Can pre-colonisation of the soil substrate increase the efficacy of entomopathogenic nematodes (Rhabditida: Steinernematidae)?

Can pre-colonisation of the soil substrate increase the efficacy of entomopathogenic nematodes (Rhabditida: Steinernematidae)? The effects of soil pre-colonisation with entomopathogenic nematodes Steinernema feltiae, S. carpocapsae and S. arenarium on the mortality of Tenebrio molitor larvae were tested under laboratory conditions. The soil was inhabited with the nematodes for 7 days prior to the addition of the larvae. Nematode concentrations of 50 and 500 infective juveniles per box were used. S. carpocapsae reacted to pre-colonisation negatively and the efficacy decreased at the concentrations tested. S. arenarium showed generally low efficacy against Tenebrio molitor larvae and pre-colonisation showed only a slight positive effect on the efficacy of this species. S. feltiae increased its efficacy at the concentration of 500 infective juveniles per box compared with other tested nematodes.