Infected host macerate enhances entomopathogenic nematode movement towards hosts and infectivity in a soil profile

Abstract

Vertical dispersal and infectivity of the infective juveniles (IJs) of three entomopathogenic nematodes (EPNs), Steinernema carpocapsae, S. feltiae, and Heterorhabditis bacteriophora, were tested in the presence or absence of cadaver macerate of nematode-infected Galleria mellonella. Infected host macerate applied on the top of column surface induced higher numbers of IJs to move to the bottom of the column for all three species, indicating a dispersal-enhancing effect of host cadaver on IJs. Among the three EPNs, H. bacteriophora was the most responsive to host macerate, followed by S. feltiae, and S. carpocapsae was the least. Also, more IJs of H. bacteriophora invaded Tenebrio molitor hosts at the bottom of soil columns in the presence of host macerate compared with the treatment without cadaver macerate. These findings suggest enhanced dispersal and/or infectivity of all three EPNs may be leveraged toward superior biocontrol efficacy.