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Author: Dr Kelvin Klemm

( Article Type: Explanation )

Pesticides can be categorised as a diverse group of chemicals that kill insects.

Domestic pesticides are used indoors to kill small clusters or individual insects, whereas agricultural pesticides are used on a large scale on crops, or livestock. Domestic pesticides have been an aspect of life for centuries in the form of 'old wives' remedies.' For example, in South Africa it has been known for many years that putting Khakibos on carpets drives out fleas, and also that filling a thatch house with smoke rids the house and thatch of many insects.

However, in more modern times a variety of aerosols, powders, liquids and smoke pellets have been available in supermarkets to attack a wide spectrum of insect pests found in and around the home. Some of these chemicals are deceptively benign, and cases are known of children - who have used the spray in large quantities in a confined space - who have suffered headaches, swollen eyes, constricted throats or even quite serious poisoning.

In the case of agricultural pesticides, they have been of great benefit to agriculture in that they have enabled crops to be grown in areas that would normally have been impossible due to resident problematic insects. They have controlled transient insect plagues before whole crops are destroyed, and they have enabled the authorities to tackle large-scale problem pests such as the major locust swarms of earlier eras that wiped out hundreds of kilometres of crops.

Insecticides are used on animal herds to tackle diseases and, as a preventative measure, to prevent parasites from infesting animals, which could lead to sickness or reduced market value of the herd. However, agricultural pesticides need to be used with skill and foresight, which has not always been the case. Incorrect use or overuse can eliminate beneficial insects as well as the target insects. Furthermore, pesticides can migrate by wind or water to areas that they were not intended to reach, thereby causing unintended damage to insect ecological systems which, in turn, can have a detrimental effect on insect pollination and other essential agricultural systems.

Over use of pesticides can creat a pesticide treadmill situation in which continued regular use becomes a necessity. As agricultural circumstances change, research and development continues to develop more advanced insecticides that have refined properties such as being more target specific.