Coach Mike Ruddock said: "It's a big blow to lose someone like Gareth but we have to keep looking forward. We've still got some big guns to come back."
Delve's Bath team-mate, scrum-half Andrew Williams, and Saracens prop Ben Broster have been called up to train with the squad. British Lions; Tom Shanklin, Brent Cockbain and Ryan Jones as well as Kevin Morgan, Jonathan Thomas and Chris Horsman are all out injured.
Gavin Henson, Dafydd Jones and Ian Evans are all suspended while Sonny Parker has retired. Wales will also assess the fitness of Ceri Sweeney.