Volatile organic compounds of Metarhizium brunneum influence the efficacy of entomopathogenic nematodes in insect control

• Metarhizium VOCs, 1-octen-3-ol and 3 octanone, influence behaviour of EPN. High doses octanone repel or kill EPN infective juveniles. volatiles reduce infectivity insect hosts. VOCs immobilise insects. Volatiles affect reproduction inside host. The entomopathogenic fungus (EPF) brunneum occupies the same ecological niche as nematodes (EPN), with both competing for insects a food source in rhizosphere. Interactions between these biocontrol agents can be antagonistic synergistic. To better understand interactions, this study focussed on investigating effect M. volatile organic compounds (VOCs), 3-octanone, survival behaviour. These proved to highly toxic juveniles (IJs) Steinernema carpocapsae , feltiae Heterorhabditis bacteriophora mortality being dose dependent. Chemotaxis studies H. IJs Pluronic F127 gel revealed significant preference compared controls all tested concentrations. also impacted test dose-dependent manner 3-octanone more Galleria mellonella Cydia splendana Curculio elephas larvae than 1-octen-3-ol. Mortality C. G. was significantly higher when exposed relatively high (>25%) 3-octanone. Lower immobilised insects, which recovered after exposure fresh air 2 hrs. In depth showed that > 10% concentration negatively affected whereas lower (0.1%, 0.01%) had no effect. IJs, reducing penetration efficacy number generations but they failed inhibit bacterial symbiont, Photorhabdus kayaii . significance how could EPF-EPN interactions is discussed.