Guix and desktop files

[hiphish]

Hello everyone,

I am using Kubuntu 18.04 and I recently installed Guix as a secondary package
manager. I'm still feeling my way around and I have been wondering whether
the desktop files provided by some applications can be integrated with the
desktop environment.

When I install an application through apt a desktop file is placed in

    /usr/share/applications

and the application shows up in my Application menu. Guix has an analogue to
this under

        ~/.guix-profile/share/applications/

and it contains Gimp at the moment, but I have no idea how to hook this
directory up to the menu. Is there an environment variable like there is for
$PATH? I know I can copy or symlink Guix's desktop file into 

        ~/.local/share/applications/

but this is manual work and the symlinks can become stale.