关键词: 松突圆蚧, 耐寒性, 耐热性, 过冷却点, 海拔梯度

Abstract: In order to explore the thermal adaptability to elevation in the pine armored scale (PAS), Hemiberlesia pitysophila Takagi, an invasive forest pest originated in Japan which had been severely attacking various ever green pines in southern China in the recent two decades, the cold and heat tolerances of 1st instar nymphs, 2nd instar nymphs before sexual differentiation and adult females of the winter field populations of PAS collected from five plots at different elevation (80, 251, 391, 510 and 725 m, respectively) were compared, based on the survival experiments exposed to extreme temperature conditions in Quanzhou, Fujian in February, 2009 and the measures of supercooling point (SCP). The results showed that (1) thermal tolerances of PAS at different elevation had significant differences, in which adult females and 2nd instar nymphs all displayed higher cold tolerance at the elevation of 391 m, and an increased heat tolerance in adult females at the same elevation was observed too. Cold tolerance seemed to increase with increasing of elevation in the 2nd instar nymphs, but not in other developmental phases. This finding though provides an opponent case of climate variation hypothesis, it suggests that elevation might be an important limit to population expansion and geographic distribution of PAS. (2) Pearson’s correlation between cold and heat tolerance in adult females was statistically remarkable and positive along an altitudinal gradient, but no correlations existed in other developmental phases, suggesting that the developmental phase of PAS might affect this correlation. (3) A separate analysis showed no marked Pearson’s correlation between SCP and median lethal low temperature of adult females in PAS exposed for 4 h along elevation gradient. These results provide a helpful foundation to profoundly understand thermal adaptability and geographic distribution in PAS.

Key words: Hemiberlesia pitysophila, cold tolerance, heat tolerance, supercooling point (SCP), altitudinal gradient