First off, what is a pest? A pest is an organism that humans consider harmful, annoying, a threat, or just simply inconvenient. For example a dandelion: it could be a pest just because it is an ugly weed that spreads throughout areas fast and easy, or it can be a pest because people are allergic to the seeds it sets off in the wind, after blooming. The removal of one pest would mean the declining or over population of other organisms in the ecosystem. There are two types of pesticides that can be used to get rid of these so called pests.
Pesticides may be naturally occurring substances or synthetic (man-made). Natural pesticides originate from venom of animals [for example snakes], and plants [for example nicotine]. Another natural pesticide is salt. Chemicals taken from plants and animals create a much lower risk for humans and ecosystems because they are natural and are not harmful to the environment. Synthetic pesticides, such as DDT, are made in the lab. They are generally more harmful because organisms don't have the enzymes to break them down. Some of the short-term benefits in using these pesticides would be that less diseases would be transmitted through insects, it aids the growth of food supplies in the agriculture industry, and it gets rid of unwanted pests. Also, current estimates are that insects, diseases, and weeds destroy approximately one-third of the world food supply, even with the use of the most current pest management technology. Losses without this technology could soar to 60 to 80 percent (Chambers, 1992). New pesticides that were recently created, are less harmful to ecosystems than DDT, because that are water soluble and animals can remove part of it from their bodies. .
Pesticides are used to remove the organisms that cannot survive, and it leaves the stronger organisms with less competition from food. However in 1980, 425 insect species had become resistant to pesticides.