Combined treatment with Purpureocillum lilacinum MTL01 and Bacillus velezensis 83 reduces galling by Meloidogyne enterolobii and improves flowering in greenhouse-grown tomato

Abstract M. enterolobii is an emergent phytopathogenic nematode that infects and reduces the yields of commercially important vegetables, such as tomatoes (Solanum lycopersicum). In Mexico, M. enterolobii has gained access to states previously unknown to be affected by it, especially northern states such as Sinaloa, which is the main producer of tomato in the country. Formulations based on antagonistic microorganisms exist in the Mexican market and are used in combination with chemically synthesized pesticides, which although effective are also unspecific and even toxic to other animals and humans. The ascomycetes Purpureocillum lilacinum (previously, Paecilomyces lilacinus) is an effective nematicide already used in different commercial formulations. Here, we aimed to determine the combined effect of an environmental strain of P. lilacinum MTL01 that we isolated, with spores of B. velezensis 83 that is also a growth promoter of tomato. Our findings of two assays in greenhouse conditions of tomato development treated with MTL01 and B. velezensis 83, either individually or in combination, and then challenged with stage-2 juveniles (J2) of M. enterolobii, indicate that the combined treatment is useful for reducing galling and stimulating flowering, with the potential of better yields to produce greenhouse-grown tomato.