Microbiota from Meloidogyne exigua egg masses and evidence for the effect of volatiles on infective juvenile survival

Abstract

Egg masses of Meloidogyne exigua from coffee plants are subjected to a range of microbial populations and these resident soil organisms in the egg masses may affect nematode communities. The incidence of fungi and bacteria in M. exigua egg masses was investigated and the toxic effect of their volatile organic compounds (VOCs) was tested on second-stage juveniles (J2). Bacteria and fungi were isolated from egg masses on coffee root and identified to species. The nematicidal activity of VOCs from bacterial and fungal strains was tested against M. exigua in in vitro experiments. Several bacterial and fungal strains were found in M. exigua egg masses and produced VOCs that were toxic to M. exigua J2. Bacterial strains induced more nematode mortality compared with fungal strains. The continued colonisation of fungi and bacteria in M. exigua egg masses occurred during the year and their VOCs reduced the viable inocula of M. exigua and should be explored as biocontrol agents.