  Dusty plasmas are known to support a diverse range of instabilities,
including both generalizations of standard plasma instabilities and ones caused
by effects specific to dusty systems. It has been recently demonstrated that a
novel broad class of streaming instabilities, termed resonant drag
instabilities (RDIs), can be attributed to a particular resonance phenomenon,
manifested by defective eigenvalues of the linearized dust/fluid system. In
this work, it is demonstrated that this resonance phenomenon is not unique to
RDIs and can be used as a framework to understand a wider range of
instabilities, termed resonant instabilities. Particular attention is given to
the filamentary ionization instability seen in laboratory dusty plasmas and to
the two-stream instability. It is shown that, due to the commonalities in
underlying physics between the dust-ion-acoustic two-stream instability and the
acoustic RDI, these instabilities should be relevant in strongly overlapping
regimes in astrophysical dusty plasmas. It is proposed that a similar overlap
in the experimental accessibility of these modes (and of the filamentary
instability) allows for the possibility of experimental investigation in the
laboratory of complex and astrophysically relevant instability dynamics.
