A pest is "a plant or animal detrimental to humans or human concerns (as agriculture or livestock production)"; alternative meanings include organisms that cause nuisance and epidemic disease associated with high mortality (specifically: plague). In its broadest sense, a pest is a competitor of humanity.
A pest is any living organism which is invasive or prolific, detrimental, troublesome, noxious, destructive, a nuisance to either plants or animals, human or human concerns, livestock, or human structures. It is a loose concept, as an organism can be a pest in one setting but beneficial, domesticated or acceptable in another.
Often animals are derided as pests as they cause damage to agriculture by feeding on crops or parasitising livestock, such as codling moth on apples, or boll weevil on cotton. An animal could also be a pest when it causes damage to a wild ecosystem or carries germs within human habitats. Examples of these include those organisms which vector human disease, such as rats and fleas which carry the plague disease, mosquitoes which vector malaria, and ticks which carry Lyme disease.
The term pest may be used to refer specifically to harmful animals but is also often taken to mean all harmful organisms including weeds, plant pathogenic fungi and viruses. Pesticides are chemicals and other agents (e.g. beneficial micro-organisms) that are used to control or protect other organisms from pests. The related term vermin has much overlap with pest, but generally only includes those creatures that are seen to be vectors of diseases.
It is possible for an animal to be a pest in one setting but beneficial or domesticated in another (for example, European rabbits introduced to Australia caused ecological damage beyond the scale they inflicted in their natural habitat). Many weeds are also seen as useful under certain conditions, for instance Patterson's curse is often valued as food for honeybees and as a wildflower, even though it can poison livestock.
The greatest importance as pests (in the order of economic importance) are insects, mites, nematodes and gastropods.
The term "plant pest" has a very specific definition in terms of the International Plant Protection Convention and phytosanitary measures worldwide. A pest is any species, strain or biotype of plant, animal, or pathogenic agent injurious to plants or plant products.
Plants may be considered pests themselves if an invasive species. Any prolific animal or plant may be considered pests.
Thus in contrast, to the single term "pest", in composite terms, e.g. "plant pest", "agricultural pest" "livestock pest", the emphasis is always on the organisms or ecosystems infested and affected. This distinction is followed below.
Classification by harmful organisms
- Pigeons and seagulls eat human food and carry disease 
- Many birds, such as crows, eat crops
- Canada goose; non-migratory birds of this species are now widely regarded as pests in the United States (see Canada goose#Relationship with humans), and introduced birds of this species have become a significant pest in New Zealand (see Canada geese in New Zealand).
- Woodpeckers peck at rooftops and also nest in them. They cause structural damage to houses.
- The common myna was declared by IUCN Species Survival Commission as one of the world's most invasive species and one of only three birds in the top 100 species that pose an impact to biodiversity, agriculture and human interests. In particular, the species poses a serious threat to the ecosystems of Australia where it was named "The Most Important Pest/Problem".
- Cowbirds are brood parasites, which cause declines in local songbird populations.
- Bullfrogs cause problems to the ecosystems.
- Cane toads have had serious negative effects on many ecosystems to which they have been introduced, especially in Australia. The toad's skin is toxic, killing many wild and domestic animals that attempt to eat it.
- Mice, rats, and other small rodents cause infestations
- Big cats, such as lions and cougars, kill and eat herbivores and the occasional person.
- Rabbits decimate native plant populations in Australia, where they are an introduced species.
- Foxes, opossums, raccoons, and bears eat waste
- Beavers destroy trees
- Gophers, groundhogs, and moles destroy lawns
- Feral cats and feral dogs eat human food and carry disease
- White-tailed deer are now seen as pests in many suburban and exurban areas of the US, though not in more rural areas.
- Coyotes and wolves prey upon livestock
- Vampire bats drink blood of livestock.
- Eastern grey squirrels are seen as pests in Britain and Ireland because of the decline of red squirrel populations
- Wild boars damage crops, spread disease, and prey upon livestock
- Ants, cockroaches, flies and wasps (including hornets and yellow jackets) are household pests, as they typically consume human food.
- Aphids, larvae, grasshoppers and crickets cause damage to crop plants
- Lice, fleas and bed bugs can all cause skin irritation
- Mosquitoes, tsetse flies and kissing bugs cause irritation and carry disease
- Termites, woodworm and wood ants cause structural damage
- Bookworms, silverfish, carpet beetles and clothes moths cause non-structural damage
- Gypsy moths attack hardwood trees (see Gypsy moths in the United States)
Land snail pests include:
- Helix aspersa damages citrus fruits in California,
- Cernuella virgata, Theba pisana and Cochlicella spp. decrease quality of grains when harvested with the product in South Australia.
- Achatina fulica damages vegetables and ornamental plants in the Pacific region.
- Succinea costaricana damages ornamental plants in Costa Rica.
- Ovachlamys fulgens damages ornamental plants and orchids in Costa Rica.
- Other species considered to be pests include: Amphibulima patula dominicensis, Zachrysia provisoria and Bradybaena similaris.
- Chiggers cause skin irritation
- Sarcoptes scabiei causes scabies
- Ticks and mites cause irritation and can spread disease
Some slugs are pests in both agriculture and gardens. Their significance is increasing drastically. Deroceras reticulatum is a worldwide distributed slug pest. Local importance slug pests include: Deroceras spp., Milax spp., Tandonia sp., Limax spp., Arion spp. and some species of Veronicellidae: Veronicella sloanei.
Tree and forest pests
- Home stored product entomology
- Invasive species
- List of common household pests
- List of parasites of humans
- Nuisance wildlife management
- Pest control
- Urban wildlife
- ↑ Merriam-Webster dictionary, accessed 22 August 2012.
- ↑ "Pest vermin". Britannica. Retrieved 24 August 2016.
- 1 2 3 4 5 6 7 8 9 10 11 Speiser B. (2002). "Chapter 219. Molluscicides". 506–508. doi:10.1201/NOE0824706326.ch219 PDF In: Pimentel D. (ed.) (2002). Encyclopedia of Pest Management. ISBN 978-0-8247-0632-6.
- ↑ FAO Corporate Document Repository: Guidelines for Phytosanitary Certificates. Retrieved 2012-08-01.
- ↑ Pest Profile Of Pigeons: Diet And Health Concerns
- ↑ Lowe S., Browne M., Boudjelas S. and de Poorter M. (2000). 100 of the World’s Worst Invasive Alien Species. A selection from the Global Invasive Species Database. The Invasive Species Specialist Group (ISSG), a specialist group of the Species Survival Commission (SSC) of the World Conservation Union (IUCN), Auckland.
- ↑ "ABC Wildwatch". Abc.net.au. Retrieved 2012-08-07.
- ↑ Greenhall, Arthur M. 1961. Bats in Agriculture. A Ministry of Agriculture Publication. Trinidad and Tobago
- ↑ Villalobos M. C., Monge-Nájera J., Barrientos Z. & Franco J. (1995). "Life cycle and field abundance of the snail Succinea costaricana (Stylommatophora: Succineidae), a tropical pest". Revista de Biología Tropical 43: 181-188. PDF.
- ↑ Barrientos Z. (1998). "Life history of the terrestrial snail Ovachlamys fulgens (Stylommatophora: Helicarionidae) under laboratory conditions". Revista de Biología Tropical 46(2): 369-384. PDF. HTM in the Google chache.
- 1 2 3 4 Stange L. A. (created September 2004, updated March 2006). "Snails and Slugs of Regulatory Significance to Florida". Division of Plant Industry, Florida Department of Agriculture and Consumer Services. Accessed 27 August 2010.
- Burch, John B.. 1960. Some snails and slugs of quarantine significance to the United States. U.S. Dept. Agriculture, Agricultural Research Service 82(1): 73 pp
- Hockings, F.D, 2014,"Pests, Diseases and Beneficials", CSIRO Publishing, Melbourne, ISBN 9781486300211
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- UF/IFAS Pest Alert Web site - arthropods, nematodes and plant diseases affecting humans, livestock/pets, agricultural and ornamental plants.