  We consider a fermionic dark matter (DM) particle in renormalizable Standard
Model (SM) gauge interactions in a simple $t$-channel model. The DM particle
interactions with SM fermions is through the exchange of scalar and vector
mediators which carry colour or lepton number. In the case of coloured
mediators considered in this study, we find that if the DM is thermally
produced and accounts for the observed relic density almost the entire
parameter space is ruled out by the direct detection observations. The bounds
from the monojet plus missing energy searches at the Large Hadron Collider are
less stringent in this case. In contrast for the case of Majorana DM, we obtain
strong bounds from the monojet searches which rule out DM particles of mass
less than about a few hundred GeV for both the scalar and vector mediators.
