Chp. 5 Management Methods for IPM > BIOLOGICAL CONTROL AGENTS > Flashcards

Flashcards in BIOLOGICAL CONTROL AGENTS Deck (11):

Biological control
(natural enemies, antagonists).

Natural Enemies Handbook: The Illustrated Guide to Biological Pest Control.

In IPM, are primarily used against, mites, insects, and weeds in uncultivated areas.
Limited to a few isolated plant pathogens and nematodes.

I.) Predators
II.)Parasites (Tue Prarsites/Parasitoids/Insect Parasites)
III.) Antagonists


I.) Predators

Is an animal that attacks, feeds on, and kills more than one prey during its lifetime. They are usually larger and stronger than prey and can be quite specialized or generalists. Sometimes predation is only existent during the larval or adult stage-sometimes during both.

The most recognized predators in biological control are predatory arthropods, such as the lady beetle.


II.) Parasite
*.)True Parasite
**.)Parasitoids (Insect Parasitoids, Insect Parasites)

Feed in or on a larger host organism, and usually have a prolonged/specialized relationship with the host; parasitizing only on one individual or a few hosts during the lifetime.
*.) Often weaken the host but do not kill it outright-and in some cases may have little negative impact.

Only those that significantly weaken or kill the host are of particular interest in biological control.

**.) Insects that parasitize and kill other insects are referred to a as parasitoids. They are parasitic during the immature stages and kill the host upon maturity.
-Not considered true parasites.


Example of Parasite

Most consist of wasps (Hymenoptera) or flies (Diptera).

The cicada killer wasp (Sphecius speciosus).
-Adult lays an egg inside a stunned living cicada.
-The cicada is burrowed underground until the egg hatches thus allowing the larva to feed and grow within the cicada.
-The larva pupates into an adult wasp and emerges from the cicada carcass.
-The wasp then flies off to parasitize another host and continue the cycle.



In phytopathology, refers to the action of microbial organisms (viruses, protozoa, nematodes, bacteria, fungi, etc.) that suppress or interfere with the normal growth and activity of harmful insects, weeds, or other plant pathogens within their own class.


IV.) Competitors

Occur when two organisms compete for limited supplies of essential resources, such as food, nutrients, water, and light in the case of plants. Whereby the selected competitor secures resources and limits those available to the population of pest organisms with little affect to the desired crops.


Example of Competitors

The use of rampant covever can outgrow and shade weedy species (particularly important if the weed species serves as a host).

Agrobaterium radiobacter K84 on a fruit tree rootstock prevents infection of the strain Agrobaterium tumefaciens (crown gall) through antibiotic production.
Bacteria and fungi can be used in the same manner as seed protectants.

Black Walnut produces a toxin that impairs the growth of most species around the base of it.


Approaches to Biological Control

1.)Importation (classical)
2.)Conservation and Enhancement

Releasing natural enemies should be followed up with a monitoring program to evaluate the effectiveness of the release.


Importation (classical)

-Involves the deliberate introduction and establishment of natural enemies into areas where they did not previously exist.
-Largely used against pests of foreign origin (usually through accidental introduction), where large populations thrive in the absence of a natural predator.
-Steps toward importation
1.)Native area of pest must be correctly identified
2.)Search for natural enemies conducted in such areas whereby appropriate species are shipped to labs for testing.
3.)Test species are held in strict quarantine to ensure the natural enemy will have minimal negative impact in the new country of release.
4.) After the following, the species may be reared as a natural enemy and released into the affected areas. (Repeated releases are often necessary) (Sometimes adapted biotypes are better suited than the native species).
(Only specialized personnel can carry out such programs.)


Conservation and Enhancement

Include any activities that improve the survival, dispersal, and reproduction of already existent endemic natural enemies.

Elimination or reduction (use of selective brands) of pesticides toxic to natural enemies is an effective way of maintaining health populations.

Ensuring microclimates or sheltered areas (e.g. not destroying) nearby where natural enemies may winter and predate from. Border harvesting, apiaries, etc.

Pruning branches or habitats that may nurture ant populations, since many times they domesticate aphids by offering protection from natural enemies.



Involves supplementing the numbers of naturally occurring biological control agents with releases.

Inoculative: Release natural enemies with the purpose of building up natural enemy population with the expectation that the progeny shall maintain control for several generations.
Inundative: Seeks biological control of released individuals, however does not expect survival to aid in long to term assistance. (Most effective during a limited period of the year when pest is most vulnerable or populations high).