9.3 pest control look, earl! no more pests!. pests damage crops stats: –na – 10% crop damage...
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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
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