Quantifying dispersal of bark beetles and their predators

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Quantifying dispersal of bark beetles and their
predators

• Arnaud COSTA
• Laboratory of Insect Ecology,
• Southern Illinois University, Carbondale,
  Illinois

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1 - Introduction gap formation in red pine
forests
? potential interactions between below and above
ground herbivory

• - predators limit the expansion of such declining
  stands by reducing Ips numbers

- interactions could be approached by measuring
dispersal of each guild member
- Dendroctonus valens (root colonizer)
- Ips pini (stem colonizer)
- Thanasimus dubius (predator)
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1 - Introduction gap formation in red pine
forests
T. dubius (Cleridae)
D. valens (Scolytidae)
I. pini (Scolytidae)
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2 - Objectives of the project

• Main objective to measure dispersal of three
  insects associated to red pine stands decline

- T. dubius (predator)
- D. valens (bark beetle, root)
- I. pini (bark beetle)
- on the same geographical area (Wisconsin)
- using the same methods (mark recapture)
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2 - Objectives of the project

• - how far do these insects fly?
• Dispersal quantile percentage of beetles
  dispersing at a particular distance

• - differences of dispersal related to
• sex
• size
• (Cronin et al., 2000)

? a study of predator-prey movement examined for
the first time on the same geographical scale
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3 - Field sites
Mirror Lake
Kettle Moraine
Spring Green
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4 - Methods
Mark recapture

• - funnel traps baited with appropriate
  semiochemicals

- T. dubius and D. valens caught are marked with
a spot of paint on the pronotum
- I. pini will be marked with fluorescent powder
while emerging from infested logs
- insects will be released at the center of a
grid of traps
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4 - Methods
Semiochemicals / lures
Species Ipsdienol lanierone ?-3 carene frontalin a-pinene
I. pini 0 0
D. valens 0 0
T. dubius 0
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4 - Methods
- grid of traps (cross shape pattern) set at
50,100, 200, 300, 400, 500, 750, 1000, 1250,
1500, 1750 and 2000 m.
Mark recapture grid
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4 - Methods
Mark recapture grid (including a pocket of
decline)
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5 Expected schedule
Set grids of traps Infest logs Capture/release Time Sites Sites Sites
Set grids of traps Infest logs Capture/release Time ML SG KM
March 8-10, 13-16 May 1st Early - Mid May T. dubius D. valens I. pini ()
March 8-10, 13-16 May 2nd Mid June () I. pini T. dubius D. valens
Timetable of mark recapture tasks Legend ML
Mirror Lake, SG Spring Green, KM Kettle
Moraine
() depending on infestation success () only
one attempt might take place