LEARNING OBJECTIVES OF SECTION
After completing this section students should have an understanding of the following ecological processes, concepts and pest management strategies:
a. Equilibrium Position.
b. Economic Threshold.
c. Economic Injury Level.
d. Economic Factors Considered.
a. Mechanical control.
(1) Fly swatters.
(2) Salvage Logging.
(4) Water treatment of cut logs.
b. Kiln drying of lumber.
a. Pesticides: Poisons.
Specificity - range of action.
Persistance - How long?
Toxicity - How dangerous?
LD 50, dose (mg/kg) lethal tol 50%.
Oral or dermal.
(2) Mode of action.
(3) Insecticide chemical groups.
Organochlorines (chlorinated hydrocarbons).
(4) Formulations and application.
Emusifiable concentrates (EC).
Ultra low volume sprays.
(5) Pesticide safety.
Keep away from children.
b. Special chemical methods.
(1) Insect growth regulators.
Development, J.H., Ecdysone (methoprene).
Cuticle formation (Diflubenzuron).
(2) Pheromones (chemicals used within species for communication).
Behavioral Chemicals = semiochemicals.
Bark beetles (frontalin and verbenone).
(3) Pheromones used in insect control and pest management. (Videos)
Detection and Monitoring.
a. Action of natural enemies suppress populations.
(2) Parasites (parasitoids).
a. Usually Density Dependent.
b. (Natural control - density independent).
c. Native Biological Control Agents.
d. Introduced Biological Control Agents.
e. Criteria for natural enemies for introduction.
(1) No harmful effects.
(2) Good searching capacity, effective at various host densities.
(3) Well-adapted to the climate, host habitat and ecology.
(4) High host specificity.
(5) High reproductive capacity.
f. Predators (Examples).
g. Parasitoids (Examples).
h. Value of parasitoids vs. predators.
Generally more host specific.
Better adapted to hosts environment.
Lower food requirements.
Immature forms do not have to search for hosts.
Can switch prey when hosts are rare.
Tend to stabilize populations.
Tend to be more effective in unstable environments.
(1) Bacteria -- Bacillus thuringiensis (B.t. control of many species).
(2) Fungi -- Entomophthorales spp. (Control of gypsy moth).
(3) Viruses -- NPV ( Control of gypsy moth).
(4) Protozoa -- Nosema (Control of fall webworm)
j. Approaches to biological control.
k. Advantages of biological control.
(1) Control is self-perpetuating.
(2) Control is selective and density dependent.
(3) Does not (normally) create new problems.
l. Disadvantages of biological control.
(1) Not effective against "direct" pests (where any damage is unacceptable).
(2) Some level of damage must be accepted.
(3) Must be implemented over large areas.
(4) May take years to become established.
a. Host resistance. Some varieties produce better at same pest levels.
Insects tend to prefer certain plant species.
Host characters adversely affect pest survival.
Plant is attacked but not damaged significantly.
b. Legislative (legal) control. Laws to prevent entry or spread of pests.
(1) Called "quarantines." Generally help but eventually fail.
Plant Quarantine Act 1912.
(a) Enforced within the United States by states.
(b). Enforced at U.S. borders by USDA.
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