Реферат на тему Pesticdes Essay Research Paper A pesticide is
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Pesticdes Essay, Research Paper
A pesticide is a substance used to kill, control or repel a pest. Pesticides have disadvantages and advantages. They are able to control pests, but it can also kill other organisms as well. Not only do they affect animals but they can effect us, as humans.
It can get into drinking water as well as people’s food. Research has proven that there are other, safer alternatives.
Pesticides have existed since the 1920’s. These types of pesticides range from Acaricides which kill bugs mites and spiders too Rodenticides that kill rodents such as mice, rats, and moles. Other pesticides include Insecticides that kill insects, Avicides which kills off unwanted birds, Algaecides affecting and killing algae and Herbicides which effect weeds, wild grass and any other unwanted plant among a crop. Herbicides are the most used form of pesticide in Canada.
Pesticides have both disadvantages and advantages. Before pesticides were invented, entire crops were lost because of pests like locusts and disease. Now that pesticides exist farmers are able to spray entire crops for bugs, rodents or disease. The pesticides not only can be sprayed on quickly but are also very effective at killing insects , and any other pests. Some pesticides have a negative affect. In the 1950s, farmers used powerful new pesticides to control pest populations. These powerful pesticides killed many different insects and they worked quickly. However, they created some serious short term effects as well as long term effects. One pesticide called DDT, was very effective in controlling pests in Ontario, not only in Ontario but in all of Canada as well as the rest of the world. Farmers in Canada used it on there fruits, corn and grain crops to prevent pests from damaging there crops. Other countries like Asia and Africa used it to kill mosquito’s which spread disease. DDT was very efficient, most insects died soon after they came in contact with the pesticide. It was also easy to apply over large areas because it could be sprayed from airplanes. Unfortunately, DDT killed many other things besides pests. Many harmless insects like bees, butterflies, and ladybugs were disappearing in the areas where DDT was used. When scientists tested animals they found high levels of DDT. The scientists concluded that once DDT entered the body of an animal it stayed there permanently. Over time the DDT would accumulate into dangerous amounts and caused sever sickness in animals . Soon, DDT lost its powerful effect. Eventually insects could not be controlled by DDT. Insects became immune and adapted to the chemical. In 1945 only 15 species were resistant to DDT. Today over 450 species are resistant.1 This shows that pesticides do have positive effects but also have very harmful consequences to animals and other harmless insects. DDT is no longer in use today, governments have banned the product due to its harmful effect.
Pesticides can be found in baby food, and fruits and vegetables. Studies have shown that 50% of baby foods contain pesticides that can be harmful to ones baby.2 Since babies are 10 times more sensitive as an adult, pesticides effective them differently. In one pear there can be up to 5 different pesticides, if a baby consumes the pear it can have several side effects. Since a babies nervous system is sensitive to toxins it can be effected. Also, if a baby is exposed to pesticides early in its life it can cause hormonal and reproductive disorders. This side effect occurs because some pesticides contain the female hormone estrogen and tampers with other hormones in the body. Though, these cases are rare and the amount of pesticides found in baby food is very low it still should be brought into consideration.
A pesticide is usually applied directly on the soil, or onto seeds that have been planted. Either way pesticides come in contact with soil. Once on the soil things several things can happen to the pesticide. The pesticides can be washed below the soils surface and be taken up by plants through there roots where it is stored in the plant. When other animals eat the plant they store the pesticide that was in the plant in there own body.3 The pesticide can also accumulate and move downwards from leaching into the water table. These pesticides can cause several problems, animals and humans can drink the contaminated water , in large quantities it can be harmful. The pesticide can stay in the soil from a day to a year depending on they type of pesticide, the soil, and weathering conditions.
Pesticides are not the only solution to getting rid of pests from crops. One method is to use bacteria that effects only one type of pest. For example, a chemical called Btk is sprayed on forests that causes a deadly disease in the Buddworm and controls it without killing other animals.4 You can also use other bugs to kill insects. For instance, lady bugs can be released on crops. The lady bugs will eat pests like the ladybird beetle and stops it from doing serious damage. Another method is extracting chemicals that smell or repel bugs from a plant. But the most simple way to keep pests from ruining crops is to simply rotate them or change the crops grown every year.
Pesticides have advantages and disadvantages. They help grow successful crops, without them they would be ruined by pests. Everyday scientists are developing new solutions to pest problems. Soon pesticides will not contaminate soils and poison harmless animal and stricter laws will prevent farmers from using other dangerous pesticides.