Editing Biological pest control (section)

==Types of biological pest control==
There are three basic biological pest control strategies: importation (classical biological control), augmentation and conservation.<ref name=Cornell>{{Cite web|url=http://www.biocontrol.entomology.cornell.edu/what.html |publisher=Cornell University |title=What is Biological Control? |access-date=7 June 2016 |url-status=dead |archive-url=https://web.archive.org/web/20160613054724/http://www.biocontrol.entomology.cornell.edu/what.html |archive-date=13 June 2016 }}</ref>

===Importation===

[[File:Vedalia Beetle (15959056801).jpg|thumb|left|''[[Rodolia cardinalis]]'', the vedalia beetle, was imported from Australia to California in the 19th century, successfully controlling [[cottony cushion scale]] on [[Orange (fruit)|orange]] trees.]]

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.<ref name="Classical">{{cite web |title=Classical Biological Control: Importation of New Natural Enemies |url=http://www.entomology.wisc.edu/mbcn/fea103.html |publisher=University of Wisconsin |access-date=7 June 2016 |url-status=dead |archive-url=https://web.archive.org/web/20160613023600/http://www.entomology.wisc.edu/mbcn/fea103.html |archive-date=13 June 2016 }}</ref>

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.<ref name=follett>{{cite book |author1=Follett, P. A. |author2=Duan, J. J.  |date=2000 |title=Nontarget effects of biological control |publisher=Kluwer}}</ref>

One of the earliest successes was in controlling ''[[Icerya purchasi]]'' (cottony cushion scale) in Australia, using a predatory insect ''[[Rodolia cardinalis]]'' (the vedalia beetle). This success was repeated in California using the beetle and a parasitoidal fly, ''[[Cryptochaetum]] [[Cryptochaetum iceryae|iceryae]]''.<ref>{{cite web|title=How to Manage Pests. Cottony Cushion Scale |url=http://www.ipm.ucdavis.edu/PMG/PESTNOTES/pn7410.html |publisher=University of California Integrated Pest Management |access-date=5 June 2016 |url-status=live |archive-url=https://web.archive.org/web/20160430061041/http://www.ipm.ucdavis.edu/PMG/PESTNOTES/pn7410.html |archive-date=30 April 2016 }}</ref> Other successful cases include the control of ''[[Antonina graminis]]'' in Texas by ''[[Neodusmetia sangwani]]'' in the 1960s.<ref>{{Cite journal|doi=10.1146/annurev.en.26.010181.001241|title=Landmark Examples in Classical Biological Control|journal=Annual Review of Entomology|volume=26|pages=213–232|year=1981|last1=Caltagirone|first1=L. E.}}</ref>

Damage from ''[[Hypera postica]]'', 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]]s in the [[alfalfa]] area treated for alfalfa weevil in the [[Northeastern United States]] remained 75 percent down.<ref>{{cite web|title=How to Manage Pests. Alfalfa |url=http://www.ipm.ucdavis.edu/PMG/r1900211.html |publisher=University of California Integrated Pest Management |access-date=5 June 2016 |url-status=live |archive-url=https://web.archive.org/web/20160525013314/http://www.ipm.ucdavis.edu/PMG/r1900211.html |archive-date=25 May 2016 }}</ref>

[[Image:Alternanthera philoxeroides NRCS-1.jpg|thumb|The invasive species ''[[Alternanthera philoxeroides]]'' (alligator weed) was controlled in [[Florida]] (U.S.) by introducing [[Agasicles hygrophila|alligator weed flea beetle]].]]

[[Alligator weed]] was introduced to the United States from [[South America]]. It takes root in shallow water, interfering with [[navigation]], [[irrigation]], and [[flood control]]. The [[Agasicles hygrophila|alligator weed flea beetle]] and two other biological controls were released in [[Florida]], greatly reducing the amount of land covered by the plant.<ref>{{cite web|title=Indian River Lagoon Species Inventory: Alternanthera philoxeroides |url=http://www.sms.si.edu/irlspec/Alternanthera_philoxeroides.htm |publisher=Smithsonian Marine Station at Fort Pierce |access-date=9 April 2017 |date=1 December 2007 |url-status=live |archive-url=https://web.archive.org/web/20170328161203/http://www.sms.si.edu/irlspec/Alternanthera_philoxeroides.htm |archive-date=28 March 2017 }}</ref> Another aquatic weed, the giant salvinia (''[[Salvinia molesta]]'') is a serious pest, covering waterways, reducing water flow and harming native species. Control with the salvinia weevil (''[[Cyrtobagous salviniae]]'') and the salvinia stem-borer moth (''[[Samea multiplicalis]])'' is effective in warm climates,<ref>{{cite web|title=Salvinia (Salvinia molesta) |url=http://www.environment.gov.au/biodiversity/invasive/weeds/publications/guidelines/wons/pubs/s-molesta.pdf |publisher=CRC Weed Management |access-date=7 June 2016 |url-status=live |archive-url=https://web.archive.org/web/20150924073642/http://www.environment.gov.au/biodiversity/invasive/weeds/publications/guidelines/wons/pubs/s-molesta.pdf |archive-date=24 September 2015 }}</ref><ref>{{Cite web|url=https://www.invasive.org/proceedings/pdfs/6_543-549.pdf|title=A summary of research into biological control of salvinia in Australia}}</ref> and in Zimbabwe, a 99% control of the weed was obtained over a two-year period.<ref>{{cite journal |author1=Chikwenhere, Godfrey P. |author2=Keswani, C. L. |year=1997 |title=Economics of biological control of Kariba weed (''Salvinia molesta'' Mitchell) at Tengwe in north-western Zimbabwe: a case study |journal=International Journal of Pest Management |volume=43 |issue=2 |pages=109–112 |doi=10.1080/096708797228780 }}</ref>

Small, commercially-reared parasitoidal [[wasp]]s,<ref name=Cornell/> ''[[Trichogramma]] [[Trichogramma ostriniae|ostriniae]]'', provide limited and erratic control of the [[European corn borer]] (''Ostrinia nubilalis''), a serious pest. Careful formulations of the bacterium ''[[Bacillus thuringiensis]]'' are more effective. The O. nubilalis integrated control releasing  ''Tricogramma brassicae'' (egg parasitoid) and later ''Bacillus thuringiensis subs. kurstaki'' (larvicide effect) reduce pest damages more than insecticide treatments <ref>{{cite web|title=Featured Creatures. European corn borer |url=http://entnemdept.ufl.edu/creatures/field/e_corn_borer.htm |publisher=University of Florida IFAS |access-date=5 June 2016 |url-status=live |archive-url=https://web.archive.org/web/20160530041733/http://entnemdept.ufl.edu/creatures/field/e_corn_borer.htm |archive-date=30 May 2016 }}</ref>

The population of ''[[Levuana iridescens]]'', the Levuana moth, a serious coconut pest in [[Fiji]], was brought under control by a classical biological control program in the 1920s.<ref>{{cite journal |last1=Kuris |first1=Armand M. |title=Did biological control cause extinction of the coconut moth, Levuana iridescens, in Fiji? |journal=Biological Invasions|date=March 2003 |volume=5 |issue=1 |pages=133–141 |doi=10.1023/A:1024015327707|bibcode=2003BiInv...5..133K |s2cid=26094065 }}</ref>

===Augmentation===

[[File:Lady bugs are a beneficial insect commonly sold for biological control of aphids..jpg|thumb|''[[Hippodamia convergens]]'', the convergent lady beetle, is commonly sold for biological control of [[aphids]].]]

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.<ref name="Augmentation">{{cite web |title=Augmentation: The Periodic Release of Natural Enemies |url=http://www.entomology.wisc.edu/mbcn/fea104.html |publisher=University of Wisconsin |access-date=7 June 2016 |url-status=dead |archive-url=https://web.archive.org/web/20160317104655/http://www.entomology.wisc.edu/mbcn/fea104.html |archive-date=17 March 2016 }}</ref>

An example of inoculative release occurs in the horticultural production of several crops in [[greenhouse]]s. Periodic releases of the parasitoidal wasp, ''[[Encarsia formosa]]'', are used to control greenhouse [[whitefly]],<ref name=Hoddle1998/> while the predatory mite ''[[Phytoseiulus persimilis]]'' is used for control of the two-spotted spider mite.<ref>{{cite web |title=Biological control. Phytoseiulus persimilis (Acarina: Phytoseiidae) |url=http://www.biocontrol.entomology.cornell.edu/predators/Phytoseiulus.php |publisher=Cornell University |access-date=7 June 2016 |url-status=dead |archive-url=https://web.archive.org/web/20151115184109/http://www.biocontrol.entomology.cornell.edu/predators/Phytoseiulus.php |archive-date=15 November 2015 }}</ref>

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 were found on moth scales. Similarly, ''Bacillus thuringiensis'' and other microbial insecticides are used in large enough quantities for a rapid effect.<ref name="Augmentation"/> 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.<ref name="Peter2009">{{cite book|last=Peter |first=K. V. |title=Basics Of Horticulture |url=https://books.google.com/books?id=NWMa741kG_gC&pg=PA288 |year=2009 |publisher=New India Publishing |isbn=978-81-89422-55-4 |page=288 |url-status=live |archive-url=https://web.archive.org/web/20170407233649/https://books.google.com/books?id=NWMa741kG_gC&pg=PA288 |archive-date=2017-04-07 }}</ref> Similarly, [[nematodes]] 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.<ref>{{cite web|title=Biological Control. Nematodes (Rhabditida: Steinernematidae & Heterorhabditidae) |url=http://www.biocontrol.entomology.cornell.edu/pathogens/nematodes.php |author1=Shapiro-Ilan, David I |author2=Gaugler, Randy |publisher=Cornell University |access-date=7 June 2016 |url-status=dead |archive-url=https://web.archive.org/web/20151215090802/http://www.biocontrol.entomology.cornell.edu/pathogens/nematodes.php |archive-date=15 December 2015 }}</ref>

===Conservation===

The conservation of existing natural enemies in an environment is the third method of biological pest control.<ref name="Conservation">{{cite web |title=Conservation of Natural Enemies: Keeping Your "Livestock" Happy and Productive |url=http://www.entomology.wisc.edu/mbcn/fea201.html |publisher=University of Wisconsin |access-date=7 June 2016 |url-status=dead |archive-url=https://web.archive.org/web/20160318120526/http://www.entomology.wisc.edu/mbcn/fea201.html |archive-date=18 March 2016 }}</ref>
Natural enemies are already adapted to 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%.<ref>{{cite journal | last=Gurr | first=Geoff M. | title=Multi-country evidence that crop diversification promotes ecological intensification of agriculture | journal=Nature Plants | date=22 February 2016 | language=en | doi=10.1038/nplants.2016.14 | pmid=27249349 | volume=2 | issue=3 | page=16014| bibcode=2016NatPl...216014G | s2cid=205458366 }}</ref> 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.<ref name="Conservation"/>

[[File:Dermaptera flowerpot.jpg|thumb|An inverted flowerpot filled with straw to attract [[Dermaptera|earwigs]]]]

Cropping systems can be modified to favor natural enemies, a practice sometimes referred to as habitat manipulation. Providing a suitable habitat, such as a [[Windbreak|shelterbelt]], [[hedgerow]], or [[beetle bank]] 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]]s and [[shrew]]s. [[Compost pile]]s and stacks of wood can provide shelter for invertebrates and small mammals. Long grass and [[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.<ref name="ReferenceA">{{cite book|author=Ruberson, John R. |title=Handbook of Pest Management |url=https://books.google.com/books?id=9b-9sIMbz38C&pg=PA428 |year=1999 |publisher=CRC Press |isbn=978-0-8247-9433-0 |pages=428–432 |url-status=live |archive-url=https://web.archive.org/web/20170410235857/https://books.google.com/books?id=9b-9sIMbz38C&pg=PA428 |archive-date=2017-04-10 }}</ref> In California, prune trees are sometimes planted in grape vineyards to provide an improved overwintering habitat or refuge for a key grape pest parasitoid.<ref>{{cite web |last1=Wilson |first1=L. Ted |last2=Pickett |first2=Charles H. |last3=Flaherty |first3=Donald L. |last4=Bates |first4=Teresa A. |title=French prune trees: refuge for grape leafhopper parasite |url=http://ucce.ucdavis.edu/files/repositoryfiles/ca4302p7-62179.pdf |publisher=University of California Davis |access-date=7 June 2016 |url-status=dead |archive-url=https://web.archive.org/web/20160923154830/http://ucce.ucdavis.edu/files/repositoryfiles/ca4302p7-62179.pdf |archive-date=23 September 2016 }}</ref> The providing of artificial shelters in the form of wooden caskets, [[box]]es or [[flowerpot]]s is also sometimes undertaken, particularly in gardens, to make a cropped area more attractive to natural enemies. For example, [[Dermaptera|earwigs]] are natural predators that can be encouraged in gardens by hanging upside-down flowerpots filled with [[straw]] or [[wood wool]]. Green [[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.<ref name="ReferenceA"/>

In cotton production, the replacement of broad-spectrum insecticides with selective control measures such as [[Bt cotton]] can create a more favorable environment for natural enemies of cotton pests due to reduced insecticide exposure risk. Such predators or [[parasitoids]] can control pests not affected by the [[Bacillus thuringiensis|Bt protein]]. Reduced prey quality and abundance associated with 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.<ref>{{cite journal|last1=Naranjo|first1=Steven E.|title=Impacts of Transgenic Cotton on Integrated Pest Management|journal=Journal of Agricultural and Food Chemistry|date=8 June 2011|volume=59|issue=11|pages=5842–5851|doi=10.1021/jf102939c|pmid=20942488|doi-access=free|bibcode=2011JAFC...59.5842N }}</ref>