  An analysis of SNIa events in early type galaxies from the Cappellaro et al
(1999) database provides conclusive evidence that the rate of type Ia
Supernovae (SNe) in radio-loud galaxies is about 4 times higher than the rate
measured in radio-quiet galaxies, i.e. SNIa-rate$(radio-loud galaxies) =
0.43^{+0.19}_{-0.14}h^2_{75}$ SNu as compared to SNIa-rate$(radio-quiet
galaxies) = 0.11^{+0.06}_{-0.03}h^2_{75}$ SNu. The actual value of the
enhancement is likely to be in the range $\sim 2-7$ (P$\sim 10^{-4}$). This
finding puts on robust empirical grounds the results obtained by Della Valle &
Panagia (2003) on the basis of a smaller sample of SNe. We analyse the possible
causes of this result and conclude that the enhancement of SNIa explosion rate
in radio-loud galaxies has the same origin as their being strong radio sources,
but there is no causality link between the two phenomena. We argue that
repeated episodes of interaction and/or mergers of early type galaxies with
dwarf companions, on times-scale of about 1 Gyr, are responsible for inducing
both strong radio activity observed in $\sim$14% of early type galaxies and to
supply an adequate number of SNIa progenitors to the stellar population of
ellipticals.
