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A pest is any organism harmful to humans or human concerns. The term is particularly used for creatures that damage crops, livestock, and forestry or cause a nuisance to people, especially in their homes. Humans have modified the environment for their own purposes and are intolerant of other creatures occupying the same space when their activities impact adversely on human objectives. Thus, an elephant is unobjectionable in its natural habitat but a pest when it tramples crops. Some animals are disliked because they bite or sting;
wolves The wolf (''Canis lupus''; : wolves), also known as the grey wolf or gray wolf, is a canine native to Eurasia and North America. More than thirty subspecies of ''Canis lupus'' have been recognized, including the dog and dingo, though gr ...
,
snake Snakes are elongated limbless reptiles of the suborder Serpentes (). Cladistically squamates, snakes are ectothermic, amniote vertebrates covered in overlapping scales much like other members of the group. Many species of snakes have s ...
s,
wasp A wasp is any insect of the narrow-waisted suborder Apocrita of the order Hymenoptera which is neither a bee nor an ant; this excludes the broad-waisted sawflies (Symphyta), which look somewhat like wasps, but are in a separate suborder ...
s,
ant Ants are Eusociality, eusocial insects of the Family (biology), family Formicidae and, along with the related wasps and bees, belong to the Taxonomy (biology), order Hymenoptera. Ants evolved from Vespoidea, vespoid wasp ancestors in the Cre ...
s,
bed bug Bed bugs are parasitic insects from the genus ''Cimex'', which are micropredators that haematophagy, feed on blood, usually at night. Their bites can result in a number of health impacts, including skin rashes, psychological effects, and aller ...
s,
flea Flea, the common name for the order (biology), order Siphonaptera, includes 2,500 species of small flightless insects that live as external parasites of mammals and birds. Fleas live by hematophagy, ingesting the blood of their hosts. Adult f ...
s and
tick Ticks are parasitic arachnids of the order Ixodida. They are part of the mite superorder Parasitiformes. Adult ticks are approximately 3 to 5 mm in length depending on age, sex, and species, but can become larger when engorged. Ticks a ...
s belong in this category. Others enter the home; these include houseflies, which land on and contaminate food;
beetles Beetles are insects that form the Taxonomic rank, order Coleoptera (), in the superorder Holometabola. Their front pair of wings are hardened into wing-cases, elytra, distinguishing them from most other insects. The Coleoptera, with about 40 ...
, which tunnel into the woodwork; and other animals that scuttle about on the floor at night, like
rat Rats are various medium-sized, long-tailed rodents. Species of rats are found throughout the order Rodentia, but stereotypical rats are found in the genus ''Rattus''. Other rat genera include '' Neotoma'' (pack rats), '' Bandicota'' (bandicoo ...
s and
cockroach Cockroaches (or roaches) are insects belonging to the Order (biology), order Blattodea (Blattaria). About 30 cockroach species out of 4,600 are associated with human habitats. Some species are well-known Pest (organism), pests. Modern cockro ...
es, which are often associated with unsanitary conditions. Agricultural and horticultural crops are attacked by a wide variety of pests, the most important being
rodent Rodents (from Latin , 'to gnaw') are mammals of the Order (biology), order Rodentia ( ), which are characterized by a single pair of continuously growing incisors in each of the upper and Mandible, lower jaws. About 40% of all mammal specie ...
s,
insect Insects (from Latin ') are Hexapoda, hexapod invertebrates of the class (biology), class Insecta. They are the largest group within the arthropod phylum. Insects have a chitinous exoskeleton, a three-part body (Insect morphology#Head, head, ...
s,
mite Mites are small arachnids (eight-legged arthropods) of two large orders, the Acariformes and the Parasitiformes, which were historically grouped together in the subclass Acari. However, most recent genetic analyses do not recover the two as eac ...
s,
nematode The nematodes ( or ; ; ), roundworms or eelworms constitute the phylum Nematoda. Species in the phylum inhabit a broad range of environments. Most species are free-living, feeding on microorganisms, but many are parasitic. Parasitic worms (h ...
s and gastropod molluscs. The damage they do results both from the direct injury they cause to the plants and from the indirect consequences of the fungal, bacterial or viral infections they transmit. Plants have their own defences against these attacks but these may be overwhelmed, especially in habitats where the plants are already stressed, or where the pests have been accidentally introduced and may have no natural enemies. The pests affecting trees are predominantly insects, and many of these have also been introduced inadvertently and lack natural enemies, and some have transmitted novel fungal diseases with devastating results. Humans have traditionally performed
pest control Pest control is the regulation or management of a species defined as a pest (organism), pest; such as any animal, plant or fungus that impacts adversely on human activities or environment. The human response depends on the importance of the da ...
in agriculture and forestry by the use of
pesticide Pesticides are substances that are used to control pests. They include herbicides, insecticides, nematicides, fungicides, and many others (see table). The most common of these are herbicides, which account for approximately 50% of all p ...
s; however, other methods exist such as mechanical control, and recently developed biological controls.


Concept

A pest is any living thing which humans consider troublesome to themselves, their possessions, or the environment. Pests can cause issues with crops, human or animal health, buildings, and wild areas or larger landscapes. An older usage of the word "pest" is of a deadly
epidemic An epidemic (from Greek ἐπί ''epi'' "upon or above" and δῆμος ''demos'' "people") is the rapid spread of disease to a large number of hosts in a given population within a short period of time. For example, in meningococcal infection ...
disease, specifically plague. In its broadest sense, a pest is a
competitor Competition is a rivalry where two or more parties strive for a common goal which cannot be shared: where one's gain is the other's loss (an example of which is a zero-sum game). Competition can arise between entities such as organisms, individ ...
to humanity. Pests include plants, pathogens, invertebrates, vertebrates, or any organism that harms an ecosystem.


Animals

Animals are considered pests or
vermin Vermin (colloquially varmint(s) or varmit(s)) are pests or nuisance animals that spread diseases and destroy crops, livestock, and property. Since the term is defined in relation to human activities, which species are included vary by regi ...
when they injure people or damage crops, forestry, or buildings. Elephants are regarded as pests by the farmers whose crops they raid and trample.
Mosquito Mosquitoes, the Culicidae, are a Family (biology), family of small Diptera, flies consisting of 3,600 species. The word ''mosquito'' (formed by ''Musca (fly), mosca'' and diminutive ''-ito'') is Spanish and Portuguese for ''little fly''. Mos ...
es and
tick Ticks are parasitic arachnids of the order Ixodida. They are part of the mite superorder Parasitiformes. Adult ticks are approximately 3 to 5 mm in length depending on age, sex, and species, but can become larger when engorged. Ticks a ...
s are vectors that can transmit ailments but are also pests because of the distress caused by their bites. Grasshoppers are usually solitary herbivores of little economic importance until the conditions are met for them to enter a swarming phase, become
locust Locusts (derived from the Latin ''locusta'', locust or lobster) are various species of short-horned grasshoppers in the family Acrididae that have a swarming phase. These insects are usually solitary, but under certain circumstances they b ...
s and cause enormous damage. Many people appreciate birds in the countryside and their gardens, but when these accumulate in large masses, they can be a nuisance. Flocks of starlings can consist of hundreds of thousands of individual birds, their roosts can be noisy and their droppings voluminous; the droppings are acidic and can cause corrosion of metals, stonework, and brickwork as well as being unsightly.
Pigeons Columbidae is a bird family consisting of doves and pigeons. It is the only family in the order Columbiformes. These are stout-bodied birds with small heads, relatively short necks and slender bills that in some species feature fleshy ceres. ...
in urban settings may be a health hazard, and
gull Gulls, or colloquially seagulls, are seabirds of the subfamily Larinae. They are most closely related to terns and skimmers, distantly related to auks, and even more distantly related to waders. Until the 21st century, most gulls were placed ...
s near the coast can become a nuisance, especially if they become bold enough to snatch food from passers-by. All birds are a risk at airfields where they can be sucked into aircraft engines.
Woodpecker Woodpeckers are part of the bird family (biology), family Picidae, which also includes the piculets, wrynecks and sapsuckers. Members of this family are found worldwide, except for Australia, New Guinea, New Zealand, Madagascar and the extreme ...
s sometimes excavate holes in buildings, fencing and utility poles, causing structural damage; they also drum on various reverberatory structures on buildings such as gutters, down-spouts, chimneys, vents and aluminium sheeting.
Jellyfish Jellyfish, also known as sea jellies or simply jellies, are the #Life cycle, medusa-phase of certain gelatinous members of the subphylum Medusozoa, which is a major part of the phylum Cnidaria. Jellyfish are mainly free-swimming marine animal ...
can form vast swarms which may be responsible for damage to fishing gear, and sometimes clog the cooling systems of power and desalination plants which draw their water from the sea. Many of the animals that we regard as pests live in our homes. Before humans built dwellings, these creatures lived in the wider environment, but co-evolved with humans, adapting to the warm, sheltered conditions that a house provides, the wooden timbers, the furnishings, the food supplies and the rubbish dumps. Many no longer exist as free-living organisms in the outside world, and can therefore be considered to be domesticated. The St Kilda house mouse rapidly became extinct when the last islander left the island of
St Kilda, Scotland St Kilda () is a remote archipelago situated west-northwest of North Uist in the North Atlantic Ocean. It contains the westernmost islands of the Outer Hebrides of Scotland. The largest island is Hirta, whose sea cliffs are the highest in the ...
in 1930, but the St Kilda field mouse survived.


Plants

Plants may be considered pests, for example, if they are
invasive species An invasive species is an introduced species that harms its new environment. Invasive species adversely affect habitats and bioregions, causing ecological, environmental, and/or economic damage. The term can also be used for native spec ...
or
weed A weed is a plant considered undesirable in a particular situation, growing where it conflicts with human preferences, needs, or goals.Harlan, J. R., & deWet, J. M. (1965). Some thoughts about weeds. ''Economic botany'', ''19''(1), 16-24. Pla ...
s. There is no universal definition of what makes a plant a pest. Some governments, such as that of Western Australia, permit their authorities to prescribe as a pest plant "any plant that, in the local government authority's opinion, is likely to adversely affect the environment of the district, the value of property in the district, or the health, comfort or convenience of the district's inhabitants." An example of such a plant prescribed under this regulation is caltrop, ''
Tribulus terrestris ''Tribulus terrestris'' is an annual plant in the caltrop family (Zygophyllaceae) widely distributed around the world. It is adapted to thrive in dry climate locations in which few other plants can survive. It is native to warm temperate and t ...
'', which can cause poisoning in sheep and goats, but is mainly a nuisance around buildings, roadsides and recreation areas because of its uncomfortably sharp spiny burrs.


Pathogens

Disease-causing pathogens such as
fungi A fungus (: fungi , , , or ; or funguses) is any member of the group of eukaryotic organisms that includes microorganisms such as yeasts and mold (fungus), molds, as well as the more familiar mushrooms. These organisms are classified as one ...
,
oomycete The Oomycetes (), or Oomycota, form a distinct phylogenetic lineage of fungus-like eukaryotic microorganisms within the Stramenopiles. They are filamentous and heterotrophic, and can reproduce both sexually and asexually. Sexual reproduction o ...
s,
bacteria Bacteria (; : bacterium) are ubiquitous, mostly free-living organisms often consisting of one Cell (biology), biological cell. They constitute a large domain (biology), domain of Prokaryote, prokaryotic microorganisms. Typically a few micr ...
, and
virus A virus is a submicroscopic infectious agent that replicates only inside the living Cell (biology), cells of an organism. Viruses infect all life forms, from animals and plants to microorganisms, including bacteria and archaea. Viruses are ...
es can cause damage to crops and garden plants.


Ecology

The term "plant pest", mainly applied to insect
micropredator Parasitism is a Symbiosis, close relationship between species, where one organism, the parasite, lives (at least some of the time) on or inside another organism, the Host (biology), host, causing it some harm, and is Adaptation, adapted str ...
s of plants, has a specific definition in terms of the
International Plant Protection Convention The International Plant Protection Convention (IPPC) is a 1951 multilateral treaty overseen by the United Nations Food and Agriculture Organization that aims to secure coordinated, effective action to prevent and to control the introduction and ...
and phytosanitary measures worldwide. A pest is any species, strain or biotype of plant, animal, or pathogenic agent injurious to plants or plant products. Worldwide, agricultural pest impacts are increased by higher degrees of interconnectedness. This is due to the increased risk that any particular pest problem anywhere in the world (as a
system A system is a group of interacting or interrelated elements that act according to a set of rules to form a unified whole. A system, surrounded and influenced by its open system (systems theory), environment, is described by its boundaries, str ...
) will propagate across the entire system.


Plant defences against pests

Plants have developed strategies that they use in their own defence, be they thorns (modified stems) or spines (modified leaves), stings, a thick cuticle or waxy deposits, with the second line of defence being toxic or distasteful
secondary metabolite Secondary metabolites, also called ''specialised metabolites'', ''secondary products'', or ''natural products'', are organic compounds produced by any lifeform, e.g. bacteria, archaea, fungi, animals, or plants, which are not directly involved ...
s. Mechanical injury to the plant tissues allows the entry of pathogens and stimulates the plant to mobilise its chemical defences. The plant soon seals off the wound to reduce further damage. Plants sometimes take active steps to reduce herbivory. '' Macaranga triloba'' for example has adapted its thin-walled stems to create ideal housing for an ant ''
Crematogaster ''Crematogaster'' is an ecologically diverse genus of ants found worldwide, which are characterised by a distinctive heart-shaped gaster (insect anatomy), gaster (abdomen), which gives them one of their common names, the Saint Valentine ant. Mem ...
'' spp., which, in turn, protects the plant from herbivores. In addition to providing housing, the plant also provides the ant with its exclusive food source in the form of food bodies located on the leaf stipules. Similarly, several ''
Acacia ''Acacia'', commonly known as wattles or acacias, is a genus of about of shrubs and trees in the subfamily Mimosoideae of the pea family Fabaceae. Initially, it comprised a group of plant species native to Africa, South America, and Austral ...
'' tree species have developed stout spines that are swollen at the base, forming a hollow structure that provides housing for ants which protect the plant. These ''Acacia'' trees also produce
nectar Nectar is a viscous, sugar-rich liquid produced by Plant, plants in glands called nectaries, either within the flowers with which it attracts pollination, pollinating animals, or by extrafloral nectaries, which provide a nutrient source to an ...
in nectaries on their leaves as food for the ants.


Climate change

Pest ranges are heavily determined by
climate Climate is the long-term weather pattern in a region, typically averaged over 30 years. More rigorously, it is the mean and variability of meteorological variables over a time spanning from months to millions of years. Some of the meteoro ...
. The most common example for the longest time has been
rainfall Rain is a form of precipitation where water droplets that have condensed from atmospheric water vapor fall under gravity. Rain is a major component of the water cycle and is responsible for depositing most of the fresh water on the Earth. ...
: Although drought stress weakens crop disease resistance, drought also retards contagion and infection; and some variability in precipitation is universal. More recently
climate change Present-day climate change includes both global warming—the ongoing increase in Global surface temperature, global average temperature—and its wider effects on Earth's climate system. Climate variability and change, Climate change in ...
has been rapidly altering ranges, mostly by pushing them towards the poles (both
North North is one of the four compass points or cardinal directions. It is the opposite of south and is perpendicular to east and west. ''North'' is a noun, adjective, or adverb indicating Direction (geometry), direction or geography. Etymology T ...
and
South South is one of the cardinal directions or compass points. The direction is the opposite of north and is perpendicular to both west and east. Etymology The word ''south'' comes from Old English ''sūþ'', from earlier Proto-Germanic ''*sunþa ...
). From 1960–2013 ranges have shifted poleward by per year - albeit with significant differences between
taxa In biology, a taxon (back-formation from ''taxonomy''; : taxa) is a group of one or more populations of an organism or organisms seen by taxonomists to form a unit. Although neither is required, a taxon is usually known by a particular name and ...
. (Especially in the case of viruses and
nematode The nematodes ( or ; ; ), roundworms or eelworms constitute the phylum Nematoda. Species in the phylum inhabit a broad range of environments. Most species are free-living, feeding on microorganisms, but many are parasitic. Parasitic worms (h ...
s which show the opposite trend, toward the
equator The equator is the circle of latitude that divides Earth into the Northern Hemisphere, Northern and Southern Hemisphere, Southern Hemispheres of Earth, hemispheres. It is an imaginary line located at 0 degrees latitude, about in circumferen ...
. This may be due to their lack of airborne dispersal, so their trend conforms with the trend of human-aided dispersal; or identification difficulties in the field.) In Europe, crop pests are expected to burgeon as the
vertebrate Vertebrates () are animals with a vertebral column (backbone or spine), and a cranium, or skull. The vertebral column surrounds and protects the spinal cord, while the cranium protects the brain. The vertebrates make up the subphylum Vertebra ...
predators which control them are expected to be suppressed by future climatic conditions.


Economic impact


In agriculture and horticulture

Together pests and
diseases A disease is a particular abnormal condition that adversely affects the structure or function of all or part of an organism and is not immediately due to any external injury. Diseases are often known to be medical conditions that are asso ...
cause up to 40% yield losses every year. The animal groups of the greatest importance as agricultural pests are (in order of economic importance)
insect Insects (from Latin ') are Hexapoda, hexapod invertebrates of the class (biology), class Insecta. They are the largest group within the arthropod phylum. Insects have a chitinous exoskeleton, a three-part body (Insect morphology#Head, head, ...
s,
mite Mites are small arachnids (eight-legged arthropods) of two large orders, the Acariformes and the Parasitiformes, which were historically grouped together in the subclass Acari. However, most recent genetic analyses do not recover the two as eac ...
s,
nematode The nematodes ( or ; ; ), roundworms or eelworms constitute the phylum Nematoda. Species in the phylum inhabit a broad range of environments. Most species are free-living, feeding on microorganisms, but many are parasitic. Parasitic worms (h ...
s and gastropod molluscs.Speiser B. (2002). "Chapter 219. Molluscicides". 506–508.
PDF
In: Pimentel D. (ed.) (2002). ''Encyclopedia of Pest Management''. .
Stange, L.A. (created September 2004, updated March 2006)

. Division of Plant Industry,
Florida Department of Agriculture and Consumer Services The Florida Department of Agriculture and Consumer Services (FDACS) is an executive department of the government of Florida. The Commissioner of Agriculture (directly elected by voters statewide for a four-year term, and a member of the Flor ...
. Accessed 27 August 2010.
Insects are responsible for two major forms of damage to crops. First, there is the direct injury they cause to the plants as they feed on the tissues; a reduction in leaf surface available for photosynthesis, distortion of growing shoots, a diminution of the plant's growth and vigour, and the wilting of shoots and branches caused by the insects' tunneling activities. Secondly there is the indirect damage, where the insects do little direct harm, but either transmit or allow entry of fungal, bacterial or viral infections. Although some insects are polyphagous, many are restricted to one specific crop, or group of crops. In many cases it is the larva that feeds on the plant, building up a nutritional store that will be used by the short-lived adult;
sawfly Sawflies are wasp-like insects that are in the suborder Symphyta within the order Hymenoptera, alongside ants, bees, and wasps. The common name comes from the saw-like appearance of the ovipositor, which the females use to cut into the plant ...
and
lepidoptera Lepidoptera ( ) or lepidopterans is an order (biology), order of winged insects which includes butterflies and moths. About 180,000 species of the Lepidoptera have been described, representing 10% of the total described species of living organ ...
n larvae feed mainly on the aerial portions of plants while
beetle Beetles are insects that form the Taxonomic rank, order Coleoptera (), in the superorder Holometabola. Their front pair of wings are hardened into wing-cases, elytra, distinguishing them from most other insects. The Coleoptera, with about 40 ...
larvae tend to live underground, feeding on roots, or tunnel into the stem or under the bark. The true bugs,
Hemiptera Hemiptera (; ) is an order of insects, commonly called true bugs, comprising more than 80,000 species within groups such as the cicadas, aphids, planthoppers, leafhoppers, assassin bugs, bed bugs, and shield bugs. They range in size from ...
, have piercing and sucking mouthparts and live by sucking sap from plants. These include
aphid Aphids are small sap-sucking insects in the Taxonomic rank, family Aphididae. Common names include greenfly and blackfly, although individuals within a species can vary widely in color. The group includes the fluffy white Eriosomatinae, woolly ...
s,
whiteflies Whiteflies are Hemipterans that typically feed on the undersides of plant leaves. They comprise the family Aleyrodidae, the only family in the superfamily Aleyrodoidea. More than 1550 species have been described. Description and taxonomy The A ...
and
scale insect Scale insects are small insects of the Order (biology), order Hemiptera, suborder Sternorrhyncha. Of dramatically variable appearance and extreme sexual dimorphism, they comprise the infraorder Coccomorpha which is considered a more convenient g ...
s. Apart from weakening the plant, they encourage the growth of sooty mould on the honeydew the insects produce, which cuts out the light and reduces photosynthesis, stunting the plant's growth. They often transmit serious viral diseases between plants. The mites that cause most trouble in the field are the spider mites. These are less than in diameter, can be very numerous, and thrive in hot, dry conditions. They mostly live on the underside of leaves and puncture the plant cells to feed, with some species forming webbing. They occur on nearly all important food crops and ornamental plants, both outdoors and under glass, and include some of the most economically important pests. Another important group of mites is the gall mites which affect a wide range of plants, several mite species being major pests causing substantial economic damage to crops. They can feed on the roots or the aerial parts of plants and transmit viruses. Some examples are the big bud mite that transmits the reversion virus of
blackcurrant The blackcurrant (''Ribes nigrum''), also known as black currant or cassis, is a deciduous shrub in the family Grossulariaceae grown for its edible berries. It is native to temperate parts of central and northern Europe and northern Asia, w ...
s, the coconut mite which can devastate coconut production, and the cereal rust mite which transmits several grass and cereal viruses. Being exceedingly minute, many plant mites are spread by wind, although others use insects or other arthropods as a means to disperse. The nematodes (eelworms) that attack plants are minute, often too small to be seen with the naked eye, but their presence is often apparent in the galls or "knots" they form in plant tissues. Vast numbers of nematodes are found in soil and attack roots, but others affect stems, buds, leaves, flowers and fruits. High infestations cause stunting, deformation and retardation of plant growth, and the nematodes can transmit viral diseases from one plant to another. When its populations are high, the
potato cyst nematode Potato root nematodes or potato cyst nematodes (PCN) are 1-mm long roundworms belonging to the genus ''Globodera'', which comprises around 12 species. They live on the roots of plants of the family Solanaceae, such as potatoes and tomatoes. PCN c ...
can cause reductions of 80% in yield of susceptible potato varieties. The nematode eggs survive in the soil for many years, being stimulated to hatch by chemical cues produced by roots of susceptible plants.
Slug Slug, or land slug, is a common name for any apparently shell-less Terrestrial mollusc, terrestrial gastropod mollusc. The word ''slug'' is also often used as part of the common name of any gastropod mollusc that has no shell, a very reduced ...
s and
snail A snail is a shelled gastropod. The name is most often applied to land snails, terrestrial molluscs, terrestrial pulmonate gastropod molluscs. However, the common name ''snail'' is also used for most of the members of the molluscan class Gas ...
s are terrestrial gastropod molluscs which typically chew leaves, stems, flowers, fruit and vegetable debris. Slugs and snails differ little from each other and both do considerable damage to plants. With novel crops being grown and with insect pests having been brought more under control by biological and other means, the damage done by molluscs becomes of greater significance. Terrestrial molluscs need moist environments; snails may be more noticeable because their shells provide protection from desiccation, while most slugs live in soil and only come out to feed at night. They devour seedlings, damage developing shoots and feed on salad crops and cabbages, and some species tunnel into potatoes and other tubers.


Weeds

A weed is a plant considered undesirable in a particular situation; the term has no botanical significance. Often, weeds are simply those native plants that are adapted to grow in
disturbed ground In ecology, a disturbance is a change in environmental conditions that causes a pronounced change in an ecosystem. Disturbances often act quickly and with great effect, to alter the physical structure or arrangement of biotic and abiotic element ...
, the disturbance caused by ploughing and cultivation favouring them over other species. Any plant is a weed if it appears in a location where it is unwanted;
Bermuda grass ''Cynodon dactylon'', commonly known as Bermuda grass, also known as couch grass in Australia and New Zealand, is a grass found worldwide. It is native to Europe, Africa, Australia and much of Asia. It has been introduced to the Americas. Contra ...
makes a good lawn plant under hot dry conditions but become a bad weed when it out-competes cultivated plants. A different group of weeds consists of those that are invasive, introduced, often unintentionally, to habitats to which they are not native but in which they thrive. Without their original competitors, herbivores, and diseases, they may increase and become a serious nuisance. One such plant is
purple loosestrife ''Lythrum salicaria'' or purple loosestrifeFlora of NW Europe''Lythrum salicaria'' is a flowering plant belonging to the family Lythraceae. It should not be confused with other plants sharing the name loosestrife that are members of the family Pr ...
, a native of Europe and Asia where it occurs in ditches,
wet meadow A wet meadow is a type of wetland with soils that are Solubility, saturated for part or all of the growing season which prevents the growth of trees and brush. Debate exists whether a wet meadow is a type of marsh or a completely separate type of ...
s and marshes; introduced into North America, it has no natural enemies to keep it in check and has taken over vast tracts of wetlands to the exclusion of native species.


In forestry

In forestry, pests may affect various parts of the tree, from its roots and trunk to the canopy far overhead. The accessibility of the part of the tree affected may make detection difficult, so that a pest problem may already be far advanced before it is first observed from the ground. The larch sawfly and spruce budworm are two insect pests prevalent in Alaska and aerial surveys can show which sections of forest are being defoliated in any given year so that appropriate remedial action can be taken. Some pests may not be present on the tree all year round, either because of their life cycle or because they rotate between different host species at different times of the year. In forestry, pests may affect various parts of the tree, from its roots and trunk to the canopy far overhead. The larvae of wood-boring beetles, for example, are notorious for spending years excavating tunnels under the bark of trees, leading to significant structural damage. These larvae only emerge into the open for brief periods as adults, primarily to mate and disperse. The import and export of timber has inadvertently assisted some insect pests to establish themselves far from their country of origin. An insect may be of little importance in its native range, being kept under control by parasitoid wasps, predators, and the natural resistance of the host trees, but be a serious pest in a region into which it has been introduced. This is the case with the
emerald ash borer The emerald ash borer (''Agrilus planipennis''), also known by the abbreviation EAB, is a green buprestid or jewel beetle native to north-eastern Asia that feeds on ash trees, ash species (''Fraxinus'' spp.). Females lay eggs in bark crevices o ...
, an insect native to north-eastern Asia, which, since its arrival in North America, has killed millions of ash trees. Another example of a beetle species that exhibits pest behavior are '' Melolontha Hippocastrani'', that cause severe, long-term damage on young trees by feeding on roots.


In buildings

Animals able to live in the dry conditions found in buildings include many
arthropod Arthropods ( ) are invertebrates in the phylum Arthropoda. They possess an arthropod exoskeleton, exoskeleton with a cuticle made of chitin, often Mineralization (biology), mineralised with calcium carbonate, a body with differentiated (Metam ...
s such as beetles, cockroaches, moths, mites, and silverfish. Another group, including
termite Termites are a group of detritivore, detritophagous Eusociality, eusocial cockroaches which consume a variety of Detritus, decaying plant material, generally in the form of wood, Plant litter, leaf litter, and Humus, soil humus. They are dist ...
s,
woodworm A woodworm is the Xylophagy, wood-eating larva of many species of beetle. It is also a generic description given to the infestation of a wooden item (normally part of a dwelling or the furniture in it) by these larvae. Types of woodworm Woodbo ...
,
longhorn beetle The longhorn beetles (Cerambycidae), also known as long-horned or longicorns (whose larvae are often referred to as roundheaded borers), are a large family of beetles, with over 35,000 species described. Most species are characterized by Antenn ...
s, and wood ants cause structural damage to buildings and furniture. The natural habitat of these is the decaying parts of trees. The deathwatch beetle infests the structural timbers of old buildings, mostly attacking
hardwood Hardwood is wood from Flowering plant, angiosperm trees. These are usually found in broad-leaved temperate and tropical forests. In temperate and boreal ecosystem, boreal latitudes they are mostly deciduous, but in tropics and subtropics mostl ...
, especially
oak An oak is a hardwood tree or shrub in the genus ''Quercus'' of the beech family. They have spirally arranged leaves, often with lobed edges, and a nut called an acorn, borne within a cup. The genus is widely distributed in the Northern Hemisp ...
. The initial attack usually follows the entry of water into a building and the subsequent decay of damp timber. Furniture beetles mainly attack the sapwood of both hard and soft wood, only attacking the
heartwood Wood is a structural tissue/material found as xylem in the stems and roots of trees and other woody plants. It is an organic materiala natural composite of cellulosic fibers that are strong in tension and embedded in a matrix of lignin t ...
when it is modified by fungal decay. The presence of the beetles only becomes apparent when the larvae gnaw their way out, leaving small circular holes in the timber. Carpet beetles and
clothes moth Clothes moth or clothing moth is the common name for several species of moth considered to be pests, whose larvae eat animal fibres (hairs), including clothing and other fabrics. These include: * ''Tineola bisselliella'', the common clothes mot ...
s cause non-structural damage to property such as clothing and carpets. It is the larvae that are destructive, feeding on wool, hair, fur, feathers and down. The moth larvae live where they feed, but the beetle larvae may hide behind skirting boards or in other similar locations between meals. They may be introduced to the home in any product containing animal fibres including upholstered furniture; the moths are feeble fliers but the carpet beetles may also enter houses through open windows. Furniture beetles, carpet beetles and clothes moths are also capable of creating great damage to museum exhibits, zoological and botanical collections, and other cultural heritage items. Constant vigilance is required to prevent an attack, and newly acquired items, and those that have been out on loan, may need
quarantining A quarantine is a restriction on the movement of people, animals, and goods which is intended to prevent the spread of disease or pests. It is often used in connection to disease and illness, preventing the movement of those who may have been ...
before being added to the general collection. There are over four thousand species of cockroach worldwide, but only four species are commonly regarded as pests, having adapted to live permanently in buildings. Considered to be a sign of unsanitary conditions, they feed on almost anything, reproduce rapidly and are difficult to eradicate. They can passively transport pathogenic microbes on their body surfaces, particularly in environments such as hospitals, and are linked with allergic reactions in humans. Various insects attack dry food products, with flour beetles, the drugstore beetle, the sawtoothed grain beetle and the Indianmeal moth being found worldwide. The insects may be present in the warehouse or maybe introduced during shipping, in retail outlets, or in the home; they may enter packets through tiny cracks or may chew holes in the packaging. The longer a product is stored, the more likely it is to become contaminated, with the insects often originating from dry pet foods. Some mites, too, infest foodstuffs and other stored products. Each substance has its own specific mite, and they multiply with great rapidity. One of the most damaging is the flour mite, which is found in grain and may become exceedingly abundant in poorly stored material. In time, predatory mites usually move in and control the flour mites.


Countermeasures


Pest control in agriculture and horticulture

The control of pests in crops is as old as civilisation. The earliest approach was mechanical, from ploughing to picking off insects by hand. Early methods included the use of sulphur compounds, before 2500 BC in Sumeria. In ancient China, insecticides derived from plants were in use by 1200 BC to treat seeds and to fumigate plants. Chinese agronomy recognised biological control by natural enemies of pests and the varying of planting time to reduce pests before the first century AD. The agricultural revolution in Europe saw the introduction of effective plant-based insecticides such as
pyrethrum ''Pyrethrum'' was a genus of several Old World plants now classified in either '' Chrysanthemum'' or '' Tanacetum'' which are cultivated as ornamentals for their showy flower heads. Pyrethrum continues to be used as a common name for plants form ...
, derris,
quassia ''Quassia'' ( or ) is a plant genus in the family Simaroubaceae. Its size is disputed; some botanists treat it as consisting of only one species, '' Quassia amara'' from tropical South America, while others treat it in a wide circumscription as ...
, and
tobacco Tobacco is the common name of several plants in the genus '' Nicotiana'' of the family Solanaceae, and the general term for any product prepared from the cured leaves of these plants. More than 70 species of tobacco are known, but the ...
extract. The
phylloxera Grape phylloxera is an insect pest of grapevines worldwide, originally native to eastern North America. Grape phylloxera (''Daktulosphaira vitifoliae'' (Fitch 1855) belongs to the family Phylloxeridae, within the order Hemiptera, bugs); orig ...
(a
powdery mildew Powdery mildew is a fungus, fungal disease that affects a wide range of plants. Powdery mildew diseases are caused by many different species of Ascomycota, ascomycete fungi in the order Erysiphales. Powdery mildew is one of the easier plant disea ...
) damage to the wine industry in the 19th century resulted in the development of resistant varieties and
grafting Grafting or graftage is a horticulture, horticultural technique whereby tissues of plants are joined so as to continue their growth together. The upper part of the combined plant is called the scion () while the lower part is called the roots ...
, and the accidental discovery of effective chemical pesticides, Bordeaux mixture (lime and copper sulphate) and
Paris Green Paris green (copper(II) acetate triarsenite or copper(II) acetoarsenite) is an arsenic-based organic pigment. As a green pigment it is also known as Mitis green, Schweinfurt green, Sattler green, emerald, Vienna green, Emperor green or Mount ...
(an
arsenic Arsenic is a chemical element; it has Symbol (chemistry), symbol As and atomic number 33. It is a metalloid and one of the pnictogens, and therefore shares many properties with its group 15 neighbors phosphorus and antimony. Arsenic is not ...
compound), both very widely used. Biological control also became established as an effective measure in the second half of the 19th century, starting with the vedalia beetle against cottony cushion scale. All these methods have been refined and developed since their discovery.


Pest control in forestry

Forest pests inflict costly damage, but treating them is often unaffordable, given the relatively low value of forest products compared to agricultural crops. It is also generally impossible to eradicate forest pests, given the difficulty of examining entire trees, and the certainty that pesticides would damage many forest organisms other than the intended pests. Forest integrated pest management therefore aims to use a combination of prevention, cultural control measures, and direct control (such as pesticide use). Cultural measures include choosing appropriate species, keeping competing vegetation under control, ensuring a suitable stocking density, and minimizing injury and stress to trees.


Pest control in buildings

Pest control in buildings can be approached in several ways, depending on the type of pest and the area affected. Methods include improving sanitation and garbage control, modifying the habitat, and using repellents, growth regulators, traps, baits and pesticides. For example, the pesticide
Boron Boron is a chemical element; it has symbol B and atomic number 5. In its crystalline form it is a brittle, dark, lustrous metalloid; in its amorphous form it is a brown powder. As the lightest element of the boron group it has three ...
can be impregnated into the fibres of cellulose insulation to kill self-grooming insects such as ants and cockroaches. Clothes moths can be controlled with airtight containers for storage, periodic laundering of garments, trapping, freezing, heating and the use of chemicals. Traditional
mothball Mothballs are small balls of chemical pesticide and deodorant, sometimes used when storing clothing and other materials susceptible to damage from silverfish, Mold (fungus), mold or moth larvae (especially clothes moths like ''Tineola bissell ...
s deter adult moths with strong-smelling
naphthalene Naphthalene is an organic compound with formula . It is the simplest polycyclic aromatic hydrocarbon, and is a white Crystal, crystalline solid with a characteristic odor that is detectable at concentrations as low as 0.08 Parts-per notation ...
; modern ones use volatile repellents such as 1,4-Dichlorobenzene. Moth larvae can be killed with insecticides such as
permethrin Permethrin is a medication and an insecticide. As a medication, it is used to treat scabies and lice. It is applied to the skin as a cream or lotion. As an insecticide, it can be sprayed onto outer clothing or mosquito nets to kill the insects ...
or
pyrethroid A pyrethroid is an organic compound similar to the natural pyrethrins, which are produced by the flowers of pyrethrums (''Chrysanthemum cinerariaefolium'' and ''Chrysanthemum coccineum, C. coccineum''). Pyrethroids are used as commercial and hou ...
s. However, insecticides cannot safely be used in food storage areas; alternative treatments include freezing foods for four days at or baking for half an hour at to kill any insects present.


In mythology, religion, folklore, and culture

Pests have attracted human attention from the birth of civilisation. Plagues of locusts caused devastation in the ancient Middle East, and were recorded in tombs in Ancient Egypt from as early as 2470 BC, and in the
Book of Exodus The Book of Exodus (from ; ''Šəmōṯ'', 'Names'; ) is the second book of the Bible. It is the first part of the narrative of the Exodus, the origin myth of the Israelites, in which they leave slavery in Biblical Egypt through the strength of ...
in the Bible, as taking place in Egypt around 1446 BC.
Homer Homer (; , ; possibly born ) was an Ancient Greece, Ancient Greek poet who is credited as the author of the ''Iliad'' and the ''Odyssey'', two epic poems that are foundational works of ancient Greek literature. Despite doubts about his autho ...
's ''
Iliad The ''Iliad'' (; , ; ) is one of two major Ancient Greek epic poems attributed to Homer. It is one of the oldest extant works of literature still widely read by modern audiences. As with the ''Odyssey'', the poem is divided into 24 books and ...
'' mentions locusts taking to the wing to escape fire. Given the impact of agricultural pests on human lives, people have prayed for deliverance. For example, the 10th century Greek monk Tryphon of Constantinople is said to have prayed "Snails, earwigs and all other creatures, hurt not the vines, nor the land nor the fruit of the trees, nor the vegetables ... but depart into the wild mountains." The 11th-century
Old English Old English ( or , or ), or Anglo-Saxon, is the earliest recorded form of the English language, spoken in England and southern and eastern Scotland in the Early Middle Ages. It developed from the languages brought to Great Britain by Anglo-S ...
medical text '' Lacnunga'' contained charms and spells to ward off or treat pests such as ''wid smeogan wyrme'', " penetrating worms", in this case requiring a charm to be sung, accompanied by covering the wound with spittle, pounded green centaury, and hot cow's urine. The 20th century "prayer against pests" including the words "By Your power may these injurious animals be driven off so that they will do no harm to any one and will leave our fields and meadows unharmed" was printed in the 1956 ''Rural Life Prayerbook''.


References


Further reading

* Hockings, F. D. 2014
''Pests, Diseases and Beneficials''
, CSIRO Publishing, Melbourne, *


External links

*
UF/IFAS Pest Alert Web site
-
arthropod Arthropods ( ) are invertebrates in the phylum Arthropoda. They possess an arthropod exoskeleton, exoskeleton with a cuticle made of chitin, often Mineralization (biology), mineralised with calcium carbonate, a body with differentiated (Metam ...
s,
nematode The nematodes ( or ; ; ), roundworms or eelworms constitute the phylum Nematoda. Species in the phylum inhabit a broad range of environments. Most species are free-living, feeding on microorganisms, but many are parasitic. Parasitic worms (h ...
s and plant diseases affecting humans, livestock/pets, agricultural and ornamental plants.
Flying moisture insects
* {{Authority control Insects in culture