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Parasitoids in Biological Control: Case Studies
part of Module 2: Parasitoids and Predators
34
Agriculture
Undergraduate 4
02/01/2017

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Term
the three approaches to biological control
Definition
-Importation
-Augmentation
-Conservation
Term
importation
Definition
Importation is also called “classical biological control”. Importation involves introduction of natural enemies from a different locality, or country to a place where they do not occur naturally and this is done to control a pest that might have been accidentally introduced to a new area. This can be a long and cumbersome process. It involves searching for the origin of the pest in question, and then extensive exploration to determine if any natural enemies are present. Then those natural enemies are collected and brought into the required country, where they are placed in quarantine and undergo several rigorous testing procedures to ensure their safety to the environment, before being ultimately released.
Term
augmentation
Definition
Augmentation is, as the word suggests refers to adding more individuals of the natural enemy to supplement those already present. Augmentation can be through inoculative releases, where a few individuals are released at a critical time or season; or through inundative releases, where millions of individuals are released.
Term
conservation
Definition
Conservation deals with protecting and encouraging the existing natural enemies in an environment, through various means like providing food sources, nesting or breeding spots, and avoiding or reducing chemical interventions.
Term
in importation, the natural enemy cones from...
Definition
elsewhere
Term
in augmentation, the natural enemy cones from...
Definition
already there
Term
in conservation, the natural enemy cones from...
Definition
already there
Term
importation is conducted by...
Definition
International, Federal, State agencies (later, farmers help)
Term
augmentation is conducted by...
Definition
Farmer/Gardener
Term
conservation is conducted by...
Definition
Farmer/Gardener
Term
how sustainable importation is
Definition
high
Term
how sustainable augmentation is
Definition
low
Term
how sustainable conservation is
Definition
high
Term
specificity of the targer in importation
Definition
highly specific
Term
specificity of the targer in augmentation
Definition
specific to a group
Term
specificity of the targer in conservation
Definition
general
Term
environmental friendliness of importation
Definition
friendly
Term
environmental friendliness of augmentation
Definition
friendly
Term
environmental friendliness of conservation
Definition
friendly
Term
cost of importation
Definition
High initial, then low
Term
cost of augmentation
Definition
Subjective to crop
Term
cost of conservation
Definition
Low
Term
efficacy of importation
Definition
high
Term
efficacy of augmentation
Definition
Moderate to high
Term
efficacy of conservation
Definition
Moderate to low
Term
example of the importation approach to biological control
Definition
the encyrtid wasp Apoanagyrus lopezi was introduced from the Americas to Africa to combat Cassava mealybug, which was a severe pest on cassava IT WORKED!
Term
an example of the inundative augmentation approach to biological control
Definition
Trichogramma wasps are used worldwide on a variety of crops, and some of these include corn, sugarcane, cotton, vegetables, tree fruits, etc. In fact, they are the most widely used egg parasitoid in the world, and about 30 million hectares of land are treated annually with these little wasps.
Term
an example of the inoculative augmentation approach to biological control
Definition
the use of Encarsia, which are parasitoids of white flies
Term
four approaches used with Encarsia as an augmentative biological control agent
Definition
1: “Pest in first” – deliberately release whiteflies
2: “Dribble method” – Start introducing wasps at planting to have wasps in place when pests arrive
3: “Banker plants” – Establish wasps on other plants that already have infestations; allow wasps to move to new infestations
4: Inundative releases: Repeated releases of large numbers of parasitoids
Term
the “Pest-in-first” method in augmentative biological control
Definition
in this method, the pest or whiteflies are deliberately introduced into the greenhouse at a fixed rate. Later the parasitoid Encarsia is introduced at a standard rate, two or three times at regular intervals so that suitable host stages are available for them. This method is not widely popular because of obvious reasons – releasing pests directly onto the crop!
Term
the "dribble method" in augmentative biological control
Definition
in this method, parasitoids are introduced into the greenhouse at planting of the crop, in anticipation of the pest development. After this, low rate releases are continued, until other parasitized nymphs are found on the crop.
Term
the "banker plants" system in augmentative biological control
Definition
in this system, Banker Plants are used, which are plants from an earlier grown crop that have established infestations of whiteflies and parasitoids. These banker plants are introduced into the fresh greenhouse crop at fixed rate, so that the parasitoids can move to find new hosts.
Term
inundative releases in augmentative biological control
Definition
large numbers of parasitoids are released and this is done in certain conditions, as when the cropping season is too short for the population to develop, or the host (whitely) or the plant are not suitable. This method is most common in ornamental crops.
Term
example of the conservation approach to biological control
Definition
reducing the use of pesticides to allow Cotesia to control beet armyworm
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