Efficacy of formulation of nematode antagonistic bacterium, Pasteuria penetrans (Thorne) Sayre and Starr, 1985 against root-knot nematode, Meloidogyne incognita

Root-knot nematodes, Meloidogyne spp. are extremely polyphagous pests of both tropical and subtropical crops that cause a great reduction in crop yields and quality. In vegetable production, 10–30% yield loss is caused by root-knot nematode infestation. Pasteuria penetrans is a hyperparasitic bacterium of M. incognita that has a high degree of biocontrol potential. Though, the application of P. penetrans in the form of root powder had been tested by a few scientists in the nurseries, it is highly impractical in the main fields. Commercial formulation of this bacterium is not available in India till date. Based on these facts, four different formulations of P. penetrans viz., kaolinite clay, Emulsifiable Concentrate (EC), wettable talc powder and sodium alginate beads were prepared and tested for its parasitization potential. Among the four, EC formulation showed the highest parasitization potential of 84.6% with a spore load of 11.2/J2 (second stage juvenile). These formulations were stored under room temperature (27±1ºC) to record spore viability. The observation showed that the spores were viable upto 60 days with the highest parasitization of 84.7% in EC formulation. An in-vitro test was carried out in tomato plants to document the infection in M. incognita by endospores released from the formulations. The observation also showed that the spores released from the formulations were multiplied in the female body. Two cell stage and four cell stages of spores were observed in J3 and pre-adult stages of the nematode. The results of this study showed that the EC formulation is highly suitable for field application.