9.3 Pest ControlLook, Earl! No more pests!

Pests damage crops

Stats:– NA – 10% crop damage– Kenya – 75% crop damage– World wide – 1/3

Pest – any org that occurs where you don’t want it or in large enough numbers to cause damage.

cotton stainer - minor pest of cotton in the southern Florida

Adult armyworm

larva of the armyworm, Pseudaletia unipuncta

barley, corn, millet, oats, rice, rye, sorghum, sugarcane, timothy, and wheat may be consumed, as well as wild or weed grasses.

Why problem for crops?

B/c easy to find & damage

Pesticides – substance that kills pests

Ex: Aldrin, DDT, Lindane, Malathion, CarbarylInsecticides – kill insects

Drawbacks of Pesticides

Health concerns– Cancer– Chemical leaks

Carlitos, child of farmworkers, born with birth defects attributable to pesticides (PBP). Source: Sarasota/Manatee Farmworker Supporters

A train derailment near Milligan, Florida. The train carried chemicals, which were spilled at the site.

(©Bettmann/Corbis. Reproduced by permission.)

Pollution & Persistence– Persistent pesticides – don’t break down fast

into harmless chem – accumulate in soil & H2O• DDT – 1940s to kill mosq. & lice (malaria

& typhus)• Water – fish – birds – thin shells• Penguins, pelicans, peregrines, eagles• Banned• In US, 60 diff pesticides found in ground

water

Penguins, pelicans, peregrines, eagles

Resistanceability to tolerate a particular chemical. It

evolves through natural selection• 500 species have developed res. Since

1940s

Biological Pest Control – using living orgs or naturally produced

chem. to control pests.

• resistance takes longer to evolve• usually don’t harm orgs other than

pests• Predators & Pathogens

– pathogen – org that causes disease. These are sometimes used against pests.

• Ex: Bacillus thuringensis – bacteria that kills insect larvae

A range of products to keep unwanted visitors out of your garden and buildings.

Predators & PathogensPathogen – org that causes disease. These are

sometimes used against pests.• Ex: Bacillus thuringensis – bacteria that kills

insect larvae

Chemicals from plants

Extracts from plants used against pests• Ex: chrysanthemum

Disrupting Insect Breeding

Pheromones – chemicals produced by one org that affect the behavior of another.

• Farmers spray to interfere w/ mating• Reduce numbers better than pesticides• Expensive to make so not widely used

Treat males w/ x-rays – can’t reproduce