Nematicidal activity of Trichoderma longibrachiatum PT6 protein culture filtrate under different environmental factors and storage periods

To determine the toxic activity and stability of Trichoderma longibrachiatum PT6 protein culture filtrate against second stage juveniles (J₂s) of Heterodera avenae, the in vitro nematicidal activity of PT6 protein culture filtrate was analyzed and evaluated under different environmental factors and storage periods. Different pH, temperature, metal ions, redox concentrations, and storage periods presented different effects on the nematicidal activity and stability of the PT6 protein culture filtrate. The PT6 protein culture filtrate had a high lethal effect on J₂s of the cereal cyst nematode, with more than 80% mortality with treatment at pH 4～10 for 72 h, and no significant difference compared with the control. At the temperature of 30～60 ℃, there was no significant difference in the nematicidal activity of PT6 protein culture filtrate in comparison to the control. The nematicidal activity decreased significantly at temperatures higher than 70 ℃. Zn²⁺ and K⁺ clearly enhanced the nematicidal activity of PT6 protein culture filtrate, whereas Cu²⁺ inhibited the nematicidal activity. However, Mg²⁺, Fe²⁺, Mn²⁺, and Na⁺ had no significant effect on the nematicidal activity of PT6 protein culture filtrate. At an oxidant concentration lower than 0.08 mol·L⁻¹ and reducing agent concentration lower than 0.06 mol·L⁻¹, no significant effect was observed on the nematicidal activity of J₂s ofH. avenae. Storage of the culture filtrate at room temperature for 0～60 days did not result in significant changes in nematicidal activity. Therefore, the PT6 protein culture filtrate had a strong lethal effect on the cereal cyst nematode, and its nematicidal activity was stable.