First Record of Pantoea conspicua Bacteria Isolated from Hypera brunneipennis and Its Ability for Biocontrol of Root-Knot Nematodes in Tomato Plants

Root-knot nematodes ( Meloidogyne spp.) are among the most destructive agricultural obligate endoparasites worldwide, causing substantial yield losses across numerous crops. Current management options are limited, and the overuse of chemical nematicides poses serious risks to human health and the environment. In this study, a bacterial isolate was investigated as a biocontrol agent against Meloidogyne incognita, identified as Pantoea conspicua strain PC (GeneBank accession ON203125) based on 16S rRNA (ribosomal RNA) gene sequencing. Exposure of second-stage juveniles (J2s) caused mortality rates of 67.9, 94.7, 97.7, and 99.3% in M. incognita at 12, 24, 48, and 96 h after exposure to a 100% concentration of bacterial filtrate, respectively. In comparison, bacterial pellets resulted in 18.5, 51.8, 62.9, and 82.9% mortality at the same time intervals. Both the bacterial filtrate and pellets significantly inhibited egg hatchability in vitro. A greenhouse experiment demonstrated that tomato plants treated with the bacterial filtrate or pellets exhibited marked improvements in root and shoot growth parameters. Specifically, the bacterial filtrate reduced the number of galls, eggs, and egg masses per gram of root by 93.12, 97.9, and 79.9%, respectively, along with a 92.7% decrease in J2s per 250 g of soil. Overall, P. conspicua strain PC demonstrated high potential as a biocontrol agent, offering advantages in its mode of action, efficacy, and contribution to ongoing nematode management while also reducing the environmental impact and supporting integrated pest management strategies.