CO₂ anesthesia enhances infection rate of Cordyceps militaris (Hypocreales: Clavicipitaceae) on pupae of the silkworm, Bombyx mori

Abstract

An entomogenous fungus, Cordyceps militaris, grows on larvae and pupae of the silkworm, Bombyx mori. To overcome problems in the establishment of fungal infection caused by advancing pupal-adult development, we tested the effects of carbon dioxide (CO₂) anesthesia. Pupae inoculated with C. militaris were held in CO₂ anesthesia for 2 days. Almost all pupae exposed to CO₂ were infected with C. militaris, but the rate of infection of chilled or untreated pupae decreased with increasing stage of pupal-adult development at inoculation. The results indicate that exposure of silkworm pupae to CO₂ enhances infection rate. This treatment will support the mass production of C. militaris for pharmacological uses.