Rachel Carson wrote early and powerfully about the risks of pesticides.

Agriculture has always had one major threat looming over it: pests. Potentially ruining a harvest, farmers are obliged to take action against pests. There are various methods to combat the problem and various advantages and disadvantages to each method.

Pesticides[edit | edit source]

One way to protect crops is to use chemical pesticides. A chemical pesticide is used to control, repel, attract or to kill pests, for example, insects and weeds that are considered a nuisance or threat to crops.

Disadvantages[edit | edit source]

  • Human health - Pesticides are most often, but not always, poisons; thus farmers must be careful not to overuse chemical pesticides as they could cause harmful side-effects to non-target organisms, especially people, including the users (farmers), who can easily come in contact with the chemicals during use, and consumers when residues of pesticide are left behind on crops that are then eaten.
  • Resurgence - It's not only people that are affected by pesticides, but also the environment. Pesticides kill not only the pests but also the natural enemies of these pests, a problem known as 'resurgence'. Resurgence means that natural control of pests is disrupted severely and crops suffer as a result. Resurgence can also create new problems: minor pests that are usually kept at low numbers will multiply quickly in the absence of their enemies. The most popular solution to this problem is in an oft-used alternative method to chemical pesticide, biological control.
  • Resistance - One of the earliest discovered problems, was that pests can and do eventually become resistant to the chemicals. When sprayed with chemicals, most pests will be entirely susceptible. However, not all pests are killed, some with a slight variation in their genetic make-up are resistant and therefore survive. Every succeeding generation of the surviving pests will have the same pesticide-resistant genetics and eventually the pests will become entirely resistant to the pesticide. Unaware of how to deal with this problem, farmers often increase their use of pesticides, causing further problems. When resistance is not a problem, pesticides in general are highly effective for controlling pests if the other disadvantages are taken into account.
  • Persistent Organic Pollutants - Another less-known trouble the environment faces as a result of pesticides are known as 'persistent organic pollutants' (POPs). POPs continue to poison non-target organisms in the environment and possibly increase chances to humans of disruption in the endocrine system, cancer, infertility and mutagenic effects, although very little is known about these 'long-term chronic effects' yet.
  • Costs - Due to the possible health risks behind the use of pesticides, the cost of developing new pesticides has risen at an increasingly rapid rate over recent years. Government regulations have become more stringent, slowing the rate of development and in turn increasing the cost of new products. Increasing problems with pest resistance have likewise resulted in shorter market lives for many pesticides than before. All of these factors result in higher costs and potentially lower profits for chemical companies and farmers.

Advantages[edit | edit source]

Despite all the drawbacks that come with chemical control of pests, there are still many reasons that can persuade farmers to still choose to use them:

  • Convenience - The biggest advantage of pesticides is they are readily available and very easy to use unlike alternative methods, such as biological control and other similar methods which can take a long while to plan and often don't have an immediate effect on pests.
  • Costs - When pests must be controlled over large areas of land, pesticides prove to be very cost effective, including when less human labor is needed to maintain the pesticide process. The general effectiveness of the program and its economic benefits are increased greatly still when pesticides are used in a way that reduces the likelihood of the pests becoming resistant to the chemicals used to fight them. If all the correct precautions are used, including using no more than the recommended level, then chemical control of pests can be used effectively.

Biological control[edit | edit source]

When the disadvantages of pesticides outweigh the advantages, farmers look to alternative methods of pest control, the most common being biological pest control. Unlike chemical pesticides, biocontrol uses natural methods to fight pests; i.e., the pests' natural predators.

Advantages[edit | edit source]

  • Natural balance - The most obvious advantage to this method over pesticides is that the natural balance in the ecosystem remains fairly undisturbed. When pesticides are put into use it isn't only the pests that can be affected, but also their natural predators; eventually the pests might even come back in more force, as their natural predators aren't around to deter them anymore.
  • Cost - Biological control proves to be very successful economically, and even when the method has been fairly unsuccessful, it still produces a benefit-to-cost ratio of 11:1. One study has estimated that a successful biocontrol program returns £32 in benefits for each £1 invested in developing and implementing the program, i.e. a 32:1 benefit-to-cost ratio.

Disadvantages[edit | edit source]

  • Reduction rather than eradication - Unlike some cases of chemical pesticide programs, biocontrol reduces, but does not eradicate pest populations. Therefore a successful biological control program relies on finding the right balance between the level of suppression (of the pests) and the level of how much a user is prepared to tolerate the pests. Pests that directly feed on a harvested product are tolerated little and it is unlikely that a suitable level of suppression can be reached solely with biocontrol.
  • Not combinable - It is also very difficult to incorporate biological control with other programs that may use pesticides and thus biological control is a not an effective method at fighting pests that can cause very large scale damage to a crop. Biocontrol is used more effectively against pests with high tolerance levels, i.e. pests that may defoliate plants but not significantly impact crop yields.

Conclusion[edit | edit source]

In conclusion, both chemical and biological control of pests can be used in different ways to fight pests. Chemical pesticides are highly effective against pests that feed directly on crops over a very large area, but must be used safely and economic problems of modern pesticide use must be taken into consideration greatly. Biological control is recognized as being more effective against pests that are tolerable enough to only need to be suppressed, not destroyed entirely – this method is friendlier to the environment and generally more profitable than chemical pesticides.

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