Biological Control of Insects

S.I. AHMED
Biological Control of Insects
Biological 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 BC
approach 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 of
interactions between natural enemies and insect pests populations.
 BC Approaches draw theory and practice together,
indicating where advancement in understanding may contribute for
improvements 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 of
Vedaliea beetle (Rodolia cardinalis) into Central America from
Australia for control of cottony cushion scale (Icerya purchasi)
on citrus.
 Patterns of success.
By 1986 (Greathead, 1986), 1162 successful introductions of
predators 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 exotic
natural enemy from one environment to a new ecosystem.
Control by introducing and establishing effective natural
enemies from pest’s area of origin called classical in view of first
use in 1800s
Some biological control practitioners consider this as "true"
biological control approach.
Exotic pest invades region without their adapted natural
enemy 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 and
enhancing the effectiveness of those natural
enemies that are already present in the ecosystem.
Reduction of pesticides use is one of the most
important tools in conservation approach.
Use of "soft" pesticides such as those based on
natural products.
Integration of other control measures like plant origin
insecticides.
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 wasps
Braconid wasps
Chalcid wasps:
Tachenid flies:
Ichneumonid wasps
Braconid wasps
Chalcid wasps:
Tachenid fiY

Parasitoids
Parasitoids 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. This
form of parasitism is especially common among
entomophagous 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, and
that 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 a
host already parasitized by a primary parasite, or it can develop as a primary
parasite in an un-parasitized host.
Heteronomous parasite: (Autoparasite and Adelphoparasite): Females
develop as primary parasites of homopterans (whiteflies, scales), but males
develop as a hyperparasite of female primary parasites of homopterans.
Heterotrophic parasite: The female is a primary parasite of
homopterans, but the male is an obligate parasite of a completely different
host, 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
,
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, prey
are generally consumed immediately.
Frequency of individual prey items in the diet may be influenced by:
Prey environment
Prey preferences
Competition with other predators
Suitability 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 the
same 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 parasite
Trichogramma 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.

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,…)
Copy Copy
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 enemy
fed on artificial diet
The right components, in the right proportions and taking account of
possible interactions among the components

Biological Control of Insects

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Biological Control of Insects