What is a Pesticide?Major Kinds of Pesticides

Benefits and Problems With Pesticides Alternatives to Pesticides Laws Controlling Pesticides Use

Types: InsecticidesHerbicidesFungicidesRodenticides

Regulated by the EPA

Broad spectrum pesticidekills a variety of organisms, not just the targeted

organismsDoesn’t degrade = doesn’t decompose = persist

and then accumulate in environment or organism.

o First generation pesticide• Inorganic compounds

• Lead and mercury• Botanicals- plant derived pesticides

• Nicotine

Second generation pesticide Synthetic poison Ex: DDT

for mosquitoesused to controlmalaria

Chlorinated HydrocarbonsOrganic compound containing Chlorine

Ex: DDTPersist (do not degrade)**Rachel Carson – “Silent Spring” = problems w/

pesticides Organophosphates

Developed during WWIIHIGHLY toxic (bees/humans), but do not persistCurrently used in agriculture

EX: Malathion, diazinon Neurotoxin, especially children

CarbamatesNot as toxic to mammals

Ex: household sprays/traps

RACHEL CARSON…ENVIRONMENTAL GODDESS

How are organophosphates different than chlorinated hydrocarbons?

Selective HerbicidesKill only certain types of plantsCan be classified to the type of plant they kill

Broad-leaf herbicidesEx: 2,4-D (2,4 dichlorophenoxyacetic

acid)Ex: 2,4,5 –T (2,4,5,

trichlorophenoxyacetic acid)Used with wheat, corn, rice (cereal

grains = grasses)Grass herbicides

Nonselective – kill all vegetation

When would you use a broad-leaf herbicide? A grass herbicide

Sprayed to kill vegetation – Agent White, Blue, Orange

Ecological damage – decades to repair – destroyed mangroves (habitat for fish and coast protection from erosion), forests destroyed

Human effectsAgent Orange = (combination of broad leaf

herbicides + dioxins) birth defects, stillbirths, cancer

Dioxin in breastmilk – Vietnamese = 1800 ppt, US = 4 ppt

Benefit 1. : Disease controlFleas, lice and mosquitoes carry disease

• MalariaMalaria- mosquito born

• 2.7 million people die each year

• Few drugs available, so focus is on killing mosquitoes

• DDT

Benefit 2. : Crop ProtectionPests eat and destroy 1/3

of world’s cropsFarmers save $3 to $5 for

every $1 they invest in pesticides

Name the 2 reasons why pesticides are used?

Problem: Evolution of Genetic ResistancePest populations are evolving resistance to

pesticides (right)Pesticide TreadmillCost of applying pesticide increases

Because they must be applied more frequently or in larger doses

While their effectiveness decreases Because of increased genetic resistance in pests

Resistance Management Refuge of untreated plants: allows mating of

treated/untreated pests to delay resistance Remove surviving weeds after herbicide application

Problem: Kills non-target organismsSpraying to kill insects can kill birds, fish, beesDespite 33-fold increase in pesticides since the

1940s, crop loss has not really changed

Problem: Creation of New PestsPesticide kills predator or competitor of minor pest

Problem: Persistence, Bioaccumulation, and Biological Magnification Bioaccumulation

The buildup of a persistent pesticide or other toxic substance in an organisms body

Biological magnification• Increased concentration

of toxic chemicals in tissues of organisms at higher trophic levels, stored in fat• Ex: Peregrine falcons (right),• Bald Eagles

Problem: Mobility in the Environment Do not stay where they are applied harm non-

target organisms. Move through soil, water (run-off) and air

Effects of PesticidesHandling food with pesticide residue

• Mild case: nausea, vomiting, headaches

• Severe case: damage to nervous system (neurotoxin!!!)

Long-term Effects of Pesticides:Cancer- lymphoma and breastSterilityMiscarriageBirth defectsHarms immune system

1984 Bhopal, India Explosion at pesticide plant released

toxic gas (cyanide) Many died immediately Others: problems to respiratory,

reproductive, nervous systems

Using cultivation methods to control pests Interplant mixtures of plants (alternating rows):

polyculture !!Crop rotation

Biological ControlUse of naturally occurring disease organisms,

parasites or predators to control pestsMust take care that introduced agent does not

attack unintended hosts

CANE TOADS

Pheromones and HormonesCan use pheromones to lure pests to traps

Reproductive ControlsSterilizing some of the membersSterile male technique: sterilize in lab and then

release

IPMCombination of pest

control methods that keeps pest population low without economic loss

Controls pests, not eradicate

Cons: requires a lot of knowledge

Conventional pesticides are used sparingly when other methods failHOW DOES IPM DIFFER FROM

ORGANIC FARMING?

Farmers MONITOR pests and act when injury threshold is reached.

EX: Cotton – 1% of land; 50% of pesticide use in US. – WOW!! Organic cotton helps reduce pesticide use.

Rice Production in IndonesiaPredators of pests normally kept in check

by pesticides

IPM IPM IntroduceIntroduce

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Food, Drug, and Cosmetics Act (1938) –FDCA – determined pesticides need regulation!

Delaney Clause (1958) – no cancer causing substances; not cover raw foods.

Federal Insecticide, Fungicide, and Rodenticide Act (1947) – FIFRA – regulates what pesticides are sold based on safety.

Food Quality Protection Act (1996) – stricter guidelines on pesticide limits, covers raw food, reduce time to ban harmful pesticide.

Some US companies still make banned or seriously restricted pesticidesProduct is exported

Importation of food tainted with banned pesticides from other countries

Global ban of persistent organic pollutantsStockholm Convention on Persistent

Organic Pollutants (2004) – requires countries to eliminate usage of the 12 most toxic chemicals.