玉树蝠蛾幼虫抗寒能力的研究

Study on cold hardiness of Hepialus yushuensis larvae

本文报道了青海冬虫夏草的优势寄主—玉树蝠蛾(Hepialus yushuensis Chu et Wang)幼虫抗寒能力。其2-4龄虫的过冷却点分别为(-19.08±1.47)℃、(-19.22±1.16)℃和(-18.43±1.05)℃。随着处理温度的降低和处理时间的延长,幼虫的存活率降低。2-4龄幼虫在-10℃下的半致死时间(Ltime50)分别为61.69d、64.68d和35.94d,低温处理2h后半致死温度(Ltemp50)分别为-14.34℃、-15.18℃和-14.12℃,高于其过冷却点。越冬幼虫在-0.2℃^-6.8℃的土壤温度中,半年也不会死亡。越冬初期幼虫体内的脂肪、糖含量升高、水分下降有利于提高其抗寒能力。幼虫经过低温适应锻炼能够显著提高其耐寒能力。

The cold hardiness of the overwintering larvae of the host moth Hepialus yushuensis was studied by determining their supercooling points. The results showed that the supercooling points of the larvae from second to fourth instars were （-19.08±1.47）℃,（-19.22± 1.16）℃ and （-18.43±1.05）℃respectively. The survival rates of larvae declined with the decrease of treatment temperature and the extension of treatment time. For 2nd, 3hi and 4th instar larva, the half lethal time of individuals （Ltime50） at -10℃ was 61.69d, 64.68d and 35.94d, respectively while the lower lethal temperature needed to kill 50% of individuals （LtempS0） after 2h exposure was -14.34℃, -15.18℃ and -14.12℃, respectively, higher than the corresponding SCPs. The larvae could live more than half a year in the alpine meadow soil where the temperature ranged from -0.2℃ to -6.8℃ during the winter. It was determined that the contents of fat, sugar and water decreased in the bodies of the overwintefing larvae and this seems to be the way to assure the greater cold tolerance of the overwintering larvae.