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Examining overwinter cold-hardiness in insects

Examining overwinter cold-hardiness in insects. Liz Manley EBIO 4120 Spring 2008. Winter Ecology – Mountain Research Station, University of Colorado, Boulder. Problems during winter conditions. Insects are little bags of water Exoskeleton and hemolymph Ectotherms

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Examining overwinter cold-hardiness in insects

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  1. Examining overwinter cold-hardiness in insects Liz Manley EBIO 4120 Spring 2008 Winter Ecology – Mountain Research Station,University of Colorado, Boulder

  2. Problems during winter conditions • Insects are little bags of water • Exoskeleton and hemolymph • Ectotherms • How do insects survive overwintering? • Why do we care?

  3. Freeze tolerance strategy • Allows ice formation between cells • Supercooling • Antifreeze proteins (AFPs) • Ice Nucleating Agents (INAs) (Danks, 2004; Halfpenny and Ozanne, 1989)

  4. Freeze avoidance strategy • Does not allow formation of ice within the body • Lowers supercooling point by 20˚C • Synthesizes polyols and sugars

  5. Comparison of strategies Main biological components of freeze tolerance and freeze avoidance strategies. (Bale, 2002)

  6. More than two categories… • SCP is below winter temperatures • Especially under snowpack • SCP in many studies is measured in isolation Freezing is not the biggest threat to freeze avoidance insects (Bale, 1996; Bale 2002)

  7. New Categories (Bale, 2002)

  8. Harmonia axyridis (Asian lady beetle) Aggregate in very large numbers during the winter; Chill tolerant Contrast is the most important feature for overwinter habitat choice (Nalepa et al., 2005)

  9. Dendroctonus ponderosae (Régnière and Bentz, 2007)

  10. Using the model to predict SCP Changing dynamics of SCP in pine beetle population based on daily and seasonal temperatures at different sites (Régnière and Bentz, 2007)

  11. Conclusions • Insects have several adaptation strategies for surviving the winter • Lady beetles use visual contrast to find overwintering sites • Mountain pine beetle populations have dynamic SCPs based on location and season.

  12. Literature cited • Bale, J.S. 2002. Insects and low temperatures: from molecular biology to distributions and abundance. Philosophical Transactions of the Royal Society of London Series B – Biological Science 357:849-861. • Bale, J.S. 1996. Insect cold hardiness: A matter of life and death. European Journal of Entomology 93:369-382. • Danks, H.V. 2004. Seasonal adaptations in Arctic insects. Integrative and Comparative Biology 44:85-94. • Halfpenny, J. C. and R. D. Ozanne. 1989. Winter: An Ecological Handbook. Johnson Publishing Company. Boulder, CO. • Nalepa, C. A., G. G. Kennedy, and C. Brownie. 2005. Role of visual contrast in the alighting behavior of Harmoniaaxyridis (Coleoptera: Coccinellidae) at overwintering sites. Environmental Entomology 34:425-431. • Régnière, J. and B. Bentz. 2007. Modeling cold tolerance in the Mountain Pine Beetle, Dendroctonusponderosae. Journal of Insect Physiology 53:559-572.

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