INSECTSpests or pollinators

The bee pollinatesthe Varroa mite preys on adult bees

and their larvae

Only 100 plants, animals, fungi and microbes cause 90% of the

problems• ¾ of all species on earth are insects

• Human disrupted ecosystems have increased the growth rate of insects

• Human disrupted ecosystems have decrease growth rate of beneficial insects

Pests annoy, distract and disrupt

Pesticides kill pests and can be general or specific

• Biocide is broad-spectrum• Herbicides kill plants• Insecticides kill insects• Fungicides kill fungi

Early Methods of Pest Control

• Smoke – Salt – Insect-Repelling Plants

5000 ya Sumarians used sulfur2500 ya Chinese describe mercury and arsenic

compounds for body lice Greeks and Romans used oil sprays,

sulfur, lime, Burned fields and rotated crops

Acids, Alcohol, spices

1939 Swiss Chemist Paul Muller discovered DDT

• Dichloro-diphenyl-trichloroethan• Inexpensive, stable, effective• Lethal to numerous insects • nontoxic to mammals • Stability leads to biomagnification, • Harmful to other non-target species

(eggshells were thinning in birds)

Use in US amounts to 5.3 bill lbs or 2.4 metric tons annually

1 ½ of this is for chlorinating water (purifying)

2 Convention Use includes insecticide, fungicides and herbicides

80% is for agriculture

3 Wood preservative

globally

• Convention use in the world is 5.7 bill lb annually

• of which 1.24 bill lb in US annually or 20%

Types of PesticidesPESTICIDE EXAMPLES STABILITY/

PERSISTENCETYPE TOXICITY

S, Ar, Cu, Hg, lead Seed storage, kill rodents

stable inorganic High, neurotoxins

Botanicals; nicotine, rotenone, pyrethrum, turpentine, phenols,

Rotenone kills fishNatural hydrocarbons herbicides general biocide

Relatively non-persistent and

variable

Organic “natural”

variable

Small molecules that gas easily and penetrate rapidly

Carbon tetrachloride, carbondisulfide, methyl bromide used to sterilize soil

Banned Fumigants Extremely dangerous for workers

Herbicideinsecticide

2,4,5TDDT

Stable and persistentMany banned

Chlorinated hydrocarbons

toxic

MALATHION Outgrowth of nerve gas, inhibit cholinesterase

unstable Organo-phosphates

toxic

Sevin Low persistence and low bioaccumulation

Carbamates Very toxic to bees

Living organism Bacillus thuringiensisParasitic wasps

Biocontrola

Pesticide Benefits

• Controls disease malaria deaths are thought to have decreased by 50mill in 50yrs (other diseases carried by mosquito, yellow fever, west nile, encephalitis or fly trypanosomiasis or sleeping sickness or by worms)

• Crop yields possibly 1/3 Farmers save $3-$5 /$1 spent pesticide

What do you think?

Pesticide ProblemsPoison nontarget species:

Pollinating bees have been killed due to nondiscriminatate use of pesticide Sevin

Insecticide Axodrin (target potato aphids ) killed 10,000 robin in 3 days

Accidental spillage can wipe out ecosystem

Increase pest resistance: The Varroa mite that parasitizes bees has developed resistance to two different pesticides since 1987. The cotton boil weeval was controlled with DDT but the weevil quickly developed resistance. 50-60 of the

resurgence is when pop rebuilds quickly and with resistancereboundpesticide treadmill the demand for greater and greater amounts of pesticide due to resurgence

Graph showing pest resistance

We are losing the battle to control pest using synthetic pesticides

• Evidence…

• Larger percentages of crops are lost now to insects, disease and weeds than in 1944

*gene transfer is thought to confer resistance in species that have never seen the pesticide.

GMO Crops having increased resistance

• Theoretically should decrease usage of pesticides

• Likely to cause even more resistance

• Pesticide misuse includes“broadcast spraying” and broad spectrum pesticidesUnder natural conditions many agr pest are kept under control with natural enemies i.e. Wasp predators

i.e. In Peru, both boll weevils and Heliothis worms began increasing rapidly following DDT use because it killed the predatory waspYield changes500kg/hec before DDT 750 kg/hec after DDT and Toxaphene330kg/hec after death of the wasp

In California

• Cotton yield down by 20% • Even with doubling of insecticide

Another part of the problem with the use of pesticides

• Farmers abandon – using mixed crops– Crop rotation– Traditional methods of management

Persistent pesticides can move long distances in the environment

• Chlorinated hydrocarbons (DDT) are stable, soluble and toxic

• High solubility in fat bioaccumulation and magnification

POP

• Accumulate in polar regions due to the “grasshopper effect” evaporate from warm regions and condense and precipitate in colder regions.

• 31 million kg (70 mil tons) of Atrazine annually makes it the biggest commercial pesticide. Shown to cause abnormal gender changes in frogs at low but not high levels due to the estrogen

Inuit people have the highest levels of POP in any human population

• Picture of inuit people

POP’S

• They are so long lasting and dangerous 127 countries agreed in 2001 to a global ban on the dirty dozen (DDT, PCB’s, dioxins)

Two varieties of Jimsom weed

(Datura wrighti)

1. with glandular trichomesfull of sticky sweet substanceMore resistant to herbivoryTrait is dominant

2. without glandular trichomes

Both produce toxic alkaloid call atropinethat protects plants from insects

Human Health Problemsare either

Acute or Chronic• Acute

– Poisoning and illnesses caused by high doses and accidental exposure

Two thirds of 9000 latin american flower worker experienced blurred vision, nausea, headaches, conjunctivitis, rashes and asthma.

Chronic include cancer, parkinson’s disease, birth defects, immune problems, degenerative diseases. Many flower and farm workers reported stillbirths and miscarriages and neurological problems.

Farmers who use pesticides have elevated levels of prostate cancer, non-Hodgkins lymphoma, Parkinson’s disease.

• Children from homes fumigated by professional bug exterminators are 3X more likely to have acute lymphocytic leukemia

ALTERNATIVES

• Crop ROTATION• Burn Crop Residues, Use cover crops • Switch from monoculture to polyculture• Adjust planting time

Biological Controls

• Pest predators (wasps, ladybugs, praying mantises)

• Pest pathogens (viruses, bacteria, fungi)– Bt naturally occurring bacterium that kills

larvae of butterfly and moth– Use 2o consumers (ducks, geese, chickens)– Herbivorous insects have been used to

control weeds.

Integrated Pest Management

• Mechanical techniques like vacuuming bugs off crops

• Use minimum amount of pesticide necessary.

• Avoid broad spectrum products

• **Risk is that it introduces new organisms into an environment**

Reduce Pesticide Exposure