Effects of parasitoids on ant competition

To test the trait-mediated indirect interactions by phorid flies on ant interactions we experimentally 1). Quantified the number of ant workers competing over time in the presence and absence of phorid flies. 2)  Transplanted nests in trees dominated by  W.  auropunctata and L. iniquum.  To  assess competitive   ant interactions,  colonies of W. auropunctata and L.  iniquum were randomly selected from coffee trees  in the plot.  To  attract  and collect phorid flies in the field,  workers of L. iniquum were squashed by  hand at each tree stand.  Phorid flies  were aspirated and placed in plastic containers in tents.  Due to   their fragility, phorid flies were kept in containers for less than 2 hours. Controls consisted of collected W. auropunctata and L. iniquum nests placed in containers connected by an artificial platform with droplets of honey resources placed at the center. Treatments consisted of W. auropunctata and L. iniquum colonies, in addition to phorid flies that were introduced at the beginning the experiment. Once the ants began foraging and replenished with honey, we recorded the number of ants at the bait ever minute for a maximum of 60 minutes or until all baits were occupied by 10 or more ants. Experiments were replicated 4 times for each interaction.

Parasitoid searching efficiency

We measured arrival times of phorid flies to trees occupied by  L. iniquum.  We  identified four major   ant clusters within the 5-ha plot. The overwhelming majority of trees were occupied by W. auropunctata, while the remaining trees were dominated by L.  iniquum and Brachymyrmex species (fig 4.2).  Within  the largest W. auropunctata cluster, several trees were occupied by L. iniquum. Within the three smaller clusters, W. auropunctata was detected on several trees. We randomly selected four trees occupied by L. iniquum in the largest cluster and four trees occupied in the smaller clusters. At each tree, we  disturbed L. iniquum nests by squashing their workers by hand and recorded the arrival time of phorid flies.