Parasitiods (Lec 3)
The term parasitoid was coined in _______ by the German writer _________(and
adopted in English by his reviewer, ___________) to describe the strategy in
which, during its development, the parasite lives in or on the body of a single host individual,
eventually killing that host, the adult parasitoid being free-living.
About __________ of described insect species are entomophagous parasitoids
1931 ; O.M. Reuter ; William Morton Wheeler ; 10%
The largest and best-known group comprises the so called _____, within the __________ suborder
Apocrita: the largest subgroups of these are the
chalcidoid wasps (superfamily Chalcidoidea) and the
ichneumon wasps (superfamily Ichneumonoidae),
followed by the Proctotrupoidea.
Parasitica ; Hymenopteran
The flies order _______ include several
families of parasitoids, the largest of which is the
family _______ and also smaller families such as
________, ________ and others.
Diptera ; Tachnidae ; Pipunculidae ; Conopidae
The _____________ which
is a small group consisting entirely of parasitoids. They
live as internal parasites of bees, wasps, grasshoppers,
leafhoppers, and other members of the order Hemiptera.
twisted-wing parasites (order Strepsiptera),
The _______ (order _________), which includes
at least two families, Ripiphordae and Rhipiceridae, that
are largely parasitoids, and rove beetles (family
Staphylinidae) of the genus Aleochara.
bettles : Coleoptera
A beneficial insects known for their round,
colorful, and spotted appearance. Both adults
and larvae feed on pests like aphids, making
them valuable for natural pest control.
Lady beetles / ladybugs
It is a plant pest, feeding
on bean leaves and damaging crops. It can be
distinguished by its spots and color as an adult,
and its larvae are yellow and spiny
Mexican bean bettles
A pale green insects with large, clear,
veined wings. While adult lacewings mostly feed on nectar and
other fluids, some species also consume small insects. They lay
distinctive stalked eggs, from which larvae (known as "aphid
lions") hatch in 4 to 10 days.
Green lacewings
It involves using natural enemies to keep weed populations at
manageable levels rather than trying to eliminate them completely.
Biological control of weeds
The goal is to reduce weeds to a
level where they don’t cause economic harm while ensuring that some weeds remain to support the
natural enemies.
Biological control of weeds
The aims to address this by introducing natural enemies from the weed’s original
habitat to restore balance and manage these invasive species effectively.
Biological Control
It is a weeds control that involves the introduction of hostspecific natural enemies of alien weeds.
Classical approach to biological control
A biological weed control involves the periodic release of natural
enemies to enhance their populations and improve control of weeds.
Augmentation
A use spore suspensions of plant pathogens, are another method
being explored to manage weeds.
Biological herbicides
Insects have been most frequently used as _____________ of weeds and this will likely continue.
biological control agents
The reasons are that there have been major successes using __________ and almost all of the research has demonstrated the potential of other organisms, including plant pathogens, nematodes, and fish.
phytophagous insects
Weeds with other uses (e.g., Echium vulgare as a honey plant) are unsuitable because
biocontrol agents can’t be localized.
Valued weeds
Weeds closely related to crops (e.g., wild oats) are less suitable as biocontrol agents may
affect both.
Crop Relatives
Generally not targeted, but introduced weeds from their native range
can be.
Native Species
Weeds in heavily cultivated areas are less suited because biocontrol is best for dominant weeds in less managed lands.
Intensive cropland
Biocontrol is reserved for widespread weed issues, not minor ones.
Minor Problem
Not suitable if total eradication is the goal.
Eradication goals
Look for natural enemies in the weed’s native region.
Overseas survey
Ensure no existing biotic agents are already controlling the weed in the target region.
Local survey
Check if potential agents can survive and function in Canadian conditions.
Survival tests
Conduct extensive tests to ensure the agent is specific to the target weed
and won’t affect other crops or plants.
Quarantine Testing
Release the agent in infested areas, with farmer cooperation, and monitor the establishment and effectiveness of the agent.
Field Trial : Establishment
Assess if the agent is controlling the weed effectively and increasing in number.
Monitor and Evaluate : Effectiveness
Prickly Pear Cactus: __________ in Australia
Cactoblastis cactorum
They are often more host specific.
Plant pathogen
They can be applied with conventional spray equipment at a time when the weed is at
its most susceptible stage.
Plant pathogen
Biological weed control involves introducing natural enemies,
such as pathogens or insects, from a weed's native range to control it in a new environment.
Conventional approach
One notable success is the control of skeleton weed
Chondrilla juncea
A new method of weed control uses fungal spores to target specific weeds. In tests, a fungus was applied early to rice fields and successfully destroyed 99% of the weed in the Northern region.
Biological Herbicides(Mycoherbicides)
This method, called
"___________ ," is being tested for broader use.
mycoherbicides
This approach doesn't introduce new organisms but uses existing fungi to control weeds at
the most effective time. It could be combined with current weed control systems to target
hard-to-control weeds like quackgrass and yellow nutsedge.
Biological Herbicides ( Mycoherbicides)
Efforts to control water weeds are underway using insects, plant pathogens, and the white
amur fish.
Aquatic Weed Control
A control has recently received renewed interest because it is an
environmentally compatible method of weed control without residue and pollution
problems.
Biological weed control