Thank you for writing.

Here is some information.  https://pnwhandbooks.org/sites/pnwhandbooks/files/insect/horticultural-landscape-ornamental/content/pdf/pdfs/insect21-fbiologicalcontrolofnurserypests.pdf

https://ag.umass.edu/greenhouse-floriculture/fact-sheets/aphids-on-greenhouse-crops

http://ipm.ucanr.edu/PMG/r280300111.html

Personally,  I have had excellent control using ladybugs. 
I hope this helps

Thank you for your reply.  Have you actually used ladybugs in an indoor nursery with seedlings?  I've used ladybugs in an outdoor setting but never indoors.  I am growing primarily edibles, except for several flats of zinnias.   Thanks.

Thank you for writing back.
I have not but the references that I sent you refer to their use in greenhouses. The search strategy that I used was for nursery aphids with a tilt to edu which means academic institutions.