2Pesticides – Agricultural Chemicals Industrial agriculture relies on pesticides to produce their crops.A pesticideIs a poison used to destroy pests, such as insects, rodents, or weedsPesticides can also harm:Beneficial plants and insects, wildlife and people
3Pesticide Resistance Pesticide Resistance Over time, spraying large amounts of pesticide to get rid of pests usually makes the pest problem worse.Pest populations may evolve resistanceMost surviving individuals have characteristics that allowed them to tolerate the pesticide.Survivors pass on genetic characteristics for tolerance.Subsequent pesticide applications become less effective.More than 500 species of insects have developed resistance to pesticides since the 1940s.
4Persistence Persistence Does not break down easily or quickly in the environment.Do not break down into harmless chemicals, and they accumulate in the water and soil.Some pesticides have been banned in the United States for decades but can still be detected in the environment.Persistent pesticides become attached to small soil particles and are easily moved by wind or water.Persistent pesticides have been discovered in polar ice and are present in detectable amounts in the bodies of animals, including humans, throughout the world.
5Agricultural Chemical Use HerbicidesAre used to control unwanted plants.About 60% of pesticides used in U.S. are herbicides.Weeds compete with crops for soil nutrients.Traditional weed control methods are expensive in terms of time and energy.Several major types of herbicides are in current use.AuxinsSynthetic plant growth regulators mimic natural growth regulatorsPhotosynthetic disruptorsEnzyme inhibitors
6Some herbicides are toxic to all plants (nonselective), and some are selective as to the plant species they affect.Atrazine is often used to control broad-leaf and grassy weeds.Glyphosate (Roundup) is a broad-spectrum, nonselective, systemic herbicide used to control plants.Fungicides are used to protect agricultural crops from spoilage, to prevent the spread of disease, and to protect seeds from rotting in the ground before they can germinate.Methylmercury is extremely toxic to humans.In some parts of the world, governments pay a bounty to people who kill rats because they can destroy agricultural crops.Rodents also carry diseases harmful to humans.Rodenticides must be used with great care to prevent poisoning nontarget organisms.
7Problems with Pesticide Use Bioaccumulationis the process of accumulating higher and higher amounts of material within an organism’s body.Many persistent pesticides are fat soluble and build up in fat tissues.Biomagnificationis the process of acquiring increasing levels of a substance in bodies of higher trophic-level organisms.DDT, mercury, and PCBs are all known to accumulate in ecosystems.DDT was banned in the U.S. in the early 1970s.
10Problems with Pesticide Use Pesticide resistance is a problem associated with the widespread use of pesticides.Most pesticides are not species-specific, and kill beneficial species as well as pest species.Many kill predator and parasitic insects that normally control pest insects.Insecticides may change the population structure of the species present so that a species not previously a problem may become a serious pest.Pesticides are designed to kill organisms, so they may also be dangerous to humans.Short-term and long-term health effects to persons applying pesticides and the public that consumes pesticide residues in food are also concerns.
11Acute poisoning during application sometimes occurs when farmers cannot read caution labels on packaging or do not have access to protective gear.The WHO estimates between 1 million and 5 million acute pesticide poisonings occur annually, resulting in 20,000 deaths.For most people, the most critical health problem is inadvertent exposure to small quantities.Farmers who were occupationally exposed to pesticides over many years show that they have higher levels of certain kinds of cancers than the general public.Chronic minute exposures to pesticide residues in food or through contaminated environments are also of concern.
12Why Are Pesticides So Widely Used ? Food ProductionWorldwide, pests destroy 35% of crops.This represents an annual loss in U.S. of $18.2 billion.Economic ConcernsPesticides increase yields and profits.Health ReasonsInsecticides curtail many diseases.
13Problems with Pesticide Use A perfect pesticide would have the following characteristics:InexpensiveOnly affect target organismsShort half-lifeBreak down into harmless materialsNewer pesticides have fewer drawbacks than early pesticides, but none are devoid of problems.
15How is Arable Land Lost? Land Degradation ha stands for hectare Which is 10,000 square meters or about 2 and a half acres.3 million ha of cropland ruined annually via erosion4 million ha transformed into deserts8 million ha converted to non-agricultural usesConverting arable land with subdivisionsOver the past 50 years, 1.9 billion ha of agricultural land has been degraded.
16Arable Land Unevenly Distributed North America and Europe are particularly well suited to growing while some other parts of the world lack suitable soil, topography and water.The amount of available cropland is shrinking.Exceptions are South America and Oceania, where forests are being converted to farmsGains in agricultural production have come from increased fertilization, pesticides and irrigation rather than more land.
17Land DegradationDefinitions of degradation are based on both biological productivity and expectations of what land should be like.Generally, land is considered degraded whenSoil is impoverished or erodedRun-off is contaminatedBiodiversity is diminished.Water and wind are the driving forces for vast majority of soil degradation.
18ErosionErosion is a natural process, resulting in redistribution of the products of geologic weathering, and is part of both soil formation and soil loss.Worldwide, erosion reduces crop production by equivalent of 1% of world cropland per year.Erosion results in sediment loading of rivers and lakes, siltation of reservoirs, and smothering of wetlands and coral reefs.Wind can equal or exceed water as an erosive force, especially in a dry climate and on flat land.
19Desertification Conversion of productive lands to desert threatens 1/3 of the earth’s surface and 1 billion peopleRangelands and pastures are highly susceptible (overgrazing, soil degradation).Africa and China are of particular concern.Rapid population growth and poverty create unsustainable pressures.Removal of trees for fodder and firewood triggers climate change that spreads desertification.
21Genetic Engineering and Agriculture Removes DNA from one organism and splices it into the chromosomes of another.Produces genetically modified organisms (GMOs) with new traits.Can produce crops with pest-resistance and wider tolerance levels to frost, drought, low nutrient soils, salty soils, etc.Can improve protein or vitamin content of cropCan incorporate oral vaccines into foods such as bananas for use in developing nationsAnimals can be modified to grow faster or produce pharmaceuticals in their milk.It differs from traditional breeding methods in that desirable genes from any organism can be used, not just those from the species of plant or animal being improvedCan also be called transgenic organisms
24Examples of GMO’sBiotechnologists have recently created plants containing genes for endogenous insecticides.A gene from the bacterium Bacillus thuringiensis (Bt) makes toxins that are lethal to butterflies and beetles. These genes have been transferred into corn, potatoes and cotton. Reduces pesticide use and increases yield.Concern has arisen over several points.Spread of genes into wild populations leading to resistance in pestsEffect on nontarget speciesTransgenic crops can be engineered to tolerate high levels of pesticides.Roundup Ready and Liberty Link are two most popular. Crops can grow in the presence of the pesticides (called Roundup and Liberty) while weeds within the field are killed.
25Issue with GMOs Concerns about GMO seed or pollen spreading in wild Produce superweeds resistant to pesticides.Native biodiversity may be reduced.Novel toxins might be createdCartagena Protocol on Biosafety regulates these concernsUS is an active observerKnowing what foods have/are GMOsDetermined to be safe for human consumptionGMOs are not currently labeledFDA finds it would be counterproductive and expensive to labelYou are already eating GMOs as 60% of processed food in the U.S. contains GMOs.Technology may only be available to the rich, making family farms uncompetitive and driving poor nations further into poverty.
26Environmental and consumer groups have campaigned against GMO’s European nations have bans on GMOs.Worry that genetically modified animals will escape captivity and outcompete their wild relatives.Salmon with added growth hormone gene grow 7X faster than their wild counterparts.
27Domestication and Genetic Diversity Domestication of crops and livestock causes a loss of genetic diversityFarmer selects and propagates animals with desirable agricultural characteristicsMany high yielding crops are genetically uniformHigh likelihood that bacteria, fungi, viruses, etc. will attack and destroy entire cropIncreasing Livestock YieldsHormone supplementsUS and Canada do thisEurope does not citing human health concerns
28Concentrated animal feeding operations In North America animals are fattened on grain in feedlotsLocal air and water pollution caused by untreated wasteWaste can contaminate soil and food.Recent spinach contaminationHigh density of animals requires constant use of antibiotics, leading to antibiotic resistance in microbes.40% of antibiotics produced in US are used in livestock operationsProblems with increased bacteria resistance
30Seafood Aquaculture supplies food, but it uses wild populations to stock and feed captive populationsdestroys mangrove forests and wetlands used as nurseries for all marine speciesallows the spread of diseasereleases large quantities of feces, antibiotics and other pollutants
32The Problems With Monocultures Biodiversity lossLoss of habitat through conversion of grasslands and forests along with wetland drainingFish kills from agricultural runoffExtermination of predatorsLoss of genetic diversity due to monoculturesGenetic pollution from bioengineered or selectively bred organisms that “escape” and interbreed with native speciesSpread of diseases from agroecosystems to natural ecosystemsWaterAquifer depletionIncreased runoff, due to land clearing and plowingSediment pollution from runoffFish kills from pesticide runoffSurface and groundwater pollution from pesticides, antibiotics, and fertilizersOver-fertilization of lakes, rivers, and coastal ocean from fertilizers, livestock wastes, and food processing wastes