S.I. AHMED

Biological Control of InsectsBiological control: Definition; History. Biological Control Agents: Parasitoids and

Predators. Mass production and release of commonly used Parasitoids and

Predators. Advantages and disadvantages of biological control.

Biological control of insect pests

Biological control can be defined

as the use of natural enemies to

reduce the damage caused by a

insect pest populations.

BC is a tactic/approach that fits

into an overall Insect Pest

Management System (IPMS), and

represents a potential ALTERNATIVE

STRATEGY to combat with the

insect pest damages to the

agriculture & forestry ecosystems.

Introduction

Manipulation of natural enemies under BCapproach for insect pest control can be achieved by introducing,

augmenting, or conserving naturally available bio agents or organisms

BCA is essentially required as there is an ample of scope for

further improvement through advanced research on the ecology ofinteractions between natural enemies and insect pests populations.

BC Approaches draw theory and practice together,indicating where advancement in understanding may contribute forimprovements in management

Plant protection is based, first of all, on a good deal of

knowledge on Forest and agro-ecosystems as well as

information about the

Identification of Target insect pests,

Assessment of damage caused

Preventive measures,

Interactions of plant- environment - pest and

use of the permissiable bio-control agents

The Role of BC in Plant Protection

Beginnings. BC Began in the late eighty century with introduction ofVedaliea beetle (Rodolia cardinalis) into Central America fromAustralia for control of cottony cushion scale (Icerya purchasi)on citrus.

Patterns of success. By 1986 (Greathead, 1986), 1162 successful introductions ofpredators and parasitoids undertaken in different parts of world

25% Successfully regulated target pests 69% Intermittent or partial control 6% Failed to provide any control at all

History of Biological Control

The history of BC may be divided into 3 periods

The preliminary efforts: (From 200 A.D. to 1887) when living agents were released haphazardly with no scientific approach. Little precise information exists on successes during this time.

The intermediate period: (from 1888 to 1955) BC started with the introduction of the Vedalia beetle, Rodolia cardinalis, for control of the cottony cushion scale in 1888. Period extended. Proper records maintained.

The modern period: (from 1956 to date) characterized by more careful planning and more precise evaluation of natural enemies. Period

Preliminary Period

(Early History: 200 A.D. to 1887 A.D.)

200 A.D. to 1200 A.D: BC agents were used in augmentation

Chinese were the first to use natural enemies to control

insect pests. Nests of an ant sp, Oecophylla smaragdina

were sold near Canton in the 3rd century for use in control

of citrus insect pests such as Tesseratoma papillosa

(Lepidoptera)

Ants were used in 1200 A.D. for control of date palm

pests in Yemen (south of Saudia Arabia). Nests were

moved from surrounding hills and placed in trees

HISTORY OF BC

1300 A.D. to 1799 A.D.: BC was just beginning to be

recognized.

The first insect pathogen was recognized by De Reaumur in 1726. It was

a Cordyceps fungus on a noctuid

In 1734, De Reaumur suggested to collect the eggs of an "aphidivorous

fly" (actually a lacewing) and place them in greenhouses to control

aphids

The mynah bird, Acridotheres tristis, was successfully introduced from

India to Mauritius (off coast of Madagascar) for control of the red

locust, Nomadacris septemfasciata, in 1762

In the late 1700's, birds were transported internationally for insect ``

control

Control of the bedbug, Cimex lectularius, was successfully accomplished

by releases of the predatory Pentatomid picromerus in 1776 in Europe

1800 A.D. to 1849 A.D. During this period advances

were made in applied and basic approaches of BC

In the 1800’s, Darwin discussed "Ichneumonids" as natural `

control factors for cabbage caterpillars

Hartig (Germany) suggested the rearing of parasites from

parasitized caterpillars for mass releases in 1827

Kollar (Austria) put forth the concept of "natural control" in 1837

Verhulst (1838) described the logistic growth equation but the idea

remained dormant until 1920 when rediscovered by Pearl.

Expressed idea of "environmental resistance".

During the 1840's releases of predators were used for control of

the gypsy moth and garden pests in Italy

1850 to 1887. During this time the focus on BC was more

emphasised through host specific natural enimies

1st successful movement of parasites for biological control when

parasites were moved from Kirkwood, Missouri, to other parts of

the US for control of the weevil, Conotrachelus nenuphar in 1870

Second successful movement In 1873 Riley sent the predatory mite,

Tyroglyphus phylloxerae to France to control the grape mite.

Third successful movement Trichogramma sp. (egg parasites) were

shipped from the U.S. to Canada for control of lepidopterous pests in

1882

Forth successful movement In 1883 the USDA imported Apanteles

glomeratus from England for control of cabbage worm.

The Intermediate Period

(1888 to 1955)

1888 to 1889: The Cottony Cushion Scale Project

Cottony cushion scale, Icerya purchasi Maskell, was introduced into

California in CA. 1868 around the Menlo Park (CA) area (near San

Francisco) controlled by using Vedaliea beetle (Rodolia

cardinalis)

C. V. Riley (Chief of the Division of Entomology, USDA) employed

Albert Koebele and D. W. Coquillett in research on control of the

cottony cushion scale

He sent 12,000 individuals of Cryptochaetum iceryae and 129

individuals of Rodolia cardinalis (the vedalia beetle)

The vedalia beetle controls the scale mainly in the inland desert

areas and C. iceryae controls it in the coastal areas of California.

1900 to 1930: New faces and more BC projects

The Lantana Weed Project in Hawaii (1902) First published work on

BC of weeds.

The Sugar-cane Leafhopper Project in Hawaii (1904-1920). Awaiian

Sugar Planters Association (HSPA) created a Division of Entomology

in 1904.

Berliner described Bacillus thuringiensis in 1911 as causative agent

of bacterial disease for control of Mediterranean flour moth

USDA laboratory for biological control established in France in

1919.

1930 to 1955: Expansion of BC projects

From 1930 to 1940 there was a peak in BC activity in the world with

57 different natural enemies established at various places.

In 1947 the Commonwealth Bureau of Biological Control (CBB)

was established from the Imperial Parasite Service.

In 1951 the name was changed to the Commonwealth Institute for

Biological Control (CIBC). Headquarters are currently in

Trinidad, West Indies.

In 1955, the Commission Internationale de Lutte Biologique

contre les Enemis des Cultures(CILB) was established. This is

a worldwide organization with headquarters in Zurich, Switzerland.

International Organization for Biological Control (IOBC) initiated

the publication of the journal “Entomophaga” in 1956, a journal

devoted to biological control of arthropod pests and weed

species.

The Modern Period: 1957 to Present.

In 1959, Vern Stern et al. (1959) conceived the idea of economic

injury level and economic threshold which enable the growers to

take decisions and apply control tactics.

During the 1970’s and 1980’s, Brian Croft and Marjorie Hoy made

impacts by using pesticide resistant natural enemies in cropping

systems.

In 1983, Frank Howarth published his landmark paper entitled

“Biological Control”

From 1990 to date, two additional biological control journals

appeared, “Biological Control- Theory and Application in Pest

Management” (Academic Press) and “Biocontrol Science and

Technology” (Carfax Publishing). additionally “Entomophaga”

changed its name to “Biocontrol”.

In India, many more Scientific Research Organisations initiated

specific work on Biological Control of injurious insect pests

3- Approaches to achieve potential

BC

Three ways to enhance effectiveness of natural enemies in

insect pest management

Classical biological control

Augmentive biological control

Conservation of indigenous natural enemies

Classical Biological Control

Importation biological control means to introduce a new exoticnatural enemy from one environment to a new ecosystem.

Control by introducing and establishing effective naturalenemies from pest’s area of origin called classical in view of firstuse in 1800s

Some biological control practitioners consider this as "true"biological control approach.

Exotic pest invades region without their adapted naturalenemy complex, and, in absence of effective natural enemies,reach very high population levels

Systematic steps to be taken in a Classical Biocontrol Programme

1. Evaluate the pest problem in the target region for the biocontrol program. Establish taxonomic identity of pest and area of origin.

2. Foreign exploration for the pest in the area of origin. Surveys to assess the complex of natural enemies of the pest, their impact and degree of specialization

3. Selection of enemies from this complex for importation and establishment in the target region.

4. Quarantine for removing hyperparasitoids, plant pathogens and insect pathogens from culture

5. Release natural enemies cleared from quarantine in the target region.

6. Regular monitoring should be done after establishment of the natural enemy and pest population

Augmentative Biological Control

Augmentation biological control basically

means adding natural enemies, either

where they are not present, or are present

but in small numbers.

Augmentation has been used more

extensively in agro or forest

ecosystem, but there are examples of

successful use in nearly all settings.

Two ways of Augmentation:

Inoculation: Begins with a small number and allows the

natural enemy populations to increase over

time. In this case, the pest population does

not decrease quickly

Inundation: Introduction of a large number of natural

enemies, with the intention of reducing the

pest population quickly.

Conservation basically means keeping alive andenhancing the effectiveness of those naturalenemies that are already present in the ecosystem.

Reduction of pesticides use is one of the mostimportant tools in conservation approach.

Use of "soft" pesticides such as those based onnatural products.

Integration of other control measures like plant origininsecticides.

Conservation of indigenous natural enemies

BIOLOGICAL CONTROL AGENTS

Parasitoids,Parasites, Predators

Entomo- Pathogens , Comptitors & Natural Products

Parasitoids:An organism that, during its development, lives in or on the body of

a single host individual, eventually killing that individual.

Major characteristics:

They are specialized in their choice of host , smaller than host, Only the female searches for host. Immatures remain on or in host; adults are free-living, mobile, and may be predaceous. Immatures almost always kill host.

Four of the most important groups are:

Ichneumonid waspsBraconid waspsChalcid wasps:Tachenid flies:

Ichneumonid wasps

Braconid wasps

Chalcid wasps:

Tachenid fiY

ParasitoidsParasitoids are holometabolous, having complete

development (egg, larval, pupal and adult stages).

Adult Parasitoids are free living; some species feed on hosts

(predators), in addition to ovipositing in or on the hosts.

Only females parasitoids are significant players, as they are

the ones that find and attack hosts.

The number of species of Parasitoids is unknown and

speculative, ranging from an estimate of 8,00,000 to as many

as 25% of all insects.

Parasite

Parasite is an organism which lives in or on another organism

(its host) and benefits by deriving nutrients at the other's

expense.

The greatest diversity of parasites is found in Hymenoptera.

Ichneumonid wasps, Braconid wasps, Chalcid wasps, Tachenid

flies, Dryinidae, Bethylidae, Chrysididae and wasps

Several Diptera families have members that are parasitic:

Acroceridae, Bombylidae, Cecidomyiidae, Cryptochetidae,

Phoridae, Pipincluidae, Tachinidae, and Sarcophagidae.

Rare representative taxa are also found in the Coleoptera,

Lepidoptera and Neuroptera.

Hymenoptera parasitic families

Source: Copping, (2004), The Manual of Biocontrol Agents

Braconidae, 7/

13%Dryinidae, 1/

2%

Encyrtidae, 1/

17%

Ichneumo-

nidae, 1/

2%

Eupelmidae, 1/

2%

Mymaridae, 1/

9%

Bethylidae, 1/

2%

Aphidiinae, 1/

2%

Aphidiidae, 4/

8%

Aphelinidae, 10/

18%

Tachinidae, 1/

2%Trichogra-

mmatidae, 6/

11%

Pteromalidae, 1/

2%Platyga-seridae,

1/

2%

Eulophidae, 1/

8%

Place of oviposition:

Ectoparasite (External Parasite): Parasite develops

externally on the host with its mouthparts inserted into the

host's body.

Endoparasite (Internal Parasite): Parasite larva develops

inside the host's body.

Ecto/Endo-Parasite:

A hyperparasite is a parasite whose host is also a parasite. Thisform of parasitism is especially common amongentomophagous parasites

Hyperparasite:

Types of Parasites

Based on their mode of parasitism, parasites are

usually studied as to:

what type of feeding habit, a parasite contains in its

immature stage (egg, larval, pupal parasite, etc.).

Whether one or more parasites progeny emerge from

the host (solitary vs. gregarious).

The feeding habit of the immature stages of inset parasites:

Egg parasite: Adult parasite attacks the host egg, and the parasite

progeny emerge from the egg only.

Egg-larval parasite: Adult parasites attacks the host egg, but the

parasite progeny emerge from the larva.

Larval parasite: Adult parasites attacks the host larva, and the

parasite progeny emerge from the larva.

Larval-pupal parasite: Adult parasites attacks the host larva, but

the parasite progeny emerge from the pupa.

Pupal parasite: Adult parasites attacks the host pupa, and the

parasite progeny emerge from the pupa.

Number of parasites’ progenies:

Gregarious parasite: Multiple parasite eggs are deposited,

the larvae feed together on a single host, and multiple parasite

offspring emerge.

Solitary parasite: Only one parasite egg is deposited per

oviposition event and generally only one progeny emerges from the

host.

Polyembryonic parasite: Many (up to several thousand)

parasites emerge from a host, having arisen from asexual

division of one or two parasite eggs. Restricted to four families of

parasitic Hymenoptera (Braconidae, Dryinidae, Encyrtidae,

Platygastridae).

Number of parasites’ progenies :

Multi-parasitism: A single host is attacked by more than one

species of parasites, and the second parasite species feeds on the

original host, not the other parasite species.

Super-parasitism: Several females of one species of parasite

attack the same host, or one female oviposits more than one egg, with

only one egg laid at a time. In this case, often, only one progeny will

survive. This is not the same as gregarious parasitism, where a single

female lays many eggs in one oviposition bout (session or stretch).

Host-parasite interactions:Primary parasite: The parasite attacks and develops in or on a host, andthat host is not a other parasite.

Cleptoparasite: A parasite that requires a host to be parasitized already.

Facultative hyper-parasite: Can develop either as a hyperparasite in ahost already parasitized by a primary parasite, or it can develop as a primaryparasite in an un-parasitized host.

Heteronomous parasite: (Autoparasite and Adelphoparasite): Femalesdevelop as primary parasites of homopterans (whiteflies, scales), but malesdevelop as a hyperparasite of female primary parasites of homopterans.

Heterotrophic parasite: The female is a primary parasite ofhomopterans, but the male is an obligate parasite of a completely differenthost, such as eggs of Lepidoptera.

Host-parasite interactions:

Idiobiont parasite: Parasite prevents continued growth by the host.

Hosts are often paralysed. Often egg, pupal, and adult parasites.

Koinobiont parasite: Parasite allows continued growth and

development of the host. Host not paralysed. Egg-larval, larval-pupal

parasites, and larval parasites. The parasite larva either suspends

development as a first instar, or the parasite larva avoids feeding on vital

organs until late in development.

Obligate hyperparasite: The hyperparasite can only develop as a

parasite of a primary parasite.

Secondary parasite (Hyperparasite): The parasite attacks a

host that is another parasite.

Predators:

Predation can be defined as a trophic level (consisting of organisms

sharing the same function in the food chain) interaction in which one

species derives energy from the consumption of individuals of another

species.

A predator is considered an entomophagous species that generally

consumes more than one prey individual to complete its

development.

Some parasitoids hosts feed as adults which could be considered a

type of predation.

Over 16 orders of insects contain predaceous members, in

approximately 200 families. Including spiders and mites, there are

probably in excess of 2,00,000 species of arthropod predators.

Predators groups

Source: Copping, (2004), The Manual of Biocontrol Agents

Heteroptera,

2/ 

4%

Coleoptera,

17/ 

32%

Acari, 10/

19%

Thysano-

ptera, 2/ 

4%

Orthoptera, 1/

2%

Neuroptera,

2/ 

4%

Diptera, 3/

6%

Gastropoda,

1/

2%

Hemiptera, 9/ 

17%

Meso-

stigmata,5/ 

10%

Predators’ characteristics

kill and consume more than one prey organism to reach maturity

Relatively large size compared to prey

Predaceous as both larvae and adults

Larvae are active with sensory and locomotory organs

Except for predatory wasps that store prey for immature stages, preyare generally consumed immediately.

Frequency of individual prey items in the diet may be influenced by:

Prey environmentPrey preferencesCompetition with other predatorsSuitability of prey.

Generally speaking the most common features of insect predators are:

Types of Entomophagous Predators

Monophagy: A highly specialized prey range, the predator

may feed on one or a very limited number of species within thesame genera.

Oligophagy: A semi-restricted prey range of a predator. For

example, aphidophagous predators feed primarily on aphids preys,or, genera of coccinellids feed primarily on whiteflies or scales.

Polyphagy: A broad prey range, may include plant materials

(fluids, nectars, pollen), insects and fungi, a generalist predator.

Advantages & Disadvantages Biological Control

Advantages Low cost

Has the potential to be permanent

Not harmful to non-target organisms

No toxicity or residue problems

The pest is unable (or very slow) to develop a resistance.

Selectivity, it does not intensify or create new pest problems.

Disadvantages

Not always applicable

Level of control may not be sufficient

Research costs are high and sometime may not produce results

It requires expert supervision.

It is difficult and expensive to develop and supply

Mass production and release of

commonly used Parasitoids and

Predators

Natural Suppliers and producers of

Bio-control agents

Parasitoids and predators are living organisms which can intervene

the life cycle of insect pests in such a way that the crop damage is

minimized

In nature every ecosystem exists in a balance. Growth and

multiplication of each organism depends on the food-chain, its

predetors, parasites, parasitoids, competitors etc.

In biological control system, these interrelations are exploited. The

natural enemy of a pest, disease or weed is selected,

Among the alternatives, biological control of pests is one of the

important means for checking pest problems in almost all agro-

ecological situations.

Mass Rearing of Bio-Control Agents

an essential tool in the pest management to bring about changes from

Natural to A Specific

Biological Control Hence,

Information on

Importance, Biology, Rearing Technique,

Equipments and Facilitates

required for mass multiplication of biocontrol agents are most important.

Scope for Commercial Production of

Bio-control Agents

About 140 bio-control agents production units existed in India

as on today

They are able to meet the demand of only less than 1% of

cropped area.

There exists a wide gap, which can only be bridged by setting

up of more and more units for production of bio-control agents.

Production and marketing of Trichoderma viride (against few

fungal diseases) and Trichogramma (against sugarcane early

shoot borer) has been started in India.

Enhancement of production and use of biological control agents

is on the increase every year in India

Mass-Production of Parasites and Predators

is useful to increase parasitism or predation by mass releases of

entomophages

over a wide area at a time in the season when these natural enemies are

few or absent.

When natural host plants or target host insects are unavailable

suitable alternate hosts, or artificial diets are to be utilised for

Mass-production of parasites and predators

Parasitoids & Predators are preferred over chemical pesticides for the following

reasons

No harmful residues

Target specific and safe to beneficial organisms like pollinators,

predetors, parasites etc

Growth of natural enemies of pests is not affected, thus reducing

the pesticide application

Environmental friendly

Cost effective

Important component of IPM as 1st line and 2nd line of defence

chemicals being the last resort

Major Advantages of Mass Production &

Release of bio-control agents

Growth of lantana weed was controlled by using the

bug Telonemia scrupulosa

Sugarcane pyrilla has been successfully controlled in a number of

States by the introduction of its natural enemy Epiricania

melanoleuca and Tetrastictus pyrillae.

Trichogramma, an egg parasitoid, has been used against the

borers in the states of Tamil Nadu, Rajasthan, UP, Bihar and

Haryana against many injurious insect pests

Similarly Trichogramma, Bracon, Chelonus and Chrysopa spp.

are being used for the control of cotton bollworms.

Trichogramma has also been used against rice stem borer and

leaf folder.

The sugarcane scale insect has been controlled with the help of

predatory coccinellid beetles in UP, West Bengal, Gujarat and

Karnataka.

Examples of successful utilisation of bio

control agents in India

INSECT PREDATORS IN AUGMENTATIVE

BIOLOGICAL CONTROL

Insects Order and Family Name Prey Insect

Coleoptera

i) Coccinellidae (Lady bird beetle)

Coccinella septumpunctata

C. rependa

Crytolaemus montrouzieri

Scymnus coccivora

Rodolia cardinalis Tapioca scales

Menochilus sexmaculata

Chilocorus nigritus

Aphids

Aphids

Grape vine mealy bug

Mealy bugs and scales

Cottony cushion scale

Grape vine mealy bug

Neuroptera

Chrysopidae (Lace wing fly)

Chrysoperla carnea

All soft bodied insects

Several species of insect predators are economically important

biological control agents

Most are polyphagous, feeding on a wide array of arthropod prey;

many species can also exploit plant resources (omnivory)

Examples of some most important predators used in augmentative

biological control include:

Major types of bio-agents available for

commercial production in India

Parasitoids Predators Insect Pathogens Trichogramma chilonis,

T.brasiliensis and

T.pretiosum (egg parasites)

- for tomato fruit borer

Trichogramma chilonis –

for brinjal shoot and fruit

borer, shoot borers of

cotton, sugarcane, rice etc.

Cryptolaemus montrouzieri

(Austrtralian ladybird beetle)

for control of several

species of mealy bugs and

soft scales

Chrysopa spp. (green

lacewing bug) - for the

control of aphids, white

flies etc.

Virus: Nuclear

Polyhedrosis Virus (NPV) -

for major polyphagous pest

like Helicoverpa armigera

(gram pod borer) and

Spodoptera litura (Tobacco

caterpillar)

Bacteria: Bacillus

thuringiences (B.t) - for

control of lepidopterous pests

Fungi: Trichoderma viride

and Trichoderma harziarum

against soil borne fungal

diseases

Namatodes : for control of

soil-borne grubs,

lepidopterans and some

foliar pests

PREDATORY INSECTS IN AUGMENTATIVE

BIOLOGICAL CONTROL

Orius laevigatus Arma chinensis

Zelus sp.

Coccinella septempunctata

Coccinella repanda Crytolaemus montrouzieri

Ideal Locations of Bio-control Units

Care be taken to set up biocontrol production units s in areas

which have appropriate climatic conditions. (where there is no

extreme conditions)

The proximity of the location of biocontrol production units

and consumer market (farming areas) is amongst the most

important aspects.

Care be taken to prevent the contamination in production

facilities to be caused by insecticides from the farming areas.

Air pollution can damage biocontrol agents, the production

should be located away from industrial and urban areas

REARING OF PARASITOIDS & PREDATORS

FOR BIOLOGICAL CONTROL

The main challenge for augmentative biological control is a wide availability of cheap and effective natural enemies for the growerscost-effective and reliable mass production of high-quality natural enemies is essential

Insect predators can be reared in mass scale keeping the following aspects in view:

Foods: natural, factitious, artificial

Plant materials and alternatives

Rearing techniques and colony maintenance

Quality assurance

REARING SYSTEMS FOR BIOCONTROL

AGENTS, BASED ON THEIR FOOD TYPES

Natural rearing systems: use the natural or target prey for production of the parasitoids and predators, usually on a host plant

Systems using factitious prey: organism that is unlikely to be

attacked by a natural enemy in its natural habitat, but that

supports its development and/or reproduction; usually a species

that is easier and less expensive to rear; with or without plant

materials

Artificial rearings systems: use inanimate (lifeless) artificial foods and preferably no plant materials

REARING OF PREDATORY BUGS FOR

BIOLOGICAL CONTROL

The main challenge for augmentative biological control is a wide availability of cheap and effective natural enemies for the growerscost-effective and reliable mass production of high-quality natural enemies is essential

The present paper will review developments in the rearing of predatory bugs as related to:

Foods: natural, factitious, artificial

Plant materials and alternatives

Rearing techniques and colony maintenance???

Quality assurance

FACTITIOUS, UNNATURAL OR ALTERNATIVE

FOODS

The use of factitious foods may allow some rationalization

or automation of production or release

Factitious host or prey: organism that is unlikely to be

attacked by a natural enemy in its natural habitat, but that

supports its development and/or reproduction

Usually a species that is easier and less expensive to rear

Examples:

Storage mites for predatory mites (Phytoseiidae, Laelapidae)

Eggs of lepidopterans for insect predators

Brine shrimp cysts for predatory insects and mites

Trichogramma egg parasiteTrichogramma spp. belongs to the category of egg parasitoid of biological

agents. Trichogramma spp., the most widely used bio-control agent in the

world and is effective against bollworms of cotton, stem borers of

sugarcane, fruit borers of fruits and vegetables.

It offers a lower cost but more effective plant protection option in

comparison to insecticides. Two species i.e., T. chilonis and T. japonicum

are predominantly used in India.

Trichogramma are dark coloured tiny wasps and the female wasp lays

20-40 eggs into the host's eggs.

The entire cycle is completed within 8-12 days. The tiny adult wasps

search for the host (pest) eggs in the field and lay their eggs into the

eggs of the pests.

NATURAL REARING SYSTEMS

In natural rearing systems the beneficial is reared on its target prey or hosts, which itself is maintained on its host plant (or on plant parts) "tritrophic" system

These systems can be economically viable: Encarsia formosa, Phytoseiulus persimilis

Possible drawbacks are:

• tritrophic rearing systems are expansive due to space and labour needed for plant production

• there may be discontinuity problems at one or more of the trophic levels to be maintained (e.g. diseases or other pests attacking host plants)

• plant materials should be free of pesticide residues

• there are risks of contamination associated with the release of beneficials reared on natural substrates

Tritrophic interactions as they relate to plant defense against herbivory describe the ecological

impacts of three trophic levels on each other: the plant, the herbivore, and its natural enemies,

predators of the herbivore.

FACTITIOUS, UNNATURAL OR ALTERNATIVE

FOODS

The use of factitious foods may allow some rationalization

or automation of production or release

Factitious host or prey: organism that is unlikely to be

attacked by a natural enemy in its natural habitat, but that

supports its development and/or reproduction

Usually a species that is easier and less expensive to rear

Examples:

Storage mites for predatory mites (Phytoseiidae, Laelapidae)

Eggs of lepidopterans for insect predators

Brine shrimp cysts for predatory insects and mites

Eggs of lepidopterans as factitious food (artificially

created or developed) for insect predators

Eggs of several easily reared lepidopteran species can be used as a factitious food (artificially created or developed) for insect predators and Trichogramma egg parasitoids such as Corcyra cephalonica, Sitotroga sp etc

Eggs are frozen or (UV, gamma) irradiated for use

Eggs of Corcyra cephalonica are a nutritionally adequate food for > 10 spp. of predators and several Trichogramma spp.

Production poses possible health hazards for workers (allergy to scales)

72% water; dry matter: 46% protein, 34% fat (>50% is 18:1), 8.5% carbohydrates

ARTIFICIAL DIETS

The availability of an artificial diet may offer further possibilities to automate the rearing process

Types of diets:

Diets with and without insect components (e.g., whole insect bodies, hemolymph...)

Oligidic, meridic and holidic diets:

- Holidic: chemically defined diets (amino acids, fatty acids, sugars, vitamins, minerals...)

- Meridic: holidic base with one or more unrefined or chemically unknown substances (e.g., yeast, liver extract...)

- Oligidic: containing only crude organic materials (e.g., meat diets)

Digestive enzymes

of the predator

ARTIFICIAL DIET

HOLISTIC METHOD FOR DEVELOPING AN ARTIFICIAL DIET

Biochemical analyses

of preferred food

(amino acids, fatty acids,

sugars, …)

Biochemical composition

of the artificial diet

(amino acids, fatty acids,

sugars,…)

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Growth factors

(vitamins, minerals,

proteins…)

Water content

Computing

Mix of fats and oils

Mix of proteins

Physical properties

(gelling or filling agents,

encapsulation…)

Preservation

Biochemical analyses of

natural enemyfed on artificial diet

The right components, in the right proportions and taking account of

possible interactions among the components