Electron paramagnetic resonance study of the migratory ant Pachycondyla marginata abdomens

Electron paramagnetic resonance was used to investigate the magnetic materi al present in abdomens of Pachycondyla marginata ants, A g congruent to 4.3 resonance of high-spin ferric ions and a very narrow g congruent to 2 line are observed, Two principal resonance broad lines, one with g > 4.5 (LF) a nd the other in the region of g congruent to 2 (HF), were associated with t he biomineralization process. The resonance field shift between these two l ines, HF and LF, associated with magnetic nanoparticles indicates the prese nce of cluster structures containing on average three single units of magne tite-based nanoparticles. Analysis of the temperature dependence of the HF resonance linewidths supports the model picture of isolated magnetite nanos tructures of similar to 13 nm in diameter with a magnetic energy of 544 K, These particles are shown to present a superparamagnetic behavior at room t emperature. The use of these superparamagnetic particle properties for the magnetoreception process of the ants is suggested.