Presentation on theme: "Food & Agriculture Chapter 15, Section 2: Pest Control Standards: SEV4a, b, c."— Presentation transcript:
Food & Agriculture Chapter 15, Section 2: Pest Control Standards: SEV4a, b, c
What is a “pest”? Any organism that occurs where it is not wanted or that occurs in large enough numbers to cause economic damage. Worldwide pests destroy about 33% of the world’s potential food harvest. Ex: ▫Fungi (ergot kills corn) ▫Plant eating insects (grasshoppers) ▫Weeds
Why are wild plants better adapted to avoid pests? Wild plants are more spread out than crops which are grown in large fields- harder for pest to find them. Wild plants have more pest predators on them that will eat the pest before it gets out of control. Wild plants have evolved poisonous chemicals to repel pests. When plants are attacked by insect, they release a signal that goes to other leaves. These leaves start producing a toxin to protect them when the insect makes its way there.
What are pesticides? Chemicals that kill insects, weeds, and other crop pests. Most are synthetic and some are petroleum based Ex: Atrizine- ▫Herbicide used to kill weeds ▫Overuse has been linked to hermaphroditism in frogs ▫Banned in Europe, still used in US Ex: Furadan ▫Insecticide ▫Linked to intentional poisoning of lions in Africa VIDEO: Lions Poisoned in Kenya
What are the negative aspects of using pesticides? Insects are developing resistance due to improper use and overuse of pesticides People who live near areas where pesticides are applied have higher cancer rates and nerve disorders (see next slide) May affect non-target species (ex: Furadan & lions) Many are persistent so they do not break down in the environment. ▫Can accumulate in soil & water ▫Ex: DDT (see following slides)
Pesticides & Child Development In the picture to the right children were asked to draw pictures of a person. The children from the foothills were not exposed to pesticide spraying. The children in the valley were exposed to pesticide spraying. Children exposed to pesticide have delayed development and mental/nerve disorders.
DDT- A Case Study DDT was used widely as a pesticide in the 1950’s. In 1970’s it was banned in the US because it was linked to problems in predatory birds ▫DDT was washing into waterways via rain runoff. ▫DDT was accumulating in the fat tissue of small fish. ▫These small fish eaten by big fish. ▫Big fish eaten by eagles, osprey, condors, etc. ▫Birds getting DDT toxin. ▫DDT made eggshells weak so when birds sit on them they would break. ▫Bird population declined. US still makes DDT but we sell it to developing countries like Africa who use it to control mosquito populations to prevent the spread of malaria. Because DDT is persistent you can still detect it in the environment and in human breast milk!
What are some alternatives to using chemical pesticides? Biological Pest Control ▫Use of living organisms to control pests ▫Pathogen- use of a disease causing organism to kill pests Ex: Bacillus thuringiensis (Bt) can kill caterpillars when ingested ▫Plant Defenses- specifically bred to have certain defenses like tougher skin or chemical compounds to repel pests ▫Chemicals from Plants- using chemicals made naturally by plants as insecticide. Biodegradable Ex: Chrysanthemums secrete chemical used as commercial insecticide.
What are some alternatives to using chemical pesticides? Disrupting Insect Breeding ▫Growth Regulators Chemical that interferes with some stage of the pest’s life cycle Ex: Flea prevention pills enter blood stream of dog and when flea sucks dogs blood the growth regulator keeps flea eggs from developing. ▫Pheromones Hormones released by one organism to communicate with another. Farmers can release excessive hormone into fields to confuse males so they can’t find females. ▫Physical Barriers Male insects may be treated with X-rays to make them sterile and then released. When mate with females they can’t produce fertilized eggs.
What is Integrated Pest Management (IPM)? Traditional farming methods apply a broad spectrum pesticide that kills any and all insect pests. ▫Con: These may kill good insects too Modern farming methods include use of IPM ▫Using a mixture of farming methods, chemical pesticides, & biological control to reduce pest damage to an economically sustainable level
How does IPM work? Fields are monitored for pest activity. When activity is detected the appropriate pest control is applied. ▫Biological controls are used 1 st - introduce natural predator or pathogen ▫Cultivation controls are used next- vacuuming or pulling insects off plants can be effective (pulling weeds) ▫Chemical control- last resort is to add chemical pesticides. Must vary the pesticide so insect does not become resistant
What is selective breeding? Choosing your plants or animals that have some desirable trait and breeding them to get a pure genetic line of that trait so offspring have that trait. ▫Ex: Save seeds of corn cob that has the most kernels of corn. Grow this corn and use pollen of one to pollinate seeds of another so offspring produce LOTS of kernels per corn cob. Teosinte is where modern corn originated from. Farmers selectively bred it to have more kernels.
What is genetic engineering? Faster way to produce plants or animals that have desirable traits. Process: ▫Isolate genes form one organism & implant them into another. ▫These organisms are called genetically modified (GM) ▫Ex: Bacillus thuringiensis (Bt) bacteria has a gene that kills caterpillars. This gene can be isolated from Bt and inserted into corn If caterpillars eat corn they die
What are the benefits & risks of GM foods? (See article page 436-437) Benefits: ▫Probably more safe than crossbreeding b/c can isolate specific gene you want ▫Vegetables & fruit can last longer on shelves ▫Can add nutrients to food (Golden Rice) ▫Crops can grow close together on small parcels of land- get higher yield ▫Make food resistant to viruses, fungi, bacteria ▫Grow faster ▫Have higher yields ▫Can grow in sandy or salty soil Risks: ▫Is it safe to put an animal gene into a plant gene? ▫Allergic reactions Arctic fish genes that resist freezing are being added to strawberries so strawberries will be resistant to frost. What if someone who eats this strawberry is allergic to fish? ▫Religious or ethical reasons What if you put a pork gene into a crop and that violates their religious or ethical (vegetarian) beliefs? ▫Wild plant contamination If you add herbicide resistance gene to crop and a weed cross breeds naturally and gets that gene then weeds will become resistant and apply herbicide will not kill them
Are you eating genetically modified food? You probably eat GM foods everyday. ▫Kool Aid ▫Coke products ▫Anything made with corn, corn syrup, or soybean Tostitos Doritos These foods do not have to be labeled as genetically modified.
What is sustainable agriculture? Low-input farming Conserves natural resources & keeps land productive indefinitely Minimizes use of water, pesticide, fertilizer Ex: ▫Using crop rotation ▫Growing crops that like sun to shade others that need less sun
You should be able to… Define the term pest Compare the benefits and environmental impact of pesticide use Describe how biological pest control is part of integrated pest management Describe how genetic engineering is used in agriculture.