted in over 1.3 million cases of infestation and the death of over 200,000 animals.During 1959, about two billion male screwworm flies sterilized by gamma-irradiation were released in FLsimilar program was initiated in the southwestern states in 1962 and later along the Texas-Mexico borderThese efforts involved the release of as many as one billion sterile male flies every yearThe screwworm was declared eradicated in the United States by 1966

No Pesticide UseOrganic Farming

Advantages of Organic Farming

Traditional haymaking, Ireland

Advantages of organic farming include:

Farmers can still make use of new high yielding crop varieties (right).Produce is pesticide free and produced sustainably.Crop type is more closely matched to the appropriate season and soil.Increases crop diversity and disrupts disease and pest cycles.Improves soil quality and structure, reducing nutrient and water loss.Decreased fossil fuels, climate impacts, extraction impacts, and air pollutants

Disadvantages of Organic Farming

Organic produce

Muck spreading

The disadvantages of organic farming include:

Yields are lower and more land is required for the same yield.Produce may be more expensive to buy, of reduced quality and with a shorter shelf life. Consumer choice may be restricted if out of season.There may be considerable bacterial contamination of produce due to high use of manures.

Image:Global Crop Diversity Trust

Photo:Global C

rop Diversity Trust M

ari Tefre

Svalbard International Seed VaultLiving Fort Knox: designed to protect the specimens from catastrophic events, used to replenish national seed banks.Some crops, such as peas, may only survive for 20-30 years. Others, such as sunflowers and grain crops, are understood to last for many decades or even hundreds of years.

Image:Global Crop Diversity Trust

Photo:Global C

rop Diversity Trust M

ari Tefre

Svalbard International Seed Vault

The Svalbard International Seed Vault on the Norwegian island of Spitsbergen, 1000km from the North pole is one of the world’s newest seed vaults.

It accepted its first seeds on the 26th of February 2008.

It is built into the side of a sandstone mountain, surrounded by permafrost and cooled to -18oC. The vault has meter thick walls, two air locks and blast-proof doors.

An integrated system of plant and animal production practices having a site-specific application that will last over the long term.The components of sustainable, low input agriculture are applicable to any type of cropping or harvesting system.

Sustainable Agriculture

High yield polyculture

Organic fertilizers

Biological pest control

Integrated pest management

Irrigation efficiency

Perennial crops

Crop rotation

Use of morewater-efficient crops

Soil conservation

Subsidies for more sustainable farming and fishing

Soil erosion

Salinization

Aquifer depletion

Overgrazing and overfishing

Loss of biodiversity

Loss of prime cropland

Food waste

Population growth

Poverty

Subsidies for unsustainable farming and fishing

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