  Type Ia Supernova Hubble residuals have been shown to correlate with host
galaxy mass, imposing a major obstacle for their use in measuring dark energy
properties. Here, we calibrate the fundamental metallicity relation (FMR) of
Mannucci et al. (2010) for host mass and star formation rates measured from
broad-band colors alone. We apply the FMR to the large number of hosts from the
SDSS-II sample of Gupta et al. (2011) and find that the scatter in the Hubble
residuals is significantly reduced when compared with using only stellar mass
(or the mass-metallicity relation) as a fit parameter. Our calibration of the
FMR is restricted to only star-forming galaxies and in the Hubble residual
calculation we include only hosts with log(SFR) > -2. Our results strongly
suggest that metallicity is the underlying source of the correlation between
Hubble residuals and host galaxy mass. Since the FMR is nearly constant between
z = 2 and the present, use of the FMR along with light curve width and color
should provide a robust distance measurement method that minimizes systematic
errors.
