A trail pheromone mediates the mutualism between ants and aphids

Area of Science:

• Ecology
• Chemical Ecology
• Entomology

Background:

• Mutualisms between ants and aphids are common and depend on balanced costs and benefits.
• Ant trail pheromones mediate interactions, but their role in enhancing mutualistic benefits is not fully understood.

Purpose of the Study:

• To investigate how Solenopsis invicta (red imported fire ant) trail pheromones affect the mutualistic relationship with Aphis gossypii (cotton aphid).
• To identify specific pheromone components and their effects on aphid dispersal and reproduction.

Main Methods:

• Behavioral assays were used to test aphid responses to specific trail pheromone components.
• The effects of Z,E-α-farnesene and E,E-α-farnesene on aphid dispersal and reproduction were quantified.

Main Results:

• Two trail pheromone components, Z,E-α-farnesene and E,E-α-farnesene, suppressed aphid dispersal.
• The major component, Z,E-α-farnesene, also stimulated aphid reproduction.
• These effects benefit both the ants (increased honeydew availability) and aphids (increased population growth and protection).

Conclusions:

• Ant trail pheromones have a previously unrecognized inter-species function that enhances mutualistic benefits.
• This pheromonal mechanism likely strengthens the stability of ant-aphid mutualisms.
• The findings reveal a novel pathway for optimizing symbiotic interactions.