I would just cut out the middle man and look at the TORC1 targets directly. Western blots assessing S6 kinase activation are one the best read-outs of TORC1 activity in any system.  Drosophila Antibodies are available through Cell Signaling (cat##9209). Although this is probably a readout of what is going on in ECs. Given signals from eb, ee, and ISCs would likely be overwhelmed. So it depends on what you're trying to address. I haven't seen any fluorescence-based reporters of TOR signaling which are accurate. I hope this helps. 

Thank you Matt!

Have a look at this article: http://journals.plos.org/plosgenetics/article?id=10.1371/journal.pgen.1003045#s4

There's a good anti-phospho-4EBP antibody described for gut immunostaining (Cell Signaling #2855) that is high in EB's with high Tor activity. Hope this helps!

Thank you, Jerome!