模拟增温下门源草原毛虫幼虫生长发育特征

Effects of simulated warming on the growth and development of Gynaephora menyuanensis larvae

采用开顶式生长室(OTC)模拟增温的方法研究温度升高对门源草原毛虫幼虫发育历期、生长发育速率、体重及存活等的影响。研究发现:在增温0—1.26℃内,随着增温幅度变大,1龄幼虫越冬后开始活动期和蛹期提前,整个幼虫的发育历期缩短;增温可以提高门源草原毛虫幼虫的相对生长速度,使其发育高峰期提前到5月份;随着增温幅度变大,门源草原毛虫幼虫的体重有减轻的趋势;0—1.26℃的温度升高导致门源草原毛虫幼虫存活率增提高,但是增温过高(1.98℃)也会导致其存活率急剧下降。

Gynaephora menyuanensis, an endemic species of the Qinghai-Tibet Plateau, has been extensively researched because of the significant damage that they cause to grasslands. However, as a result of their adaptation to the plateau, this species could be regarded as a model organism to explore the response of herbivores to extreme environments and climate change. To explore the effect of global warming on this species, we conducted a simulated warming trial by using open top chambers （OTCs） at the Haibei Alpine Meadow Ecosystem Research Station, Northwest Institute of Plateau Biology of Chinese Academy of Science. To simulate different warming levels, we adopted four OTCs of different calibers and five replications of each size （20 OTCs in total）. The temperature of each OTC was recorded using a HOBO thermograph. From April to September 2014, 10 G. menyuanensis larvae finishing diapause were maintained under casings （35 cm × 25 cm × 40 cm） of thin wire, and the length, weight, survival, and width of the head capsule were measured every seven days. G. menyuanensis instar larvae were estimated based on their head width. The results showed the following： higher warming amplitudes resulted in earlier first instar larval activity anct pupm ucw.,,e larvae development durations with temperatures from ＋ 0℃ （ ambient temperature ） to ＋ 1.26℃ ; warming enhanced the relative growth rate of caterpillar larvae and advanced the peak of its development to May; higher temperature elevations resulted in lower weights of caterpillar larvae; and temperatures from ＋0 to ＋ 1.26℃ enhanced the survival rate of larvae, but increased temperature to ＋ 1.98℃ reduced it. Therefore, we concluded that there was a range of elevated temperatures positively＂ affecting G. menyuanensis larvae and enhancing their adaptation to the grassland. However, when the temperature or the warming rate exceeded this range, G. menyuanensis larvae could not adapt to the change, but the response of grasses to G. menyuanensis larvae under these warming conditions is still unknown. There were two innovations in this article： First, we explored the response of herbivore insects to different warming levels in the Qinghai-Tibet Plateau by focusing on G. menyuanensis. Second, we improved the traditional OTC to simulate different elevated temperatures.