Population Ecology

Question 1

What are the six factors that affect populations?

Answer 1

1. natality
2. mortality
3. movement
4. age distribution
5. density
6. dispersion

Question 2

Define natality.

Answer 2

Birth rate… influenced by fecundity.

Question 3

Define mortality.

Answer 3

Death rate… disease? lack of hosts?

Question 4

Define movement.

Answer 4

Entering (immigrating) and exiting (emigrating) a target area.

Question 5

Define age distribution.

Answer 5

Percent of insects in a particular development stage.

Question 6

Define density.

Answer 6

Number of individuals per unit of measure

Question 7

Define dispersion.

Answer 7

Spatial arrangement of density numbers… usually one of three types.

Question 8

What’s the difference between density and dispersion?

Answer 8

Density - # individuals per unit of measure

Dispersion - spatial arrangement (placement) of density numbers.

Question 9

What are the three dispersion types?

Answer 9

1. Random… rare.
2. Uniform… rare.
3. Clumping… most common

Question 10

Which dispersion types do insects normally have?

Answer 10

Clumping

Question 11

Define equilibrium position.

Answer 11

Average population density

Question 12

Define carrying capacity.

Answer 12

limit of population sustainable

Question 13

What is the primary abiotic factor that influences populations?

Answer 13

Weather

Question 14

Define phenology.

Answer 14

the study of any sequence of biological events that coincide with one another

Question 15

Why is phenology important in pest management?

Answer 15

Easily identifiable events that can be recorded and related to insect activity… more user friendly than DD calcuation

Question 16

What is a degree day and how are they used in pest management?

Answer 16

Amount of heat that accumulates above a base temperature for a 24 hour period.

Can help predict insect emergence, therefore better treatment

Question 17

Define biofix.

Answer 17

calendar date when degree day calculating begins (usually January 1)

Question 18

Define base temperature.

Answer 18

typical growth temperature

Question 19

How do you calculate degree days using the average method?

Answer 19

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!

Question 20

What are some limits to using degree days for determining pest emergence?

Answer 20

• Microclimates
• temps vary in small areas … airport hotter than farm
• Accurate local or relative temperatures
• Software for calculations