Hyperparasitic Attack of Trichothecium roseum on Conidia of Pestalotiopsis funerea

Trichothecium roseum (Tr) has been shown to be a highly effective hyperparasite on conidia of Pestalotiopsis funerea (Pf) in vivo and in vitro. The stages of this spore parasitism are: positive tropism of Tr towards Pf conidia, contact between Tr and Pf, formation of simple or lobed appressoria of Tr on the host conidial surface, penetration of the attacked host cells from the base of the appressoria, development of host-internal, mostly branching parasitic hyphae by Tr, desintegration, lysis and death of the parasitized host cells, exit of Tr from the destroyed host cells and its intensive sporulation over Pf remnants. Pf did not show any defence reactions against the attack by Tr. In addition to the antagonistic activities of Tr against Pf reported previously, which are due to extracellular toxins released by Tr, direct hyperparasitism is a second mechanism of antagonism, which contributes to the successful competitive ability of Tr in this fungal interaction.