Synnematal form of Beauveria bassiana from Hawkmoth
Image from MycoAlbum CD
Sometimes we are just lucky. Some entomologists were working on a biocontrol project that involved rearing Hawkmoths. During the experiments some of the larvae were killed and consumed by a remarkable fungus. The fungus produced a tuft of yellow synnemata (fused conidiophores) with each synnema bearing an ellipsoid powdery white spore head at its tip. There are not that many (hundreds!) synnematous Hyphomycetes so I made a mount to see if I could identify it. I was amazed because the mount proved to be identical in all its microscopic features to Beauveria bassiana. To confirm this I streaked some of the spores on several differend kinds of agar media. In all cases, the fungud grew out as a typical Beauveria bassiana culture but never produced the synnemata on the petri dishes. This is not surprising as many synnematous hyphomycetes do not produce the synnemata in culture.
I was impressed by all this so I sent a slide and a piece of the herbarium specimen to an authority on synnematous hyphomycetes and he didn't seem at all surprised. Maybe he was just playing it cool. At any rate I have never seen this remarkable form of Beauveria again nor have I chanced across anything in the literature.
Students: What should I have done to satisfy Koch's postulates regarding this isolate of Beauveria?