  Nonequilibrium instabilities are known to lead to exponential amplification
of boson occupation numbers for low momentum modes on time scales much shorter
than the asymptotic thermal equilibration time. We show for Yukawa-type
interactions that this growth induces very efficient fermion production, which
proceeds with the maximum primary boson growth rate. The description is based
on a 1/N expansion of the 2PI effective action to NLO including boson-fermion
loops, which are crucial to observe this phenomenon. For long enough
amplification in the boson sector, fermion production terminates when the
thermal occupancy is reached in the infrared. At higher momenta, where boson
occupation numbers are low, the fermion modes exhibit a power-law regime with
exponent two.
