Transcript Mountain Pine Beetle Winter Mortalities.

Winter Mortalities of the Mountain
Pine Beetle
Andrew Habig
Winter Ecology
Spring 2009
Mountain Research Station, University of Colorado, Boulder
Question
How does winter affect populations of the
Mountain Pine Beetle (MPB)?
Outline
• MPB life cycle.
• MPB winter survival strategy.
– Variable freeze resistance
• Blue Stain fungi winter survival.
• Conclusion
• Climate change implications
Beetle Life cycle
• Adults attack live trees in late summer.
• Lay eggs in tree’s phloem.
• Larvae survive the
winter in tree phloem.
MPB Winter Survival Strategies
•
•
•
•
Bark of host provides very little protection
MPB’s are Freeze resistance.
Use of glycerol primarily as a cryoprotectant.
Level of freeze resistance changes over life
stages and temperature changes.
Variation in Freeze Resistance due to
life cycle
• MPB have different levels of freeze resistance
during each stage of their lives.
• Egg and pupa stage, which occur in fall and
spring, respectively are least freeze resistant.
• MPB populations subject to high mortalities in
cold falls and springs.
Temperature Induced Variation in
Freeze Resistance
• MPB will change level of freeze
resistance in response to changes
in temperature.
• Warmer temperatures cause
beetles to begin to loose their
antifreeze.
• Sudden drops in temperature will
cause beetle deaths.
Blue Stain Fungi Winter Survival
• Three strains of fungi:
– Grosmannia clavigera, Ophiostoma montium and
Leptographium longiclavatum
• Different cold tolerance for each strain
• G. clavigera and L. Leptographium adapted to
cold winters.
• O. montium adapted to warm summers.
MPB Winter Mortalities
•Decline
wintertime
in beetle
populations
mortality
is common
due
••70-80%
Mortality
from
all sources
must
add to
upcold
toin97most
usually
MPB
only
populations.
occurs
when winter
mortalities
98%
in order
to
see significant
population
are above 80%.
decline.
Implications of Warmer Winters.
• Milder springs and falls would allow MPB to
survive and spread at higher latitudes and
elevations.
• Climate change could allow MBP population
to grow to large numbers because of fewer
winter mortalities.
Conclusion
• MPB populations are severely limited by
winter mortalities.
• In spite of high winter population loss,
population size can still increase because of
the high number of offspring per
reproduction. (r selected)
• Could not find data that MPB were limited by
blue-stain fungi winter mortalities.
• Climate change could cause further spread of
the MPB.
Works Cited
Modeling cold tolerance in the mountain pine beetle, Dendroctonus ponderosae. Régnière, Jacques;
Bentz,Barbara. J.Insect Physiol., 2007, 53, 6, 559-572
Mountain pine beetle-associated blue-stain fungi are differentially adapted to boreal temperatures
Rice,A.V.; Thormann,M.N.; Langor,D.W. For.Pathol., 2008, 38, 2, 113-123
Mountain Pine Beetle and Climate Change. Jacques Régnière and Barbara Bentz. USDA Research Forum on
Invasive Species
Ecology of the Mountain Pine Beetle (Coleoptera: Scolytidae) Cold Hardening in the Intermountain West. BJ
Bentz; DE Mullins. Environ. Entomol., 1999, 28, 4, 577-587
Mountain Pine Beetle. D.A. Leatherman, I. Aguayo, and T.M. Mehall. CSU Extension. No 5.528.
Natural Recourses Canada, 2007 <http://cfs.nrcan.gc.ca/subsite/mpb/mpb-mortality>