Effect of host condition and soil texture on host finding by the entomogenous nematodes Heterorhabditis bacteriophora (Rhabditida: Heterorhabditidae) and Steinernema carpocapsae (rhabditida: Steinernematidae)

Laboratory experiments were conducted to determine the effect of soil texture and condition of Galleria mellonella larvae (infected with Beauveria bassiana, uninfected and alive, or uninfected and killed by freezing) on host-finding by the entomogenous nematodes, Heterorhabditis bacteriophora and Steinernema carpocapsae. H. bacteriophora was more motile than S. carpocapsae in organic and fine sandy loam soils, but less motile in clay soil. In soil-filled tubes, H. bacteriophora and S. carpocapsae usually occurred more frequently near healthy hosts when healthy hosts were present in choice tests. When a Beauveriainfected host was included in a choice test, nematodes tended to occur more frequently at the host not infected with B. bassiana. This behavior may minimize antagonistic interactions between entomogenous nematodes and B. bassiana in soil.