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The Issues Associated With Pest Control.

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The Issues Associated With Pest Control The two main types of pest control are biological and chemical control, and there are different types of these, each of which has issues associated with them. Chemical pesticides can be split into three categories: insecticides, herbicides and fungicides. Each of these combat different types of pests: insects, weeds and disease causing fungi. There are three types of pesticides which work in different ways to eliminate pests and increase the yield of the crops. Contact pesticides are sprayed directly onto crops. They are absorbed by insects through spiracles, which are gas exchange pores, and are absorbed by weeds and fungi through their surfaces. The pests are poisoned and therefore cannot compete with or destroy the crop plants. Contact pesticides are relatively cheap, but their effects are short lived and they have to be applied regularly. This method is not completely effective; however, because spraying of the crops does not guarantee that each pest is poisoned and killed therefore the plants can still be destroyed. ...read more.


Chemical pesticides are very expensive to develop because they have to be extensively tested before being used widely. It needs to be specific and not damage any organisms that do not affect the crop plants. They also need to be chemically stable, yet biodegradable so that they do not decompose before application, yet will be broken down easily in the soil to harmless substances. Pesticide developers must spend money ensuring that their product will be effective, but they also need to make sure that these costs will be covered by sales. Increased use of pesticides can result in the development of resistance. Genetic mutations in pests can mean that specific pesticides no longer work; therefore new ones must be developed. This results in more costs for manufacturers, which can be covered by sales, but the process must begin again as the pests become resistant once again. Environmentally, pesticides can be very damaging. If they are not specific, they can wipe out populations of organisms which were natural predators of the pests, and can result in plants not being pollinated because of eradication of insects which would do this. ...read more.


This can then prove fatal for the bird of prey, and can lead to a decrease in fertility, and sometimes can almost wipe out populations. Many pesticides which have been found to have highly dangerous effects have been banned from use in some countries, especially if they have been found dangerous to humans. Biological control uses other organisms such as predators or parasites of the pest to control them. There are none of the environmental issues of chemical control associated with biological control because each pest is preyed on by one specific predator which does not affect any other organism. Toxic chemicals are not involved; therefore bioaccumulation is not a problem. Persistence is also eradicated, because as the pest numbers decrease, the prey decreases and therefore the population of predators will decrease. In most cases of biological control, the pest cannot become resistant to the method of control, but in cases where viruses are used it is possible. For example, the myxomatosis virus is used to control rabbits as pests, but some rabbits now have genetic resistance to the virus and therefore it does not work as effectively. ...read more.

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