mODULE 2: Beneficial-Arthropods-Biocon-Agents.pdf

the importance of using natural organisms such as predators, parasitoids, entomopathogens, and antagonist pathogens in managing agricultural pests.

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BENEFICIAL ARTHROPODS and BIOLOGICAL AGENTS
TOPIC 1.
PREDATORS
Beneficial arthropods that chases prey for food

2. TOPIC 1. PREDATORS
Insect predators
Consume multiple prey for developmenttosurvive.
They are free-living, and generally larger than their
food, killing their prey immediately.
Key characteristics include;
a. active hunting or ambush tactics,
b. a diverse diet (generalist) or a specialized diet
(specialist), and
c.hasthe ability toattack both immature and
adult prey.

3. TOPIC 1. PREDATORS
1.Core component of biological pest management
2.Insect predators help suppress pest populations
and prevent them from reaching damaging levels.
3.They contribute to a more balanced and resilient
agricultural ecosystem by reducing the need for
chemical interventions, which often harm
beneficial insects along with pests.
4.This creates a more stable, self-regulating
environment
Role of Predators in Agriculture

4. TOPIC 1. PREDATORS
Predatory Behavior
1.Ambush Predators:
hide and wait for prey to come within reach before capturing
them. (e.g., mantids and flower flies)
2. Active Hunters:
actively search for and chase their prey.
e.g., lady beetles and dragonflies
3. Specialized Killing Methods:
Devouring: Chewing and consuming prey whole,
e.g.lady beetles andsome ground beetles.
Piercing and Sucking: Using sharp mouthparts to inject fluids and
extract the body contents from prey,
e.g.assassinbugs.

5. 1.Pesticide incompatibility.
pesticides are highly toxic to beneficial insects2. Prey-density dependence:
Predator populations fluctuate with the availability of prey.
3.Environmental conditions:
Predators are highly sensitive to temperature and humidity.
TOPIC 1. PREDATORS
Challenges and Considerations

6. 4. Generalist predators:
Some predators, particularly when pest populations are
low, may also feed on other beneficial insects
5. Habitat requirements:
Some predators require alternative food sources.6. Cost:
releasing mass-reared predators can be significant.
TOPIC 1. PREDATORS
Challenges and Considerations

7. Examples of insect predators

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BENEFICIAL ARTHROPODS and BIOLOGICAL AGENTS
TOPIC 2.
PARASITOIDS
organism that spends its larval stage in or on
another organism, also known as a host.
“Parasitism”

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BENEFICIAL ARTHROPODS and BIOLOGICAL AGENTS
ParasitoidPredatorCharacteristic
Larvae develop in or on a single host, feeding on it and
ultimately killing it. Adult parasitoids are free-living and
feed on nectar or pollen, not the host.
Kills and consumes many different individuals (prey) to
survive. Both adults and young typically consume prey
directly.
Diet and life cycle
Typicallysmaller than their host.Often larger than their prey, though social predators
like ants or cooperative mammals can attack much
larger animals.
Size
The host may remain alive and mobile for some time
while the larva develops inside it. Death occurs later
when the parasitoid is ready to emerge.
Kills prey relatively quickly, either during the capture or
immediately after.
Speed of killing
Highly specific and often target only one or a few closely
related host species.
Often generalists that feed on a wide range of prey
species, though some are highly specialized.
Specificity
Parasitoid wasps and flies, which lay their eggs in insects
like aphids or caterpillars.
Lions, wolves, sharks, and praying mantises.
Carnivorous plants like the Venus flytrap are also
predators.
Examples
The relationship is a specialized form of parasitism
where the host is always killed, unlike a traditional
parasite which does not kill its host.
The interaction is a simple hunter-prey relationship.Relationship to the
host

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BENEFICIAL ARTHROPODS and BIOLOGICAL AGENTS
Life cycle and host strategies
1.Host selection:
An adult female uses a tube-like organ called an ovipositor to deposit
her eggs in, on, or near the host
2. Feeding strategies:
Ectoparasitoids:
Develop on the outside of the host's body.
They often inject venom to permanently paralyze the host
before laying an egg on it.
Endoparasitoids:
Develop inside the host's body, typically feeding on non-
essential tissues first to keep the host alive longer.

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BENEFICIAL ARTHROPODS and BIOLOGICAL AGENTS
Life cycle and host strategies
3.Host development:
Idiobiontparasitoids:Prevent further development of the host
after they lay their eggs.
Koinobiont parasitoids:Allow the host to continue growing,
providing a larger food source for the developing larvae.
4. Offspring per host:
Solitary:Only a single parasitoid can develop in each host.
Gregarious:Multiple larvae develop within the same host.
5. Mummification:parasitoid causes the host's body to swell and harden,
creating a protective "mummy" for the parasitoid's pupation.

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BENEFICIAL ARTHROPODS and BIOLOGICAL AGENTS
Role of Parasitoids inAgriculture
parasitoids are valuable natural enemies of pest insects and are widely used
in agriculture and integrated pest management (IPM).
1.Pest suppression: The efficiency and host-specificity of parasitoids make
them a powerful tool for suppressing pest populations below economically
damaging levels.
2. Methods of release:
•inundative-released in large numbers to immediately overwhelm a pest
population
•classical introduced to establish a long-term presence for ongoing control
3.Protecting parasitoids: limit pesticide use and plant a variety of nectar-
producing flowers

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BENEFICIAL ARTHROPODS and BIOLOGICAL AGENTS
Examples of Insect Parasitoids

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BENEFICIAL ARTHROPODS and BIOLOGICAL AGENTS
Examples of Insect Parasitoids

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BENEFICIAL ARTHROPODS and BIOLOGICAL AGENTS
TOPIC 3.
ENTOMOPATHOGENS
“natural insect destroyers"

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BENEFICIAL ARTHROPODS and BIOLOGICAL AGENTS
a microorganism, such as a fungus, bacterium, virus, or
nematode, that can infect and kill or incapacitate insects
an eco-friendly and targeted alternative to synthetic chemical
insecticides.
Types of entomopathogens
a. Fungi:
Entomopathogenic fungi are among the most common
and widespread typesof insect pathogens.
They infect insects by direct contact, as fungal spores stick
to the cuticle, germinate, and penetrate the insect's body.
ENTOMOPATHOGENS

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BENEFICIAL ARTHROPODS and BIOLOGICAL AGENTS
b. Bacteria:
Several species of bacteria are used in pest control.
They typically work by producing toxins that are lethal to
insects after the
bacteria or their spores are ingested.
c.Viruses:
Insect-specific viruses, particularly baculoviruses, are
highly host-specific .Cause lethal infections.
d.Nematodes:
These are soft-bodied, non-segmented roundworms that
act as parasites.
The nematodes carry symbiotic bacteria in their gut, which
they release inside the insect host.
ENTOMOPATHOGENS

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BENEFICIAL ARTHROPODS and BIOLOGICAL AGENTS
•ENTOMOPATHOGENS-
Fungi
Metarhizium anisopliae
•the mighty fungus
•green muscardine

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BENEFICIAL ARTHROPODS and BIOLOGICAL AGENTS
•ENTOMOPATHOGENS- Bacteria

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•ENTOMOPATHOGENS- Virus

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•ENTOMOPATHOGENS- Nematode

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BENEFICIAL ARTHROPODS and BIOLOGICAL AGENTS

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BENEFICIAL ARTHROPODS and BIOLOGICAL AGENTS
TOPIC 4
ANTAGONIST PATHOGEN
“microbial antagonism
”

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BENEFICIAL ARTHROPODS and BIOLOGICAL AGENTS
ANTAGONISTPATHOGEN
a microorganism
that inhibits or
suppresses the
growth and
activity of
another

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BENEFICIAL ARTHROPODS and BIOLOGICAL AGENTS
ANTAGONIST PATHOGEN

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ANTAGONIST PATHOGEN–MODE of ACTION

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BENEFICIAL ARTHROPODS and BIOLOGICAL AGENTS
ANTAGONIST PATHOGEN-Direct Mechanism

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BENEFICIAL ARTHROPODS and BIOLOGICAL AGENTS
ANTAGONIST PATHOGEN-Indirect Mechanism