Population Ecology Flashcards
What are the six factors that affect populations?
- natality
- mortality
- movement
- age distribution
- density
- dispersion
Define natality.
Birth rate… influenced by fecundity.
Define mortality.
Death rate… disease? lack of hosts?
Define movement.
Entering (immigrating) and exiting (emigrating) a target area.
Define age distribution.
Percent of insects in a particular development stage.
Define density.
Number of individuals per unit of measure
Define dispersion.
Spatial arrangement of density numbers… usually one of three types.
What’s the difference between density and dispersion?
Density - # individuals per unit of measure
Dispersion - spatial arrangement (placement) of density numbers.
What are the three dispersion types?
- Random… rare.
- Uniform… rare.
- Clumping… most common
Which dispersion types do insects normally have?
Clumping
Define equilibrium position.
Average population density
Define carrying capacity.
limit of population sustainable
What is the primary abiotic factor that influences populations?
Weather
Define phenology.
the study of any sequence of biological events that coincide with one another
Why is phenology important in pest management?
Easily identifiable events that can be recorded and related to insect activity… more user friendly than DD calcuation
What is a degree day and how are they used in pest management?
Amount of heat that accumulates above a base temperature for a 24 hour period.
Can help predict insect emergence, therefore better treatment
Define biofix.
calendar date when degree day calculating begins (usually January 1)
Define base temperature.
typical growth temperature
How do you calculate degree days using the average method?
DD = (Temp max - Temp min)/2 - Temp base
ex.
325 DD, Feb. 15 @ base 50° F … requires 275 = emerged!
325 DD, Feb, 15 @ base 50° F … requires 345 = not yet emerged!
What are some limits to using degree days for determining pest emergence?
- Microclimates
- temps vary in small areas … airport hotter than farm
- Accurate local or relative temperatures
- Software for calculations
