@article {11879,
	title = {Prepupal diapause and instar IV developmental rates of the spruce beetle, Dendroctonus rufipennis (Coleoptera: Curculionidae, Scolytinae)},
	journal = {Journal of Insect Physiology},
	volume = {57},
	number = {10},
	year = {2011},
	month = {Oct},
	pages = {1347-1357},
	abstract = {The spruce beetle, Dendroctonus rufipennis (Kirby), is an important mortality agent of native spruces throughout North America. The life-cycle duration of this species varies from 1 to 3 years depending temperature. The univoltine cycle (one generation per year) is thought to maximize outbreak risk and accelerate host mortality in established outbreaks. Prepupal diapause is associated with the semivoltine cycle (one generation per 2 years) and we investigated thermal conditions that result in diapause induction. Preliminary experiments used respirometry in an attempt to distinguish the diapause state of experimental insects but the technique was apparently confounded by low respiration before and during pupation, regardless of diapause status. Therefore, diapause induction was deduced using developmental delays. The observed developmental response was not a "switch", with developmental delay either present or absent, but instead varied continuously. We found that temperatures <15 [degree]C from instar Ill through mid-instar IV were associated with developmental delays beyond that expected from cool temperatures. Moreover, the duration of exposure to cool temperatures was important in determining the degree of developmental delay. Small, if any, delays were observed if the cumulative exposure to <15 [degree]C was <20 d whereas >40 d cumulative exposure was associated with distinct developmental suppression. Intermediate exposure to cool temperatures resulted in minor developmental delays. We used our results to parameterize a maximum likelihood estimation model of temperature-dependent instar IV developmental rates, including the effect of diapause. This model can be included as part of a spruce beetle phenology model for predicting population dynamics. Published by Elsevier Ltd.},
	keywords = {Dendroctonus rufipennis},
	isbn = {0022-1910},
	author = {Hansen, E. Matthew and Bentz, Barbara J. and Powell, James A. and Gray, David R. and Vandygriff, James C.}
}
@article {9361,
	title = {Climate Change and Bark Beetles of the Western United States and Canada: Direct and Indirect Effects},
	journal = {Bioscience},
	volume = {60},
	number = {8},
	year = {2010},
	month = {Sep 10},
	pages = {602-613},
	abstract = {Climatic changes are predicted to significantly affect the frequency and severity of disturbances that shape forest ecosystems. We provide a synthesis of climate change effects on native bark beetles, important mortality agents of conifers in western North America. Because of differences in temperature-dependent life-history strategies, including cold-induced mortality and developmental timing, responses to warming will differ among and within bark beetle species. The success of bark beetle populations will also be influenced indirectly by the effects of climate on community associates and host-tree vigor, although little information is available to quantify these relationships. We used available population models and climate forecasts to explore the responses of two eruptive bark beetle species. Based on projected warming, increases in thermal regimes conducive to population success are predicted for Dendroctonus rufipennis (Kirby) and Dendroctonus ponderosae Hopkins, although there is considerable spatial and temporal variability. These predictions from population models suggest a movement of temperature suitability to higher latitudes and elevations and identify regions with a high potential for bark beetle outbreaks and associated tree mortality in the coming century.},
	keywords = {Dendroctonus rufipennis},
	isbn = {0006-3568},
	author = {Bentz, Barbara J. and Regniere, Jacques and Fettig, Christopher J. and Hansen, E. Matthew and Hayes, Jane L. and Hicke, Jeffrey A. and Kelsey, Rick G. and Negron, Jose F. and Seybold, Steven J.}
}
