Argentine ant (Hymenoptera : Formicidae) trail pheromone enhances consumption of liquid sucrose solution

We investigated whether the Argentine ant, Linepithema humile (Mayr), trail pheromone, ZS-16:Ald, could. enhance recruitment to and consumption of liq uid sucrose solutions. All tests were done as paired comparisons with a 10% sucrose solution as food. In the laboratory, mixing 20 mu l of a 10-mu g/m l solution of the pheromone with 50 mu l of the 10% sucrose solution increa sed the number of ants feeding by >150%. In a field test, we combined the t rail pheromone with a 10% sucrose solution in 50-ml vials. These vials were covered with a plastic membrane that has 1.5-mm-diameter holes punched uni formly across its surface. Ants could drink from the holes after the vials were inverted. For half of the vials, 1 mu g of the pheromone was put onto the plastic membrane before the vials were filled with a 10% sucrose soluti on. The remaining vials had no pheromone on the plastic membrane. After 4 h we measured the consumption in each vial. Bait consumption with the pherom one was enhanced by 29%. In a 2nd series of tests, vials were left outside for 24 h. The consumption rate was 33% higher with the pheromone compared w ith the controls that didn't have pheromone.