Effect of exsheathment on motility and pathogenicity of two entomopathogenic nematode species

Area of Science:

• Entomology
• Nematology
• Molecular Biology

Background:

• Entomopathogenic nematodes (EPNs) are crucial biological control agents.
• The sheath, a protective cuticle layer, plays a role in nematode survival and infectivity.
• Understanding sheath dynamics is key to optimizing EPN applications.

Purpose of the Study:

• To investigate the impact of sheath loss on the motility and pathogenicity of Heterorhabditis bacteriophora and Steinernema carpocapsae.
• To determine if sheath loss, independent of host stimuli, influences nematode behavior.

Main Methods:

• EPNs were exsheathed naturally and chemically.
• Motility was assessed on agar plates with and without host presence.
• Pathogenicity was evaluated using standard bioassays.

Main Results:

• Exsheathed Steinernema carpocapsae exhibited enhanced motility on agar.
• Host presence significantly increased motility in all S. carpocapsae treatments.
• Desheathed Heterorhabditis bacteriophora showed reduced motility, potentially due to chemical treatment side effects.
• Sheath loss did not alter the pathogenicity of either nematode species.

Conclusions:

• Sheath loss can activate host-finding behaviors in S. carpocapsae, complementing host stimuli.
• The effect of sheath loss on motility is species-specific.
• EPN pathogenicity remains robust despite sheath loss, indicating resilience in biological control applications.