  Neptune Trojans and Plutinos are two subpopulations of trans-Neptunian
objects located in the 1:1 and the 3:2 mean motion resonances with Neptune,
respectively, and therefore protected from close encounters with the planet.
However, the orbits of these two kinds of objects may cross very often,
allowing a higher collisional rate between them than with other kinds of
trans-Neptunian objects, and a consequent size distribution modification of the
two subpopulations.
  Observational colors and absolute magnitudes of Neptune Trojans and Plutinos
show that i) there are no intrinsically bright (large) Plutinos at small
inclinations, ii) there is an apparent excess of blue and intrinsically faint
(small) Plutinos, and iii) Neptune Trojans possess the same blue colors as
Plutinos within the same (estimated) size range do.
  For the present subpopulations we analyzed the most favorable conditions for
close encounters/collisions and address any link there could be between those
encounters and the sizes and/or colors of Plutinos and Neptune Trojans. We also
performed a simultaneous numerical simulation of the outer Solar System over 1
Gyr for all these bodies in order to estimate their collisional rate.
  We conclude that orbital overlap between Neptune Trojans and Plutinos is
favored for Plutinos with large libration amplitudes, high eccentricities, and
small inclinations. Additionally, with the assumption that the collisions can
be disruptive creating smaller objects not necessarily with similar colors, the
present high concentration of small Plutinos with small inclinations can thus
be a consequence of a collisional interaction with Neptune Trojans and such
hypothesis should be further analyzed.
