short answer , NO...
But, if you buy the Informix Gateway you can access the mysql from Informix and maybe use triggers (i don't know the limits of IDS Gateway)
IBM - Informix Enterprise Gateway Manager - Add-on Overview
I don't know if on mysql you can access Informix with ODBC (my guess is yes, you can).
On version 11.50 of Informix have a new feature called , Change Data Capture , what is a interface to capture information on-line on Informix, or something like that. I don't study about it yet... but to do this you probably will need coding in C .