ヨモギハムシの地理的個体群間における発育零点, 有効積算温度, 生存率の比較

概要

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Six geographic populations of Chrysolina aurichalcea were reared at seven constant temperatures to analyze the species wide distribution range. The developmental zero was about 7℃ for all populations. It is rather lower than that of general insects in temperate regions, reflecting the active life-cycle in the cold season. The thermal constant was split into two groups (467-490 and 524-538 degree-days). The former group includes Yakushima, Mikkabi, Matsumoto and Sanjiro (southern populations); the latter group includes Utsukushigahara and Sapporo (northern and alpine populations). The groups also seem to correspond to the 31 and 41 male chromosome numbers, respectively. Body weight decreased with increasing temperature for Yakushima and Sanjiro. The survival rate was highest from 15℃ to 26℃, quite high even at 13℃ or 10℃, but at 30℃, most individuals from the fourth instar to pupa died. These characteristics suggest that the species or a closely-related ancient species originated from the northern temperate zone and that it has adapted to different environments by shifting its seasonal cycle to maintain its active stages in the cooler season.
1996-08-25