Potent Ant Deterrents Emitted from Nematode-Infected Insect Cadavers

Area of Science:

• Agricultural Science
• Entomology
• Chemical Ecology

Background:

• Entomopathogenic nematodes (EPNs) are natural insect parasites, often relying on symbiotic bacteria for host mortality.
• Insects, particularly ants, avoid EPN-infected cadavers, suggesting evolved defense mechanisms against these pathogens.
• The specific chemical cues (semiochemicals) responsible for this ant avoidance behavior remain unidentified.

Purpose of the Study:

• To identify the semiochemicals emitted by EPN-infected insects that deter ants.
• To investigate the repellent properties of identified compounds against ants.
• To explore the potential application of these compounds in pest management.

Main Methods:

• Behavioral assays using ants (Lasius niger) and EPN-infected vs. uninfected insect larvae.
• Chemical analysis (e.g., gas chromatography-mass spectrometry) to identify volatile compounds from infected larvae.
• Laboratory experiments to test the deterrent effect of isolated compounds on ant feeding behavior.

Main Results:

• Hexadecanal and 2-heptadecanone were identified as compounds emitted specifically by larvae infected with the EPN Steinernema feltiae.
• These two compounds significantly deterred ants (Lasius niger) when added to a food source.
• Uninfected larvae did not emit these repellent compounds.

Conclusions:

• Hexadecanal and 2-heptadecanone act as semiochemical repellents, mediating ant avoidance of EPN-infected insect cadavers.
• These naturally occurring compounds represent promising, environmentally benign agents for deterring ants and potentially other pests.
• Further research is warranted to fully assess the practical applications of these semiochemicals in pest control strategies.