Argentine ant chemical profiles vary by location on the Stanford University campus

The Argentine ant ( Linepithema humile ) is an invasive ant species found across California. Many invasive ant species, including the Argentine ant, can use chemical defense compounds to ward off predators or compete with native ant species, which aids in invasive spread. Previously, Stanford undergraduate researchers found variation in the potency of Argentine ant chemical profiles (collected in varying locations on campus) in repelling Caenorhabditis elegans during chemotaxis assays. Here, we asked if variation in Argentine ant chemical extracts was related to collection location on the Stanford campus. We collected Argentine ants from five different locations and analyzed differences in their chemical profiles. Using gas chromatography coupled to mass spectrometry, we found variation in ant chemical profiles based on location collected, where many metabolites contributed to these differences. Five of these compounds were successfully annotated, including pyrazines that are known to have a repulsive function in insects. This work highlights the importance of sampling location impacting naturally-derived ant compounds and the importance of this variable in future chemotaxis assays in the classroom.