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

Area of Science:

• Entomology
• Nematology
• Biological Control

Background:

• Entomopathogenic nematodes (EPNs) are crucial biological control agents.
• Understanding factors influencing EPN dispersal and infectivity is key to optimizing their use.
• Host cadaver cues are known to influence nematode behavior.

Purpose of the Study:

• To investigate the effect of host cadaver macerate on the vertical dispersal and infectivity of three EPN species.
• To compare the responsiveness of Steinernema carpocapsae, Steinernema feltiae, and Heterorhabditis bacteriophora to host cues.
• To assess the potential for enhanced biocontrol through manipulation of host-derived signals.

Main Methods:

• Soil columns were used to assess vertical dispersal of EPN infective juveniles (IJs).
• EPNs were tested in the presence and absence of Galleria mellonella cadaver macerate.
• Infectivity was evaluated by observing the invasion of Tenebrio molitor hosts at the bottom of the columns.

Main Results:

• Host cadaver macerate significantly increased the downward movement of IJs for all three EPN species.
• Heterorhabditis bacteriophora showed the highest responsiveness to cadaver macerate, followed by S. feltiae, then S. carpocapsae.
• The presence of cadaver macerate led to increased invasion of T. molitor hosts by H. bacteriophora IJs.

Conclusions:

• Host cadaver macerate enhances both dispersal and infectivity of the tested EPNs.
• H. bacteriophora exhibits a stronger response to host cues compared to the Steinernema species.
• Leveraging host cadaver cues could significantly improve the efficacy of EPN-based biological control strategies.