冬虫夏草寄主昆虫选育及生殖退化研究

Hybrid breeding of high quality of Hepialus sp., the host of Ophiocordyceps sinensis, and prevention of the host insect reproductive degradation

选育发育速度快、繁殖能力强、中国被毛孢侵染率和冬虫夏草产出率高的寄主昆虫品系是冬虫夏草培植的基础,同时明确冬虫夏草的寄主昆虫蝙蝠蛾退化机制是保证冬虫夏草培植的条件。本文从冬虫夏草产区采集蝙蝠蛾种群种质资源,分别针对蝙蝠蛾发育速度、繁殖能力、中国被毛孢侵染率、冬虫夏草产出率4个方面通过杂交及四代选育,获得新种群(A1),该种群对冬虫夏草繁育环境的适应力强,发育整齐度高,繁育一代的种群扩繁倍数从8.2倍提高至26.3倍;对中国被毛孢的敏感性较好,侵染率高,冬虫夏草产出率从原始种群的11.2%提高至18.5%。同时,仿照高原生态环境长期饲养冬虫夏草的寄主昆虫蝙蝠蛾,其子代出现雌雄比失调、发育历期分化、生殖力降低等退化现象。经过研究分析得知卵孵化率下降的主要原因是雄性的生殖力下降。组织切片观察蝙蝠蛾雄性生殖系统,在幼虫后期、蛹、成虫期会出现生精囊减少及畸形等异常情况,推测此为雄性生殖力降低、卵孵化率下降的生理原因。研究结果为高效、稳定地饲养蝙蝠蛾保证冬虫夏草培植具有重要意义。

Hybrid breeding of host insect Hepialus sp. improved breeds with high reproductive capacity, sensitive to theOphiocordyceps sinensis infection, with high rate of fruitbody formation as well as prevention of the reproductive degradation are the essential requirements for the artificial cultivation of O. sinensis. Wild Hepialus sp. was sampled from its naturally typical habitat in Qinghai-T ibet Plateau. After hybrid breeding for 4 generations, the new population（A1） with high reproduction rate, high susceptibility and high capability of fruitbody formation was established. Compared with the wild population, the new breeding population showed more synchronized development, increases of the reproductive capacity, sensitive to fungus infection and high cordyceps yield. The propagation coefficient of the breeding population was increased from 8.2 times to 26.3 times and the cordyceps yield was also increased from 11.2% to 18.5% as compared with the initial population. In the meanwhile, the reproductive degradation of host Hepialus sp. was observed under long-term artificial feeding. The phenomena include sex ratio imbalance, developmental duration differentiation and fertility decline. After detailed tissue examination, the hatchability decrease mainly caused by the male whose spermatotheca was reduced and deformed in older stage larva, pupa and adult. The malformed reproductive organs and germ cell development of the males may cause the fertility decline and hatchability decrease. The results in this study provide an essential reference for the artificial feeding and prevention of the reproductive degradation of the Hepialus sp.