  We use direct and stochastic numerical simulations of the magnetohydrodynamic
equations to explore the influence of turbulence on the dynamo threshold. In
the spirit of the Kraichnan-Kazantsev model, we model the turbulence by a
noise, with given amplitude, injection scale and correlation time. The addition
of a stochastic noise to the mean velocity significantly alters the dynamo
threshold. When the noise is at small (resp. large) scale, the dynamo threshold
is decreased (resp. increased). For a large scale noise, a finite correlation
time reinforces this effect.
