| Summary: | Abstract Background In the current years, nematotoxic or antagonistic compounds for example, toxins, enzymes, or compounds derived from the metabolites of fungal culture filtrates have greatly increased. Objective This research was designed to evaluate two fungi, Beauveria bassiana and Metarhizium anisopliae, commonly used only as bio-insecticides in Egypt for their nematicidal potential compared to Paecilomyces lilacinus, one of the most important fungi parasitizing on eggs of root-knot nematode, Meloidogyne incognita. Results The tested fungi either as filtrate or spore affected egg hatching and survival of second stage juveniles at different degrees according to fungal filtrate dilution and spore concentration and exposure period under in vitro study. Under screen house conditions, the tested fungi as filtrates or spores were used to control root-knot nematode on cowpea. The overtopped significant results were gained with P. lilacinus filtrate at standard dilution and recorded the highest mean overall percentages nematode reduction (84.5%). The second rank was obtained by B. bassiana culture filtrate, where it significantly reduced all nematode numbers with a mean of 81.1% at standard dilution. M. anisopliae caused 78.5% as a mean percentages nematode reduction followed by other dilutions and untreated check. When using spore concentrations, the overtopped significant results were gained with P. lilacinus at the highest spore concentration (1 × 108) and recorded the highest mean percentages nematode reduction (85.3%). The second rank was obtained by M. anisopliae, where it reduced all nematode numbers as an average of 83.6%. B. bassiana caused 77.1% as a mean percentages nematode reduction at the highest spore concentration. At all cases, all treatments significantly promoted plant growth and yield criteria and these increases were positively proportional to the filtrate dilution or spore concentration higher than the untreated plants. Conclusions It can be concluded that B. bassiana, M. Anisopliae, and P. lilacinus as antagonistic fungi proved to be efficient against root-knot nematode, incognita infecting cowpea as they reduced nematode criteria which subsequently improved plant growth and yield of cowpea.
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