SWES 210 1st Edition Lecture 13Outline of Last Lecture II. World food productions since 1960a. Norman Borlaug and the green revolutionb. MonocultureIII. Nutrients and fertilizersa. Essential plant nutrients b. Mineral nutrients (macro and micronutrients)c. Photosynthesisi. Necessity for N and P (limiting for primary productivity)d. Iron also a limiting plant nutriente. Algae blooms (affecting coastal and open ocean waters)f. Fertilizer (N and P) from Midwestern farms affecting water quality in gulfIV. Dead Zones globallyOutline of Current Lecture V. Green revolution lead to the development of monoculturea. PesticidesVI. Pests evolve resistance to pesticidesa. Mutationsb. Selection acts on diversityVII. Geens to proteinsa. DNA RNA ribosomeb. tRNAVIII. example of herbicide resistancea. roundup ready seedsb. glyphosate (NPR report)IX. biocontrola. biological controlb. cactus moths and the prickly pearc. biocontrol agents may become pestsd. bacillus thuringiensis (Bt)X. integrated pest management (IPM)Current Lecture- Green revolution monoculture farming with high inputs: water, fertilizers, pesticides, machineryo Monoculture= large expanses of a single cropThese notes represent a detailed interpretation of the professor’s lecture. GradeBuddy is best used as a supplement to your own notes, not as a substitute.o Disconnection from natural fertilization and pest control measures- complex natural systems simplifiedo Pesticides= poisons that target pest organisms (insecticides= kill insects, herbicides= kill plants, fungicides= kill fungi)- Pesticides are “greener” than they used to be: compare glyphosate and DDT (dichloro-diphenyl-richloroethane)o Use? o Toxicity?o Contamination of water soil and air?o Pest resistance to pesticide (i.e. pesticide no longer does the job)?- Pests evolve resistance to pesticideso As of 2008, 8000 known cases of resistance by 556 insects to over 300 pesticides- How to pests get “innate resistance”?o Mutations= genetic diversityo Selection acts on that diversityo Most pests are killed. Those with innate resistance survive- Genes to proteinso DNA RNAo Then to ribosomeo tRNA bring protein building blocks (amino acids)o DNA= double helix, RNA= single strando Segments of DNA are called genes. Genes code for proteins.- An example of herbicide resistanceo Roundup ready seeds: seeds that are genetically modified to withstand application of the round-up herbicide (glyphosate)o How do they work?: plant roundup ready seeds, spray the field with roundup and weedsare killed, the crop is now.o How could the weeds develop roundup resistance?: palmer amaranth (pigweed) for example- Crops engineered to withstand spraying with roundup (glyphosate)o NPR report- march 7th, 2012 Farmers face tough choice on ways to fight new strains of weeds National summit on strategies to manage herbicide- resistant weeds- Another approach; biological control (bio control)o Biological control= uses a pest predators to control the pest Reduces pest populations without chemicals Reduces chemical useo Cactus moths control prickly pear ( in this case the pest)o Following this success, cactus moths were introduced in other parts of the worldo Used in Caribbean islands- spread to Florida- Biocontrol agents may become pestso It is risky to introduce an organism from a foreign ecosystem into a new ecological context The effects of an introduced species are unpredictableo The agent may have “nontarget” effects on the environent and surrounding economies Cactus moths are eating rare Florida cactio Removing a biocontrol agent is harder than halting pesticide use Biocontrol use must be carefully planned and regulated- Another example of biological controlo Bacillus thuringiensis (Bt)= soil bacterium that kills many pests (caterpillars and some play and beetle larvae) naturallyo Commonly used as a biological pesticideo Alternatively, the Cry toxin produced by the bacteria may be extracted and used as a pesticideo The gene responsible for the Cry toxin has been isolated and incorporated into Monsanto’s GM “Bt” cotton, corn, and potatoeso Bt is a gram positive soil dwelling bacterium, can also occur naturally on the cut of many caterpillars and various types of moths and butterflies as well as on leaf surfaces, aquaticenvironments, animal feces, insect rich environments, flour mills, and grain storage facilities- Integrated pest management (IPM)o “IPM is a scientifically based, world wide standard for managing pests. It encourages the use of multiple and flexible strategies for the control of insects, weeds, rodents, and other vertebrates and plant, animal, and human diseases”o biocontrolo chemicals, if necessaryo population monitoringo habitat alterationo crop rotation and transgenic cropso alternative tillage methodso mechanical pest