A Pseudacteon sp. of decapitating phorid fly parasitizes the aggressive arboreal ant species, A. instabilis through the use of chemical and visual host location cues, thus preventing the ants from dominating resources and preying on herbivores within coffee agroecosystems. Experiments were performed in Chiapas, Mexico on a shade coffee farm with extracts of A. instabilis body parts to determine the anatomical source of the phorid attractants. Two compounds, 2-methyl-cyclopentan-1-one and 1-acetyl-2-methyl-cyclopentane, known to be present within the Pigidial gland of the A. instabilis were then tested as potential phorid attractants. Visual cues used by the phorid flies were also tested using a 3-D model of swarming ants in order to determine the importantace of motion, size, shape and color of individuals attacked.
Results/Conclusions
The kairomone was determined to be present within the dorsal section of the abdomen where the Pigidial gland is located. This gland is responsible for the production of alarm-defense pheromones in Azteca spp. Further observations indicate that one compound 1-acetyl-2-methylcyclopentane, known to be present within the pigidial gland of A. instabilis is at least partially responsible for attracting these phorid flies to their host. While visual cues such as movement and shape were found to be important in host location, other factors such as size of the ant and color were found to have no effect of phorid host choice.
