Biological pest control
Encyclopedia
Biological control of pests in agriculture
is a method of controlling pests
(including insect
s, mite
s, weed
s and plant diseases
) that relies on predation
, parasitism
, herbivory, or other natural mechanisms. It can be an important component of integrated pest management
(IPM) programs.
Biological control is defined as the reduction of pest population
s by natural enemies and typically involves an active human role. Natural enemies of insect pests, also known as biological log control agents; and include predators, parasitoid
s, and pathogen
s. Biological control agents of plant disease
s are most often referred to as antagonists. Biological control agents of weeds include herbivore
s and plant pathogens. Predators, such as bird
s, lady beetles and lacewings, are mainly free-living species that consume a large number of prey during their whole lifetime. Parasitoids are species whose immature develops on or within a single insect host, ultimately killing or fatally infecting the host. Most have a very narrow host range. Many species of wasps and some flies are parasitoids. Pathogens are disease-causing organisms including bacteria
, fungi, and viruses. They kill or debilitate their own host and are relatively specific. There are three basic types of biological control strategies; conservation, classical biological control, and augmentation.
to the open field
. They are adapted to the habitat
and to the target pest, and their conservation is generally simple and cost-effective. Lacewings, lady beetles, hover fly larvae, and parasitized aphid
mummies are almost always present in aphid colonies. Fungus-infected adult flies are often common following periods of high humidity
. These naturally occurring biological controls are often susceptible to the same pesticide
s used to target their pest hosts. Preventing the accidental eradication of natural enemies is termed "simple conservation."
To conserve and encourage pest insect
eating bird
s, including native plant
s and ornamental plant
s that supply berries
, acorn
s, nut
s, seed
s, nectar, and other vegetative foods, and also bird nest
building materials, encourages their presence, health, and new generations. These qualities can also increase the visible population to enjoy in a garden. Using companion planting
and the birds' insect
cuisine habits is a traditional method for biological control agent pest control
in an organic garden and any landscape, and in organic farming
and sustainable agriculture
. Installing specified nest box
es for mosquito
-eating bat
s reduces a pest and increases endangered species
conservation.
Biological control can potentially have positive and negative effects on biodiversity
. Usually a biological control is introduced to an area to protect a native species from an invasive
or exotic species that has moved into its area. The control is introduced to lessen the competition between native and introduced species
. However, the introduced control does not always target only the intended species. It can also target native species.
When introducing a high biological control to a new area, a primary concern is the host- or prey-specificity of the control agent. Generalist feeders (control agents that are not restricted to a single species or a small range of species) often make poor biological control agents, and may become invasive species themselves. For this reason, potential biological control agents should be subject to extensive testing and quarantine
before release into any new environment. If a species is introduced and attacks a native species, the biodiversity in that area can change dramatically. When one native species is removed from an area, it may have filled an essential ecological niche
. When this niche is absent it may directly affect the entire ecosystem
.
Because they tend to be generalist feeders, vertebrate animals seldom make good biological control agents, and many of the classic cases of "biocontrol gone awry" involve vertebrates. For example, the cane toad, Bufo marinus, was introduced as a biological control and had significant negative impact on biodiversity
. The cane toad was intentionally introduced to Australia
to control the introduced French’s Cane Beetle
and the Greyback Cane Beetle. When introduced, the cane toad thrived and did not only feed on cane beetles but other insects as well. The cane toad soon spread very rapidly, thus taking over native amphibian
habitat
. The introduction of the cane toad also brought foreign disease to native reptile
s. This drastically reduced the population of native toad
s and frog
s. “The cane toad also exudes and can squirt poison
from the parotid glands on their shoulders when threatened or handled. This toxin contains a cocktail of chemicals that can kill animals that eat it. Freshwater crocodile
s, goanna
s, tiger snakes, dingo
s and northern quoll
s have all died after eating cane toads, as have pet dogs (Cane toad, 2003). This example shows how small mis-introduced organisms can alter the native biodiversity
in large ecosystems in a rapid manner. A pyramid
effect can take place if native species are reduced or eradicated. The domino effect
keeps on going and can potentially exude on other bordering ecosystems until an equilibrium is reached.
A second example of a biological control agent that subsequently crossed over to native species is the Rhinocyllus conicus
. The seed feeding weevil was introduced to North America to control exotic thistle
s (Musk and Canadian). However, the weevil did not target only the exotic thistles, it also targeted native thistles that are essential to various native insects. The native insects rely solely on native thistles and do not adapt to other plant species. Therefore, they cannot survive. Biological controls do not always have negative impacts on biodiversity (Corry 2000).
Successful biological control reduces the population density
of the target species over several years, thus providing the potential for native species to re-establish. In addition, regeneration and reestablishment programs can aid to the recovery of native species. Native species can be affected in a positive way as well. To develop or find a biological control that exerts control only on the targeted species is a very lengthy process of research
and experiment
s. In the late 19th century, the citrus
industry was in great fear when the cottony cushion scale
was discovered. This organism could cause a great deal of economic loss to the industry. However, a biological control was introduced. The vedalia beetle and a parasitoid
fly
were introduced to control the pest. Within a few years time, the cottony cushion scale was controlled by the natural enemies and the citrus industry suffered little financial loss. Many exotic or invasive species can suppress the development of native species. The introduction of an effective biological control that reduces the population of the invasive species allows the rejuvenation of the native species. Biological controls can reduce competition for biotic
and abiotic factors which can result in the re-establishment of the once over ran native species.
Invasive species are closely associated with biological controls because the environment in which they are invasive most likely does not contain their natural enemies. If invasive species are not controlled, biodiversity may be at great threat in the affected area. An example of an invasive species is the alligator weed
. This plant was introduced to the United States from South America
. This aquatic weed spreads rapidly and causes many problems in lakes and rivers. The weed takes root in shallow water causing major problems for navigation
, irrigation
, and flood control
. The alligator weed flea beetle
and two other biological controls were released in Florida
. Because of their success, Florida banned the use of herbicides to control alligator weed three years after the controls were introduced. Similarly, Galerucella calmariensis
, a leaf beetle, has been introduced in North America as a control agent for purple loosestrife (Lythrum salicaria).
Biological controls for invasive species also can have a negative impact on biodiversity. The cane toad, as mentioned previously, is an example of trying to control an invasive species. The cane toad was introduced to eradicate an invasive species. It became invasive, thus altering the biodiversity. The introduction of the cane toad could have caused more of a disturbance in biodiversity than the targeted species did.
. Examples of introduced vegetable pests include the European corn borer
(Ostrinia nubilalis), one of the most destructive insects in North America
. To obtain the needed natural enemies, scientists turned to classical biological control. This is the practice of importing, and releasing for establishment, natural enemies to control an introduced (exotic) pest, although it is also practiced against native insect pests. The first step in the process is to determine the origin of the introduced pest and then collect appropriate natural enemies associated with the pest or closely related species. The natural enemy is then passed through a rigorous quarantine
process, to ensure that no unwanted organisms (such as hyperparasitoids) are introduced, then they are mass produced, and released. Follow-up studies are conducted to determine if the natural enemy becomes successfully established at the site of release, and to assess the long-term benefit of its presence.
There are many examples of successful classical biological control programs.
oseph Ne name="wpEdittime"
2011112522ing from 304AD, Records of the Plants and Trees of the Southern Regions, by Hsi Han, which describes mandarin oranges protected by biological pest control techniques that are still in use today.
One of the earliest successes in the west was in controlling Icerya purchasi
, the cottony cushion scale, a pest that was devastating the California
citrus industry in the late 19th century. A predatory insect Rodolia cardinalis
(the Vedalia Beetle), and a parasitoid fly were introduced from Australia by Charles Valentine Riley
. Within a few years the cottony cushion scale was completely controlled by these introduced natural enemies.
Damage from Hypera postica Gyllenhal, the alfalfa weevil, a serious introduced pest of forage, was substantially reduced by the introduction of several 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
was reduced by 75 percent. A small wasp
, Trichogramma ostriniae, was introduced from China
to help control the European corn borer
making it a recent example of a long history of classical biological control efforts for this major pest. Many classical biological control programs for insect pests and weeds are under way across the United States and Canada
. The population of Levuana irridescens (the Levuana moth), a serious coconut pest in Fiji
, was brought under control by a classical biological control program in the 1920s.
Classical biological control is long lasting and inexpensive. Other than the initial costs of collection, importation, and rearing, little expense is incurred. When a natural enemy is successfully established it rarely requires additional input and it continues to kill the pest with no direct help from humans and at no cost. Classical biological control does not always work. It is usually most effective against exotic pests and less so against native insect pests. The reasons for failure are not often known but may include the release of too few individuals, poor adaptation of the natural enemy to environmental conditions at the release location, and lack of synchrony between the life cycle
of the natural enemy and host pest.
, are used to control greenhouse whitefly
, and the predaceous mite, Phytoseiulus persimilis, is used for control of the two-spotted spider mite.
Lady beetles, lacewings, or parasitoids such as those from the genus Trichogramma
are frequently released in large numbers (inundative release). 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 depending on level of pest infestation. Similarly, entomopathogenic nematodes are released at rates of millions and even billions per acre for control of certain soil-dwelling insect pests.
The spraying of octopamine analogues (such as 3-FMC) has been suggested as a way to boost the effectiveness of augmentation. Octopamine
, regarded as the invertebrate
counterpart of dopamine
plays a role in activating the insects' flight-or-fight response. The idea behind using octopamine analogues to augment biological control is that natural enemies will be more effective in their eradication of the pest, since the pest will be behaving in an unnatural way because its flight-or-fight mechanism has been activated. Octopamine analogues are purported to have two desirable characteristics for this type of application: (1) they affect insects at very low dosages (2) they do not have a physiological effect in humans (or other vertebrates).
Habitat or environmental manipulation is another form of augmentation. This tactic involves altering the cropping system to augment or enhance the effectiveness of a natural enemy. Many adult parasitoids and predators benefit from sources of nectar and the protection provided by refuges such as hedgerows, cover crops, and weedy borders. Also, the provisioning of natural shelters in the form of wooden caskets, box
es or (turnaround) flowerpot
s is a form of this. For example, the stimulation of the natural predator Dermaptera is done in gardens by hanging up turnaround flowerpots with straw
or wood wool.
Mixed plantings and the provision of flowering borders can increase the diversity of habitats and provide shelter and alternative food sources. They are easily incorporated into home gardens and even small-scale commercial plantings, but are more difficult to accommodate in large-scale crop production. There may also be some conflict with pest control for the large producer because of the difficulty of targeting the pest species and the use of refuges by the pest insects as well as natural enemies.
Examples of habitat manipulation include growing flowering plants (pollen and nectar sources) such as Buckwheat
near crops to attract and maintain populations of natural enemies. For example, hover fly adults can be attracted to umbelliferous plants in bloom.
Biological control experts in California have demonstrated that planting prune trees in grape vineyards provides an improved overwintering habitat or refuge for a key grape pest parasitoid. The prune trees harbor an alternate host for the parasitoid, which could previously overwinter only at great distances from most vineyards. Caution should be used with this tactic because some plants attractive to natural enemies may also be hosts for certain plant diseases, especially plant viruses that could be vectored by insect pests to the crop. Although the tactic appears to hold much promise, only a few examples have been adequately researched and developed.
s such as greenfly
and blackfly
, and will also consume mites
, scale insect
s and small caterpillar
s. The ladybug is a very familiar beetle with various colored markings, whilst its larvae are initially small and spidery, growing up to 17 mm long. The larvae have a tapering segmented grey/black body with orange/yellow markings and ferocious mouthparts. They can be encouraged by cultivating a patch of nettle
s in the garden and by leaving hollow stems and some plant debris over winter so that they can hibernate.
Hoverflies
resemble slightly darker bee
s or wasp
s and they have characteristic hovering, darting flight patterns. There are over 100 species of hoverfly whose larvae principally feed upon greenfly, one larva devouring up to fifty a day, or 1000 in its lifetime. They also eat fruit tree spider mite
s and small caterpillars. Adults feed on nectar and pollen
, which they require for egg production. Eggs are minute (1 mm), pale yellow white and laid singly near greenfly colonies. Larvae are 8–17 mm long, disguised to resemble bird droppings, they are legless and have no distinct head. Semi-transparent in a range of colours from green, white, brown and black.
Hoverflies can be encouraged by growing attractant flowers such as the poached egg plant
(Limnanthes douglasii), marigolds or phacelia
throughout the growing season.
Dragonflies
are important predators of mosquitoes, both in the water, where the dragonfly naiads
eat mosquito
larva
e, and in the air, where adult dragonflies capture and eat adult mosquitoes. Community-wide mosquito control programs that spray adult mosquitoes also kill dragonflies, thus removing an important biocontrol agent, and can actually increase mosquito populations in the long term.
Other useful garden predators include lacewings
, pirate bugs
, rove and ground beetles, aphid midge, centipede
s, spider
s, predatory mites, as well as larger fauna such as frog
s, toad
s, lizard
s, hedgehog
s,
slow-worms and birds. Cats and rat terriers kill field mice, rats, June bugs, and birds. Dogs chase away many types of pest animals. Dachshund
s are bred specifically to fit inside tunnels underground to kill badgers.
More examples:
. Parasitoids comprise a diverse range of insects that lay their egg on or in the body of an insect host, which is then used as a food for developing larvae. Parasitic wasp
s take much longer than predators to consume their victims, for if the larvae were to eat too fast they would run out of food before they became adults. Such parasites are very useful in the organic garden, for they are very efficient hunters, always at work searching for pest invaders. As adults they require high energy fuel as they fly from place to place, and feed upon nectar, pollen and sap, thereby pollinating plenty of flowering plants, particularly buckwheat
, umbellifers, and composites
will encourage their presence.
Four of the most important groups are:
Examples of parasitoids:
wasp
is the most widely applied species of bacteria used for biological control, with at least four sub-species used to control Lepidoptera
n (moth
, butterfly
), Coleopteran (beetle) and Diptera
n (true flies) insect pests.
are used to manage some soilborne plant pathogens. Beauveria bassiana
is used to manage different types of pest such whiteflies, thrips, aphids and weevils.
Examples of entomopathogenic fungi:
(Agrilus planipennis Fairmaire, family Buprestidae), an invasive beetle
from China
, which has destroyed tens of millions of ash trees in its introduced range in North America
. s part of the campaign against the emerald ash borer (EAB), American scientists in conjunction with the Chinese Academy of Forestry searched since 2003 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 been introduced and released into the United States of America as a possible biological control of the emerald ash borer. Initial results have shown promise with Tetrastichus planipennisi and it is now being released along with Beauveria bassiana
, a fungal pathogen
with known insecticidal properties.
is used in the countries of Benin
and Vietnam
as a biological control for problematic Imperata cylindrica grass. Mucuna pruriens is said not to be invasive outside its cultivated area. Desmodium
uncinatum can be used in push-pull farming
to stop the parasitic plant
, Striga
.
Most of the biological controls listed above depend on providing incentives in order to 'naturally' attract beneficial insects to the garden. However there are occasions when biological controls can be directly introduced. Common biocontrol agents include parasitoids, predators, pathogens or weed feeders. This is particularly appropriate in situations such as the greenhouse, a largely artificial environment, and are usually purchased by mail order.
Some biocontrol agents that can be introduced include;
. For example:
Living organisms, through the process of evolution, may achieve increased resistance to biological, chemical, and physical methods of control over time. In the event the target pest population is not completely exterminated or is still capable of reproduction (were the pest control means a form of sterilization), the surviving population could acquire a tolerance to the applied pressures - this can result in an evolutionary arms race
with the control method.
Building organic pest-free gardens
Effects on native biodiversity
Effects on invasive species
Effects on the future
Economic effects
News
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de:Biologische Schädlingsbekämpfung
et:Biotõrje
es:Control biológico
eo:Biologia plagokontrolo
fa:کنترل زیستی آفت
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Agriculture
Agriculture is the cultivation of animals, plants, fungi and other life forms for food, fiber, and other products used to sustain life. Agriculture was the key implement in the rise of sedentary human civilization, whereby farming of domesticated species created food surpluses that nurtured the...
is a method of controlling pests
Pest control
Pest control refers to the regulation or management of a species defined as a pest, usually because it is perceived to be detrimental to a person's health, the ecology or the economy.-History:...
(including insect
Insect
Insects are a class of living creatures within the arthropods that have a chitinous exoskeleton, a three-part body , three pairs of jointed legs, compound eyes, and two antennae...
s, mite
Mite
Mites, along with ticks, are small arthropods belonging to the subclass Acari and the class Arachnida. The scientific discipline devoted to the study of ticks and mites is called acarology.-Diversity and systematics:...
s, weed
Weed
A weed in a general sense is a plant that is considered by the user of the term to be a nuisance, and normally applied to unwanted plants in human-controlled settings, especially farm fields and gardens, but also lawns, parks, woods, and other areas. More specifically, the term is often used to...
s and plant diseases
Phytopathology
Plant pathology is the scientific study of plant diseases caused by pathogens and environmental conditions . Organisms that cause infectious disease include fungi, oomycetes, bacteria, viruses, viroids, virus-like organisms, phytoplasmas, protozoa, nematodes and parasitic plants...
) that relies on predation
Predation
In ecology, predation describes a biological interaction where a predator feeds on its prey . Predators may or may not kill their prey prior to feeding on them, but the act of predation always results in the death of its prey and the eventual absorption of the prey's tissue through consumption...
, parasitism
Parasitism
Parasitism is a type of symbiotic relationship between organisms of different species where one organism, the parasite, benefits at the expense of the other, the host. Traditionally parasite referred to organisms with lifestages that needed more than one host . These are now called macroparasites...
, herbivory, or other natural mechanisms. It can be an important component of integrated pest management
Integrated Pest Management
Integrated pest management is an ecological approach to agricultural pest control that integrates pesticides/herbicides into a management system incorporating a range of practices for economic control of a pest...
(IPM) programs.
Biological control is defined as the reduction of pest population
Population
A population is all the organisms that both belong to the same group or species and live in the same geographical area. The area that is used to define a sexual population is such that inter-breeding is possible between any pair within the area and more probable than cross-breeding with individuals...
s by natural enemies and typically involves an active human role. Natural enemies of insect pests, also known as biological log control agents; and include predators, parasitoid
Parasitoid
A parasitoid is an organism that spends a significant portion of its life history attached to or within a single host organism in a relationship that is in essence parasitic; unlike a true parasite, however, it ultimately sterilises or kills, and sometimes consumes, the host...
s, and pathogen
Pathogen
A pathogen gignomai "I give birth to") or infectious agent — colloquially, a germ — is a microbe or microorganism such as a virus, bacterium, prion, or fungus that causes disease in its animal or plant host...
s. Biological control agents of plant disease
Disease
A disease is an abnormal condition affecting the body of an organism. It is often construed to be a medical condition associated with specific symptoms and signs. It may be caused by external factors, such as infectious disease, or it may be caused by internal dysfunctions, such as autoimmune...
s are most often referred to as antagonists. Biological control agents of weeds include herbivore
Herbivore
Herbivores are organisms that are anatomically and physiologically adapted to eat plant-based foods. Herbivory is a form of consumption in which an organism principally eats autotrophs such as plants, algae and photosynthesizing bacteria. More generally, organisms that feed on autotrophs in...
s and plant pathogens. Predators, such as bird
Bird
Birds are feathered, winged, bipedal, endothermic , egg-laying, vertebrate animals. Around 10,000 living species and 188 families makes them the most speciose class of tetrapod vertebrates. They inhabit ecosystems across the globe, from the Arctic to the Antarctic. Extant birds range in size from...
s, lady beetles and lacewings, are mainly free-living species that consume a large number of prey during their whole lifetime. Parasitoids are species whose immature develops on or within a single insect host, ultimately killing or fatally infecting the host. Most have a very narrow host range. Many species of wasps and some flies are parasitoids. Pathogens are disease-causing organisms including bacteria
Bacteria
Bacteria are a large domain of prokaryotic microorganisms. Typically a few micrometres in length, bacteria have a wide range of shapes, ranging from spheres to rods and spirals...
, fungi, and viruses. They kill or debilitate their own host and are relatively specific. There are three basic types of biological control strategies; conservation, classical biological control, and augmentation.
Conservation
The conservation of natural enemies is probably the most important and readily available biological control practice available to homeowners and gardeners. Natural enemies occur in all areas, from the private gardenGarden
A garden is a planned space, usually outdoors, set aside for the display, cultivation, and enjoyment of plants and other forms of nature. The garden can incorporate both natural and man-made materials. The most common form today is known as a residential garden, but the term garden has...
to the open field
Field (agriculture)
In agriculture, the word field refers generally to an area of land enclosed or otherwise and used for agricultural purposes such as:* Cultivating crops* Usage as a paddock or, generally, an enclosure of livestock...
. They are adapted to the habitat
Habitat
* Habitat , a place where a species lives and grows*Human habitat, a place where humans live, work or play** Space habitat, a space station intended as a permanent settlement...
and to the target pest, and their conservation is generally simple and cost-effective. Lacewings, lady beetles, hover fly larvae, and parasitized aphid
Aphid
Aphids, also known as plant lice and in Britain and the Commonwealth as greenflies, blackflies or whiteflies, are small sap sucking insects, and members of the superfamily Aphidoidea. Aphids are among the most destructive insect pests on cultivated plants in temperate regions...
mummies are almost always present in aphid colonies. Fungus-infected adult flies are often common following periods of high humidity
Humidity
Humidity is a term for the amount of water vapor in the air, and can refer to any one of several measurements of humidity. Formally, humid air is not "moist air" but a mixture of water vapor and other constituents of air, and humidity is defined in terms of the water content of this mixture,...
. These naturally occurring biological controls are often susceptible to the same pesticide
Pesticide
Pesticides are substances or mixture of substances intended for preventing, destroying, repelling or mitigating any pest.A pesticide may be a chemical unicycle, biological agent , antimicrobial, disinfectant or device used against any pest...
s used to target their pest hosts. Preventing the accidental eradication of natural enemies is termed "simple conservation."
To conserve and encourage pest insect
Insect
Insects are a class of living creatures within the arthropods that have a chitinous exoskeleton, a three-part body , three pairs of jointed legs, compound eyes, and two antennae...
eating bird
Bird
Birds are feathered, winged, bipedal, endothermic , egg-laying, vertebrate animals. Around 10,000 living species and 188 families makes them the most speciose class of tetrapod vertebrates. They inhabit ecosystems across the globe, from the Arctic to the Antarctic. Extant birds range in size from...
s, including native plant
Native plant
Native plant is a term to describe plants endemic or naturalized to a given area in geologic time.This includes plants that have developed, occur naturally, or existed for many years in an area...
s and ornamental plant
Ornamental plant
Ornamental plants are plants that are grown for decorative purposes in gardens and landscape design projects, as house plants, for cut flowers and specimen display...
s that supply berries
Berry
The botanical definition of a berry is a fleshy fruit produced from a single ovary. Grapes are an example. The berry is the most common type of fleshy fruit in which the entire ovary wall ripens into an edible pericarp. They may have one or more carpels with a thin covering and fleshy interiors....
, acorn
Acorn
The acorn, or oak nut, is the nut of the oaks and their close relatives . It usually contains a single seed , enclosed in a tough, leathery shell, and borne in a cup-shaped cupule. Acorns vary from 1–6 cm long and 0.8–4 cm broad...
s, nut
Nut (fruit)
A nut is a hard-shelled fruit of some plants having an indehiscent seed. While a wide variety of dried seeds and fruits are called nuts in English, only a certain number of them are considered by biologists to be true nuts...
s, seed
Seed
A seed is a small embryonic plant enclosed in a covering called the seed coat, usually with some stored food. It is the product of the ripened ovule of gymnosperm and angiosperm plants which occurs after fertilization and some growth within the mother plant...
s, nectar, and other vegetative foods, and also bird nest
Bird nest
A bird nest is the spot in which a bird lays and incubates its eggs and raises its young. Although the term popularly refers to a specific structure made by the bird itself—such as the grassy cup nest of the American Robin or Eurasian Blackbird, or the elaborately woven hanging nest of the...
building materials, encourages their presence, health, and new generations. These qualities can also increase the visible population to enjoy in a garden. Using companion planting
Companion planting
Companion planting is the planting of different crops in proximity , on the theory that they assist each other in nutrient uptake, pest control, pollination, and other factors necessary to increasing crop productivity...
and the birds' insect
Insect
Insects are a class of living creatures within the arthropods that have a chitinous exoskeleton, a three-part body , three pairs of jointed legs, compound eyes, and two antennae...
cuisine habits is a traditional method for biological control agent pest control
Pest control
Pest control refers to the regulation or management of a species defined as a pest, usually because it is perceived to be detrimental to a person's health, the ecology or the economy.-History:...
in an organic garden and any landscape, and in organic farming
Organic farming
Organic farming is the form of agriculture that relies on techniques such as crop rotation, green manure, compost and biological pest control to maintain soil productivity and control pests on a farm...
and sustainable agriculture
Sustainable agriculture
Sustainable agriculture is the practice of farming using principles of ecology, the study of relationships between organisms and their environment...
. Installing specified nest box
Nest box
A nest box, also spelled nestbox is a man-made box provided for animals to nest in. Nest boxes are most frequently utilized for wild and domesticated birds, in which case they are also called birdhouses, but some mammalian species may also use them. Birdhouses are the most common types of nest...
es for mosquito
Mosquito
Mosquitoes are members of a family of nematocerid flies: the Culicidae . The word Mosquito is from the Spanish and Portuguese for little fly...
-eating bat
Bat
Bats are mammals of the order Chiroptera "hand" and pteron "wing") whose forelimbs form webbed wings, making them the only mammals naturally capable of true and sustained flight. By contrast, other mammals said to fly, such as flying squirrels, gliding possums, and colugos, glide rather than fly,...
s reduces a pest and increases endangered species
Endangered species
An endangered species is a population of organisms which is at risk of becoming extinct because it is either few in numbers, or threatened by changing environmental or predation parameters...
conservation.
Effects on native biodiversity
Biodiversity
Biodiversity is the degree of variation of life forms within a given ecosystem, biome, or an entire planet. Biodiversity is a measure of the health of ecosystems. Biodiversity is in part a function of climate. In terrestrial habitats, tropical regions are typically rich whereas polar regions...
. Usually a biological control is introduced to an area to protect a native species from an invasive
Invasive species
"Invasive species", or invasive exotics, is a nomenclature term and categorization phrase used for flora and fauna, and for specific restoration-preservation processes in native habitats, with several definitions....
or exotic species that has moved into its area. The control is introduced to lessen the competition between native and introduced species
Introduced species
An introduced species — or neozoon, alien, exotic, non-indigenous, or non-native species, or simply an introduction, is a species living outside its indigenous or native distributional range, and has arrived in an ecosystem or plant community by human activity, either deliberate or accidental...
. However, the introduced control does not always target only the intended species. It can also target native species.
When introducing a high biological control to a new area, a primary concern is the host- or prey-specificity of the control agent. Generalist feeders (control agents that are not restricted to a single species or a small range of species) often make poor biological control agents, and may become invasive species themselves. For this reason, potential biological control agents should be subject to extensive testing and quarantine
Quarantine
Quarantine is compulsory isolation, typically to contain the spread of something considered dangerous, often but not always disease. The word comes from the Italian quarantena, meaning forty-day period....
before release into any new environment. If a species is introduced and attacks a native species, the biodiversity in that area can change dramatically. When one native species is removed from an area, it may have filled an essential ecological niche
Ecological niche
In ecology, a niche is a term describing the relational position of a species or population in its ecosystem to each other; e.g. a dolphin could potentially be in another ecological niche from one that travels in a different pod if the members of these pods utilize significantly different food...
. When this niche is absent it may directly affect the entire ecosystem
Ecosystem
An ecosystem is a biological environment consisting of all the organisms living in a particular area, as well as all the nonliving , physical components of the environment with which the organisms interact, such as air, soil, water and sunlight....
.
Because they tend to be generalist feeders, vertebrate animals seldom make good biological control agents, and many of the classic cases of "biocontrol gone awry" involve vertebrates. For example, the cane toad, Bufo marinus, was introduced as a biological control and had significant negative impact on biodiversity
Biodiversity
Biodiversity is the degree of variation of life forms within a given ecosystem, biome, or an entire planet. Biodiversity is a measure of the health of ecosystems. Biodiversity is in part a function of climate. In terrestrial habitats, tropical regions are typically rich whereas polar regions...
. The cane toad was intentionally introduced to Australia
Australia
Australia , officially the Commonwealth of Australia, is a country in the Southern Hemisphere comprising the mainland of the Australian continent, the island of Tasmania, and numerous smaller islands in the Indian and Pacific Oceans. It is the world's sixth-largest country by total area...
to control the introduced French’s Cane Beetle
Cane beetle
The cane beetle, Dermolepida albohirtum, is a native Australian beetle and a pest of the sugar cane. Adult beetles eat the leaves of sugar cane but greater damage is the done by their larvae hatching underground and eating the roots, which either kills or stunts the growth of the plant.Larvae,...
and the Greyback Cane Beetle. When introduced, the cane toad thrived and did not only feed on cane beetles but other insects as well. The cane toad soon spread very rapidly, thus taking over native amphibian
Amphibian
Amphibians , are a class of vertebrate animals including animals such as toads, frogs, caecilians, and salamanders. They are characterized as non-amniote ectothermic tetrapods...
habitat
Habitat
* Habitat , a place where a species lives and grows*Human habitat, a place where humans live, work or play** Space habitat, a space station intended as a permanent settlement...
. The introduction of the cane toad also brought foreign disease to native reptile
Reptile
Reptiles are members of a class of air-breathing, ectothermic vertebrates which are characterized by laying shelled eggs , and having skin covered in scales and/or scutes. They are tetrapods, either having four limbs or being descended from four-limbed ancestors...
s. This drastically reduced the population of native toad
Toad
A toad is any of a number of species of amphibians in the order Anura characterized by dry, leathery skin , short legs, and snoat-like parotoid glands...
s and frog
Frog
Frogs are amphibians in the order Anura , formerly referred to as Salientia . Most frogs are characterized by a short body, webbed digits , protruding eyes and the absence of a tail...
s. “The cane toad also exudes and can squirt poison
Poison
In the context of biology, poisons are substances that can cause disturbances to organisms, usually by chemical reaction or other activity on the molecular scale, when a sufficient quantity is absorbed by an organism....
from the parotid glands on their shoulders when threatened or handled. This toxin contains a cocktail of chemicals that can kill animals that eat it. Freshwater crocodile
Crocodile
A crocodile is any species belonging to the family Crocodylidae . The term can also be used more loosely to include all extant members of the order Crocodilia: i.e...
s, goanna
Goanna
Goanna is the name used to refer to any number of Australian monitor lizards of the genus Varanus, as well as to certain species from Southeast Asia.There are around 30 species of goanna, 25 of which are found in Australia...
s, tiger snakes, dingo
Dingo
The Australian Dingo or Warrigal is a free-roaming wild dog unique to the continent of Australia, mainly found in the outback. Its original ancestors are thought to have arrived with humans from southeast Asia thousands of years ago, when dogs were still relatively undomesticated and closer to...
s and northern quoll
Northern Quoll
The Northern Quoll , also known as the Northern Native Cat, the Satanellus, the North Australian Native Cat or the Njanmak , is a carnivorous marsupial mammal, native to Australia.- Taxonomy :The Northern Quoll is a member of the family Dasyuridae, and is often stated to be the most distinctive...
s have all died after eating cane toads, as have pet dogs (Cane toad, 2003). This example shows how small mis-introduced organisms can alter the native biodiversity
Biodiversity
Biodiversity is the degree of variation of life forms within a given ecosystem, biome, or an entire planet. Biodiversity is a measure of the health of ecosystems. Biodiversity is in part a function of climate. In terrestrial habitats, tropical regions are typically rich whereas polar regions...
in large ecosystems in a rapid manner. A pyramid
Pyramid
A pyramid is a structure whose outer surfaces are triangular and converge at a single point. The base of a pyramid can be trilateral, quadrilateral, or any polygon shape, meaning that a pyramid has at least three triangular surfaces...
effect can take place if native species are reduced or eradicated. The domino effect
Domino effect
The domino effect is a chain reaction that occurs when a small change causes a similar change nearby, which then will cause another similar change, and so on in linear sequence. The term is best known as a mechanical effect, and is used as an analogy to a falling row of dominoes...
keeps on going and can potentially exude on other bordering ecosystems until an equilibrium is reached.
A second example of a biological control agent that subsequently crossed over to native species is the Rhinocyllus conicus
Rhinocyllus conicus
Rhinocyllus conicus is a species of true weevil. It is best known as a controversial agent of biological pest control which has been used against noxious thistles in the genera Carduus, Cirsium, Onopordum, and Silybum....
. The seed feeding weevil was introduced to North America to control exotic thistle
Thistle
Thistle is the common name of a group of flowering plants characterised by leaves with sharp prickles on the margins, mostly in the family Asteraceae. Prickles often occur all over the plant – on surfaces such as those of the stem and flat parts of leaves. These are an adaptation that protects the...
s (Musk and Canadian). However, the weevil did not target only the exotic thistles, it also targeted native thistles that are essential to various native insects. The native insects rely solely on native thistles and do not adapt to other plant species. Therefore, they cannot survive. Biological controls do not always have negative impacts on biodiversity (Corry 2000).
Successful biological control reduces the population density
Population density
Population density is a measurement of population per unit area or unit volume. It is frequently applied to living organisms, and particularly to humans...
of the target species over several years, thus providing the potential for native species to re-establish. In addition, regeneration and reestablishment programs can aid to the recovery of native species. Native species can be affected in a positive way as well. To develop or find a biological control that exerts control only on the targeted species is a very lengthy process of research
Research
Research can be defined as the scientific search for knowledge, or as any systematic investigation, to establish novel facts, solve new or existing problems, prove new ideas, or develop new theories, usually using a scientific method...
and experiment
Experiment
An experiment is a methodical procedure carried out with the goal of verifying, falsifying, or establishing the validity of a hypothesis. Experiments vary greatly in their goal and scale, but always rely on repeatable procedure and logical analysis of the results...
s. In the late 19th century, the citrus
Citrus
Citrus is a common term and genus of flowering plants in the rue family, Rutaceae. Citrus is believed to have originated in the part of Southeast Asia bordered by Northeastern India, Myanmar and the Yunnan province of China...
industry was in great fear when the cottony cushion scale
Icerya purchasi
Icerya purchasi is a scale insect that feeds on several species of woody plants, most notably on Citrus and Pittosporum. Originally identified in 1878 as a New Zealand located pest of kangaroo acacia, it is now found worldwide where citrus crops are grown.-Life cycle:This scale infests twigs and...
was discovered. This organism could cause a great deal of economic loss to the industry. However, a biological control was introduced. The vedalia beetle and a parasitoid
Parasitoid
A parasitoid is an organism that spends a significant portion of its life history attached to or within a single host organism in a relationship that is in essence parasitic; unlike a true parasite, however, it ultimately sterilises or kills, and sometimes consumes, the host...
fly
Fly
True flies are insects of the order Diptera . They possess a pair of wings on the mesothorax and a pair of halteres, derived from the hind wings, on the metathorax...
were introduced to control the pest. Within a few years time, the cottony cushion scale was controlled by the natural enemies and the citrus industry suffered little financial loss. Many exotic or invasive species can suppress the development of native species. The introduction of an effective biological control that reduces the population of the invasive species allows the rejuvenation of the native species. Biological controls can reduce competition for biotic
Biotic component
Biotic components are the living things that shape an ecosystem. A biotic factor is any living component that affects another organism, including animals that consume the organism in question, and the living food that the organism consumes. Each biotic factor needs energy to do work and food for...
and abiotic factors which can result in the re-establishment of the once over ran native species.
Effects on invasive species
Alligator weed
Alternanthera philoxeroides, commonly known as Alligator weed, is an immersed aquatic plant. It originated in South America, but has spread to many parts of the world and is considered an invasive species in Australia, China, New Zealand, Thailand and the United States.Alligator weed can grow in a...
. This plant was introduced to the United States from South America
South America
South America is a continent situated in the Western Hemisphere, mostly in the Southern Hemisphere, with a relatively small portion in the Northern Hemisphere. The continent is also considered a subcontinent of the Americas. It is bordered on the west by the Pacific Ocean and on the north and east...
. This aquatic weed spreads rapidly and causes many problems in lakes and rivers. The weed takes root in shallow water causing major problems for navigation
Navigation
Navigation is the process of monitoring and controlling the movement of a craft or vehicle from one place to another. It is also the term of art used for the specialized knowledge used by navigators to perform navigation tasks...
, irrigation
Irrigation
Irrigation may be defined as the science of artificial application of water to the land or soil. It is used to assist in the growing of agricultural crops, maintenance of landscapes, and revegetation of disturbed soils in dry areas and during periods of inadequate rainfall...
, and flood control
Flood control
In communications, flood control is a feature of many communication protocols designed to prevent overwhelming of a destination receiver. Such controls can be implemented either in software or in hardware, and will often request that the message be resent after the receiver has finished...
. The alligator weed flea beetle
Agasicles hygrophila
Agasicles hygrophila is a species of leaf beetle known by the common name alligator weed flea beetle. It has been used successfully as an agent of biological pest control against the noxious aquatic plant known as alligator weed .This beetle is native to South America but has been imported to areas...
and two other biological controls were released in Florida
Florida
Florida is a state in the southeastern United States, located on the nation's Atlantic and Gulf coasts. It is bordered to the west by the Gulf of Mexico, to the north by Alabama and Georgia and to the east by the Atlantic Ocean. With a population of 18,801,310 as measured by the 2010 census, it...
. Because of their success, Florida banned the use of herbicides to control alligator weed three years after the controls were introduced. Similarly, Galerucella calmariensis
Galerucella calmariensis
Galerucella calmariensis is a species of leaf beetle in the family Chrysomelidae. It is commonly known as the black-margined loosestrife beetle and is native to Europe and Asia where both adults and larvae feed on purple loosestrife...
, a leaf beetle, has been introduced in North America as a control agent for purple loosestrife (Lythrum salicaria).
Biological controls for invasive species also can have a negative impact on biodiversity. The cane toad, as mentioned previously, is an example of trying to control an invasive species. The cane toad was introduced to eradicate an invasive species. It became invasive, thus altering the biodiversity. The introduction of the cane toad could have caused more of a disturbance in biodiversity than the targeted species did.
Classical biological control
Classical biological control is the introduction of natural enemies to a new locale where they did not originate or do not occur naturally. This is usually done by government authorities. In many instances the complex of natural enemies associated with an insect pest may be inadequate. This is especially evident when an insect pest is accidentally introduced into a new geographic area without its associated natural enemies. These introduced pests are referred to as exotic pests and comprise about 40% of the insect pests in the United StatesUnited States
The United States of America is a federal constitutional republic comprising fifty states and a federal district...
. Examples of introduced vegetable pests include the European corn borer
European Corn Borer
The European corn borer , also known as the European high-flyer, is a pest of grain, particularly maize. The insect is native to Europe, originally infesting varieties of millet, including broom corn. The European corn borer was first reported in North America in 1917 in Massachusetts, but was...
(Ostrinia nubilalis), one of the most destructive insects in North America
North America
North America is a continent wholly within the Northern Hemisphere and almost wholly within the Western Hemisphere. It is also considered a northern subcontinent of the Americas...
. To obtain the needed natural enemies, scientists turned to classical biological control. This is the practice of importing, and releasing for establishment, natural enemies to control an introduced (exotic) pest, although it is also practiced against native insect pests. The first step in the process is to determine the origin of the introduced pest and then collect appropriate natural enemies associated with the pest or closely related species. The natural enemy is then passed through a rigorous quarantine
Quarantine
Quarantine is compulsory isolation, typically to contain the spread of something considered dangerous, often but not always disease. The word comes from the Italian quarantena, meaning forty-day period....
process, to ensure that no unwanted organisms (such as hyperparasitoids) are introduced, then they are mass produced, and released. Follow-up studies are conducted to determine if the natural enemy becomes successfully established at the site of release, and to assess the long-term benefit of its presence.
There are many examples of successful classical biological control programs.
oseph Ne name="wpEdittime"
2011112522ing from 304AD, Records of the Plants and Trees of the Southern Regions, by Hsi Han, which describes mandarin oranges protected by biological pest control techniques that are still in use today.
One of the earliest successes in the west was in controlling Icerya purchasi
Icerya purchasi
Icerya purchasi is a scale insect that feeds on several species of woody plants, most notably on Citrus and Pittosporum. Originally identified in 1878 as a New Zealand located pest of kangaroo acacia, it is now found worldwide where citrus crops are grown.-Life cycle:This scale infests twigs and...
, the cottony cushion scale, a pest that was devastating the California
California
California is a state located on the West Coast of the United States. It is by far the most populous U.S. state, and the third-largest by land area...
citrus industry in the late 19th century. A predatory insect Rodolia cardinalis
Rodolia cardinalis
Rodolia cardinalis is a species of ladybird beetle that is sometimes described as endemic to Australia.-New Zealand:...
(the Vedalia Beetle), and a parasitoid fly were introduced from Australia by Charles Valentine Riley
Charles Valentine Riley
Charles Valentine Riley was a British-born American entomologist and artist.-Early Life:The son of a Church of England minister, Charles Valentine Riley was born on 19 September, 1843 in London’s Chelsea district. When he was around eleven his parents, the Rev. Charles and Mary Riley, chose to...
. Within a few years the cottony cushion scale was completely controlled by these introduced natural enemies.
Damage from Hypera postica Gyllenhal, the alfalfa weevil, a serious introduced pest of forage, was substantially reduced by the introduction of several natural enemies. 20 years after their introduction the population of weevil
Weevil
A weevil is any beetle from the Curculionoidea superfamily. They are usually small, less than , and herbivorous. There are over 60,000 species in several families, mostly in the family Curculionidae...
s in the alfalfa
Alfalfa
Alfalfa is a flowering plant in the pea family Fabaceae cultivated as an important forage crop in the US, Canada, Argentina, France, Australia, the Middle East, South Africa, and many other countries. It is known as lucerne in the UK, France, Australia, South Africa and New Zealand, and known as...
area treated for alfalfa weevil in the Northeastern United States
Northeastern United States
The Northeastern United States is a region of the United States as defined by the United States Census Bureau.-Composition:The region comprises nine states: the New England states of Connecticut, Maine, Massachusetts, New Hampshire, Rhode Island and Vermont; and the Mid-Atlantic states of New...
was reduced by 75 percent. A small wasp
Wasp
The term wasp is typically defined as any insect of the order Hymenoptera and suborder Apocrita that is neither a bee nor an ant. Almost every pest insect species has at least one wasp species that preys upon it or parasitizes it, making wasps critically important in natural control of their...
, Trichogramma ostriniae, was introduced from China
China
Chinese civilization may refer to:* China for more general discussion of the country.* Chinese culture* Greater China, the transnational community of ethnic Chinese.* History of China* Sinosphere, the area historically affected by Chinese culture...
to help control the European corn borer
European Corn Borer
The European corn borer , also known as the European high-flyer, is a pest of grain, particularly maize. The insect is native to Europe, originally infesting varieties of millet, including broom corn. The European corn borer was first reported in North America in 1917 in Massachusetts, but was...
making it a recent example of a long history of classical biological control efforts for this major pest. Many classical biological control programs for insect pests and weeds are under way across the United States and Canada
Canada
Canada is a North American country consisting of ten provinces and three territories. Located in the northern part of the continent, it extends from the Atlantic Ocean in the east to the Pacific Ocean in the west, and northward into the Arctic Ocean...
. The population of Levuana irridescens (the Levuana moth), a serious coconut pest in Fiji
Fiji
Fiji , officially the Republic of Fiji , is an island nation in Melanesia in the South Pacific Ocean about northeast of New Zealand's North Island...
, was brought under control by a classical biological control program in the 1920s.
Classical biological control is long lasting and inexpensive. Other than the initial costs of collection, importation, and rearing, little expense is incurred. When a natural enemy is successfully established it rarely requires additional input and it continues to kill the pest with no direct help from humans and at no cost. Classical biological control does not always work. It is usually most effective against exotic pests and less so against native insect pests. The reasons for failure are not often known but may include the release of too few individuals, poor adaptation of the natural enemy to environmental conditions at the release location, and lack of synchrony between the life cycle
Biological life cycle
A life cycle is a period involving all different generations of a species succeeding each other through means of reproduction, whether through asexual reproduction or sexual reproduction...
of the natural enemy and host pest.
Augmentation
This third type of biological control involves the supplemental release of natural enemies. Relatively few natural enemies may be released at a critical time of the season (inoculative release) or literally millions may be released (inundative release). Additionally, the cropping system may be modified to favor or augment the natural enemies. This latter practice is frequently referred to as habitat manipulation. An example of inoculative release occurs in greenhouse production of several crops. Periodic releases of the parasitoid, Encarsia formosaEncarsia formosa
Encarsia formosa is a species of wasp and a well known parasitoid of greenhouse whitefly. The tiny females are black with a yellow abdomen and opalescent wings. There are many fewer males than females...
, are used to control greenhouse whitefly
Whitefly
The whiteflies, comprising only the family Aleyrodidae, are small hemipterans. More than 1550 species have been described. Whiteflies typically feed on the underside of plant leaves.-Agricultural threat:...
, and the predaceous mite, Phytoseiulus persimilis, is used for control of the two-spotted spider mite.
Lady beetles, lacewings, or parasitoids such as those from the genus Trichogramma
Trichogramma
The wasps of genus Trichogramma, commonly known as "stingless wasps", are some of the most widely-studied agents of biological control in the field of entomology. Trichogramma wasps are tiny Hymenopteran insects, measuring 1 millimeter in length or less, that parasitize the eggs of many types of...
are frequently released in large numbers (inundative release). 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 depending on level of pest infestation. Similarly, entomopathogenic nematodes are released at rates of millions and even billions per acre for control of certain soil-dwelling insect pests.
The spraying of octopamine analogues (such as 3-FMC) has been suggested as a way to boost the effectiveness of augmentation. Octopamine
Octopamine
Octopamine is an endogenous biogenic amine that is closely related to norepinephrine, and has effects on the adrenergic and dopaminergic systems. It is also found naturally in numerous plants, including bitter orange. Biosynthesis of the D--enantiomer of octopamine is by β-hydroxylation of...
, regarded as the invertebrate
Invertebrate
An invertebrate is an animal without a backbone. The group includes 97% of all animal species – all animals except those in the chordate subphylum Vertebrata .Invertebrates form a paraphyletic group...
counterpart of dopamine
Dopamine
Dopamine is a catecholamine neurotransmitter present in a wide variety of animals, including both vertebrates and invertebrates. In the brain, this substituted phenethylamine functions as a neurotransmitter, activating the five known types of dopamine receptors—D1, D2, D3, D4, and D5—and their...
plays a role in activating the insects' flight-or-fight response. The idea behind using octopamine analogues to augment biological control is that natural enemies will be more effective in their eradication of the pest, since the pest will be behaving in an unnatural way because its flight-or-fight mechanism has been activated. Octopamine analogues are purported to have two desirable characteristics for this type of application: (1) they affect insects at very low dosages (2) they do not have a physiological effect in humans (or other vertebrates).
Box
Box describes a variety of containers and receptacles for permanent use as storage, or for temporary use often for transporting contents. The word derives from the Greek πύξος , "box, boxwood"....
es or (turnaround) flowerpot
Flowerpot
A flower pot or plant pot is a container in which flowers and other plants are cultivated. Historically, and still to a significant extent today, they are made from terracotta. Flower pots are now often made from plastic, wood, stone, or sometimes biodegradable material. An example of...
s is a form of this. For example, the stimulation of the natural predator Dermaptera is done in gardens by hanging up turnaround flowerpots with straw
Straw
Straw is an agricultural by-product, the dry stalks of cereal plants, after the grain and chaff have been removed. Straw makes up about half of the yield of cereal crops such as barley, oats, rice, rye and wheat. It has many uses, including fuel, livestock bedding and fodder, thatching and...
or wood wool.
Mixed plantings and the provision of flowering borders can increase the diversity of habitats and provide shelter and alternative food sources. They are easily incorporated into home gardens and even small-scale commercial plantings, but are more difficult to accommodate in large-scale crop production. There may also be some conflict with pest control for the large producer because of the difficulty of targeting the pest species and the use of refuges by the pest insects as well as natural enemies.
Examples of habitat manipulation include growing flowering plants (pollen and nectar sources) such as Buckwheat
Buckwheat
Buckwheat refers to a variety of plants in the dicot family Polygonaceae: the Eurasian genus Fagopyrum, the North American genus Eriogonum, and the Northern Hemisphere genus Fallopia. Either of the latter two may be referred to as "wild buckwheat"...
near crops to attract and maintain populations of natural enemies. For example, hover fly adults can be attracted to umbelliferous plants in bloom.
Biological control experts in California have demonstrated that planting prune trees in grape vineyards provides an improved overwintering habitat or refuge for a key grape pest parasitoid. The prune trees harbor an alternate host for the parasitoid, which could previously overwinter only at great distances from most vineyards. Caution should be used with this tactic because some plants attractive to natural enemies may also be hosts for certain plant diseases, especially plant viruses that could be vectored by insect pests to the crop. Although the tactic appears to hold much promise, only a few examples have been adequately researched and developed.
Examples of predators
Ladybugs, and in particular their larvae which are active between May and July in the northern hemisphere, are voracious predators of aphidAphid
Aphids, also known as plant lice and in Britain and the Commonwealth as greenflies, blackflies or whiteflies, are small sap sucking insects, and members of the superfamily Aphidoidea. Aphids are among the most destructive insect pests on cultivated plants in temperate regions...
s such as greenfly
Aphid
Aphids, also known as plant lice and in Britain and the Commonwealth as greenflies, blackflies or whiteflies, are small sap sucking insects, and members of the superfamily Aphidoidea. Aphids are among the most destructive insect pests on cultivated plants in temperate regions...
and blackfly
Black fly
A black fly is any member of the family Simuliidae of the Culicomorpha infraorder. They are related to the Ceratopogonidae, Chironomidae, and Thaumaleidae. There are over 1,800 known species of black flies . Most species belong to the immense genus Simulium...
, and will also consume mites
MITES
MITES, or Minority Introduction to Engineering and Science, is a highly selective six-week summer program for rising high school seniors held at the Massachusetts Institute of Technology. Its purpose is to expose students from minority, or otherwise disadvantaged backgrounds, to the fields of...
, scale insect
Scale insect
The scale insects are small insects of the order Hemiptera, generally classified as the superfamily Coccoidea. There are about 8,000 species of scale insects.-Ecology:...
s and small caterpillar
Caterpillar
Caterpillars are the larval form of members of the order Lepidoptera . They are mostly herbivorous in food habit, although some species are insectivorous. Caterpillars are voracious feeders and many of them are considered to be pests in agriculture...
s. The ladybug is a very familiar beetle with various colored markings, whilst its larvae are initially small and spidery, growing up to 17 mm long. The larvae have a tapering segmented grey/black body with orange/yellow markings and ferocious mouthparts. They can be encouraged by cultivating a patch of nettle
Nettle
Nettles constitute between 24 and 39 species of flowering plants of the genus Urtica in the family Urticaceae, with a cosmopolitan though mainly temperate distribution. They are mostly herbaceous perennial plants, but some are annual and a few are shrubby...
s in the garden and by leaving hollow stems and some plant debris over winter so that they can hibernate.
Hoverflies
Hoverfly
Hoverflies, sometimes called flower flies or syrphid flies, make up the insect family Syrphidae. As their common name suggests, they are often seen hovering or nectaring at flowers; the adults of many species feed mainly on nectar and pollen, while the larvae eat a wide range of foods...
resemble slightly darker bee
Bee
Bees are flying insects closely related to wasps and ants, and are known for their role in pollination and for producing honey and beeswax. Bees are a monophyletic lineage within the superfamily Apoidea, presently classified by the unranked taxon name Anthophila...
s or wasp
Wasp
The term wasp is typically defined as any insect of the order Hymenoptera and suborder Apocrita that is neither a bee nor an ant. Almost every pest insect species has at least one wasp species that preys upon it or parasitizes it, making wasps critically important in natural control of their...
s and they have characteristic hovering, darting flight patterns. There are over 100 species of hoverfly whose larvae principally feed upon greenfly, one larva devouring up to fifty a day, or 1000 in its lifetime. They also eat fruit tree spider mite
Spider mite
Spider mites are members of the Acari family Tetranychidae, which includes about 1,200 species. They generally live on the under sides of leaves of plants, where they may spin protective silk webs, and they can cause damage by puncturing the plant cells to feed...
s and small caterpillars. Adults feed on nectar and pollen
Pollen
Pollen is a fine to coarse powder containing the microgametophytes of seed plants, which produce the male gametes . Pollen grains have a hard coat that protects the sperm cells during the process of their movement from the stamens to the pistil of flowering plants or from the male cone to the...
, which they require for egg production. Eggs are minute (1 mm), pale yellow white and laid singly near greenfly colonies. Larvae are 8–17 mm long, disguised to resemble bird droppings, they are legless and have no distinct head. Semi-transparent in a range of colours from green, white, brown and black.
Poached egg plant
Limnanthes douglasii is a species of annual flowering plant in the meadowfoam family commonly known as poached egg plant and Douglas' meadowfoam. It is native to California and Oregon, where it grows in wet, grassy habitat, such as vernal pools and spring meadows. It can grow in poorly drained clay...
(Limnanthes douglasii), marigolds or phacelia
Phacelia
Phacelia is a genus of about 200 species of annual or perennial herbaceous plants, native to North and South America....
throughout the growing season.
Dragonflies
Dragonfly
A dragonfly is a winged insect belonging to the order Odonata, the suborder Epiprocta or, in the strict sense, the infraorder Anisoptera . It is characterized by large multifaceted eyes, two pairs of strong transparent wings, and an elongated body...
are important predators of mosquitoes, both in the water, where the dragonfly naiads
Nymph (biology)
In biology, a nymph is the immature form of some invertebrates, particularly insects, which undergoes gradual metamorphosis before reaching its adult stage. Unlike a typical larva, a nymph's overall form already resembles that of the adult. In addition, while a nymph moults it never enters a...
eat mosquito
Mosquito
Mosquitoes are members of a family of nematocerid flies: the Culicidae . The word Mosquito is from the Spanish and Portuguese for little fly...
larva
Larva
A larva is a distinct juvenile form many animals undergo before metamorphosis into adults. Animals with indirect development such as insects, amphibians, or cnidarians typically have a larval phase of their life cycle...
e, and in the air, where adult dragonflies capture and eat adult mosquitoes. Community-wide mosquito control programs that spray adult mosquitoes also kill dragonflies, thus removing an important biocontrol agent, and can actually increase mosquito populations in the long term.
Other useful garden predators include lacewings
Chrysopidae
Green lacewings are insects in the large family Chrysopidae of the order Neuroptera. There are about 85 genera and 1,300–2,000 species in this widespread group...
, pirate bugs
Anthocoridae
The Anthocoridae are a family of bugs, commonly called minute pirate bugs or flower bugs.-Name:The vernacular name probably stems from the notion that these very small animals can do much pain to humans, just like small pirate vessels can do so to big ships.The scientific name is a combination of...
, rove and ground beetles, aphid midge, centipede
Centipede
Centipedes are arthropods belonging to the class Chilopoda of the subphylum Myriapoda. They are elongated metameric animals with one pair of legs per body segment. Despite the name, centipedes can have a varying number of legs from under 20 to over 300. Centipedes have an odd number of pairs of...
s, spider
Spider
Spiders are air-breathing arthropods that have eight legs, and chelicerae with fangs that inject venom. They are the largest order of arachnids and rank seventh in total species diversity among all other groups of organisms...
s, predatory mites, as well as larger fauna such as frog
Frog
Frogs are amphibians in the order Anura , formerly referred to as Salientia . Most frogs are characterized by a short body, webbed digits , protruding eyes and the absence of a tail...
s, toad
Toad
A toad is any of a number of species of amphibians in the order Anura characterized by dry, leathery skin , short legs, and snoat-like parotoid glands...
s, lizard
Lizard
Lizards are a widespread group of squamate reptiles, with nearly 3800 species, ranging across all continents except Antarctica as well as most oceanic island chains...
s, hedgehog
Hedgehog
A hedgehog is any of the spiny mammals of the subfamily Erinaceinae and the order Erinaceomorpha. There are 17 species of hedgehog in five genera, found through parts of Europe, Asia, Africa, and New Zealand . There are no hedgehogs native to Australia, and no living species native to the Americas...
s,
slow-worms and birds. Cats and rat terriers kill field mice, rats, June bugs, and birds. Dogs chase away many types of pest animals. Dachshund
Dachshund
The dachshund is a short-legged, long-bodied dog breed belonging to the hound family. The standard size dachshund was bred to scent, chase, and flush out badgers and other burrow-dwelling animals, while the miniature dachshund was developed to hunt smaller prey such as rabbits...
s are bred specifically to fit inside tunnels underground to kill badgers.
More examples:
- Phytoseiulus persimilis (against spider mites)
- Amblyseius californicus (against spider mites)
- Amblyseius cucumeris (against spider mites)
- Typhlodromips swirskii (against spider mites, thrips, and white flies)
- Feltiella acarisugaFeltiella acarisugaFeltiella acarisuga is a predatory gall midge which will feed on various species of spider mites. It is especially common when spider mites occur in colonies. It requires a high spider mite density and high humidities to become established....
(against spider mites) - Stethorus punctillum (against spider mites)
- Macrolophus caluginosus (against spider mites)
Parasitoid insects
Most insect parasitoids are wasps or fliesDiptera
Diptera , or true flies, is the order of insects possessing only a single pair of wings on the mesothorax; the metathorax bears a pair of drumstick like structures called the halteres, the remnants of the hind wings. It is a large order, containing an estimated 240,000 species, although under half...
. Parasitoids comprise a diverse range of insects that lay their egg on or in the body of an insect host, which is then used as a food for developing larvae. Parasitic wasp
Wasp
The term wasp is typically defined as any insect of the order Hymenoptera and suborder Apocrita that is neither a bee nor an ant. Almost every pest insect species has at least one wasp species that preys upon it or parasitizes it, making wasps critically important in natural control of their...
s take much longer than predators to consume their victims, for if the larvae were to eat too fast they would run out of food before they became adults. Such parasites are very useful in the organic garden, for they are very efficient hunters, always at work searching for pest invaders. As adults they require high energy fuel as they fly from place to place, and feed upon nectar, pollen and sap, thereby pollinating plenty of flowering plants, particularly buckwheat
Buckwheat
Buckwheat refers to a variety of plants in the dicot family Polygonaceae: the Eurasian genus Fagopyrum, the North American genus Eriogonum, and the Northern Hemisphere genus Fallopia. Either of the latter two may be referred to as "wild buckwheat"...
, umbellifers, and composites
Asteraceae
The Asteraceae or Compositae , is an exceedingly large and widespread family of vascular plants. The group has more than 22,750 currently accepted species, spread across 1620 genera and 12 subfamilies...
will encourage their presence.
Four of the most important groups are:
- Ichneumonid waspsIchneumon waspThe Ichneumonoidea are insects classified in the hymenopteran suborder Apocrita. The superfamily is made up of the ichneumon wasps and the braconids...
: (5–10 mm). Prey mainly on caterpillarCaterpillarCaterpillars are the larval form of members of the order Lepidoptera . They are mostly herbivorous in food habit, although some species are insectivorous. Caterpillars are voracious feeders and many of them are considered to be pests in agriculture...
s of butterflies and mothsMothsMoths may refer to:* Gustav Moths , German rower* The Moths!, an English indie rock band* MOTHS, members of the Memorable Order of Tin Hats...
. - Braconid wasps: Tiny wasps (up to 5 mm) attack caterpillars and a wide range of other insects including greenfly. A common parasite of the cabbage white caterpillar- seen as clusters of sulphur yellow cocoons bursting from collapsed caterpillar skin.
- Chalcid waspChalcid waspChalcid wasps belong to the insect order Hymenoptera, and are one of the largest groups within the order, with some 22,000 known species, and an estimated total diversity of anywhere from 60,000 to more than 500,000 species, meaning the vast majority have yet to be discovered and described.Most of...
s: Among the smallest of insects (<3 mm). Parasitize eggs/larvae of greenflyGreenflyGreenfly is the artist name of Lawrence Green, a drum and bass music producer and DJ from Reading, England. His music style leans towards the more soul/funk influenced styles of drum'n'bass. He is currently signed to and has been releasing music since 2001...
, whiteflyWhiteflyThe whiteflies, comprising only the family Aleyrodidae, are small hemipterans. More than 1550 species have been described. Whiteflies typically feed on the underside of plant leaves.-Agricultural threat:...
, cabbage caterpillars, scale insectScale insectThe scale insects are small insects of the order Hemiptera, generally classified as the superfamily Coccoidea. There are about 8,000 species of scale insects.-Ecology:...
s and Strawberry Tortrix Moth (Acleris comarianaAcleris comarianaThe Strawberry Tortrix is a moth of the Tortricidae family. It is found in Europe, the Caucasus, Amur, Kamchatka, China, Korea and Japan.The wingspan is 13-18 mm....
). - Tachinid fliesTachinidaeTachinidae is a large and rather variable family of true flies within the insect order Diptera, with more than 8,200 known species and many more to be discovered. There are over 1300 species in North America. Insects in this family are commonly called tachina flies or simply tachinids...
: Parasitize a wide range of insects including caterpillars, adult and larval beetleBeetleColeoptera is an order of insects commonly called beetles. The word "coleoptera" is from the Greek , koleos, "sheath"; and , pteron, "wing", thus "sheathed wing". Coleoptera contains more species than any other order, constituting almost 25% of all known life-forms...
s, true bugs, and others.
Examples of parasitoids:
wasp
- Encarsia formosaEncarsia formosaEncarsia formosa is a species of wasp and a well known parasitoid of greenhouse whitefly. The tiny females are black with a yellow abdomen and opalescent wings. There are many fewer males than females...
(against white flies) - Eretmocerus spp. (against white flies)
- Aphidius colemani (against aphids)
Biological control with micro-organisms
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 and biological control
Bacteria used for biological control infect insects via their digestive tracts, so insects with sucking mouth parts like aphids and scale insects are difficult to control with bacterial biological control. Bacillus thuringiensisBacillus thuringiensis
Bacillus thuringiensis is a Gram-positive, soil-dwelling bacterium, commonly used as a biological pesticide; alternatively, the Cry toxin may be extracted and used as a pesticide. B...
is the most widely applied species of bacteria used for biological control, with at least four sub-species used to control Lepidoptera
Lepidoptera
Lepidoptera is a large order of insects that includes moths and butterflies . It is one of the most widespread and widely recognizable insect orders in the world, encompassing moths and the three superfamilies of butterflies, skipper butterflies, and moth-butterflies...
n (moth
Moth
A moth is an insect closely related to the butterfly, both being of the order Lepidoptera. Moths form the majority of this order; there are thought to be 150,000 to 250,000 different species of moth , with thousands of species yet to be described...
, butterfly
Butterfly
A butterfly is a mainly day-flying insect of the order Lepidoptera, which includes the butterflies and moths. Like other holometabolous insects, the butterfly's life cycle consists of four parts: egg, larva, pupa and adult. Most species are diurnal. Butterflies have large, often brightly coloured...
), Coleopteran (beetle) and Diptera
Diptera
Diptera , or true flies, is the order of insects possessing only a single pair of wings on the mesothorax; the metathorax bears a pair of drumstick like structures called the halteres, the remnants of the hind wings. It is a large order, containing an estimated 240,000 species, although under half...
n (true flies) insect pests.
Fungi and biological control
Fungi that cause disease in insects are known as entomopathogenic fungi, including at least fourteen species of entomophthoraceous fungi attack aphids. Species in the genus TrichodermaTrichoderma
Trichoderma is a genus of fungi that is present in all soils, where they are the most prevalent culturable fungi. Many species in this genus can be characterized as opportunistic avirulent plant symbionts.-Species:...
are used to manage some soilborne plant pathogens. Beauveria bassiana
Beauveria bassiana
Beauveria bassiana is a fungus that grows naturally in soils throughout the world and acts as a parasite on various arthropod species, causing white muscardine disease; it thus belongs to the entomopathogenic fungi. It is being used as a biological insecticide to control a number of pests such as...
is used to manage different types of pest such whiteflies, thrips, aphids and weevils.
Examples of entomopathogenic fungi:
- Beauveria bassianaBeauveria bassianaBeauveria bassiana is a fungus that grows naturally in soils throughout the world and acts as a parasite on various arthropod species, causing white muscardine disease; it thus belongs to the entomopathogenic fungi. It is being used as a biological insecticide to control a number of pests such as...
(against white flies, thrips, aphids and weevils) - Paecilomyces fumosoroseusPaecilomyces fumosoroseusPaecilomyces fumosoroseus is a microscopic fungus that infects and kills insects. It shows promise as a biological pesticide with an extensive host range.-Life cycle:...
(against white flies, thrips and aphids) - MetarhiziumMetarhiziumMetarhizium is a genus of entomopathogenic fungi in the Clavicipitaceae family. With the advent of genetic profiling, it has now become possible to place these fungi in proper taxa. Most turn out to be the asexual forms of fungi in the phylum Ascomycota.- Species :Nine distinct species have now...
spp. (against beetles, locusts, HemipteraHemipteraHemiptera is an order of insects most often known as the true bugs , comprising around 50,000–80,000 species of cicadas, aphids, planthoppers, leafhoppers, shield bugs, and others...
, spider mites and other pests) - Lecanicillium lecaniiLecanicillium lecaniiLecanicillium lecanii is now an approved name of an entomopathogenic fungus species, that was previously widely known as Verticillium lecanii Viegas), but is now understood to be an anamorphic form in the Cordyceps group of genera in the Clavicipitaceae . It now appears that isolates formerly...
(against white flies, thrips and aphids) - CordycepsCordycepsCordyceps is a genus of ascomycete fungi that includes about 400 described species. All Cordyceps species are endoparasitoids, mainly on insects and other arthropods ; a few are parasitic on other fungi. The best known species of the genus is Cordyceps sinensis, first recorded as yartsa gunbu in...
species (sometines teleomorphs of the above: that infect a wide spectrum of arthropods)
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 being, that of the emerald ash borerEmerald ash borer
The emerald ash borer is a green beetle native to Asia.In North America the borer is an invasive species, highly destructive to ash trees in its introduced range. The potential damage of this insect rivals that of Chestnut blight and Dutch Elm Disease...
(Agrilus planipennis Fairmaire, family Buprestidae), an invasive beetle
Beetle
Coleoptera is an order of insects commonly called beetles. The word "coleoptera" is from the Greek , koleos, "sheath"; and , pteron, "wing", thus "sheathed wing". Coleoptera contains more species than any other order, constituting almost 25% of all known life-forms...
from China
China
Chinese civilization may refer to:* China for more general discussion of the country.* Chinese culture* Greater China, the transnational community of ethnic Chinese.* History of China* Sinosphere, the area historically affected by Chinese culture...
, which has destroyed tens of millions of ash trees in its introduced range in North America
North America
North America is a continent wholly within the Northern Hemisphere and almost wholly within the Western Hemisphere. It is also considered a northern subcontinent of the Americas...
. s part of the campaign against the emerald ash borer (EAB), American scientists in conjunction with the Chinese Academy of Forestry searched since 2003 for its natural enemies in the wild leading to the discovery of several parasitoid wasps, namely Tetrastichus planipennisi, a gregarious larval endoparasitoid,Oobius agrili
Oobius agrili
Oobius agrili is a parasitic non-stinging wasp of family Encyrtidae which is native to North Asia. It is a parasitoid of the emerald ash borer , an invasive species which has destroyed tens of millions of ash trees in its introduced range in North America...
, a solitary, parthenogenic egg parasitoid, and Spathius agrili
Spathius agrili
Spathius agrili is a parasitic non-stinging wasp of family Braconidae which is native to North Asia. It is a parasitoid of the emerald ash borer , an invasive species which has destroyed tens of millions of ash trees in its introduced range in North America...
, a gregarious larval ectoparasitoid. These have been been introduced and released into the United States of America as a possible biological control of the emerald ash borer. Initial results have shown promise with Tetrastichus planipennisi and it is now being released along with Beauveria bassiana
Beauveria bassiana
Beauveria bassiana is a fungus that grows naturally in soils throughout the world and acts as a parasite on various arthropod species, causing white muscardine disease; it thus belongs to the entomopathogenic fungi. It is being used as a biological insecticide to control a number of pests such as...
, a fungal pathogen
Pathogen
A pathogen gignomai "I give birth to") or infectious agent — colloquially, a germ — is a microbe or microorganism such as a virus, bacterium, prion, or fungus that causes disease in its animal or plant host...
with known insecticidal properties.
Plants to regulate insect pests
Choosing a diverse range of plants for the garden can help to regulate pests in a variety of ways, including;- Masking the crop plants from pests, depending on the proximity of the companion or intercrop.
- Producing olfactory inhibitors, odors that confuse and deter pests.
- Acting as trap plants by providing an alluring food that entices pests away from crops.
- Serving as nursery plants, providing breeding grounds for beneficial insectsBeneficial insectsBeneficial insects are any of a number of species of insects that perform valued services like pollination and pest control. The concept of beneficial is subjective and only arises in light of desired outcomes from a human perspective...
. - Providing an alternative habitat, usually in a form of a shelterbeltWindbreakA windbreak or shelterbelt is a plantation 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 to protect soil from erosion. They are commonly planted around the edges of fields on farms. If designed properly, windbreaks around a...
, hedgerow, or beetle bankBeetle bankA Beetle bank, In agriculture and horticulture, is a form of biological pest control. It is a strip planted with grasses and-or perennial plants, within a crop field or a garden, that fosters and provides habitat for beneficial insects, birds, and other fauna that prey on...
where beneficial insects can live and reproduce. Nectar-rich plants that bloom for long periods are especially good, as many beneficials are nectivorous during the adult stage, but parasitic or predatory as larvae. A good example of this is the soldier beetle which is frequently found on flowers as an adult, but whose larvae eat aphids, caterpillars, grasshopper eggs, and other beetles. - Some plants have chemical defenses in order to regulate pests. The geranium has developed such a defense against Japanese beetles, one of the most damaging and expensive pests to control when it comes to ornamental and turf plants. The geranium’s petals contain a chemical compound that paralyzes the beetle within 30 minutes of ingestion. The beetle will remain paralyzed for several hours and will typically regain movement within 24 hours. However, while paralyzed the beetle is very vulnerable to its predators and is usually hunted before the paralysis subsides. Agricultural Research ServiceAgricultural Research ServiceThe Agricultural Research Service is the principal in-house research agency of the United States Department of Agriculture . ARS is one of four agencies in USDA's Research, Education and Economics mission area...
(ARS) scientists are working to isolate the chemical compound in geraniums that causes the paralysis in the beetles. Scientists hope to one day use this natural pesticide to control the population of beetles. In addition to this research ARS scientists are studying ways to help geranium leaves better hold on to pesticide chemicals that are sprayed on them, that way less pesticides will have to be applied to the leaves.
Plants to regulate plants
The legume vine Mucuna pruriensMucuna pruriens
Mucuna pruriens is a tropical legume known as velvet bean or cowitch and by other common names , found in Africa, India and the Caribbean. The plant is infamous for its extreme itchiness produced on contact, particularly with the young foliage and the seed pods...
is used in the countries of Benin
Benin
Benin , officially the Republic of Benin, is a country in West Africa. It borders Togo to the west, Nigeria to the east and Burkina Faso and Niger to the north. Its small southern coastline on the Bight of Benin is where a majority of the population is located...
and Vietnam
Vietnam
Vietnam – sometimes spelled Viet Nam , officially the Socialist Republic of Vietnam – is the easternmost country on the Indochina Peninsula in Southeast Asia. It is bordered by China to the north, Laos to the northwest, Cambodia to the southwest, and the South China Sea –...
as a biological control for problematic Imperata cylindrica grass. Mucuna pruriens is said not to be invasive outside its cultivated area. Desmodium
Desmodium
Desmodium is a genus in the flowering plant family Fabaceae, sometimes called tick-trefoil, tick clover or beggar lice. There are dozens of species and the delimitation of the genus has shifted much over time....
uncinatum can be used in push-pull farming
Push-pull technology
The push–pull technology is a strategy for controlling agricultural pests by using repellent "push" plants and trap "pull" plants. For example, cereal crops like maize or sorghum are often infested by stem borers...
to stop the parasitic plant
Parasitic plant
A parasitic plant is one that derives some or all of its sustenance from another plant. About 4,100 species in approximately 19 families of flowering plants are known. Parasitic plants have a modified root, the haustorium, that penetrates the host plant and connects to the xylem, phloem, or...
, Striga
Striga (plant)
Striga, commonly known as witches weed, is a genus of 28 species of parasitic plants that occur naturally in parts of Africa, Asia, and Australia. Witchweeds are characterized by bright-green stems and leaves and small, brightly colored flowers. Furthermore, they are obligate parasites of roots...
.
Directly introducing biological controls
Some biocontrol agents that can be introduced include;
- Encarsia formosa. This is a small predatory chalcid waspChalcid waspChalcid wasps belong to the insect order Hymenoptera, and are one of the largest groups within the order, with some 22,000 known species, and an estimated total diversity of anywhere from 60,000 to more than 500,000 species, meaning the vast majority have yet to be discovered and described.Most of...
which is parasitical on whiteflyWhiteflyThe whiteflies, comprising only the family Aleyrodidae, are small hemipterans. More than 1550 species have been described. Whiteflies typically feed on the underside of plant leaves.-Agricultural threat:...
, a sap-feeding insect which can cause wilting and black sooty mouldSooty moldSooty molds are Ascomycete fungi which grow on plant exudates and the sugary honeydew secreted by insects such as aphids, scales, the whitefly, and other insects which suck sap from their host plants. The name itself is descriptive, as sooty mold is a black, powdery coating adhering to the leaves...
s. 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 pupates. It should be introduced as soon as possible after the first adult whitefly are seen. Should be used in conjunction with insecticidal soapInsecticidal soapInsecticidal soap is defined as any of the potassium fatty acid soaps used to control many plant pests. Insecticidal soap is typically sprayed on plants in the same manner as other insecticides. Insecticidal soap works only on direct contact with the pests. The fatty acids disrupt the structure and...
.
- Red spider mite, another pest found in the greenhouse, can be controlled with the predatory mite Phytoseilus persimilis. This is slightly larger than its prey and has an orange body. It develops from egg to adult twice as fast as the red spider mite and once established quickly overcomes infestation.
- A fairly recent development in the control of slugSlugSlug is a common name that is normally applied to any gastropod mollusc that lacks a shell, has a very reduced shell, or has a small internal shell...
s is the introduction of 'Nemaslug', a microscopic nematodeNematodeThe nematodes or roundworms are the most diverse phylum of pseudocoelomates, and one of the most diverse of all animals. Nematode species are very difficult to distinguish; over 28,000 have been described, of which over 16,000 are parasitic. It has been estimated that the total number of nematode...
(Phasmarhabditis hermaphroditaPhasmarhabditis hermaphroditaPhasmarhabditis hermaphrodita is a microscopic nematode in the family Rhabditidae. It is a lethal parasite of the slug, Deroceras reticulatum and a large number of other slug species from the families Milacidae, Limacidae and Arionidae...
) which will seek out and parasitize slugs, reproducing inside them and killing them. The nematode is applied by watering onto moist soil, and gives protection for up to six weeks in optimum conditions, Nemaslug nematodes are mainly effective with small and young slugs under the soil surface.
- A bacterial biological control which can be introduced in order to control butterfly caterpillars is Bacillus thuringiensisBacillus thuringiensisBacillus thuringiensis is a Gram-positive, soil-dwelling bacterium, commonly used as a biological pesticide; alternatively, the Cry toxin may be extracted and used as a pesticide. B...
. This available in sachets of dried spores which are mixed with water and sprayed onto vulnerable plants such as brassicaBrassicaBrassica is a genus of plants in the mustard family . The members of the genus may be collectively known either as cabbages, or as mustards...
s and fruit treeFruit treeA fruit tree is a tree which bears fruit that is consumed or used by people — all trees that are flowering plants produce fruit, which are the ripened ovaries of flowers containing one or more seeds. In horticultural usage, the term 'fruit tree' is limited to those that provide fruit for...
s. The bacterial disease will kill the caterpillars, but leave other insects unharmed. There are strains of Bt that are effective against other insect larvae. Bt israelensisBacillus thuringiensis israelensisBacillus thuringiensis serovar israelensis is a group of bacteria used as biological control agents for larvae stages of certain Dipterans. Bti produces toxins which are effective in killing various species of mosquitoes, fungus gnats, and blackflies, while having almost no effect on other...
is effective against mosquitoMosquitoMosquitoes are members of a family of nematocerid flies: the Culicidae . The word Mosquito is from the Spanish and Portuguese for little fly...
larvae and some midges.
- A viral biological control which can be introduced in order to control the overpopulation of European rabbitEuropean RabbitThe European Rabbit or Common Rabbit is a species of rabbit native to south west Europe and north west Africa . It has been widely introduced elsewhere often with devastating effects on local biodiversity...
in Australia is the rabbit haemorrhagic disease virus that causes the rabbit haemorrhagic diseaseRabbit haemorrhagic diseaseRabbit haemorrhagic disease , also known as rabbit calicivirus disease or viral haemorrhagic disease , is a highly infectious and often fatal disease that affects wild and domestic rabbits of the species Oryctolagus cuniculus...
.
- A biological control being developed for use in the treatment of plant disease is the fungusFungusA fungus is a member of a large group of eukaryotic organisms that includes microorganisms such as yeasts and molds , as well as the more familiar mushrooms. These organisms are classified as a kingdom, Fungi, which is separate from plants, animals, and bacteria...
Trichoderma viride. This has been used against Dutch Elm diseaseDutch elm diseaseDutch elm disease is a disease caused by a member of the sac fungi category, affecting elm trees which is spread by the elm bark beetle. Although believed to be originally native to Asia, the disease has been accidentally introduced into America and Europe, where it has devastated native...
, and to treat the spread of fungal and bacterial growth on tree wounds. It may also have potential as a means of combating silver leaf diseaseChondrostereum purpureumSilver leaf is a fungal disease of trees caused by the fungus plant pathogen Chondrostereum purpureum. It attacks most species of the rose family Rosaceae, particularly the genus Prunus. The disease is progressive and often fatal. The common name is taken from the progressive silvering of leaves on...
.
- Several species of dung beetleDung beetleDung beetles are beetles that feed partly or exclusively on feces. All of these species belong to the superfamily Scarabaeoidea; most of them to the subfamilies Scarabaeinae and Aphodiinae of the family Scarabaeidae. This beetle can also be referred to as the scarab beetle. As most species of...
were introduced to Australia from South Africa and Europe during the Australian Dung Beetle ProjectAustralian Dung Beetle ProjectThe Australian Dung Beetle Project , conceived and led by Dr. George Bornemissza, of the Commonwealth Scientific and Industrial Research Organisation , was an international scientific research and biological control project with the primary goal to introduce foreign species of dung beetle to...
(1965–1985) led by Dr. George BornemisszaGeorge BornemisszaGeorge Francis Bornemissza is a Hungarian-born entomologist and ecologist. He studied science at the University of Budapest before obtaining his PhD in zoology at the University of Innsbruck in Austria in 1950. At the end of that year he emigrated to Australia...
of the Commonwealth Scientific and Industrial Research OrganisationCommonwealth Scientific and Industrial Research OrganisationThe Commonwealth Scientific and Industrial Research Organisation is the national government body for scientific research in Australia...
in order to biologically control the population of pestilent bush flies and parasitic worms.
- The parasitoidParasitoidA parasitoid is an organism that spends a significant portion of its life history attached to or within a single host organism in a relationship that is in essence parasitic; unlike a true parasite, however, it ultimately sterilises or kills, and sometimes consumes, the host...
Gonatocerus ashmeadi (HymenopteraHymenopteraHymenoptera is one of the largest orders of insects, comprising the sawflies, wasps, bees and ants. There are over 130,000 recognized species, with many more remaining to be described. The name refers to the heavy wings of the insects, and is derived from the Ancient Greek ὑμήν : membrane and...
: Mymaridae) has been introduced to control the glassy-winged sharpshooterGlassy-winged sharpshooterThe glassy-winged sharpshooter is a large leafhopper insect from the family Cicadellidae, similar to other species of sharpshooter.-Description:These sharpshooters are about in length...
Homalodisca vitripennis (Hemipterae: Cicadellidae) in French PolynesiaFrench PolynesiaFrench Polynesia is an overseas country of the French Republic . It is made up of several groups of Polynesian islands, the most famous island being Tahiti in the Society Islands group, which is also the most populous island and the seat of the capital of the territory...
and has successfully controlled ~95% of the pest density.
Negative consequences of biological pest control
In some cases, biological pest control could have unforeseen averse consequences that outweigh all benefits, often by becoming an invasive speciesInvasive species
"Invasive species", or invasive exotics, is a nomenclature term and categorization phrase used for flora and fauna, and for specific restoration-preservation processes in native habitats, with several definitions....
. For example:
- When the mongooseMongooseMongoose are a family of 33 living species of small carnivorans from southern Eurasia and mainland Africa. Four additional species from Madagascar in the subfamily Galidiinae, which were previously classified in this family, are also referred to as "mongooses" or "mongoose-like"...
was introduced to HawaiiHawaiiHawaii is the newest of the 50 U.S. states , and is the only U.S. state made up entirely of islands. It is the northernmost island group in Polynesia, occupying most of an archipelago in the central Pacific Ocean, southwest of the continental United States, southeast of Japan, and northeast of...
in order to control the ratRatRats are various medium-sized, long-tailed rodents of the superfamily Muroidea. "True rats" are members of the genus Rattus, the most important of which to humans are the black rat, Rattus rattus, and the brown rat, Rattus norvegicus...
population, it preyed on the endemic birds of HawaiiEndemic birds of HawaiiThis article is one of a series providing information about endemism among birds in the World's various zoogeographic zones. For an overview of this subject see Endemism in birds....
, especially their eggsEgg (biology)An egg is an organic vessel in which an embryo first begins to develop. In most birds, reptiles, insects, molluscs, fish, and monotremes, an egg is the zygote, resulting from fertilization of the ovum, which is expelled from the body and permitted to develop outside the body until the developing...
, more often than it ate the rats. (Note, however, that the introduction of the mongoose was not undertaken based on scientific—or perhaps any—understanding of the consequences of such an action. The introduction of a generalist mammal for biocontrol of anything would be unthinkable by any reasonable standards today.)
- Cane toadCane ToadThe Cane Toad , also known as the Giant Neotropical Toad or Marine Toad, is a large, terrestrial true toad which is native to Central and South America, but has been introduced to various islands throughout Oceania and the Caribbean...
s (Bufo marinus) were introduced to AustraliaAustraliaAustralia , officially the Commonwealth of Australia, is a country in the Southern Hemisphere comprising the mainland of the Australian continent, the island of Tasmania, and numerous smaller islands in the Indian and Pacific Oceans. It is the world's sixth-largest country by total area...
in the 1930s in a failed attempt to control the cane beetle, a pest of sugar cane crops. 102 toads were obtained from HawaiiHawaiiHawaii is the newest of the 50 U.S. states , and is the only U.S. state made up entirely of islands. It is the northernmost island group in Polynesia, occupying most of an archipelago in the central Pacific Ocean, southwest of the continental United States, southeast of Japan, and northeast of...
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 they could not eat the cane beetles which stayed up on the upper stalks of the cane plants. The toad population grew dramatically and eventually out-competed native species. Not only were these toads very harmful to the Australian environment, they were also very toxic to would-be predators such as the native snakes.
- 5 cats brought to the subantarcticSubantarcticThe Subantarctic is a region in the southern hemisphere, located immediately north of the Antarctic region. This translates roughly to a latitude of between 46° – 60° south of the Equator. The subantarctic region includes many islands in the southern parts of the Indian Ocean, Atlantic Ocean and...
Marion Islands to catch mice in 1949 multiplied to 3,400 in about two decades and started to threaten local extinction of birds. They had to be infected with feline distemper virus. The rest were shot and completely eliminated by the 1990s.
- The sturdy and prolific mosquito fish was introduced from around the Gulf of Mexico to around the world in the 1930s and 40s to combat malariaMalariaMalaria is a mosquito-borne infectious disease of humans and other animals caused by eukaryotic protists of the genus Plasmodium. The disease results from the multiplication of Plasmodium parasites within red blood cells, causing symptoms that typically include fever and headache, in severe cases...
; however, it was found to cause the decline of local fish and frogs through competition of other food source as well as eating their eggs. (See Mosquitofish in AustraliaMosquitofish in AustraliaMosquitofish were introduced to Australia in 1925, spreading from the northeast coasts south to New South Wales, Southern Australia, and parts of Western Australia by 1934...
)
Living organisms, through the process of evolution, may achieve increased resistance to biological, chemical, and physical methods of control over time. In the event the target pest population is not completely exterminated or is still capable of reproduction (were the pest control means a form of sterilization), the surviving population could acquire a tolerance to the applied pressures - this can result in an evolutionary arms race
Evolutionary arms race
In evolutionary biology, an evolutionary arms race is an evolutionary struggle between competing sets of co-evolving genes that develop adaptations and counter-adaptations against each other, resembling an arms race, which are also examples of positive feedback...
with the control method.
See also
- Association of Natural Biocontrol ProducersAssociation of Natural Biocontrol ProducersThe Association of Natural Biocontrol Producers is an international not-for-profit professional association representing the biological pest management industry....
- Beneficial insectsBeneficial insectsBeneficial insects are any of a number of species of insects that perform valued services like pollination and pest control. The concept of beneficial is subjective and only arises in light of desired outcomes from a human perspective...
- Biological pesticide
- ChitosanChitosanChitosan is a linear polysaccharide composed of randomly distributed β--linked D-glucosamine and N-acetyl-D-glucosamine...
(Natural Biocontrol for Agricultural & Horticultural use) - Companion plantingCompanion plantingCompanion planting is the planting of different crops in proximity , on the theory that they assist each other in nutrient uptake, pest control, pollination, and other factors necessary to increasing crop productivity...
- Insectary plantsInsectary plantsInsectary plants is a term used to describe plants that attract insects. As such, beneficial insectary plants are intentionally introduced into an ecosystem to increase pollen resources and nectar resources required by the natural enemies of harmful or unwanted insect pests...
- Integrated Pest ManagementIntegrated Pest ManagementIntegrated pest management is an ecological approach to agricultural pest control that integrates pesticides/herbicides into a management system incorporating a range of practices for economic control of a pest...
- International Organization for Biological ControlInternational Organization for Biological ControlThe International Organization for Biological and Integrated Control of Noxious Animals and Plants is usually referred to as the International Organization for Biological Control or IOBC...
- Inundative applicationInundative applicationInundative biological control refers to the release of overwhelming numbers of a mass-produced biological control agent in the expectation of achieving a rapid reduction of a pest population without necessarily achieving continuing impact....
- Japanese beetleJapanese beetleThe beetle species Popillia japonica is commonly known as the Japanese beetle. It is about long and wide, with iridescent copper-colored elytra and green thorax and head...
(article includes information on biological control methods) - Mating disruptionMating disruptionMating disruption is a pest management technique designed to control certain insect infestations. Specifically, mating disruption involves the use of synthesized sex pheromones to disrupt the reproductive cycle of insects.- Mechanism:...
- Nematophagous fungusNematophagous fungusNematophagous fungi are carnivorous fungi specialized in trapping and digesting nematodes. Around 160 species are known. There exist both species that live inside the nematodes from the beginning and others that catch them mostly with glue traps or in rings, some of which constrict on contact. Some...
- Organic gardening
- Organic farmingOrganic farmingOrganic farming is the form of agriculture that relies on techniques such as crop rotation, green manure, compost and biological pest control to maintain soil productivity and control pests on a farm...
- Pest controlPest controlPest control refers to the regulation or management of a species defined as a pest, usually because it is perceived to be detrimental to a person's health, the ecology or the economy.-History:...
- Sterile insect techniqueSterile insect techniqueThe sterile insect technique is a method of biological control, whereby overwhelming numbers of sterile insects are released. The released insects are normally male as it is the female that causes the damage, usually by laying eggs in the crop, or, in the case of mosquitoes, taking a bloodmeal from...
- Sustainable farming
- Sustainable gardeningSustainable gardeningSustainable gardening comprises a disparate group of horticultural interests that share, to a greater or lesser extent, the aims and objectives associated with the international post-1980s sustainable development and sustainability programs...
Further reading
- Wiedenmann, R. (2000). Introduction to Biological Control. Midwest Institute for Biological Control. Illinois. Available from http://www.inhs.uiuc.edu/research/biocontrol
- Cowie R. H. (2001) "Can snails ever be effective and safe biocontrol agents?". International Journal of Pest Management 47(1): 23-40. PDF
Building organic pest-free gardens
- The Time Saving Garden by David and Charles PLC/Reader's Digest, ISBN 978-0-276-44245-2
Effects on native biodiversity
- Pereira, M.J. et al. (1998) Conservation of natural vegetation in Azores Islands. Bol. Mus. Munic. Funchal 5, 299–305
- Weeden, C.R., A. M. Shelton, and M. P. Hoffman. Biological Control: A Guide to Natural Enemies in North America. Available from http://www.nysaes.cornell.edu/ent/biocontrol/predators/rodolia_cardinalis.html (accessed December 2007)
- Cane toad: a case study. 2003. Available from http://www.biotechnologyonline.gov.au/enviro/canetoad.cfm (accessed December 2007)
- Humphrey, J. and Hyatt. 2004. CSIRO Australian Animal Health Laboratory. Biological Control of the Cane Toad Bufo marinus in Australia
- Cory, J. and Myers, J. 2000. Direct and indirect ecological effects of biological control. Trends in Ecology & Evolution. 15, 4, 137-139.
- Johnson, M. 2000. Nature and Scope of Biological Control. Biological Control of Pests
Effects on invasive species
- Cofrancesco, A. 2007. U.S. National Management Plan: An Action Plant for the Nation- Control and Management. Army Corps of Engineers. Available from http://www.invasivespeciesinfo.gov/index.shtml
Effects on the future
- Cooksey D. 2002. Biological Control in Pest Management Systems of Plants. Western Regional Committee, Riverside, CA.
Economic effects
- Griffiths, G.J.K. 2007. Efficacy and economics of shelter habitats for conservation. Biological Control: in press. doi:10.1016/j.biocontrol.2007.09.002
- Collier T. and Steenwyka, R. 2003. A critical evaluation of augmentative biological control. Economics of augmentation: 31, 245-256.
External links
- Biological Pest Control, National Invasive Species Information Center, United States National Agricultural LibraryUnited States National Agricultural LibraryThe United States National Agricultural Library is one of the world's largest agricultural research libraries, and serves as a National Library of the United States and as the library of the United States Department of Agriculture...
. Lists general information and resources for biological pest control. - Biological fight applied to the South countries - 10 minute video
- Biological Control: A Guide to Natural Enemies in North America
- Construction of a garden and implementation of natural pest control
- Educational movies about biological pest control of white flies, aphids and spider mites in greenhouses
- Association of Natural Biocontrol Producers Trade association of biological pest control industry
- Alternative Methods of Mole Cricket Control at the University of FloridaUniversity of FloridaThe University of Florida is an American public land-grant, sea-grant, and space-grant research university located on a campus in Gainesville, Florida. The university traces its historical origins to 1853, and has operated continuously on its present Gainesville campus since September 1906...
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