Optimization of a Bacillus-based bioproduct for Meloidogyne incognita (Kofoid & White, 1919) Chitwood, 1949 (Tylenchida: Meloidogynidae) control using response surface methodology

Root-knot nematodes (RKNs) cause significant yield losses in agriculture. Environmentally friendly bioproducts are important components of sustainable nematode management. This study evaluated the efficacy of two commercial Bacillus bioproducts, Bacillus amyloliquefaciens MBI 600 (Bioproduct-I) and Bacillus subtilis QST 713 (Bioproduct-II), against Meloidogyne incognita (Kofoid & White, 1919) Chitwood, 1949 (Tylenchida: Meloidogynidae), a major RKN species, on tomato plants. The trial, conducted in 2024 at Bolu Abant İzzet Baysal University, Faculty of Agriculture, Department of Plant Protection, assessed root gall index, number of second-stage juveniles (J2) and number of egg masses in pot experiments at seed and seedling stages. The dose of Bioproduct-I was optimized using response surface methodology (RSM) and design of experiments (DOE), with results visualized using Pareto and normal plots. The 1000 ml/ha dose of Bioproduct-I was characterized by the lowest root gall index (2.37 in seed, 2.75 in seedling) and the lowest number of J2 (382.5 in seed, 415.0 in seedling). However, higher doses showed reduced efficacy, indicating that increasing concentrations did not increase biological activity. This study highlights the potential of Bacillus spp. for biological control and demonstrates the usefulness of statistical tools in optimizing Bioproduct applications against RKN.