Abstract: The nematophagous fungus Pochonia chlamydosporia (Clavicipitaceae) can parasitizeeggs of cyst (Globodera spp., Heterodera spp.), root-knot (Meloidogyne spp.) and false root-knot(Nacobbus spp.) nematodes. Its potential as a biological control agent has been the subject ofnumerous studies to understand the micro-ecological conditions, including the tri-trophic (e.g.,plant, fungus, nematode) and host-parasite relationships that allow the fungus to thrive in the soiland rhizosphere environment. Pochonia survives in soil in the absence of a nematode host and,although it behaves as a saprophyte, research evidence points to a physiological ‘switch’ fromsaprophytic to parasite stages triggered by nutrition. Fungal chlamydospore-based products forapplication to soil as an inoculum have been shown to be commercially viable. However, adeeper understanding of the biology and physiology of the host-parasite interaction could providenew insights leading to an improvement in commercial production methodology.