Antagonistic Activity of Purpureocillium lilacinum PL2 Against Root-Knot Nematode (Meloidogyne incognita) Infection on Pepper Plants

Abstract

Root-knot nematodes, particularly Meloidogyne incognita, pose a significant threat to pepper (Piper nigrum) cultivation, causing substantial agricultural losses. This study aimed to isolate, characterise and evaluate the effectiveness of the local nematophagous fungus Purpureocillium lilacinum PL2 as a biological control agent against M. incognita. The fungal strain was isolated from pepper plantation soils and underwent comprehensive morphological, molecular and functional characterisation. P. lilacinum PL2 demonstrated remarkable adaptability, surviving in pH ranges of 5–8 and showing consistent growth under various lighting conditions. Enzymatic analysis revealed the potential synthesis of degrading enzymes, including chitinase and protease, which facilitate the destruction of nematode eggshells and cuticles. Sporulation was successfully achieved through solid-state fermentation using cost-effective substrates like rice and maize. In vitro lethal assays demonstrated the fungus's high efficacy in parasitising both nematode eggs (74.33% ± 8.52% mortality) and females (92.5% ± 6.12% mortality). Field trials further validated its potential, revealing a significant 57.7% ± 11.76% reduction in mobile nematode populations after 15 days of treatment. These findings highlight P. lilacinum PL2 as a promising eco-friendly biological control agent, offering a sustainable approach to managing root-knot nematodes in pepper plantations.