Effect of Acrostalagmus luteoalbus ACRO1 on Mortality of the Second-stage Juveniles of the Citrus Nematode Tylenchulus semipenetrans under Laboratory Conditions

This study investigates the nematicidal activity of Acrostalagmus luteoalbus ACRO1 as a potential biocontrol agent against the citrus nematode Tylenchulus semipenetrans under laboratory conditions. The ACRO1 isolate was cultured in potato extract-dextrose broth, and its nematicidal metabolites were extracted using ethyl acetate. Its effectiveness was assessed in comparison to Purpureocillium lilacinum, a known biocontrol agent, and abamectin, a chemical nematicide. ACRO1 demonstrated remarkable nematicidal efficacy, achieving an average mortality rate of 81.5% within 72 hours, significantly surpassing P. lilacinum (46.3%) and the negative control (6.5%). In a secondary experiment, ACRO1 induced 58.7% mortality in 72 hours, again outperforming P. lilacinum (26.2%) and the control (6.25%). Its cell-free culture extract exhibited rapid activity, reaching 76.0% mortality within 24 hours, while its metabolites achieved complete nematicidal efficacy with 100% mortality. By comparison, abamectin induced mortality rates of 53.2%, 62.2%, and 100% at concentrations of 5 ppm, 10 ppm, and 3%, respectively. These findings underscore ACRO1’s potential as an effective and environmentally friendly alternative to synthetic nematicides, offering a sustainable solution for managing the citrus nematode, a persistent threat to global citrus production.