• Join over 1.2 million students every month
  • Accelerate your learning by 29%
  • Unlimited access from just £6.99 per month

Chemical control needs effective government. Discuss the use and abuse of pesticides of modern agriculture.

Extracts from this document...

Introduction

AS Level Biology Essay - Chemical control needs effective government. Discuss the use and abuse of pesticides of modern agriculture. Rachel Miller L6T Today, pesticides are widely used as a way of maximising the output of crops and animals in agriculture. By growing or maintaining large populations of one species of animal or crop plant in one particular area, a large food supply is created for other organisms such as insects. These other organism's populations are then allowed to become much bigger than they would normally be. These organisms rapidly become pests diminishing the yields of the cultivation. As world hunger is a problem that is prevalent today, to be able to maximise world food production is an important issue that needs close attention, and any possible solution to this problem should be considered. Estimates indicate that without the problem of insect pests alone, world food production would increase by about a third; as this represents the loss with the current control measures, it would indisputably be disastrous if control of insect pests alone was not attempted. ...read more.

Middle

Furthermore weeds can prove toxic to animals that graze on the land. Herbicides make up the majority of pesticides used today, and also seldom cause serious environmental damage. They are important for the control of weeds and furthermore the farmer no longer has to turn the soil or till it before use. This reduces the risk of soil erosion, and saves time, money and effort There is a range of herbicides with different actions on weeds: * Pre-emergence herbicides - used before the plant grows. For example, Paraquat is very toxic and will kill any plant above the ground that it comes into contact with. Yet it is broken down before any crop plants emerge from the soil. * Post emergence herbicides - sprayed over the crop plants, killing only weeds (being selective). The best known ones are the phenoxy compounds, e.g. 2,4-D (2,4-dichlorophenoxyethanoic acid), 2,4,5-T (2,4,5-trichlorophenoxyethanoic acid) and MCPA (2-methyl-4-chlorophenoxyethanoic acid). These are used against broad-leaved plants (dicotyledons), not those such as grasses and cereals (monocotyledons), and use natural plant growth regulators (synthetic auxins) ...read more.

Conclusion

These include pyrethrins extracted from the flowers of the African daisy Pyrethrum cinereafolium, and nicotine from the tobacco plant Nicotiana tabacum. Substances have been synthesised to act as insecticides. These fall into four categories: pyrethroids, organochlorines, organophosphates and carbamates. There are many problems with using pesticides. The over-use of pesticides has led to a number of ecological problems. Insects have developed that are resistant to pesticides, the toxicity to non-target species, pest resurgence, pesticide persistence and mobility within the environment and bioaccumulation within an ecosystem; as discussed previously. When strains of insects appear which are resistant to a pesticide they have a superior advantage over the non-resistant insects (as long the particular pesticide they are resistant to is in use). While the non-resistant organisms are killed, the resistant insects will increase in numbers as competition is reduced. This is very common; as in the 1940s DDT was used extensively to success, in the 1950s DDT was used in the fight against insect-bourne diseases, only to discover that many insects had evolved strains resistant to DDT. By 1987, over 500 species of insect had been identified as resistant to one insecticide or another. ...read more.

The above preview is unformatted text

This student written piece of work is one of many that can be found in our GCSE Living Things in their Environment section.

Found what you're looking for?

  • Start learning 29% faster today
  • 150,000+ documents available
  • Just £6.99 a month

Not the one? Search for your essay title...
  • Join over 1.2 million students every month
  • Accelerate your learning by 29%
  • Unlimited access from just £6.99 per month

See related essaysSee related essays

Related GCSE Living Things in their Environment essays

  1. Marked by a teacher

    The Issues of Pesticides.

    4 star(s)

    Most insects have rapid reproduction rates, so the evolution of resistance can be quite quick. Another difficulty is pest replacement, or secondary pest outbreak. This occurs where crops become affected by another pest species. Once one pest species that is not affected by the insecticide may become a pest (Food, Farming and the Environment, Damian Allen and Gareth Williams, 1997).

  2. Branded Bleach is more effective at killing E. coli than Non branded bleach - ...

    As bleach is chlorine based product chlorine gas can be produced on rare occasions, which is toxic as it irritates the respiratory system. * The Escherichia coli bacterium - risk as a bacterial infection. To prevent spreading and contraction cuts on hands should be covered with a waterproof plaster, avoid

  1. The comparison of bacterial content in a range of milks.

    Phenolphthalein: dispose of down the sink, flushed with plenty of water. Date: The burette must be held at 90� to eye level in order to prevent the meniscus of the sodium hydroxide from angling and therefore producing inaccurate results. Apparatus - Burette-25cm� - Conical flask x6 - Milk: - Semi-skimmed

  2. DISCUSS THE CONCEPT OF HOMEOSTASIS PARTICULARLY IN RELATION TO TEMPERATURE CONTROL

    the internal environment All animals produce body heat as the result of metabolic processes. Even in the most efficient animal most of the energy released is lost for useful work. Some animals are able to use this waste heat, to rise above the restrictions of the environmental temperature variation and remain active all year round.

  1. The Effects Of Large Scale Use Of Pesticides.

    For example fungicides can be important pollutants. Many of them contain either Copper or Mercury, as fungi are very sensitive to these two elements. Mercury is toxic to humans. Cases have arisen, for instance in Japan, where people have died as a result of eating fish and molluscs, which had accumulated high concentrations of Mercury (Advanced Biology, Michael Roberts, 2000).

  2. Soil erosion

    Both Dryland salinity and soil erosion lead to land degradation. Land degradation is the decrease in the state of the land due to misuse and/or overuse, usually from a chain of events starting from loss of vegetation and other causes.

  1. Monitoring an Organism

    They sleep on trees in nests they construct. Therefore we are doing this coursework to help them survive. We are monitoring their behaviours to help them survive in the zoo and in the wild. The zoo keepers need to know how to keep them the same in both conditions, in the zoo and in the wild.

  2. What Factors are responsible for the success of Insects?

    Shape, too, is important - in a short fat animal the extended distances from the external environment to the active muscles would simply be too great for the diffusion of oxygen to operate. Hence most existent large insects are generally narrow, so that the maximum distance between the external oxygen source and the muscles is not increased greatly.

  • Over 160,000 pieces
    of student written work
  • Annotated by
    experienced teachers
  • Ideas and feedback to
    improve your own work