No!
Wall wart chargers for any device, radio, electric shaver, power tools, etc... provide a constant charge rate as specified on their plugs and are not designed to trickle charge or maintain batteries.
This is an excerpt from the user's manual for your radio:
"WARNING! DO NOT charge or leave the battery in the bat- tery charger beyond the specified time for charging. If the bat- tery is not completely charged by the specified time, stop charging and remove the battery from the battery charger. Continuing to charge the battery beyond the specified time limit may cause a fire, overheating, or the battery may rupture"
There is also a paragraph in all Icom manuals stating that you should remove the battery from the radio for prolonged storage periods.