  Kappa distributions are ubiquitous in space and astrophysical poorly
collisional plasmas, such as the solar wind, suggesting that microscopic and
macroscopic properties of these non-equilibrium plasmas are highly conditioned
by the wave-particle interactions. The present work addresses the evolution of
anisotropic bi-Kappa (or bi-$\kappa$-)distributions of electrons triggering
instabilities of electromagnetic electron-cyclotron (or whistler) modes. The
new quasi-linear approach proposed here includes time variations of the
$\kappa$ parameter during the relaxation of temperature anisotropy. Numerical
results show that $\kappa$ may increase for short interval of times at the
beginning, but then decreases towards a value lower than the initial one, while
the plasma beta and temperature anisotropy indicate a systematic relaxation.
Our results suggest that the electromagnetic turbulence plays an important role
on the suprathermalization of the plasma, ultimately lowering the parameter
$\kappa$. Even though the variation of $\kappa$ is in general negative ($\Delta
\kappa <0$) this variation seems to depend of the initial conditions of
anisotropic electrons, which can vary very much in the inner heliosphere.
