Search National Agricultural Library Digital Collections
Back to Search
NALDC Record Details:
Do leaf-cutter ants Atta colombica obtain their magnetic sensors from soil?
How animals sense, process and use magnetic information has remained largely elusive. In insects, ferromagnetic particles are candidates for a magnetic sensor. Recent studies suggest that ferromagnetic minerals from soil can be incorporated into the antennae of the migratory ant Pachycondola marginata (Oliveira et al. 2010). We used Neotropical leaf-cutter ants Atta colombica to test whether soil contact is necessary for the acquisition and use of a magnetic compass. Atta colombica typically relies on pheromonal trails, but is the only invertebrate known to use a magnetic compass to update a calculated path integrated home vector (Riveros and Srygley 2008). Here we show that contact with soil is necessary for A. colombica to incorporate magnetic particles that can be used as a magnetic compass, and yet we also show that ants can biosynthesize magnetic particles. Workers from a soil-free colony ignored a 90° shift in the horizontal component of the magnetic field, yet significantly oriented homeward despite the experimental occlusion of any geocentric cues. In contrast, workers from a soil-exposed colony oriented homeward, shifted with the magnetic field or oriented in an intermediate direction. Homeward orientations under shifted magnetic fields suggest that leaf-cutter ants are able to determine a path integrated home vector in conditions where only proprioceptive information is available. Strikingly, ants from the soil-free colony also had ferromagnetic particles, yet, as observed by Ferromagnetic Resonance (FMR), these particles differed from those in soil-exposed ants and evidently were not associated with a magnetic compass sensitive to the horizontal shift in the magnetic field.
Robert B Srygley
Behavioral Ecology and Sociobiology 2014 v.68
Journal Articles, USDA Authors, Peer-Reviewed
Works produced by employees of the U.S. Government as part of their official duties are not copyrighted within the U.S. The content of this document is not copyrighted.
Agricultural Research Service
Web Policies and Important Links