Dear colleague, 

That is a very common problem when using media which are too rich in simple sugars and substrates that fungi can assimilate easily. When this happens, a possible solution is to try media with natural substrates, depending on the ecology of the studied organism. 

There is a paper in which N. rileyi yielded very good sporulation on media containing sterilized rice (http://scielo.sld.cu/scielo.php?script=sci_arttext&pid=S1010-27522009000300004). You may also try oatmeal agar, cornmeal agar and even water agar supplemented with plant material. Considering that N. rileyi is an entomopathogenic species, you might even try water agar with sterilized chitinous substrates or sterilized insects. 

Also take into account that fungi sometimes lose the ability to sporulate if maintained in culture for a long time, especially very old isolates. If this is the case, try to work with several isolates of the same species. They can differ greatly in the amount of sporulation produced.  

Success!

Hugo

Spore formation is a developmental process accomplished through a dynamic change in gene expression profile and happens as a response to environmental factors (both internal and external).

In agreement with the previous answer, the work with fungi is very delicate because any change in their growth conditions (culture media preparation, incubation temperature....) affect directly their colony feature, metabolites production..etc...

So it is ideal to know exactly in which condition (cuture media....) Nomuraea rileyi properly and produce spore to be able to reproduce the experiment any time.

Dear colleague, 

That is a very common problem when using media which are too rich in simple sugars and substrates that fungi can assimilate easily. When this happens, a possible solution is to try media with natural substrates, depending on the ecology of the studied organism. 

There is a paper in which N. rileyi yielded very good sporulation on media containing sterilized rice (http://scielo.sld.cu/scielo.php?script=sci_arttext&pid=S1010-27522009000300004). You may also try oatmeal agar, cornmeal agar and even water agar supplemented with plant material. Considering that N. rileyi is an entomopathogenic species, you might even try water agar with sterilized chitinous substrates or sterilized insects. 

Also take into account that fungi sometimes lose the ability to sporulate if maintained in culture for a long time, especially very old isolates. If this is the case, try to work with several isolates of the same species. They can differ greatly in the amount of sporulation produced.  

Success!

Hugo