Magnetic nanoparticles in the body parts of Polistes versicolor and Polybia paulista wasps are biomineralized: evidence from magnetization measurements and ferromagnetic resonance spectroscopy

The detection of the geomagnetic field by animals to use as a cue in homing and migration is known as magnetoreception. The ferromagnetic hypothesis explains magnetoreception assuming that magnetic nanoparticles in cellular structures are used as magnetic field transducers. Considering magnetoreception in social insects, the most studied has been the honeybee Apis mellifera and only in two wasp species ( Vespa orientalis and Polybia paulista ) have been shown a magnetosensitive behavior. In the present report the body parts (abdomen, head and antennae) of Polistes versicolor and Polybia paulista wasps were studied aiming to find biomineralized magnetic nanoparticles, using magnetometry measurements and ferromagnetic resonance spectroscopy. The magnetometry measurements show the presence of magnetic nanoparticles in all body parts, being characterized as mixtures of superparamagnetic, single domain and pseudo-single domain nanoparticles. From the ferromagnetic resonance spectra were obtained the asymmetry ratio A and the effective g factor g eff , and those parameters are consistent with the presence of biomineralized magnetic nanoparticles in both wasps. In the case of Polybia paulista , the magnetic nanoparticles can be associated with some sort of magnetosensor once this wasp is magnetosensitive. For Polistes versicolor , the results indicate that this wasp can be magnetosensitive as Polybia paulista once their magnetic nanoparticles are biomineralized in the body. Behavioral studies with Polistes versicolor wasps deserve to be performed.