Pest control is the regulation or management of a species defined as a pest, a member of the animal kingdom that impacts adversely on human activities. The human response depends on the importance of the damage done and will range from tolerance, through deterrence and management, to attempts to completely eradicate the pest. Pest control measures may be performed as part of an integrated pest management strategy.
In agriculture, pests are kept at bay by cultural, chemical and biological means. Ploughing and cultivation of the soil before sowing mitigate the pest burden and there is a modern trend to limit the use of pesticides as far as possible.
This can be achieved by monitoring the crop, only applying insecticides when necessary, and by growing varieties and crops which are resistant to pests. Where possible, biological means are used, encouraging the natural enemies of the pests and introducing suitable predators or parasites.
In homes and urban environments, the pests are the rodents, birds, insects and other organisms that share the habitat with humans, and that feed on and spoil possessions. Control of these pests is attempted through exclusion, repulsion, physical removal or chemical means. Alternatively, various methods of biological control can be used including sterilisation programmes.
Contents
In agriculture, horticulture, and forestry
Control methods
Biological pest control
Cultural control
Trap cropping
Pesticides
Hunting
Forestry
in homes and cities
General methods
Physical pest control
Poisoned bait
Fumigation
Sterilization
Insulation
Methods for specific pests
Rodent control
Urban rodent control
Natural rodent control
Pantry pests
Clothes moths
Carpet beetles
Bookworms
Beetles
Termites
Mosquitoes
United Kingdom
Modern pest control was stimulated by the spread across the United States of the Colorado potato beetle. After much discussion, arsenical compounds were used to control the beetle and the predicted poisoning of the human population did not occur.
This led the way to a widespread acceptance of insecticides across the continent. With the industrialisation and mechanization of agriculture in the 18th and 19th centuries, and the introduction of the insecticides pyrethrum and derris, chemical pest control became widespread. In the 20th century, the discovery of several synthetic insecticides, such as DDT, and herbicides boosted this development.
Chemical pest control is still the predominant type of pest control today, although a renewed interest in traditional and biological pest control developed towards the end of the 20th century and continues to this day.
In agriculture, horticulture, and forestry
Biological pest control
Biological pest control: parasitoid wasp (Cotesia congregata) adult with pupal cocoons on its host, a tobacco hornworm Manduca sexta (green background)
Biological pest control is a method of controlling pests such as insects and mites by using other organisms.
It relies on predation, parasitism, herbivory, parasitody or other natural mechanisms, but typically also involves an active human management role. Classical biological control involves the introduction of natural enemies of the pest that are bred in the laboratory and released into the environment.
An alternative approach is to augment the natural enemies that occur in a particular area by releasing more, either in small, repeated batches, or in a single large-scale release.
Ideally, the released organism will breed and survive, and provide long-term control. Biological control can be an important component of an integrated pest management programme.
For example: mosquitoes are often controlled by putting Bt Bacillus thuringiensis ssp. israelensis, a bacterium that infects and kills mosquito larvae, in local water sources.
Trap cropping
Main article: Trap crop
A trap crop is a crop of a plant that attracts pests, diverting them from nearby crops.[13] Pests aggregated on the trap crop can be more easily controlled using pesticides or other methods.
However, trap-cropping, on its own, has often failed to cost effectively reduce pest densities on large commercial scales, without the use of pesticides, possibly due to the pests' ability to disperse back into the main field.
Pesticides
Main article: Pesticide
Spraying pine logs with insecticide against Ips sexdentatus, a pine engraver beetle
Pesticides are applied to crops by agricultural aircraft, tractor-mounted crop sprayers, aerial spray by modern aircraft or as seed dressings to control pests.
However, successful control by pesticides is not easy; the right formulation must be chosen, the timing is often critical, the method of application is important, adequate coverage and retention on the crop are necessary. The killing of natural enemies of the target pest should be minimized.
This is particularly important in countries where there are natural reservoirs of pests and their enemies in the countryside surrounding plantation crops, and these co-exist in a delicate balance. Often in less-developed countries, the crops are well adapted to the local situation and no pesticides are needed.
Where progressive farmers are using fertilizers to grow improved crop varieties, these are often more susceptible to pest damage, but the indiscriminate application of pesticides may be detrimental in the longer term.
The efficacy of chemical pesticides tends to diminish over time. This is because any organism that manages to survive the initial application will pass on its genes to its offspring and a resistant strain will be developed.
In this way, some of the most serious pests have developed resistance and are no longer killed by pesticides that used to kill their ancestors.
This necessitates higher concentrations of chemical, more frequent applications and a movement to more expensive formulations.
Pesticides are formulated to kill pests, but many have detrimental effects on non-target species; of particular concern is the damage done to honey-bees, solitary bees and other pollinating insects and in this regard, the time of day when the spray is applied can be important.
The widely used neonicotinoids have been banned on flowering crops in some countries because of their effects on bee
Some pesticides may cause cancer and other health problems in humans, as well as being harmful to wildlife. There can be acute effects immediately after exposure or chronic effects after continuous low-level, or occasional exposure.Maximum residue limits for pesticides in foodstuffs and animal feed are set by many nations.
Forestry
Further information: Forestry
Forest pests present a significant problem because it is not easy to access the canopy and monitor pest populations. In addition, forestry pests such as bark beetles, kept under control by natural enemies in their native range, may be transported large distances in cut timber to places where they have no natural predators, enabling them to cause extensive economic damage.
Pheromone traps have been used to monitor pest populations in the canopy. These release volatile chemicals that attract males. Pheromone traps can detect the arrival of pests or alert foresters to outbreaks.
For example, the spruce budworm, a destructive pest of spruce and balsam fir, has been monitored using pheromone traps in Canadian forests for several decades. In some regions, such as New Brunswick, areas of forest are sprayed with pesticide to control the budworm population and prevent the damage caused during outbreaks.
In homes and cities
Many unwelcome animals visit or make their home in residential buildings, industrial sites and urban areas. Some contaminate foodstuffs, damage structural timbers, chew through fabrics or infest stored dry goods.
Some inflict great economic loss, others carry diseases or cause fire hazards, and some are just a nuisance. Control of these pests has been attempted by improving sanitation and garbage control, modifying the habitat, and using repellents, growth regulators, traps, baits and pesticides.
General methods
Physical pest control
Main article: Physical pest control
Physical pest control involves trapping or killing pests such as insects and rodents. Historically, local people or paid rat-catchers caught and killed rodents using dogs and traps. On a domestic scale, sticky flypapers are used to trap flies.
In larger buildings, insects may be trapped using such means as pheromones, synthetic volatile chemicals or ultraviolet light to attract the insects; some have a sticky base or an electrically charged grid to kill them. Glueboards are sometimes used for monitoring cockroaches and to catch rodents.
Rodents can be killed by suitably baited spring traps and can be caught in cage traps for relocation. Talcum powder or "tracking powder" can be used to establish routes used by rodents inside buildings and acoustic devices can be used for detecting beetles in structural timbers.
Poisoned bait is a common method for controlling rats, mice, birds, slugs, snails, ants, cockroaches, and other pests. The basic granules, or other formulation, contains a food attractant for the target species and a suitable poison.
For ants, a slow-acting toxin is needed so that the workers have time to carry the substance back to the colony, and for flies, a quick-acting substance to prevent further egg-laying and nuisance.[29] Baits for slugs and snails often contain the molluscide metaldehyde, dangerous to children and household pets.
An article in Scientific American in 1885 described effective elimination of a cockroach infestation using fresh cucumber peels.
Bait being placed in a rodent bait box.
Warfarin has traditionally been used to kill rodents, but many populations have developed resistance to this anticoagulant, and difenacoum may be substituted. These are cumulative poisons, requiring bait stations to be topped up regularly. Poisoned meat has been used for centuries to kill animals such as wolves and birds of prey.
Poisoned carcasses however kill a wide range of carrion feeders, not only the targeted species.[32] Raptors in Israel were nearly wiped out following a period of intense poisoning of rats and other crop pests.
Fumigation
Main article: Fumigation
Tent fumigation of a house in America
Fumigation is the treatment of a structure to kill pests such as wood-boring beetles by sealing it or surrounding it with an airtight cover such as a tent, and fogging with liquid insecticide for an extended period, typically of 24–72 hours.
This is costly and inconvenient as the structure cannot be used during the treatment, but it targets all life stages of pests
An alternative, space treatment, is fogging or misting to disperse a liquid insecticide in the atmosphere within a building without evacuation or airtight sealing, allowing most work within the building to continue, at the cost of reduced penetration. Contact insecticides are generally used to minimize long-lasting residual effects.
Sterilization
Populations of pest insects can sometimes be dramatically reduced by the release of sterile individuals. This involves the mass rearing of a pest, sterilising it by means of X-rays or some other means, and releasing it into a wild population. It is particularly useful where a female only mates once and where the insect does not disperse widely.
This technique has been successfully used against the New World screw-worm fly, some species of tsetse fly, tropical fruit flies, the pink bollworm and the codling moth, among others.
Laboratory studies conducted with U-5897 (3-chloro-1,2-propanediol) were attempted in the early 1970s for rat control, although these proved unsuccessful.
In 2013, New York City tested sterilization traps,[39] demonstrating a 43% reduction in rat populations. The product ContraPest was approved for the sterilization of rodents by the United States Environmental Protection Agency in August 2016.
Urban rodent control
Rodent control is vital in cities. New York City and cities across the state dramatically reduced their rodent populations in the early 1970s. Rio de Janeiro claims a reduction of 80% over only 2 years shortly thereafter.
To better target efforts, London began scientifically surveying populations in 1972 and this was so useful that all Local Authorities in England and Wales soon followed.
