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The mountain pine beetle, Dendroctonus ponderosae Hopkins, spends the majority of its life cycle within the phloem of pine trees, experiencing exposure to temperatures below Ϫ30ЊC in many parts of their expansive range. To better understand cold tolerance capabilities of this insect, seasonal patterns of cold-hardiness, as measured by supercooling points in the laboratory, were compared with seasonal patterns of host tree phloem temperatures at several geographic sites for 2 beetle generations. Larvae were found to be intolerant of tissue freezing, and supercooling points measured appear to be a reasonable estimate of the lower limit for survival. Of the compounds analyzed, glycerol was found to be the major cryoprotectant. No differences in supercooling points were found among instars or between larvae collected from the north and south aspect of tree boles. Both phloem temperatures and supercooling points of larvae collected from within the phloem were found to be different among the geographic sites sampled. Mountain pine beetle larvae appear to respond to seasonal and yearly ßuctuations in microhabitat temperatures by adjusting levels of cold hardening.

The brown marmorated stink bug, Halyomorpha halys (Stål), is native to eastern Asia and is presently invading North America. Little is known about the exposure to and effects of winter temperatures in newly invaded regions on H. halys The overwintering habitats that this species utilizes vary greatly in their thermal buffering capacity. They naturally overwinter in aggregations beneath loose bark on trees and in cliff outcroppings, but will also commonly aggregate in buildings. Effects of cold temperatures such as mortality and freezing have yet to be quantified in the invading population. We report that H. halys is chill intolerant (i.e., dies before reaching its freezing point), and that the degree of cold tolerance of populations in North America differs by season, sex, and acclimation location. The mean winter supercooling point (± SEM) of individuals acclimated in Minnesota was -17.06 °C ± 0.13 and in Virginia was -13.90 °C ± 0.09. By using laboratory assays of lower lethal temperatures and ambient air temperature records, we accurately forecasted mortality for field experiments in Minnesota and Virginia. Temperature refugia provided by human-built structures are likely crucial for overwintering survival during atypically cold winters and possibly contribute to the northern geographic range expansion of this economically damaging insect in the temperate climates of North America.

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Cockroaches are a group of insects that evolved early in geological time. Because of their antiquity, they for the most part display generalized behavior and physiology and accordingly have frequently been used as model insects to examine physiological and biochemical mechanisms involved with water balance, nutrition, reproduction, genetics, and insecticide resistance. As a result, a considerable amount of information on these topics is available. However, there is much more to be learned by employing new protocols, microchemical analytical techniques, and molecular biology tools to explore many unanswered questions.

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