First Report on the Parasitic Potential of Paraconiothyrium cyclothyrioides Against Meloidogyne incognita

Meloidogyne incognita , the root‐knot nematode (RKN), poses a significant threat to agricultural productivity by inflicting severe damage on a wide range of crops. This study examined the potential of the fungus Paraconiothyrium cyclothyrioides as a biological control agent against M. incognita using in vitro and greenhouse experiments. In vitro assays demonstrated a strong parasitic effect on second‐stage juveniles (J2s), achieving a 93.4% mortality rate at 1.3 × 10 8 conidia mL −1 after 72 h. The fungus also significantly inhibited egg hatching, reducing it by up to 71.5% at 1.3 × 10 8 conidia mL −1 . Greenhouse trials further confirmed the efficacy of P. cyclothyrioides , with treated plants exhibiting an 80.0% reduction in root galling, a 90.5% decrease in egg numbers, and an 88.7% decline in J2s in soil at the highest fungal concentration. Additionally, plant growth parameters, including stem diameter, root and shoot length, root and shoot weight, flower and fruit production, were significantly enhanced. Microscopic observations revealed fungal colonisation of the nematode bodies, leading to deformation, rupture, and complete parasitisation. These findings suggest that P. cyclothyrioides exerts nematicidal effects through direct parasitism and secondary metabolite production. Given its dual role in nematode suppression and plant growth promotion, P. cyclothyrioides has potential as a sustainable approach for managing M. incognita .