Some pesticides inhibit photosynthesis and prevent chlorophyll formation.
Ex. Stampede, Pyrazon.
The vapors kill the pest by suffocating the animal. Soap can smother soft bodies of insects.
Ex. flea collars, pest strip, and soap.
Dehydration 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 and the Nightmare Insect Pest
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. It would stay exactly where it was put and not move around in the environment.
There is no such thing !
The EPA & USDA are responsible for the overseeing the laws.
Pesticides and the Law
Pesticide companies must use 3 methods to determine pesticides health threats:
Case Reports – (made to physicians) about people suffering from adverse health effects
Laboratory 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.
The EPA sets a tolerance level specifying the amount of toxic pesticide residue that can legally remain on the crop when the consumer eats it.
The Federal Insecticide, Fungicide & Rodenticide Act
It was first established in 1947 & revised as recently as 1996.
States what must be on a pesticide label & requires registration of all pesticides.
Federal Food, Drug, and Cosmetic Act
Strengthened in 1996
Sets pesticide tolerance levels
Food Quality Protection Act
Established in 1996
Amends both FIFRA and FFDCA.
Rachel Carson lived from 1907 to 1964.
She published her famous work Silent Spring in 1962.
“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 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.
Alternatives to Pesticides
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.
Other Ways to Control Pests
Biological pest control : Wasp parasitizing a gypsy moth caterpillar.
Using natural predators & parasites to control population of pests.
Synthetic chemicals can pollute and be health hazards.
Biological control (biocontrol ) avoids this.
Biocontrol entails battling pests and weeds with other organisms that are natural enemies of those pests and weeds.
(“The enemy of my enemy is my friend.”)
But biocontrol is risky
Most biocontrol agents are introduced from elsewhere.
Some may turn invasive and become pests themselves!
Cactus moths brought to the Caribbean jumped to Florida, are eating native cacti, and spreading.
Using disease organisms (bacteria and viruses) to control pests.
Garlic, sulfur, pyrethrins (from chrysanthemums) to help control pests.
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.
Using plastic that degrades slowly in sunlight to keep weeds from sprouting between crops.
Synthesized bug sex attractant used to lure pests into traps or attract their predators.
Males 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.
Genetic modification of food
Manipulating and engineering genetic material in the lab may represent the best hope for increasing agricultural production further without destroying more natural lands.
But many people remain uneasy about genetically engineering crop plants and other organisms.
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.
Plants 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.
Prevalence of GM foods
Although many early GM crops ran into bad publicity or other problems, biotechnology is already transforming the U.S. food supply.
Two-thirds of U.S. soybeans, corn, and cotton are now genetically modified strains.
Prevalence of GM foods
17 nations plant GM crops on 200 million acres.
But most are grown by 5 nations.
The U.S. grows 58.8% of the world’s GM crops.
The number of plantings have
grown > 10%/year
Integrated pest management (IPM)
Combines the following methods:
• Close population monitoring
• Habitat modification
• Crop rotation
• Transgenic crops
• Alternative tillage
• Mechanical pest removal
Indonesia (left) turned to IPM, and increased rice production while decreasing pesticide production and eliminating pesticide subsidies.
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.