Traditionally studies of cold tolerance in insects have focused on seasonal adaptations related to overwintering that are observed after weeks or months of exposure to low temperature. In contrast, an extremely rapid cold-hardening response was observed in nonoverwintering stages that confers protection against injury due to cold shock at temperatures above the supercooling point. This response was observed in nondiapausing larvae and pharate adults of the flesh fly, Sarcophaga crassipalpis , nondiapausing adults of the elm leaf beetle, Xanthogaleruca luteola , and the milkweed bug, Oncopeltus fasciatus . The rapid hardening response is correlated with the accumulation of glycerol.

Direct exposure to-10 C, in the absence of tissue freezing, causes high mortality in Sarcophaga crassipalpis: this result suggests that injury is due to cold shock. However, brief acclimation at 0 C enables larvae, pupae, and pharate adults of Sarcophaga crassipalpis to survive-10 C. Chilling for as short a period as 10 min enabled 50% of the flies to survive a 2-h exposure to-10 C. Enhancement of cold tolerance was linear over the first hour of chilling at 0 C. The optimal temperature range eliciting the rapid acclimation response was 6-0 C, but the effect could also be stimulated by high temperature (36 C). The rapid increase in cold tolerance correlates with concomitant increases in hemolymph osmolality and glycerol levels. This response suggests a novel role for glycerol in protecting insects against injury resulting from cold shock, although other unidentified mechanisms may be involved in this response. That both nondiapause-and diapause-programmed flies respond to short-term chilling indicates that this rapid response is not part of the diapause syndrome but probably functions in either type of fly as an adaptation to survive brief periods of low temperature.

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This study explores the performance implications of internal resources and external networks for entrepreneurial firms. A relationship of trust among network members is essential because of the high risk during the initial start-up stage. However, once high-tech firms initiate mass production and enter the growth stage, whether trust influences competitiveness more than resources becomes uncertain. This study examines Taiwanese firms to elucidate the main influences on firm competitiveness. In conclusion, the result indicates the competitiveness of high-tech firms during the growth stage is determined by firm resources and the willingness of support firms to cooperate-where willingness is determined by the trust of the support firms in the high-tech firm but is unrelated to firm resources.

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