  We study the transition to turbulence of channel flow of finite-size particle
suspensions at low volume fraction, i.e. $\Phi \approx 0.001$. The critical
Reynolds number above which turbulence is sustained reduces to $Re \approx
1675$, in the presence of few particles, independently of the initial
condition, a value lower than that of the corresponding single-phase flow, i.e.
$Re\approx1775$. In the dilute suspension, the initial arrangement of the
particles is important to trigger the transition at a fixed Reynolds number and
particle volume fraction. As in single phase flows, streamwise elongated
disturbances are initially induced in the flow. If particles can induce oblique
disturbances with high enough energy within a certain time, the streaks
breakdown, flow experiences the transition to turbulence and the particle
trajectories become chaotic. Otherwise, the streaks decay in time and the
particles immigrate towards the channel core in a laminar flow.
