  We derive the equations of motion of a test particle in the equatorial plane
around a static and spherically symmetric wormhole influenced by a radiation
field including the general relativistic Poynting-Robertson effect. From the
analysis of this dynamical system, we develop a diagnostic to distinguish a
black hole from a wormhole, which can be timely supported by several and
different observational data. This procedure is based on the possibility of
having some wormhole metrics, which smoothly connect to the Schwarzschild
metric in a small transition surface layer very close to the black hole event
horizon. To detect such a metric-change, we analyse the emission proprieties
from the critical hypersurface (stable region where radiation and gravitational
fields balance) together with those from an accretion disk in the Schwarzschild
spacetime toward a distant observer. Indeed, if the observational data are well
fitted within such model, it immediately implies the existence of a black hole;
while in case of strong departures from such description it means that a
wormhole could be present. Finally, we discuss our results and draw the
conclusions.
