State Key Laboratory of Integrated Management of Insect Pests & Rodents, Institute of Zoology, Chinese Academy of Sciences, Beijing, China.
PLoS One. 2012;7(7):e41764. doi: 10.1371/journal.pone.0041764. Epub 2012 Jul 27.
Global warming is characterized by not only an increase in the daily mean temperature, but also a diel asymmetric pattern. However, most of the current studies on climate change have only concerned with the mean values of the warming trend. Although many studies have been conducted concerning the responses of insects to climate change, studies that address the issue of diel asymmetric warming under field conditions are not found in the literature.
METHODOLOGY/PRINCIPAL FINDINGS: We conducted a field climate manipulative experiment and investigated developmental and demographic responses to diel asymmetric warming in three grasshopper species (an early-season species Dasyhippus barbipes, a mid-season species Oedaleus asiaticus, and a late-season species Chorthippus fallax). It was found that warming generally advanced the development of eggs and nymphs, but had no apparent impacts on the hatching rate of eggs, the emergence rate of nymphs and the survival and fecundity of adults in all the three species. Nighttime warming was more effective in advancing egg development than the daytime warming. The emergence time of adults was differentially advanced by warming in the three species; it was advanced by 5.64 days in C. fallax, 3.55 days in O. asiaticus, and 1.96 days in D. barbipes. This phenological advancement was associated with increases in the effective GDDs accumulation.
CONCLUSIONS/SIGNIFICANCE: Results in this study indicate that the responses of the three grasshopper species to warming are influenced by several factors, including species traits, developmental stage, and the thermal sensitivity of the species. Moreover, species with diapausing eggs are less responsive to changes in temperature regimes, suggesting that development of diapausing eggs is a protective mechanism in early-season grasshopper for avoiding the risk of pre-winter hatching. Our results highlight the need to consider the complex relationships between climate change and specificity responses of invertebrates.
全球变暖的特点不仅在于日平均温度的升高，还在于昼夜不对称模式。然而，当前大多数关于气候变化的研究仅关注变暖趋势的平均值。尽管已经有许多关于昆虫对气候变化响应的研究，但在文献中找不到关于野外昼夜不对称变暖问题的研究。
方法/主要发现：我们进行了野外气候操纵实验，研究了三种蝗虫（早季物种 Dasyhippus barbipes、中季物种 Oedaleus asiaticus 和晚季物种 Chorthippus fallax）对昼夜不对称变暖的发育和种群动态响应。结果发现，变暖通常会加速卵和若虫的发育，但对卵的孵化率、若虫的羽化率以及三种物种成虫的存活率和繁殖力没有明显影响。夜间变暖比白天变暖更有效地促进卵的发育。三种物种成虫的出现时间因变暖而不同，C. fallax 提前 5.64 天，O. asiaticus 提前 3.55 天，D. barbipes 提前 1.96 天。这种物候期的提前与有效 GDD 积累的增加有关。
结论/意义：本研究结果表明，三种蝗虫对变暖的响应受到多种因素的影响，包括物种特征、发育阶段和物种的热敏感性。此外，具有休眠卵的物种对温度变化的响应较小，这表明休眠卵的发育是早季蝗虫避免初冬孵化风险的一种保护机制。我们的结果强调了需要考虑气候变化与无脊椎动物特异性响应之间的复杂关系。
