Presentation on theme: "Chapter 15, Section 2: Pest Control Standards: SEV4a, b, c"— Presentation transcript:
1 Chapter 15, Section 2: Pest Control Standards: SEV4a, b, c Food & AgricultureChapter 15, Section 2: Pest ControlStandards: SEV4a, b, c
2 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
3 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.
4 What are pesticides?Chemicals that kill insects, weeds, and other crop pests.Most are synthetic and some are petroleum basedEx: Atrizine-Herbicide used to kill weedsOveruse has been linked to hermaphroditism in frogsBanned in Europe, still used in USEx: FuradanInsecticideLinked to intentional poisoning of lions in AfricaVIDEO: Lions Poisoned in Kenya
5 What are the negative aspects of using pesticides? Insects are developing resistance due to improper use and overuse of pesticidesPeople 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 & waterEx: DDT (see following slides)
6 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.
7 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 birdsDDT 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!
8 What are some alternatives to using chemical pesticides? Biological Pest ControlUse of living organisms to control pestsPathogen- use of a disease causing organism to kill pestsEx: Bacillus thuringiensis (Bt) can kill caterpillars when ingestedPlant Defenses- specifically bred to have certain defenses like tougher skin or chemical compounds to repel pestsChemicals from Plants- using chemicals made naturally by plants as insecticide. BiodegradableEx: Chrysanthemums secrete chemical used as commercial insecticide.Bottom picture:Some plants produce volatile chemicals which they release into the air when they are being attacked by an insect. These volatile chemicals attract insect predators that come and attack the insect and the plant gets protected.
9 What are some alternatives to using chemical pesticides? Disrupting Insect BreedingGrowth RegulatorsChemical that interferes with some stage of the pest’s life cycleEx: Flea prevention pills enter blood stream of dog and when flea sucks dogs blood the growth regulator keeps flea eggs from developing.PheromonesHormones 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 BarriersMale insects may be treated with X-rays to make them sterile and then released. When mate with females they can’t produce fertilized eggs.
10 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 tooModern farming methods include use of IPMUsing a mixture of farming methods, chemical pesticides, & biological control to reduce pest damage to an economically sustainable level
11 How does IPM work? Fields are monitored for pest activity. When activity is detected the appropriate pest control is applied.Biological controls are used 1st- introduce natural predator or pathogenCultivation 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
12 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.
13 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 cornIf caterpillars eat corn they die
14 What are the benefits & risks of GM foods? (See article page 436-437) Probably more safe than crossbreeding b/c can isolate specific gene you wantVegetables & fruit can last longer on shelvesCan add nutrients to food (Golden Rice)Crops can grow close together on small parcels of land- get higher yieldMake food resistant to viruses, fungi, bacteriaGrow fasterHave higher yieldsCan grow in sandy or salty soilRisks:Is it safe to put an animal gene into a plant gene?Allergic reactionsArctic 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 reasonsWhat if you put a pork gene into a crop and that violates their religious or ethical (vegetarian) beliefs?Wild plant contaminationIf 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
15 Are you eating genetically modified food? You probably eat GM foods everyday.Kool AidCoke productsAnything made with corn, corn syrup, or soybeanTostitosDoritosThese foods do not have to be labeled as genetically modified.
16 What is sustainable agriculture? Low-input farmingConserves natural resources & keeps land productive indefinitelyMinimizes use of water, pesticide, fertilizerEx:Using crop rotationGrowing crops that like sun to shade others that need less sun
17 You should be able to… Define the term pest Compare the benefits and environmental impact of pesticide useDescribe how biological pest control is part of integrated pest managementDescribe how genetic engineering is used in agriculture.