Aerosol delivery of trail pheromone disrupts the foraging of the red imported fire ant, Solenopsis invicta.

BACKGROUND The fire ant, Solenopsis invicta, is one of the most aggressive and invasive species in the world. The trail pheromone Z,E-α-farnesene (91% purity) was prepared, and disruption of worker trail orientation was tested using an ethanol-based aerosol formulation presenting a single puff of this compound by airbrush and compressed air. Trail-following behaviour was recorded by overhead webcam and ants digitised before and after presentation of the aerosol treatment at four rates (1.6, 16, 160 and 1600 ng cm(-2)). RESULTS Ants preferred 110 ng cm(-1) over 11, 1.1 and 0.11 ng cm(-1) for trail following. Within seconds of presentation of 1600 ng cm(-2), the highest dose tested, trail disruption was observed. Disruption was evident as reduced arrival success and reduction in the trail integrity statistic (r(2)), as well as increased deviation from the trail (deg). The distribution of walking track angles was also flattened. CONCLUSIONS The feasibility of using aerosol for delivery of trail pheromone was demonstrated, but the need for high purity combined with the difficulty of commercial supply makes this technique impractical. However, the commercial production of Z,E-α-farnesene of high purity by industrial biotechnology or from (E)-nerolidol may be possible in future, which would facilitate further development of trail pheromone disruption of S. invicta.