Global food production
World agricultural production has risen faster than human population.
Global food security However, the world still has 850 million hungry people, largely due to inadequate distribution. And considering soil degradation, can we count on food production continuing to rise?
Global food security is a goal of scientists and policymakers worldwide.
Nutrition (especially developing world) (especially developed world) Malnutrition = lack of nutritional requirements
(causes numerous diseases, especially in developing world)
The green revolution Techniques to increase crop output per unit area of cultivated land (since world was running out of arable land). Technology transfer to developed world in 1940s – 80s: Norman Borlaug began in Mexico, then India . Special crop breeds (drought-tolerant, salt-tolerant, etc.) are a key component.
It enabled food production to keep pace with population.
The green revolution
The green revolution enabled India’s food production to keep up with population growth.
Green revolution: Environmental impacts Intensification of agriculture causes environmental harm: • Pollution from synthetic fertilizers • Pollution from synthetic pesticides • Water depleted for irrigation • Fossil fuels used for heavy equipment
However , without the green revolution, much more land would have been converted for agriculture, destroying forests, wetlands, and other ecosystems.
Monocultures Intensified agriculture meant monocultures , vast spreads of a single crop. Wheat monoculture in Washington
This is economically efficient, but increases risk of catastrophic failure (“all eggs in one basket”).
Crop diversity Monocultures also have reduced crop diversity. 90% of all human food now comes from only 15 crop species and 8 livestock species.
Moncultures have also contributed to a narrowing of the human diet.
Pesticides Artificial chemicals have been developed to kill insects ( insecticides ), plants ( herbicides ), and fungi ( fungicides ). These poisons are collectively called pesticides .
Many pests evolve resistance to pesticides.
Synthetic poisons that target organisms judged to be pests.
A toxic chemical that kills plants
A toxic chemical that kills insects
A toxic chemical that kills rodents
A toxic chemical that kills fungi
A toxic chemical that kills nematodes (roundworms)
A toxic chemical that kills algae
A toxic chemical that kills bacteria
A toxic chemical that kills fish (unwanted species)
Characteristics: Hard/Persistent Pesticides DDT and many other chlorinated hydrocarbons. Examples:
Composed of compounds that retain their toxicity for long periods of time. They work their way up the food chain through animals and may accumulate in their fatty tissues and stay indefinitely .
Characteristics Soft Pesticides soaps, oils, plant extracts, baking soda, and dish liquid. Examples:
Reduced-risk pesticides. They are short-term and don’t harm the environment or man.
Benefits of Pesticide Use
Prevent insect-transmitted diseases, such as malaria, bubonic plague, typhus, & sleeping sickness.
Food Production Increase food supplies and lower food costs. About 55% of the world’s food supply is lost to pests before (35%) and after (20%) harvest.
These losses would be worse and food prices would rise.
Kills pests like the cotton boll weevil.
Efficiency When Compared to Alternatives Pesticides control most pests quickly and at a reasonable cost. They have a long shelf life Easily shipped and applied Are safe when handled properly. When genetic resistance occurs, farmers can use stronger doses or switch to other pesticides.
Proponents feel they are safer than the alternative
Development of Safer Pesticides such as botanicals and micro-botanicals safer to users and less damaging to the environment. Genetic engineering holds promise in developing pest-resistant crop strains.
It is very expensive to develop these, so they are only doing it for large-market crops like wheat, corn, and soybeans.
Impact on Non-target Organisms Pesticides don’t stay put. The USDA says that only 2% of the insecticides from aerial or ground spraying actually reaches the target pests Only 5% of herbicides applied to crops reaches the target weeds.
They end up in the environment
Superbugs Genetic resistance to pesticides. Weeds and plant-disease organisms also become resistant. 520 insect and mite species, 273 weed species, 150 plant diseases, and 10 rodent species (mostly rats) have developed genetic resistance to pesticides.
At least 17 insect pest species are resistant to all major classes of insecticides
Pests evolve resistance to pesticides
Pests evolve resistance to pesticides, continued 4. Survivors breed and produce pesticide-resistant population.
3. All pests except a few with innate resistance are killed.
Pests evolve resistance to pesticides, continued 6. Has little effect. More-toxic chemicals must be developed. 5. Pesticide aplied again.
Many pesticides stay in the environment for a very long time. Ex. DDT
Bioaccumulation Increase in the concentration of a chemical in specific organs or tissues at a level higher than normal. Stored in body fat and can be passed along to offspring.
Usually a concern to organisms higher on the food chain.
Formation of New Pests Turning of minor pest into major pests. The natural predators, parasites, & competitors of a pest may be killed by a pesticide it allows the pest population to rebound.
EX. DDT to control insect pests on lemon trees caused an outbreak of a scale insect (a sucking insect that attacks plants) that had not been a problem.
Pesticides run off into our water as we spray for bugs & stay on our food.
Pesticide Poisoning Short-term exposure to high levels of pesticides can result in harm to organs and even death Long-term exposure to lower levels of pesticides can cause cancer.
Children are at a greater risk than adults.
National Cancer Institute Pesticides have been shown to cause lymphomas, leukemia, brain, lung, and testicular cancers. The issue of whether certain pesticides cause breast cancer remains unresolved
Researchers have noted a correlation between a high level of pesticides in the breast's fatty tissue and cancer.
Pollination Process of plant reproduction: male pollen meets female sex cells In many plants, animals transfer pollen to pollinate female plants, in mutualistic interaction to obtain nectar or pollen. Honeybee pollinating apple blossom
Pollinating insects are vital for many of our crop plants.
Pollinator conservation European honeybees commercially used to pollinate crop plants have been hit hard by parasites lately. So it’s important to conserve native bees and other insects that pollinate crop plants naturally.
Overuse of pesticides can backfire by killing beneficial pollinators.
the percentage or amount of active ingredient(s) by weight the net contents of the container the name and address of the manufacturer Registration and establishment numbers Statement of practical treatment Environmental hazard statement Harvesting and/or grazing restrictions Label Requirements
Storage and disposal statement.
How Pesticides Function
LD-50 (Median Lethal Dose) The LD-50 is the amount of pesticide it will take, in one dose, to kill ½ of all the target organisms.
It is usually referring to rats & mice in a laboratory experiment.
Nervous System Some interfere with the nervous system, cause uncontrollable muscle twitching or paralysis. Some are nervous system poisons.
Ex. Spectracide, Nicotine, DDT, Dursban, & Diazinon.
Some pesticides inhibit photosynthesis and prevent chlorophyll formation.
Smothering 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: 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.
EPA Pesticides and the Law
The EPA & USDA are responsible for the overseeing the laws.
Research 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
Restrictions 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.
FIFRA 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.
FFDCA Federal Food, Drug, and Cosmetic Act
Sets pesticide tolerance levels
FQPA Food Quality Protection Act
Amends both FIFRA and FFDCA.
Rachel Carson lived from 1907 to 1964. Rachel Carson
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 Figure 13-27
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 Figure 13-31
Biological pest control : Wasp parasitizing a gypsy moth caterpillar.
Using natural predators & parasites to control population of pests.
Biological control 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.
Microbials 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.
Sterilization 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. Figure 13-32
Both tomato plants were exposed to destructive caterpillars. The genetically altered plant (right) shows little damage.
Resistant Crops 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
Integrated pest management (IPM) Combines the following methods: • Close population monitoring
• 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.