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| pest control- Biological control of pests |
introduction
Pests are a designation of insects that are harmful to humans. Some of them are plants and animals that cause diseases, animals like rats and vertebrates... and plants like some herbs and fungi, which are destructive to human crops.
Eliminating pests or preventing their reproduction, development, or migration is known as pest control. Pests have a significant impact on the global economy if it is controlled Even with current pest control measures, agricultural pests are responsible for the annual destruction of millions of acres of crops worldwide. In Southeast Asia, rodents are known to destroy up to 50 percent of the rice crop before it is harvested. In the United States, more than $500 million is lost each year due to insect and rodent infestations in stored food and grain.
Some insects are considered pests because they eat wood. They pose a threat to wooden structures - houses and other buildings, trees, fences. Several types of ants, bees, and beetles can also damage wooden structures.
To protect agricultural crops and forests use pest control. Rinderpest and many of the pests that threaten human health helped pest control to manage it well and practically. encephalitis, yellow fever, malaria and typhu
chemical control
Chemicals are the only and most common pest control method. or inhibit their growth. For example, insecticides are used to control insects; herbicides to control plants; fungicides and fungicides. Pesticides and rodents. Birds and bird repellents. and bactericides to control bacteria. Pesticides also include chemical activators and growth regulators, which are used to interfere with the normal reproduction or development of pests.
Perhaps chemical pest control began with toxic plant compounds. In the 18th and 19th centuries, farmers planted plants that were poisonous to insects or rodents, such as chrysanthemums or tobacco. Then the plant "soup" was applied directly either to the crops or to the pests. Chemists later discovered that they could extract toxic compounds from these poisonous plants and use the compounds as a liquid mist. Chemicals such as nicotine, petroleum, coal tar, creosote, turpentine, and pyrethrum (obtained from a type of chrysanthemum) were extracted for use in sprayers. Organic compounds such as these were eventually replaced by more effective inorganic chemicals, including arsenic, lime, sulfur, strychnine, and cyanide.
With the advent of synthetic organic compounds during World War II, a radical change occurred in pest control. The discovery of the insecticidal properties of the synthetic compounds DDT (dichlorodiphenyltrichloroethane) - widely used against disease-carrying insects - during the war and BHC (benzene hexachloride) made the idea of pest-free crops realistic. The development of another synthetic organic compound, the selective herbicide 2,4-D (2,4-dichlorophenoxyacetic acid), led to the development of other selective herbicides.
With the advent of synthetic organic compounds during World War II, a radical change occurred in pest control. The discovery of the insecticidal properties of the synthetic compounds DDT (dichlorodiphenyltrichloroethane) - which was widely used against disease-carrying insects - during the war and BHC (benzene hexachloride) made the concept of pest-free crops realistic. The development of another synthetic organic compound, the selective herbicide 2,4-D (2,4-dichlorophenoxyacetic acid), led to the development of other selective herbicides.
With the discovery of DDT, 2,4-D, and BHC, researchers began to develop other synthetic organo-pesticides, including growth regulators, chemical insulators, pyrethroids (compounds with insecticidal properties similar to pyrethrum), and organophosphorus chemicals. This research was extended to develop other non-chemical methods of pest control after the harmful persistence of pesticides in the environment was recognized. It was discovered in the 1950s that DDT and its related compounds do not degrade easily in the environment. The high stability of DDT leads to its accumulation in insects that are food for other animals. Scientists have also found that many insect species rapidly develop pesticide-resistant populations. (See also ecology; pollution, ecology.)
By the 1960s, DDT's value as an insecticide had declined and by the 1970s, strict restrictions were placed on its use. In the United States, the Federal Environmental Pesticide Control Act of 1972 and the Federal Insecticide, Fungicide, and Rodenticide Act of 1972 require pesticide manufacturers to conduct scientific tests on the biological activity, defects, stability, and toxicity of any new pesticide before the chemical can be used. In the late 1980s, the average cost of developing and registering a pesticide was $10 million. In the 1960s and 1970s, public objections were raised against the indiscriminate use of pesticides. The Environmental Protection Agency (EPA) was established in 1970 to determine the past and future environmental damage caused by the widespread use of pesticides, and to prepare programs to address environmental problems.
An alternative concept of integrated pest management has been adopted for many agricultural pests. This approach includes non-chemical pest control methods, including crop exclusion, crop rotation, sanitation, and biological control. These methods complement other pest management programs designed to reduce pesticide use.
biological control
Biological control of pests involves exposing them to predators or parasites. The use of predators and parasites is usually accompanied by a program in which pest-damaged fields are surveyed and pest populations are estimated.
Biological pest control was used by the ancient Chinese, who used predatory ants to control phytophagous insects. In 1776, the use of predators was recommended for the control of bed bugs. The modern era of biological pest control began in 1888 when the Vidalia beetle was brought from Australia to California to control mealybugs. This biological control project saved the citrus industry. (See also citrus; fruit growing; mealybug).
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Insect predators have also been used to control Colorado bean beetle, tomato worm, and aphids. Another biological method is the use of bacteria against insect larvae or grubs. For example, the bacterium Bacillus thuringiensis is used to control gypsy moth larvae, as well as mosquito larvae. In the 1980s, piscivorous nematodes and mosquitoes that attack soil insects such as maize beetles were introduced as biological control agents.
Since the 18th century, the selection of pest-resistant host plants has also been used to control pestsSuccessful wheat breeding programs have led to the development of new wheat varieties resistant to rust and several parasitic fungi that infect the leaves and stems of the plant (see Wheat). The spread of maize has resulted in cultivars resistant to other fungal diseases, including anthrax and leaf blight (see Maize). The classic example of this approach to plant resistance to pest control was the fight against phylloxera, insects that attacked the roots of European wine grapes and almost completely destroyed the European wine industry. The problem was solved by grafting European plants onto resistant American grape rootstocks.
The development of predatory insects to control skeletal pests has had little success. Nematodes have been used against termites in the laboratory, but field tests have been inconclusive. Parasitic wasps used against various types of cockroaches have also failed in the field.
other controls
Cultural control methods are used to alter the environment of the pest and thus reduce access to breeding areas, food and shelter. Cultural methods have been used to control yellow fever mosquitoes, which breed in swamps and small ponds. By draining swamps and eliminating stagnant puddles and other receptacles in which water collects, the number of potential breeding sites for the pest is reduced (see Mosquitoes). Crop control has also been used against structural pests, which depend on protected sites such as cracks in pavements, roads, or buildings; rubbish; and grasses to survive. Structural pests are often effectively deterred when openings to potential hiding places are closed and debris and waste is removed.
Crops are sometimes protected from harmful pests by various cultural techniques. Crop rotation, for example, prevents the development of groups of fungi and bacteria. Outdoor cultivation relies on wind to prevent flies and other insects from damaging vegetable crops.
Physical or mechanical control methods are effective against some pests. These controls include adhesive barriers, heat destruction (for storage pests), and flooding (for ground pests). Pressure-treated wood is protected against many wood-damaging fungi and insects. Traps are another mechanical method of pest control. Some traps are designed to kill or capture rodents and other vertebrate pests. Metal nets and shields are used to prevent birds from damaging fruit crops or standing on buildings. Electric light traps attract insects and electrocute them. In some buildings, fans are installed above the doors to prevent flying insects from entering.
One area of pest control research that has received particular attention in recent years is traps with pest-specific sex attractants or pheromones. Pheromone traps have been widely used against fruit flies and gypsy moths. Pheromones are also used to attract and trap pests that invade stored food and grain.
Fruit is particularly susceptible to the spread of insects and diseases. In the United States, the Animal and Plant Health Inspection Service monitors incoming products and materials and requires certain products to be treated before entry. Similar controls exist in other countries. Some areas have quarantine regulations to ensure that certain pests do not enter the area. In the United States, each state has its own inspection services. Some states even have border controls to prevent the unauthorized transfer of plants across state borders.
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