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Is Biological Pest Control Better Than Chemical Control?

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Is Biological Pest Control Better Than Chemical Control? A pest is an organism that reduces the quality or the yield of a crop. They spread disease, and damage crops, which reduces the yield. Aphids and other insects do a lot of damage, as well as slugs and snails. Viruses, fungi and bacteria are also pests that cause disease, such as, potato blight. Weeds, such as wild oats, grow in the wrong place and cause interspecific competition. This makes the crop compete for space, nutrients, light etc. therefore, it is extremely important to control pests, and there are two methods for doing this. Chemical pest control is the use of insecticides, herbicides and fungicides. Biological pest control is the use of other organisms which are predators or parasites of that pest. A proper definition would be "biological control is the use of natural predators, parasites, fungi; pheromone lures etc to control pests, without the use of chemical pesticides." There are many advantages and disadvantages of both forms of pest control, and I will investigate in this essay which method of pest control is more effective. There are three types of chemical pesticides used to control pests: contact, systemic and residual. Contact pesticides are sprayed directly onto the crop. They are absorbed by the insect through spiracles (gas exchange pores) along its body. Contact herbicides and fungicides are absorbed directly through the surface. Systemic pesticides are also sprayed onto crops, but they're absorbed by the leaf and transported around the plant. Insects that suck sap, such as aphids, take in the insecticide and are poisoned. Residual pesticides are sprayed onto the soil or the seeds before they are planted. They remain active in the soil and kill fungal pores, insect eggs and larvae, and weed seedlings as they germinate. The advantages of using chemical control are that there are economic benefits. Many of the chemicals are cost effective. They are relatively inexpensive, such as contact herbicides and fungicides, compared to the benefits of their use. ...read more.


This chemical pollution may kill many organisms some distance from the crop. DDT was even found in the penguins in the Antarctic. Presumably it had been in the fish they had eaten. It took years to discover the harmful effects of DDT. There is the danger that other harmful effects of pesticides have not yet been discovered, so the amount of chemicals on our food is extremely dangerous. Biological control is the intentional manipulation of natural enemies by man for the purpose of controlling pests. Biological control involves the use of other living organisms to control the pests. They are usually predators or parasites of the pest. Pests are not usually native to the environment in which they are pests in. They have no predators to control their growth and activities. For biological control to be effective, their predators and parasites need to be traced form their original environment, and then introduced into their new environment. Trials need to be carried out to ensure the predator will only attack the pest and no other organism as it will disrupt population growth curves. The predator must not carry any diseases that it might spread to the crops and it must be able to survive in its new environment. It forms a predator prey relationship if it is successful, where the number of predators increases once the number of prey increase, and the number of predators decreases if the number of prey decrease. There are three ways to apply biological control: conservative, augmentation, and classical. Classical is when the natural enemy is introduced into the environment. The predator is not native to the environment, so classical biological control is when exotic predators are used to combat native pests. This form of biological control was used on a weed that was out of control in Arizona called puncture vine. It had spines that could puncture tyres and it had a major impact on vehicle traffic in rural Arizona. ...read more.


These are its only advantages however, as it has a negative effect on the environment. It causes the build up of poison throughout the food chain, making lethal concentrations occur at the top of the food chain. This is called Biomagnification - pesticides accumulate in plants, insects and are concentrated more and more as they move up the food chain. This causes problems with fish and wildlife. Pesticides are also a lot more expensive in the long term, and pests keep becoming resistant to it, so money is lost on pesticides that are not effective any longer, and it has to be constantly re-applied. It requires input and additional effort periodically. I think biological pest control is environmental friendly, and a much safer way of controlling pests. It is also much less expensive and pests do not become resistant to its predators. Biological control is more specific and does not affect other non target organisms, and it is a more permanent way of controlling pests as they cannot develop any resistance. Chemical control has too many dangerous side effects to humans, especially, unlike biological control which does not affect any other organism other than the target one. Chemical control can lead to greater crop damage than if no pesticide had been used due to resurgence of pest populations. When pests are killed the predators are either killed, leave the area for lack of food, or starve. When the next generation of pests arrive, the populations explode, because predators are not present to keep numbers in balance. Biological control, on the other hand, develops a predator-prey relationship to prevent this from happening. There are secondary pest outbreaks associated with chemical control, which is not the case with biological control. Once a pest and its predators have been removed, another pest replaces it. There are also many non-target side effects, such as contamination of water, food, and death of workers. Biological control is better than chemical control because it does not cause death of humans, and does not have a severe impact on the ecosystem. ...read more.

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