Pest control is a term that identifies various methods used to reduce or eliminate pests. Any living thing that kills plants or stunts their growth, carries disease, or is harmful in other ways may be considered a pest. Pests include insects, weeds, mammals, pathogens (disease-causing microorganisms), and nematodes (microscopic roundworms). The two major pest control methods are (1) pesticides, chemicals used to kill pests, and (2) natural pest control, which uses various preventive measures instead of chemicals. Many pest control experts favor a diverse approach called integrated pest management, which combines pesticides and natural control methods.
Pesticides
are classified according to the pests they control. The four main types of pesticides are (1) herbicides, (2) fungicides, (3) rodenticides, and (4) insecticides.
Herbicides
eliminate plants that grow where they are not wanted. Farmers use them to reduce weeds among their crops. Herbicides also control weeds in such public areas as parks and ponds. People use herbicides in their yards to get rid of crab grass, dandelions, and other weeds
Fungicides.
Certain fungi cause disease and may infect both plants and animals, including human beings. Fungicides control plant diseases that infect food crops. Wood used for building houses is often treated with fungicides to prevent dry rot.
Rodenticides
are used to control rats and other rodents that destroy stored food. Rats also carry bacteria that cause such diseases as rabies and typhus.
Insecticides.
Farmers use insecticides to protect their crops from insect damage. In urban areas, public health officials use them to fight mosquitoes and other insects that carry germs. People use insecticides indoors to control such pests as ants and cockroaches.
Effects of pesticide use.
Pests may develop resistance to pesticides so that higher dosages need to be used over time. Eventually pesticides can become ineffective, so there is a constant need to create new pesticides. Hundreds of species of plant and animal pests have been found to be resistant to at least one type of pesticide.
Pesticides are poisons that can have unintended effects on people and on the environment. Wind or rain can carry herbicides from weeds to desirable plant species, such as trees and flowers. Insecticides kill beneficial insects, such as honey bees and ladybugs. Health officials worry about small amounts of pesticides that remain on food. Most people and many animals have pesticide traces in their fat tissue.
People used chemical pesticides for many years without realizing their harmful effects on humans and the environment. In 1962, American marine biologist Rachel Carson wrote the book Silent Spring to call public attention to pesticide dangers. The book helped to reduce pesticide use throughout the world.
In the 1980’s, scientists developed the first neonicotinoid, a type of pesticide that kills insects by disrupting the nervous system. Neonicotinoids, also called neonics, were thought to have little effect on humans and other vertebrates (animals with backbones). This made them popular with farmers and gardeners. By the mid-2000’s, neonicotinoids were the most commonly used insecticides in the world. In 2006, bee colony die-offs were increasingly reported in many countries. People began to worry about the possible link between neonicotinoids and colony collapse disorder , a syndrome that was behind many of the die-offs. The European Food Safety Authority (EFSA) and other organizations have judged neonicotinoids to be harmful to both wild bees and managed honey bees. In 2018, the European Union voted to ban the use of three neonicotinoids—clothianidin, imidacloprid, and thiametheoxam—on all outdoor crops.
In the United States, the Federal Insecticide, Fungicide, and Rodenticide Act, originally enacted in 1947, limits pesticide use on food. It requires users of the most dangerous pesticides—called restricted use pesticides—to have a special license to use them. The federal government may order people who use pesticides improperly to pay large fines.
Natural pest control
helps avoid pest attacks without the use of chemical pesticides. For example, destroying plants after harvest will deny pests food and shelter. Crop rotation (planting a different crop each year) prevents excess numbers of any one pest from building up. Pest managers also use biological control methods, such as encouraging a pest’s natural enemies.
Integrated pest management,
also known as IPM, has largely replaced reliance on pesticides as an approach to pest control. IPM combines a limited use of chemical pesticides with natural control methods. Pest managers track levels of pest infestation and apply pesticides only when they will produce the greatest benefits. For example, if a pest left untreated would produce $50 worth of damage and applying a pesticide would cost $100, then the best decision is to leave the pest untreated. Pest managers use natural control measures until the cost of not controlling a pest exceeds the cost of applying a pesticide.
