The tolerance of Trichoderma species to organophosphorus pesticides is necessary for their application in the bioremediation of pesticide-polluted environments. In some cases, such a requirement is also key to the synergistic use of these fungi with chemical pesticides, aiming to broaden the scope of control targets to include both plant pathogens and insect pests. However, the mechanism of Trichoderma tolerance of organophosphorus pesticides remains unclear. To address this, we have analyzed the function of the putative dichlorvos-tolerance gene hex1 by knocking it out. The hex1-deleted mutant showed loss of Woronin bodies and decreased tolerance to the organophosphate, dichlorvos. Moreover, HEX1 localizes at the septal plugs in mycelium which may be involved in controlling intracellular movement of dichlorvos. hex1 thus is involved the tolerance to dichlorvos and the formation of Woronin bodies in Trichoderma atroviride.