Laboratory Rearing of Thitarodes armoricanus and Thitarodes jianchuanensis (Lepidoptera: Hepialidae), Hosts of the Chinese Medicinal Fungus Ophiocordyceps sinensis (Hypocreales: Ophiocordycipitaceae).

Abstract

Ophiocordyceps sinensis (Ophiocordycipitaceae) is an entomopathogenic fungus endemic to the Tibetan Plateau, at elevations ranging between 3,000 and 5,000 m. The fungus-insect complex is useful in healthcare but limited in the field, so there is an urgent need to develop an artificial rearing system of both the fungus and its insect hosts. Large-scale artificial rearing of the Thitarodes insect hosts is crucial. This paper reports results of the artificial cultivation and complete life tables of two host species of O. sinensis, Thitarodes armoricanus and Thitarodes jianchuanensis (Lepidoptera: Hepialidae), under low-altitude laboratory conditions. The larvae were reared on carrots in plastic containers at 9–13°C and 50–80% RH. Both experimental insect species had long and unusual life cycle; it took 263–494 and 443–780 d for T. jianchuanensis and T. armoricanus, respectively, to complete a developmental cycle, including egg, larval instars L1-L9, pupa, and adult. The larvae did develop into pupae from the L7, L8, or L9 instar larvae. Although the total survival rates of both insect species were low (12.0% for T. jianchuanensis and 1.6% for T. armoricanus), the experimental populations successfully developed into the next generation owing to high egg production by fertilized females (averages of 703 and 355 eggs per female in the Yunnan and Sichuan species, respectively). Successful artificial rearing of host insect species for O. sinensis under low temperature conditions will allow the cultivation of this important fungus-insect complex to ensure its protection as a bio-resource and for commercial supply.