Identification of a pheromone regulating caste differentiation in termites

Area of Science:

• Chemical Ecology
• Insect Behavior
• Social Biology

Background:

• Social insects exhibit a caste system where queens monopolize reproduction and workers perform other tasks.
• Queen-produced pheromones are hypothesized to inhibit reproductive differentiation in workers, but specific compounds remain largely unidentified.

Purpose of the Study:

• To identify the chemical components of inhibitory pheromones regulating caste differentiation in social insects.
• To investigate the dual role of identified volatiles in caste regulation and worker attraction.

Main Methods:

• Gas chromatography-mass spectrometry (GC-MS) for chemical identification of pheromones.
• Behavioral assays using artificial pheromone blends to test inhibitory and attractant effects.
• Analysis of volatile emissions from reproductives and eggs.

Main Results:

• Identification of n-butyl-n-butyrate and 2-methyl-1-butanol as key components of a volatile inhibitory pheromone produced by secondary queens (neotenics).
• An artificial blend of these compounds effectively suppressed reproductive differentiation, mimicking the effect of live neotenics.
• The same volatiles are emitted by eggs, acting as worker attractants and inhibitors of reproductive differentiation.

Conclusions:

• A volatile pheromone regulates caste differentiation in termites, providing insights into social insect colony dynamics.
• The dual role of these compounds as both attractants and inhibitors suggests a mechanism for honest signaling of reproductive status.
• This discovery opens new avenues for understanding the developmental pathways of reproductive and non-reproductive castes.