Ants communicate using chemical signals, often called pheromones, that enable them to swarm in response to danger or quickly congregate on a picnic blanket. These cues, according to Dr. Athula Attygalle of Stevens Institute of Technology, may also signal fly parasites that rely on ants as hosts.
Dr. Attygalle, an expert in both natural products chemistry and mass spectrometry, has recently been awarded a National Science Foundation (NSF) grant to investigate ant pheromones. Together with evolutionary biologist Dr. Donald Feener of the University of Utah, Salt Lake City, Professor Attygalle intends to find how certain parasitic flies eavesdrop on ants' chemical signals to locate their preferred hosts.
"Prof. Attygalle's research exemplifies the critical connection between chemical expertise and biological research," reports Dr. Philip Leopold, Director of the Department of Chemistry, Chemical Biology and Biomedical Engineering at Stevens. "In this case, Prof. Attygalle is employing highly sensitive analytical chemistry techniques to reveal biological molecules of great significance. Ultimately, this research may identify novel chemical compounds with biological activities that could be used for highly targeted insecticides or possibly even pharmaceuticals."
While pheromones are often associated with chemicals intended to attract the opposite sex, these signals actually do much more. In fact, most organisms "speak" to one another primarily by using the language of chemistry, much as humans use voice and body language. Because most organisms "whisper," rather than "shout" their chemical communications, scientists require very sensitive tools to decipher the enigmatic chemical languages around them.
Mass spectrometry is the only analytical technique that meets the sensitivity demands required to eavesdrop on these messages. Dr. Attygalle has applied his expertise in mass spectrometry to analyze chemicals found throughout nature, which has included characterizing the mandibular gland nodules of over 100 species of ants. Containing a fine cocktail of organic chemicals used to create an assortment of messages that alert the colony to danger or food, ant mandibles provide the voicebox for their chemical speech. For this research, Dr. Attygalle will analyze ant mandibular glands from samples of focal species collected by Dr. Feener's field research teams working in Texas, Costa Rica, Panama, and Peru.
This NSF funded collaborative project seeks to discover the ecological and evolutionary processes that govern host selection and specificity of insect parasitoids of ants in the Phoridae fly family. The group of parasitoids under investigation consists of several hundred species in the Neotropical Region, most of which are extremely specialized, attacking one of a few closely related ant species. The researchers will focus on the chemical signals host ants use in communications—the pheromones—as the primary cue by which the flies locate hosts and lay their eggs in them. From this premise, they will then build a framework for studying the evolution of host specificity and how phorids have selected and switched preferences for host species over time.
Once the chemical signals parasitoids use are identified, the research team will be able to use synthesized versions to test their effects on host behavior in the field as well as in the lab. Their observations will experimentally quantify the limits of host specificity for attracting parasitoids. The chemical signals will then be mapped onto the phylogenetic tree of hosts and compared to the phylogenetic tree of the parasitoids to determine how the distribution of chemical signals shape the evolution of host specificity and shifts to novel hosts.
In addition to the research goals, this NSF project supports an impressive range of educational and outreach efforts. The field studies will recruit and train US, Latin America, and Caribbean graduate and undergraduate students so that they gain broad expertise in natural products chemistry and the ecological, behavioral, and evolutionary aspects of life history specialization in insects. In Utah, the project will develop learning activities for K-12 science classrooms and incorporate at least one secondary school science teacher in Utah in the process of scientific research.