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Biological control or biocontrol is a method of controlling pests such as
insect Insects (from Latin Latin (, or , ) is a classical language A classical language is a language A language is a structured system of communication Communication (from Latin ''communicare'', meaning "to share" or "to be in ...

insect
s,
mite Mites are small arachnid Arachnida () is a class Class or The Class may refer to: Common uses not otherwise categorized * Class (biology), a taxonomic rank * Class (knowledge representation), a collection of individuals or objects * Cl ...
s,
weed A weed is a plant Plants are predominantly photosynthetic Photosynthesis is a process used by plants and other organisms to Energy transformation, convert light energy into chemical energy that, through cellular respiration, can late ...

weed
s and
plant diseases Plant pathology (also phytopathology) is the scientific study of disease A disease is a particular abnormal condition that negatively affects the structure A structure is an arrangement and organization of interrelated elements in ...
using other organisms. It relies on
predation Predation is a biological interaction In ecology Ecology (from el, οἶκος, "house" and el, -λογία, label=none, "study of") is the study of the relationships between living organisms, including humans, and their physical en ...

predation
,
parasitism Parasitism is a close relationship between species In biology Biology is the natural science that studies life and living organisms, including their anatomy, physical structure, Biochemistry, chemical processes, Molecular biology, ...

parasitism
,
herbivory A herbivore is an animal Animals (also called Metazoa) are multicellular A multicellular organism is an organism In biology, an organism () is any organic, life, living system that functions as an individual entity. All ...
, or other natural mechanisms, but typically also involves an active human management role. It can be an important component of
integrated pest management Integrated pest management (IPM), also known as integrated pest control (IPC) is a broad-based approach that integrates practices for economic . IPM aims to suppress pest populations below the economic injury level (EIL). The UN's defines IPM as ...
(IPM) programs. There are three basic strategies for biological pest control: classical (importation), where a natural enemy of a pest is introduced in the hope of achieving control; inductive (augmentation), in which a large population of natural enemies are administered for quick pest control; and inoculative (conservation), in which measures are taken to maintain natural enemies through regular reestablishment. Natural enemies of insect pests, also known as biological control agents, include predators,
parasitoid In evolutionary ecology, a parasitoid is an organism that lives in close association with its host (biology), host at the host's expense, eventually resulting in the death of the host. Parasitoidism is one of six major evolutionarily stable str ...
s,
pathogen In biology, a pathogen ( el, πάθος, "suffering", "passion" and , "producer of") in the oldest and broadest sense, is any organism that can produce disease. A pathogen may also be referred to as an infectious agent, or simply a Germ theory ...
s, and
competitors Competition is a rivalry A rivalry is the state of two people or groups engaging in a lasting competitive relationship. Rivalry is the "against each other" spirit between two competing sides. The relationship itself may also be called "a ri ...
. Biological control agents of plant diseases are most often referred to as antagonists. Biological control agents of weeds include seed predators,
herbivore A herbivore is an animal Animals (also called Metazoa) are organisms that form the Animalia. With few exceptions, animals , , are , can , and grow from a hollow sphere of , the , during . Over 1.5 million animal have been —of ...
s, and plant pathogens. Biological control can have side-effects on
biodiversity Biodiversity is the biological variety and Genetic variability, variability of life, life on Earth. Biodiversity is a measure of variation at the Genetics, genetic, species, and ecosystem level. Terrestrial biodiversity is usually greater near ...

biodiversity
through attacks on non-target species by any of the above mechanisms, especially when a species is introduced without a thorough understanding of the possible consequences.


History

The term "biological control" was first used by
Harry Scott Smith Harry Scott Smith (November 29, 1883 – November 28, 1957), an entomologist and professor at University of California, Riverside (UCR), was a pioneer in the field of biological pest control. United States Department of Agriculture Smith grew up ...
at the 1919 meeting of the Pacific Slope Branch of the American Association of Economic Entomologists, in
Riverside, California Riverside is a city in, and the county seat of, Riverside County, California, Riverside County, California, United States, located in the Inland Empire metropolitan area. It is named for its location beside the Santa Ana River. It is the most p ...
. It was brought into more widespread use by the entomologist Paul H. DeBach (1914–1993) who worked on citrus crop pests throughout his life. However, the practice has previously been used for centuries. The first report of the use of an insect species to control an insect pest comes from "
Nanfang Caomu Zhuang The (c. 304 CE) ''Nanfang caomu zhuang'' (南方草木狀 ''Plants of the Southern Regions''), attributed to the Western Jin dynasty scholar and botanist Ji Han (嵇含, 263-307), is a Flora Flora is all the plant life present in a particula ...
" (南方草木狀 ''Plants of the Southern Regions'') (c. 304 AD), attributed to
Western Jin dynasty Western may refer to: Places *Western, Nebraska Western is a village in Saline County, Nebraska, Saline County, Nebraska, United States. The population was 235 at the 2010 United States Census, 2010 census. History Western was laid out in 1 ...
botanist ''Ji Han'' (嵇含, 263–307), in which it is mentioned that "''
Jiaozhi Jiaozhi (standard Chinese Standard Chinese (), in linguistics known as Standard Northern Mandarin, Standard Beijing Mandarin or simply Mandarin, is a dialect of Mandarin that emerged as the lingua franca among the speakers of various Man ...
people sell ants and their nests attached to twigs looking like thin cotton envelopes, the reddish-yellow ant being larger than normal. Without such ants, southern citrus fruits will be severely insect-damaged''". The ants used are known as ''huang gan'' (''huang'' = yellow, ''gan'' = citrus) ants (''
Oecophylla smaragdina ''Oecophylla smaragdina'' (common name Common may refer to: Places * Common, a townland in County Tyrone, Northern Ireland * Boston Common Boston Common (also known as the Common) is a central public park in downtown Boston, Massachusetts. ...

Oecophylla smaragdina
''). The practice was later reported by Ling Biao Lu Yi (late
Tang Dynasty The Tang dynasty (, ; ), or Tang Empire, was an imperial dynasty of China that ruled from 618 to 907, with an interregnum An interregnum (plural interregna or interregnums) is a period of discontinuity or "gap" in a government, organiza ...
or Early
Five Dynasties The Five Dynasties and Ten Kingdoms period (907–979) was an era of political upheaval and division in 10th-century Imperial China. Five states quickly succeeded one another in the Central Plain, and more than a dozen concurrent states were e ...
), in ''Ji Le Pian'' by ''Zhuang Jisu'' (
Southern Song Dynasty The Song dynasty (; ; 960–1279) was an imperial dynasty of China that began in 960 and lasted until 1279. The dynasty was founded by Emperor Taizu of Song Emperor Taizu of Song (21 March 927 – 14 November 976), personal name Zhao Kua ...
), in the ''Book of Tree Planting'' by Yu Zhen Mu (
Ming Dynasty The Ming dynasty (), officially the Great Ming, was the Dynasties in Chinese history, ruling dynasty of China from 1368 to 1644 following the collapse of the Mongol Empire, Mongol-led Yuan dynasty. The Ming dynasty was the last imperial dynas ...

Ming Dynasty
), in the book ''Guangdong Xing Yu'' (17th century), ''Lingnan'' by Wu Zhen Fang (Qing Dynasty), in ''Nanyue Miscellanies'' by Li Diao Yuan, and others. Biological control techniques as we know them today started to emerge in the 1870s. During this decade, in the US, the Missouri State Entomologist C. V. Riley and the Illinois State Entomologist W. LeBaron began within-state redistribution of parasitoids to control crop pests. The first international shipment of an insect as a biological control agent was made by Charles V. Riley in 1873, shipping to France the predatory mites ''Tyroglyphus phylloxera'' to help fight the grapevine phylloxera () that was destroying grapevines in France. The
United States Department of Agriculture The United States Department of Agriculture (USDA), also known as the Agriculture Department, is the federal executive department responsible for developing and executing federal laws related to farming, forestry, rural economic development, ...
(USDA) initiated research in classical biological control following the establishment of the Division of Entomology in 1881, with C. V. Riley as Chief. The first importation of a parasitoidal wasp into the United States was that of the braconid ''
Cotesia glomerata ''Cotesia glomerata'', the white butterfly parasite, is a small parasitic wasp species belonging to family Braconidae The Braconidae are a family of parasitoid In evolutionary ecology, a parasitoid is an organism that lives in close assoc ...

Cotesia glomerata
'' in 1883–1884, imported from Europe to control the invasive cabbage white butterfly, ''
Pieris rapae ''Pieris rapae'' is a small- to medium-sized butterfly species of the whites-and-yellows family (biology), family Pieridae. It is known in Europe as the small white, in North America as the cabbage white or cabbage butterfly, on several continent ...

Pieris rapae
''. In 1888–1889 the vedalia beetle, ''
Rodolia cardinalis ''Novius cardinalis'' (common names vedalia beetle or cardinal ladybird) is a species of ladybird beetle that is sometimes described as endemism, endemic to Australia. It was formerly placed in the genus ''Rodolia'', but that genus was synony ...

Rodolia cardinalis
'', a lady beetle, was introduced from
Australia Australia, officially the Commonwealth of Australia, is a Sovereign state, sovereign country comprising the mainland of the Australia (continent), Australian continent, the island of Tasmania, and numerous List of islands of Australia, sma ...

Australia
to
California California is a state State may refer to: Arts, entertainment, and media Literature * ''State Magazine'', a monthly magazine published by the U.S. Department of State * The State (newspaper), ''The State'' (newspaper), a daily newspaper i ...

California
to control the cottony cushion scale, ''
Icerya purchasi ''Icerya purchasi'' (common name Common may refer to: Places * Common, a townland in County Tyrone, Northern Ireland * Boston Common Boston Common (also known as the Common) is a central public park in downtown Boston, Massachusetts. It is ...

Icerya purchasi
''. This had become a major problem for the newly developed citrus industry in California, but by the end of 1889, the cottony cushion scale population had already declined. This great success led to further introductions of beneficial insects into the US.Coulson, J. R.; Vail, P. V.; Dix M.E.; Nordlund, D.A.; Kauffman, W.C.; Eds. 2000. 110 years of biological control research and development in the United States Department of Agriculture: 1883–1993. U.S. Department of Agriculture, Agricultural Research Service. pages=3–11 In 1905 the USDA initiated its first large-scale biological control program, sending entomologists to Europe and Japan to look for natural enemies of the gypsy moth, ''
Lymantria dispar dispar ''Lymantria dispar dispar'', commonly known as the gypsy moth, European gypsy moth, or North American gypsy moth, is a species of moth in the family Erebidae that is of Eurasian origin. It has a range that extends over Europe, Africa, and North A ...
'', and brown-tail moth, ''Euproctis chrysorrhoea'', invasive pests of trees and shrubs. As a result, nine parasitoids (solitary wasps) of the gypsy moth, seven of brown-tail moth, and two predators of both moths became established in the US. Although the gypsy moth was not fully controlled by these natural enemies, the frequency, duration, and severity of its outbreaks were reduced and the program was regarded as successful. This program also led to the development of many concepts, principles, and procedures for the implementation of biological control programs. were introduced into
Queensland Queensland ( ) is a state situated in northeastern Australia Australia, officially the Commonwealth of Australia, is a Sovereign state, sovereign country comprising the mainland of the Australia (continent), Australian continent, the ...

Queensland
, Australia as ornamental plants, starting in 1788. They quickly spread to cover over 25 million hectares of Australia by 1920, increasing by 1 million hectares per year. Digging, burning, and crushing all proved ineffective. Two control agents were introduced to help control the spread of the plant, the cactus moth ''
Cactoblastis cactorum ''Cactoblastis'' is a genus of snout moths. It was described by Émile Louis Ragonot in 1901 and is known from Argentina Argentina (), officially the Argentine Republic ( es, link=no, República Argentina), is a country located mostly in the ...
'', and the scale insect ''
Dactylopius ''Dactylopius'' is a genus Genus (plural genera) is a taxonomic rank Taxonomy (general) is the practice and science of classification of things or concepts, including the principles that underlie such classification. The term may also refer t ...
''. Between 1926 and 1931, tens of millions of cactus moth eggs were distributed around Queensland with great success, and by 1932, most areas of prickly pear had been destroyed. The first reported case of a classical biological control attempt in
Canada Canada is a country in the northern part of North America North America is a continent A continent is any of several large landmasses. Generally identified by convention (norm), convention rather than any strict criteria, ...

Canada
involves the parasitoidal wasp '' Trichogramma minutum''. Individuals were caught in
New York State New York is a state State may refer to: Arts, entertainment, and media Literature * ''State Magazine'', a monthly magazine published by the U.S. Department of State * The State (newspaper), ''The State'' (newspaper), a daily newspaper in Col ...
and released in
Ontario ("Loyal she began, loyal she remains") , Label_map = yes , image_map = Ontario in Canada 2.svg , map_alt = Map showing Ontario's location east/central of Canada. , coordinates = , cap ...

Ontario
gardens in 1882 by William Saunders, a trained chemist and first Director of the Dominion Experimental Farms, for controlling the invasive currantworm ''''. Between 1884 and 1908, the first Dominion Entomologist, James Fletcher, continued introductions of other parasitoids and pathogens for the control of pests in Canada.


Types of biological pest control

There are three basic biological pest control strategies: importation (classical biological control), augmentation and conservation.


Importation

Importation or classical biological control involves the introduction of a pest's natural enemies to a new locale where they do not occur naturally. Early instances were often unofficial and not based on research, and some introduced species became serious pests themselves. To be most effective at controlling a pest, a biological control agent requires a colonizing ability which allows it to keep pace with changes to the habitat in space and time. Control is greatest if the agent has temporal persistence so that it can maintain its population even in the temporary absence of the target species, and if it is an opportunistic forager, enabling it to rapidly exploit a pest population. One of the earliest successes was in controlling ''
Icerya purchasi ''Icerya purchasi'' (common name Common may refer to: Places * Common, a townland in County Tyrone, Northern Ireland * Boston Common Boston Common (also known as the Common) is a central public park in downtown Boston, Massachusetts. It is ...

Icerya purchasi
'' (cottony cushion scale) in Australia, using a predatory insect ''
Rodolia cardinalis ''Novius cardinalis'' (common names vedalia beetle or cardinal ladybird) is a species of ladybird beetle that is sometimes described as endemism, endemic to Australia. It was formerly placed in the genus ''Rodolia'', but that genus was synony ...

Rodolia cardinalis
'' (the vedalia beetle). This success was repeated in California using the beetle and a parasitoidal fly, '' Cryptochaetum iceryae''. Other successful cases include the control of '' Antonina graminis'' in Texas by '' Neodusmetia sangwani'' in the 1960s. Damage from '''', the alfalfa weevil, a serious introduced pest of forage, was substantially reduced by the introduction of natural enemies. 20 years after their introduction the population of
weevil Weevils are beetles belonging to the Taxonomic rank, superfamily Curculionoidea, known for their elongated snouts. They are usually small, less than in length, and Herbivore, herbivorous. Approximately 97,000 species of weevils are known. They b ...

weevil
s in the
alfalfa Alfalfa () (''Medicago sativa''), also called lucerne, is a perennial A perennial plant or simply perennial is a plant Plants are predominantly photosynthetic eukaryotes of the Kingdom (biology), kingdom Plantae. Historically, the ...

alfalfa
area treated for alfalfa weevil in the
Northeastern United States The Northeastern United States (also referred to as the American Northeast, the Northeast, and the East Coast) is a geographical region In geography, regions are areas that are broadly divided by physical characteristics (physical geography), ...
remained 75 percent down. Alligator weed was introduced to the United States from
South America South America is a continent A continent is any of several large landmasses. Generally identified by convention (norm), convention rather than any strict criteria, up to seven geographical regions are commonly regarded as continent ...

South America
. It takes root in shallow water, interfering with
navigation Navigation is a field of study that focuses on the process of monitoring and controlling the movement of a craft or vehicle from one place to another.Bowditch, 2003:799. The field of navigation includes four general categories: land navigation, ...

navigation
,
irrigation Irrigation is the agricultural Agriculture is the practice of cultivating plants and livestock. Agriculture was the key development in the rise of sedentary Image:Family watching television 1958.jpg, Exercise trends, Increases in seden ...

irrigation
, and
flood control Flood control methods are used to reduce or prevent the detrimental effects of flood A flood is an overflow of water that submerges land that is usually dry. In the sense of "flowing water", the word may also be applied to the inflow of the ...
. The alligator weed flea beetle and two other biological controls were released in
Florida Florida is a U.S. state, state located in the Southeastern United States, Southeastern region of the United States. Florida is bordered to the west by the Gulf of Mexico, to the northwest by Alabama, to the north by Georgia (U.S. state), Geor ...

Florida
, greatly reducing the amount of land covered by the plant. Another aquatic weed, the giant salvinia (''
Salvinia molesta 250px, Giant salvinia completely cover Lake Wilson in Hawaii ''Salvinia molesta'', commonly known as giant salvinia, or as kariba weed after it infested a large portion of Lake Kariba between Zimbabwe and Zambia, is an aquatic fern, native to ...

Salvinia molesta
'') is a serious pest, covering waterways, reducing water flow and harming native species. Control with the salvinia weevil (''
Cyrtobagous salviniae ''Cyrtobagous salviniae'' is a species of Curculionidae, weevil known as the salvinia weevil. It is used as an agent of biological pest control against the noxious weed, noxious aquatic plant giant salvinia (''Salvinia molesta''). The adult weev ...
'') and the salvinia stem-borer moth (''
Samea multiplicalis ''Samea multiplicalis'', the salvinia stem-borer moth, is an aquatic moth commonly found in freshwater habitats from the southern United States to Argentina, as well as in Australia where it was introduced in 1981. Salvinia stem-borer moths lay t ...
)'' is effective in warm climates, and in Zimbabwe, a 99% control of the weed was obtained over a two-year period. Small commercially reared parasitoidal
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. The ...

wasp
s, '' Trichogramma ostriniae'', provide limited and erratic control of the
European corn borer#REDIRECT European corn borer {{Redirect category shell, 1= {{R from move {{R from other capitalisation ...
(''Ostrinia nubilalis''), a serious pest. Careful formulations of the bacterium ''
Bacillus thuringiensis ''Bacillus thuringiensis'' (or Bt) is a Gram-positive 300px, Violet-stained gram-positive cocci and pink-stained gram-negative bacillus (shape), bacilli In bacteriology, gram-positive bacteria are bacteria that give a positive result in the G ...

Bacillus thuringiensis
'' are more effective. The O. nubilalis integrated control releasing Tricogramma brassicae (egg parasitoiod) and later Bacillus thuringiensis subs. kurstaki (larvicidae effect) reduce pest damages as better than insecticide treatments The population of '''', the Levuana moth, a serious coconut pest in
Fiji Fiji ( ; fj, Viti, ; hif, फ़िजी, ''Fijī''), officially the Republic of Fiji, is an island country in Melanesia, part of Oceania in the South Pacific Ocean. It lies about northeast of New Zealand. Fiji consists of an archipelago ...

Fiji
, was brought under control by a classical biological control program in the 1920s.


Augmentation

Augmentation involves the supplemental release of natural enemies that occur in a particular area, boosting the naturally occurring populations there. In inoculative release, small numbers of the control agents are released at intervals to allow them to reproduce, in the hope of setting up longer-term control and thus keeping the pest down to a low level, constituting prevention rather than cure. In inundative release, in contrast, large numbers are released in the hope of rapidly reducing a damaging pest population, correcting a problem that has already arisen. Augmentation can be effective, but is not guaranteed to work, and depends on the precise details of the interactions between each pest and control agent. An example of inoculative release occurs in the horticultural production of several crops in
greenhouse A greenhouse (also called a glasshouse, or, if with sufficient heating, a hothouse) is a structure with walls and roof made chiefly of transparent material, such as glass, in which plant Plants are predominantly photosynthetic Photo ...

greenhouse
s. Periodic releases of the parasitoidal wasp, ''
Encarsia formosa ''Encarsia formosa'' is a species of chalcidoid 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 ...

Encarsia formosa
'', are used to control greenhouse
whitefly Whiteflies are Hemipterans that typically feed on the undersides of plant leaves. They comprise the family (biology), family Aleyrodidae, the only family in the superfamily Aleyrodoidea. More than List of whitefly species, 1550 species have been d ...

whitefly
, while the predatory mite ''
Phytoseiulus persimilis ''Phytoseiulus'' is a genus of mites in the Phytoseiidae family. A predatory mite, this is the mite predator most frequently used to control Tetranychus urticae, two-spotted spider mites in greenhouses and outdoor crops grown in mild environments. ...

Phytoseiulus persimilis
'' is used for control of the two-spotted spider mite. The egg parasite '' Trichogramma'' is frequently released inundatively to control harmful moths. New way for inundative releases are now introduced i.e. use of drones. Egg parasitoids are able to find the eggs of the target host by means of several cues. Kairomones wer found on moth scales. Similarly, ''Bacillus thuringiensis'' and other microbial insecticides are used in large enough quantities for a rapid effect. Recommended release rates for ''Trichogramma'' in vegetable or field crops range from 5,000 to 200,000 per acre (1 to 50 per square metre) per week according to the level of pest infestation. Similarly,
nematodes The nematodes ( or grc-gre, Νηματώδη; la, Nematoda) or roundworms constitute the phylum In biology, a phylum (; plural The plural (sometimes list of glossing abbreviations, abbreviated ), in many languages, is one of the valu ...
that kill insects (that are entomopathogenic) are released at rates of millions and even billions per acre for control of certain soil-dwelling insect pests.


Conservation

The conservation of existing natural enemies in an environment is the third method of biological pest control. Natural enemies are already adapted to the
habitat In ecology Ecology (from el, οἶκος, "house" and el, -λογία, label=none, "study of") is the study of the relationships between living organisms, including humans, and their physical environment. Ecology considers at the ...

habitat
and to the target pest, and their conservation can be simple and cost-effective, as when nectar-producing crop plants are grown in the borders of rice fields. These provide nectar to support parasitoids and predators of planthopper pests and have been demonstrated to be so effective (reducing pest densities by 10- or even 100-fold) that farmers sprayed 70% less insecticides and enjoyed yields boosted by 5%. Predators of aphids were similarly found to be present in tussock grasses by field boundary hedges in England, but they spread too slowly to reach the centers of fields. Control was improved by planting a meter-wide strip of tussock grasses in field centers, enabling aphid predators to overwinter there. Cropping systems can be modified to favor natural enemies, a practice sometimes referred to as habitat manipulation. Providing a suitable habitat, such as a
shelterbelt , designed by Ralph Erskine (architect), Ralph Erskine, which forms a long windbreak A windbreak (shelterbelt) is a planting usually made up of one or more rows of trees or shrubs planted in such a manner as to provide shelter from the wind and ...
,
hedgerow A hedge or hedgerow is a line of closely spaced shrubs and sometimes trees, planted and trained to form a barrier or to mark the boundary of an area, such as between neighbouring properties. Hedges that are used to separate a road from adjoining ...
, or
beetle bank A beetle bank, in agriculture Agriculture is the science, art and practice of cultivating plants and livestock. Agriculture was the key development in the rise of sedentism, sedentary human civilization, whereby farming of domestication, dome ...
where beneficial insects such as parasitoidal wasps can live and reproduce, can help ensure the survival of populations of natural enemies. Things as simple as leaving a layer of fallen leaves or mulch in place provides a suitable food source for worms and provides a shelter for insects, in turn being a food source for such beneficial mammals as
hedgehog A hedgehog is a spiny mammal of the subfamily Erinaceinae, in the eulipotyphlan family (biology), family Erinaceidae. There are seventeen species of hedgehog in five genus, genera found throughout parts of Europe, Asia, and Africa, and in Ne ...

hedgehog
s and
shrew Shrews (family In human society A society is a Social group, group of individuals involved in persistent Social relation, social interaction, or a large social group sharing the same spatial or social territory, typically subject to ...
s.
Compost pile Compost ( or ) is made by decomposing organic materials into simpler organic and inorganic compounds in a process called composting. This process recycles various organic material Organic matter, organic material, or natural organic matter ...

Compost pile
s and stacks of wood can provide shelter for invertebrates and small mammals. Long grass and
pond A pond is an area filled with water, either natural or Artificiality, artificial, that is smaller than a lake. Ponds are small bodies of freshwater with shallow and still water, marsh, and aquatic plants.Clegg, J. (1986). Observer's Book of ...

pond
s support amphibians. Not removing dead annuals and non-hardy plants in the autumn allow insects to make use of their hollow stems during winter. In California, prune trees are sometimes planted in grape vineyards to provide an improved overwintering habitat or refuge for a key grape pest parasitoid. The providing of artificial shelters in the form of wooden caskets,
box File:Box with cover MET DP241878.jpg, alt=A small, elaborate box, featuring a hinged lid, two swing doors at the front and a small pull-out drawer; the interior is entirely red and features small items that seem to be part of a toilette set, An el ...

box
es or
flowerpot A flowerpot, flower pot, planter, planterette, or alternatively plant pot is a container in which flower A flower, sometimes known as a bloom or blossom Image:Cerisier du Japon Prunus serrulata.jpg, Cherry blossoms in Paris in full bloom ...
s is also sometimes undertaken, particularly in gardens, to make a cropped area more attractive to natural enemies. For example, earwigs are natural predators that can be encouraged in gardens by hanging upside-down flowerpots filled with
straw Straw is an agricultural byproduct A by-product or byproduct is a secondary product derived from a production process, manufacturing Manufacturing is the Production (economics), production of goods through the use of Work (human activity ...

straw
or
wood wool Wood wool, known primarily as excelsior in North America, is a product made of wood slivers cut from logs. It is mainly used in packaging, for cooling pads in home evaporative cooling systems known as swamp cooler An evaporative cooler (also ev ...
. Green
lacewings The insect order (biology), order Neuroptera, or net-winged insects, includes the lacewings, Mantispidae, mantidflies, antlions, and their relatives. The order consists of some 6,000 species. Neuroptera can be grouped together with the Megalopte ...

lacewings
can be encouraged by using plastic bottles with an open bottom and a roll of cardboard inside. Birdhouses enable insectivorous birds to nest; the most useful birds can be attracted by choosing an opening just large enough for the desired species. In cotton production, the replacement of broad-spectrum insecticides with selective control measures such as
Bt cotton Bt cotton is a genetically modified organism A genetically modified organism (GMO) is any organism whose gene In biology, a gene (from ''genos'' "...Wilhelm Johannsen coined the word gene to describe the Mendelian_inheritance#History, ...
can create a more favorable environment for natural enemies of cotton pests due to reduced insecticide exposure risk. Such predators or
parasitoids In evolutionary ecology, a parasitoid is an organism In biology, an organism (from Ancient Greek, Greek: ὀργανισμός, ''organismos'') is any individual contiguous system that embodies the Life#Biology, properties of life. It i ...
can control pests not affected by the . Reduced prey quality and abundance associated increased control from Bt cotton can also indirectly decrease natural enemy populations in some cases, but the percentage of pests eaten or parasitized in Bt and non-Bt cotton are often similar.


Biological control agents


Predators

Predators are mainly free-living species that directly consume a large number of
prey Predation is a biological interaction In ecology Ecology (from el, οἶκος, "house" and el, -λογία, label=none, "study of") is the study of the relationships between living organisms, including humans, and their physical env ...

prey
during their whole lifetime. Given that many major crop pests are insects, many of the predators used in biological control are insectivorous species. , and in particular their larvae which are active between May and July in the northern hemisphere, are voracious predators of
aphid Aphids are small sap-sucking insects and members of the Taxonomic rank, superfamily Aphidoidea. Common names include greenfly and blackfly, although individuals within a species can vary widely in color. The group includes the fluffy white Erio ...

aphid
s, and also consume
mites Mites are small arachnid Arachnida () is a class Class or The Class may refer to: Common uses not otherwise categorized * Class (biology), a taxonomic rank * Class (knowledge representation), a collection of individuals or objects * Cl ...

mites
,
scale insect Scale insects are small insect Insects (from Latin Latin (, or , ) is a classical language belonging to the Italic languages, Italic branch of the Indo-European languages. Latin was originally spoken in the area around Rome, known as L ...

scale insect
s and small
caterpillar Caterpillars ( ) are the larval stage A larva (plural larvae ) is a distinct juvenile form many animal Animals (also called Metazoa) are multicellular eukaryotic organisms that form the Kingdom (biology), biological kingdom Anim ...

caterpillar
s. The spotted lady beetle ('''') is also able to feed on the eggs and larvae of the
Colorado potato beetle The Colorado potato beetle (''Leptinotarsa decemlineata''), also known as the Colorado beetle, the ten-striped spearman, the ten-lined potato beetle, or the potato bug, is a major Pest (organism), pest of potato crops. It is about long, with a ...

Colorado potato beetle
(''Leptinotarsa decemlineata''). The larvae of many
hoverfly Hover flies, also called flower flies or syrphid flies, make up the insect family In , family (from la, familia) is a of people related either by (by recognized birth) or (by marriage or other relationship). The purpose of families is ...

hoverfly
species principally feed upon
aphid Aphids are small sap-sucking insects and members of the Taxonomic rank, superfamily Aphidoidea. Common names include greenfly and blackfly, although individuals within a species can vary widely in color. The group includes the fluffy white Erio ...

aphid
s, one larva devouring up to 400 in its lifetime. Their effectiveness in commercial crops has not been studied. The running crab spider '''' also prey heavily on aphids, and act as a biological control agent in European fruit orchards. Several species of
entomopathogenic nematodeEntomopathogens are pathogen In biology Biology is the natural science that studies life and living organisms, including their anatomy, physical structure, Biochemistry, chemical processes, Molecular biology, molecular interactions, Physiolog ...
are important predators of insect and other invertebrate pests. Entomopathogenic nematodes form a stress–resistant stage known as the infective juvenile. These spread in the soil and infect suitable insect hosts. Upon entering the insect they move to the
hemolymph Hemolymph, or haemolymph, is a fluid, analogous to the blood in vertebrates, that circulates in the interior of the arthropod (invertebrate) body remaining in direct contact with the animal's tissues. It is composed of a fluid plasma in which ...
where they recover from their stagnated state of development and release their
bacterial Bacteria (; common noun bacteria, singular bacterium) are a type of biological cell. They constitute a large domain of prokaryotic microorganism A microorganism, or microbe,, ''mikros'', "small") and ''organism In biology, an ...
symbionts Symbiosis (from Greek , , "living together", from , , "together", and , bíōsis, "living") is any type of a close and long-term biological interaction In ecology Ecology (from el, οἶκος, "house" and el, -λογία, label=none, ...

symbionts
. The bacterial symbionts reproduce and release toxins, which then kill the host insect. '' Phasmarhabditis hermaphrodita'' is a microscopic nematode that kills slugs. Its complex life cycle includes a free-living, infective stage in the soil where it becomes associated with a pathogenic bacteria such as ''Moraxella osloensis''. The nematode enters the slug through the posterior mantle region, thereafter feeding and reproducing inside, but it is the bacteria that kill the slug. The nematode is available commercially in Europe and is applied by watering onto moist soil. Entomopathogenic nematodes have a limited shelf life because of their limited resistance to high temperature and dry conditions. The type of soil they are applied to may also limit their effectiveness. Species used to control spider mites include the predatory mites ''
Phytoseiulus persimilis ''Phytoseiulus'' is a genus of mites in the Phytoseiidae family. A predatory mite, this is the mite predator most frequently used to control Tetranychus urticae, two-spotted spider mites in greenhouses and outdoor crops grown in mild environments. ...

Phytoseiulus persimilis
'', ''Neoseilus Neoseilus californicus, californicus,'' and ''Amblyseius Amblyseius cucumeris, cucumeris'', the predatory midge ''Feltiella acarisuga'', and a ladybird ''Stethorus punctillum''. The bug ''Orius insidiosus'' has been successfully used against the Tetranychus urticae, two-spotted spider mite and the western flower thrips (''Frankliniella occidentalis''). Predators including ''Cactoblastis cactorum'' (mentioned above) can also be used to destroy invasive plant species. As another example, the Agonopterix alstroemeriana, poison hemlock moth (''Agonopterix alstroemeriana)'' can be used to control Conium maculatum, poison hemlock (''Conium maculatum''). During its larval stage, the moth strictly consumes its host plant, poison hemlock, and can exist at hundreds of larvae per individual host plant, destroying large swathes of the hemlock. For Rodent#As pests and disease vectors, rodent pests, Farm cat, cats are effective biological control when used in conjunction with reduction of Refuge (ecology), "harborage"/hiding locations. While cats are effective at preventing rodent Irruptive growth, "population explosions", they are not effective for eliminating pre-existing severe infestations. Barn owls are also sometimes used as biological rodent control. Although there are no quantitative studies of the effectiveness of barn owls for this purpose, they are known rodent predators that can be used in addition to or instead of cats; they can be encouraged into an area with nest boxes. In Honduras, where the mosquito ''Aedes aegypti'' was transmitting dengue fever and other infectious diseases, biological control was attempted by a community action plan; copepods, baby turtles, and juvenile tilapia were added to the wells and tanks where the mosquito breeds and the mosquito larvae were eliminated. Even amongst arthropods usually thought of as obligate predators of animals (especially other arthropods), flower, floral food sources (nectar and to a lesser degree pollen) are often useful adjunct sources. It had been noticed in one study that adult ''Adalia bipunctata'' (predator and common biocontrol of ''Mediterranean flour moth, Ephestia kuehniella'') could survive on flowers but never completed its biological life cycle, life cycle, so a meta-analysis was done to find such an overall trend in previously published data, if it existed. In some cases floral resources are outright necessary. Overall, floral resources (and an imitation, i.e. sugar water) increase longevity and fecundity, meaning even predatory population numbers can depend on non-prey food abundance. Thus biocontrol population maintenance - and success - may depend on nearby flowers.


Parasitoids

Parasitoids lay their eggs on or in the body of an insect host, which is then used as a food for developing larvae. The host is ultimately killed. Most insect
parasitoid In evolutionary ecology, a parasitoid is an organism that lives in close association with its host (biology), host at the host's expense, eventually resulting in the death of the host. Parasitoidism is one of six major evolutionarily stable str ...
s are Parasitoid wasp, wasps or Fly, flies, and many have a very narrow host range. The most important groups are the Ichneumonidae, ichneumonid wasps, which mainly use
caterpillar Caterpillars ( ) are the larval stage A larva (plural larvae ) is a distinct juvenile form many animal Animals (also called Metazoa) are multicellular eukaryotic organisms that form the Kingdom (biology), biological kingdom Anim ...

caterpillar
s as hosts; Braconidae, braconid wasps, which attack caterpillars and a wide range of other insects including aphids; chalcid wasps, which parasitize eggs and larvae of many insect species; and Tachinidae, tachinid flies, which parasitize a wide range of insects including caterpillars, beetle adults and larvae, and Hemiptera, true bugs. Parasitoids are most effective at reducing pest populations when their host organisms have limited refuge (ecology), refuges to hide from them. Parasitoids are among the most widely used biological control agents. Commercially, there are two types of rearing systems: short-term daily output with high production of parasitoids per day, and long-term, low daily output systems. In most instances, production will need to be matched with the appropriate release dates when susceptible host species at a suitable phase of development will be available. Larger production facilities produce on a yearlong basis, whereas some facilities produce only seasonally. Rearing facilities are usually a significant distance from where the agents are to be used in the field, and transporting the parasitoids from the point of production to the point of use can pose problems. Shipping conditions can be too hot, and even vibrations from planes or trucks can adversely affect parasitoids. ''
Encarsia formosa ''Encarsia formosa'' is a species of chalcidoid 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 ...

Encarsia formosa
'' is a small predatory chalcid wasp which is a parasitoid of
whitefly Whiteflies are Hemipterans that typically feed on the undersides of plant leaves. They comprise the family (biology), family Aleyrodidae, the only family in the superfamily Aleyrodoidea. More than List of whitefly species, 1550 species have been d ...

whitefly
, a sap-feeding insect which can cause wilting and Sooty mold, black sooty moulds in glasshouse vegetable and ornamental crops. It is most effective when dealing with low level infestations, giving protection over a long period of time. The wasp lays its eggs in young whitefly 'scales', turning them black as the parasite larvae pupate. ''Gonatocerus ashmeadi'' (Hymenoptera: Mymaridae) has been introduced to control the glassy-winged sharpshooter ''Homalodisca vitripennis'' (Hemiptera: Cicadellidae) in French Polynesia and has successfully controlled ~95% of the pest density. The Choristoneura fumiferana, eastern spruce budworm is an example of a destructive insect in fir and spruce forests. Birds are a natural form of biological control, but the ''Trichogramma minutum'', a species of parasitic wasp, has been investigated as an alternative to more controversial chemical controls. There are a number of recent studies pursuing sustainable methods for controlling urban cockroaches using parasitic wasps. Since most cockroaches remain in the sewer system and sheltered areas which are inaccessible to insecticides, employing active-hunter wasps is a strategy to try and reduce their populations.


Pathogens

Pathogenic micro-organisms include bacteria, fungi, and viruses. They kill or debilitate their host and are relatively host-specific. Various microbial insect diseases occur naturally, but may also be used as biological pesticides. When naturally occurring, these outbreaks are density-dependent in that they generally only occur as insect populations become denser.


Bacteria

Bacteria used for biological control infect insects via their digestive tracts, so they offer only limited options for controlling insects with sucking mouth parts such as aphids and scale insects. ''
Bacillus thuringiensis ''Bacillus thuringiensis'' (or Bt) is a Gram-positive 300px, Violet-stained gram-positive cocci and pink-stained gram-negative bacillus (shape), bacilli In bacteriology, gram-positive bacteria are bacteria that give a positive result in the G ...

Bacillus thuringiensis
'', a soil-dwelling bacterium, is the most widely applied species of bacteria used for biological control, with at least four sub-species used against Lepidopteran (moth, butterfly), Coleopteran (beetle) and Dipteran (true fly) insect pests. The bacterium is available to organic farmers in sachets of dried spores which are mixed with water and sprayed onto vulnerable plants such as brassicas and fruit trees. Genes from ''B. thuringiensis'' have also been incorporated into Genetically modified crops, transgenic crops, making the plants express some of the bacterium's toxins, which are proteins. These confer resistance to insect pests and thus reduce the necessity for pesticide use. If pests develop resistance to the toxins in these crops, ''B. thuringiensis'' will become useless in organic farming also. The bacterium ''Paenibacillus popilliae'' which causes Milky spore, milky spore disease has been found useful in the control of Japanese beetle, killing the larvae. It is very specific to its host species and is harmless to vertebrates and other invertebrates.


Fungi

Entomopathogenic fungi, which cause disease in insects, include at least 14 species that attack
aphid Aphids are small sap-sucking insects and members of the Taxonomic rank, superfamily Aphidoidea. Common names include greenfly and blackfly, although individuals within a species can vary widely in color. The group includes the fluffy white Erio ...

aphid
s. ''Beauveria bassiana'' is mass-produced and used to manage a wide variety of insect pests including whiteflies, thrips, aphids and weevils. ''Lecanicillium'' spp. are deployed against white flies, thrips and aphids. ''Metarhizium'' spp. are used against pests including beetles, locusts and other grasshoppers, Hemiptera, and spider mites. ''Paecilomyces fumosoroseus'' is effective against white flies, thrips and aphids; ''Purpureocillium lilacinus'' is used against root-knot nematodes, and 89 ''Trichoderma'' List of Trichoderma species, species against certain plant pathogens. ''Trichoderma viride'' has been used against Dutch elm disease, and has shown some effect in suppressing Chondrostereum purpureum, silver leaf, a disease of stone fruits caused by the pathogenic fungus ''Chondrostereum purpureum''. The fungi ''Cordyceps'' and ''Metacordyceps'' are deployed against a wide spectrum of arthropods. ''Entomophaga (fungus), Entomophaga'' is effective against pests such as the Myzus persicae, green peach aphid. Several members of Chytridiomycota and Blastocladiomycota have been explored as agents of biological control. From Chytridiomycota, ''Synchytrium, Synchytrium solstitiale'' is being considered as a control agent of the Centaurea solstitialis, yellow star thistle (''Centaurea solstitialis'') in the United States.


Viruses

Baculoviridae, Baculoviruses are specific to individual insect host species and have been shown to be useful in biological pest control. For example, the Lymantria dispar multicapsid nuclear polyhedrosis virus has been used to spray large areas of forest in North America where larvae of the Lymantria dispar dispar, gypsy moth are causing serious defoliation. The moth larvae are killed by the virus they have eaten and die, the disintegrating cadavers leaving virus particles on the foliage to infect other larvae. A mammalian virus, the rabbit haemorrhagic disease virus was introduced to Australia to attempt to control the European rabbit populations there. It escaped from quarantine and spread across the country, killing large numbers of rabbits. Very young animals survived, passing immunity to their offspring in due course and eventually producing a virus-resistant population. Introduction into New Zealand in the 1990s was similarly successful at first, but a decade later, immunity had developed and populations had returned to pre-RHD levels.


Oomycota

''Lagenidium Lagenidium giganteum, giganteum'' is a water-borne mold that parasitizes the larval stage of mosquitoes. When applied to water, the motile spores avoid unsuitable host species and search out suitable mosquito larval hosts. This mold has the advantages of a dormant phase, resistant to desiccation, with slow-release characteristics over several years. Unfortunately, it is susceptible to many chemicals used in mosquito abatement programmes.


Competitors

The legume vine ''Mucuna pruriens'' is used in the countries of Benin and Vietnam as a biological control for problematic ''Imperata cylindrica'' grass: the vine is extremely vigorous and suppresses neighbouring plants by Competition (biology), out-competing them for space and light. ''Mucuna pruriens'' is said not to be invasive outside its cultivated area. ''Desmodium Desmodium uncinatum, uncinatum'' can be used in push-pull technology, push-pull farming to stop the parasitic plant, witchweed (''Striga (plant), Striga''). The Australian bush fly, ''Musca vetustissima'', is a major nuisance pest in Australia, but native decomposers found in Australia are not adapted to feeding on cow dung, which is where bush flies breed. Therefore, the Australian Dung Beetle Project (1965–1985), led by George Bornemissza of the Commonwealth Scientific and Industrial Research Organisation, released forty-nine species of dung beetle, to reduce the amount of dung and therefore also the potential breeding sites of the fly.


Combined use of parasitoids and pathogens

In cases of massive and severe infection of invasive pests, techniques of pest control are often used in combination. An example is the emerald ash borer, ''Agrilus planipennis'', an invasive beetle from China, which has destroyed tens of millions of ash trees in its introduced range in North America. As part of the campaign against it, from 2003 American scientists and the Chinese Academy of Forestry searched for its natural enemies in the wild, leading to the discovery of several parasitoid wasps, namely ''Tetrastichus planipennisi'', a gregarious larval endoparasitoid, ''Oobius agrili'', a solitary, parthenogenic egg parasitoid, and ''Spathius agrili'', a gregarious larval ectoparasitoid. These have been introduced and released into the United States, United States of America as a possible biological control of the emerald ash borer. Initial results for ''Tetrastichus planipennisi'' have shown promise, and it is now being released along with ''Beauveria bassiana'', a fungal
pathogen In biology, a pathogen ( el, πάθος, "suffering", "passion" and , "producer of") in the oldest and broadest sense, is any organism that can produce disease. A pathogen may also be referred to as an infectious agent, or simply a Germ theory ...
with known insecticidal properties.


Difficulties

Many of the most important pests are exotic, invasive species that severely impact agriculture, horticulture, forestry, and urban environments. They tend to arrive without their co-evolved parasites, pathogens and predators, and by escaping from these, populations may soar. Importing the natural enemies of these pests may seem a logical move but this may have unintended consequences; regulations may be ineffective and there may be unanticipated effects on biodiversity, and the adoption of the techniques may prove challenging because of a lack of knowledge among farmers and growers.


Side effects

Biological control can affect
biodiversity Biodiversity is the biological variety and Genetic variability, variability of life, life on Earth. Biodiversity is a measure of variation at the Genetics, genetic, species, and ecosystem level. Terrestrial biodiversity is usually greater near ...

biodiversity
through predation, parasitism, pathogenicity, competition, or other attacks on non-target species. An introduced control does not always target only the intended pest species; it can also target native species. In Hawaii during the 1940s parasitic wasps were introduced to control a lepidopteran pest and the wasps are still found there today. This may have a negative impact on the native ecosystem; however, host range and impacts need to be studied before declaring their impact on the environment. Vertebrate animals tend to be generalist feeders, and seldom make good biological control agents; many of the classic cases of "biocontrol gone awry" involve vertebrates. For example, the cane toad (''Rhinella marina'') was intentionally introduced to
Australia Australia, officially the Commonwealth of Australia, is a Sovereign state, sovereign country comprising the mainland of the Australia (continent), Australian continent, the island of Tasmania, and numerous List of islands of Australia, sma ...

Australia
to control the cane beetle, greyback cane beetle (''Dermolepida albohirtum''), and other pests of sugar cane. 102 toads were obtained from Hawaii and bred in captivity to increase their numbers until they were released into the sugar cane fields of the tropic north in 1935. It was later discovered that the toads could not jump very high and so were unable to eat the cane beetles which stayed on the upper stalks of the cane plants. However, the toad thrived by feeding on other insects and soon spread very rapidly; it took over native amphibian
habitat In ecology Ecology (from el, οἶκος, "house" and el, -λογία, label=none, "study of") is the study of the relationships between living organisms, including humans, and their physical environment. Ecology considers at the ...

habitat
and brought foreign disease to native toads and frogs, dramatically reducing their populations. Also, when it is threatened or handled, the cane toad releases poison from parotoid glands on its shoulders; native Australian species such as goannas, tiger snakes, dingos and northern quolls that attempted to eat the toad were harmed or killed. However, there has been some recent evidence that native predators are adapting, both physiologically and through changing their behaviour, so in the long run, their populations may recover. ''Rhinocyllus conicus'', a seed-feeding weevil, was introduced to North America to control exotic Carduus nutans, musk thistle (''Carduus nutans'') and Cirsium arvense, Canadian thistle (''Cirsium arvense''). However, the weevil also attacks native thistles, harming such species as the Endemism, endemic Cirsium neomexicanum, Platte thistle (''Cirsium neomexicanum'') by selecting larger plants (which reduced the gene pool), reducing seed production and ultimately threatening the species' survival. Similarly, the weevil ''Larinus planus'' was also used to try to control the Cirsium arvense, Canadian thistle, but it damaged other thistles as well. This included one species classified as threatened. The small Asian mongoose (''Herpestus javanicus'') was introduced to Hawaii in order to control the rat population. However, the mongoose was diurnal, and the rats emerged at night; the mongoose, therefore, preyed on the endemic birds of Hawaii, especially their eggs, more often than it ate the rats, and now both rats and mongooses threaten the birds. This introduction was undertaken without understanding the consequences of such an action. No regulations existed at the time, and more careful evaluation should prevent such releases now. The sturdy and prolific eastern mosquitofish (''Gambusia holbrooki'') is a native of the southeastern United States and was introduced around the world in the 1930s and '40s to feed on mosquito larvae and thus combat malaria. However, it has thrived at the expense of local species, causing a decline of endemic fish and frogs through competition for food resources, as well as through eating their eggs and larvae. In Australia, control of the mosquitofish is the subject of discussion; in 1989 researchers A. H. Arthington and L. L. Lloyd stated that "biological population control is well beyond present capabilities".


Grower education

A potential obstacle to the adoption of biological pest control measures is that growers may prefer to stay with the familiar use of pesticides. However, pesticides have undesired effects, including the development of resistance among pests, and the destruction of natural enemies; these may in turn enable outbreaks of pests of other species than the ones originally targeted, and on crops at a distance from those treated with pesticides. One method of increasing grower adoption of biocontrol methods involves letting them learn by doing, for example showing them simple field experiments, enabling them to observe the live predation of pests, or demonstrations of parasitised pests. In the Philippines, early-season sprays against leaf folder caterpillars were common practice, but growers were asked to follow a 'rule of thumb' of not spraying against leaf folders for the first 30 days after transplanting; participation in this resulted in a reduction of insecticide use by 1/3 and a change in grower perception of insecticide use.


Related techniques

Related to biological pest control is the technique of introducing sterile individuals into the native population of some organism. This technique is widely practised with Sterile insect technique, insects: a large number of males sterilized by gamma radiation, radiation are released into the environment, which proceed to Competition (biology), compete with the native males for females. Those females that copulate with the sterile males will lay infertile eggs, resulting in a decrease in the size of the population. Over time, with repeated introductions of sterile males, this could result in a significant decrease in the size of the organism's population. A similar technique has recently been applied to weeds using irradiated pollen, resulting in deformed seeds that do not sprout.


See also

* Beneficial insects * Biological control of gorse in New Zealand * Chitosan * Companion planting * Insectary plants * International Organization for Biological Control * Inundative application * Mating disruption * Nematophagous fungus * Organic gardening * Organic farming * Permaculture#Zones, Permaculture zone 5 * Sustainable farming * Sustainable gardening * Zero Budget Farming


References


Further reading


General

* Wiedenmann, R. (2000)
Introduction to Biological Control
Midwest Institute for Biological Control, Illinois. * * * *


Effects on native biodiversity

* * Weeden, C. R.; Shelton, A. M.; Hoffman, M. P

* [https://web.archive.org/web/20071123044914/http://www.biotechnologyonline.gov.au/enviro/canetoad.cfm Cane toad: a case study]. 2003. * Humphrey, J. and Hyatt. 2004. CSIRO Australian Animal Health Laboratory. ''Biological Control of the Cane Toad Bufo marinus in Australia'' * * Johnson, M. 2000. Nature and Scope of Biological Control. ''Biological Control of Pests''.


Economic effects

* *


External links


Association of Natural Biocontrol ProducersInternational Organization for Biological Control
{{DEFAULTSORT:Biological Pest Control Biological pest control, American inventions Chinese inventions Insects in culture