Maximum dust density fluctuations and maximum transverse magnetic field as a function of time upon propagation of a circularly polarized Alfvén wave, for different values of wavelength (as a fraction of the box length L) and wave amplitudes δ_B within the dusty ideal MHD regime and dusty non-ideal MHD regime (see Sects. 2.2 and 2.1). The early sharp rise in dust density is due to a mechanism similar to the parametric instability (Del Zanna et al. 2001). Note that growth rates measured here compare well with analytical predictions of the standard parametric instability (see Appendix C). Afterwards, the dust density decreases as a consequence of gas dust friction. The gas density is not displayed because subject to negligible variations. Parameters: n_H=10⁶ cm⁻³, s_d=10 μm(St = 0.01) and β=0.1.