Entomophagous Insects – The Insect-Consuming Insects Predators and Parasitoids.
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Transcript of Entomophagous Insects – The Insect-Consuming Insects Predators and Parasitoids.
Entomophagous Entomophagous Insects – The Insect-Insects – The Insect-Consuming InsectsConsuming Insects
Predators and ParasitoidsPredators and Parasitoids
What is “Natural Control” ?What is “Natural Control” ?
Natural Control is the everyday occurrence of predation of one insect upon another. In so
doing, populations of predators effect populations of prey and vice versa.
This is analogous to the classic relationship between the arctic hare and
fox populations.
In the Natural World Predators Are Abundant and Are Always Searching For
a Meal
A Ground Beetle Attacking a Land Snail
Ground Beetle Attacking Ground Beetle Attacking CaterpillarCaterpillar
As you can see, ground beetles are not very choosy. They will eat about anything that they can overpower.
Forest Tent Caterpillar
Yellow Jacket Wasp Collects Yellow Jacket Wasp Collects Many Insects for its NestMany Insects for its Nest
What is Biological Control?What is Biological Control?
► Biological Control is natural control that Biological Control is natural control that involves manipulation of predator populations involves manipulation of predator populations to control pest populations in agro-ecosytems.to control pest populations in agro-ecosytems.
► ““Biocontrol” has been an active area of Biocontrol” has been an active area of applied population ecology for about 50 years.applied population ecology for about 50 years.
► Today it is highly commercialized and is a Today it is highly commercialized and is a viable addition to the arsenal used to combat viable addition to the arsenal used to combat pests. pests.
► It is part of a larger approach called It is part of a larger approach called “Integrated Pest Management” or I.P.M.“Integrated Pest Management” or I.P.M.
““Beneficials”Beneficials”
►May be predators, parasitoids or May be predators, parasitoids or pathogenspathogens
►May serve singly or in combination as May serve singly or in combination as “natural enemies” but populations often “natural enemies” but populations often have to be manipulated.have to be manipulated.
► Reduce pest populations to economically Reduce pest populations to economically tolerable levels rather than eliminating tolerable levels rather than eliminating the pest.the pest.
►Environmentally compatible.Environmentally compatible.►Costs are comparable to pesticides. Costs are comparable to pesticides.
PredatorsPredators
►Commonly used predators include Commonly used predators include lady-bird beetles, green lacewings, lady-bird beetles, green lacewings, mantids and predatory mites.mantids and predatory mites.
►Commercially available from Commercially available from insectaries.insectaries.
Qualities of Good PredatorsQualities of Good Predators
► Considerably larger in size than the prey. Considerably larger in size than the prey. Why?Why?
► Feed in juvenile stage as well as in the adult.Feed in juvenile stage as well as in the adult.► Focused feeding habits - specific predators Focused feeding habits - specific predators
are better than general ones usually.are better than general ones usually.► Ability to switch to an alternative food source Ability to switch to an alternative food source
when prey populations are reduced.when prey populations are reduced.►Must be able to adapt to local environmental Must be able to adapt to local environmental
conditions.conditions.
The Mealybug Destroyer – An The Mealybug Destroyer – An Australian ImportAustralian Import
A member of the ladybird beetle family.
Other Well-Known Predators – Other Well-Known Predators – Most Available CommerciallyMost Available Commercially
►Preying MantidsPreying Mantids►Some stink bugs (Hemiptera)Some stink bugs (Hemiptera)►Minute pirate bug ( “ )Minute pirate bug ( “ )►Some nabid bugsSome nabid bugs►Some mites are predatorySome mites are predatory
Why Aren’t All Insect Predators Why Aren’t All Insect Predators Effective As Good Biological Effective As Good Biological
Control Agents? Control Agents? ►??
ParasitoidsParasitoids
►Generally a non-social wasp (braconids Generally a non-social wasp (braconids and ichneumonids are commonly used) and ichneumonids are commonly used) or a tachinid fly or a tachinid fly
►Egg(s) are laid on/into host by female Egg(s) are laid on/into host by female using a modified stinger (ovipositor)using a modified stinger (ovipositor)
►Larvae hatch and consume tissues of Larvae hatch and consume tissues of prey.prey.
►Move to surface of prey, pupate and Move to surface of prey, pupate and emerge as adultsemerge as adults
Typical Posture of Ichneumonid Wasp Female Preparing to
Oviposit
After ovipositing, the wasps deposits a pheromone on surface that deters oviposition by a 2nd. female. Why is this behavior very adaptive?
Tachinid Eggs on CaterpillarTachinid Eggs on Caterpillar
Female Fly Attaches Eggs to Exterior of Body. They Hatch and
Bore In.
Host Caterpillar Containing Half Dozen Tachinid Pupae
In this example, pupation is occurring inside the
host.
Parasitoids Attack All Parasitoids Attack All Developmental Stages of Developmental Stages of
InsectsInsects►EggEgg►LarvaLarva►PupaPupa►AdultAdult
In nature, it turns out that different species of wasps occupy
different trophic levels ...
some wasps attack caterpillar hosts while other wasps attack
the wasps that attack the caterpillars.
How are Parasitoids Different How are Parasitoids Different From Hyperparasitoids?From Hyperparasitoids?
►A parasitoid attacks a host organism.A parasitoid attacks a host organism.►What is the impact of a parasitoid What is the impact of a parasitoid
population on a host population?population on a host population?
►A hyperparasitoid attacks a parasitoid.A hyperparasitoid attacks a parasitoid.►What is the impact of a What is the impact of a
hyperparasitoid population on a host hyperparasitoid population on a host population?population?