Stingless bee antennae: a magnetic sensory organ?

Magnetic material in the body parts of the stingless bee Schwarziana quadripunctata, heads, pairs of antennae, thorax and abdomens, were investigated by SQUID magnetometry and Ferromagnetic Resonance (FMR). The saturation, J(s) and remanent, J(r), magnetizations and coercive field H(c) are determined from the hysteresis curves. From H(c) and J(r)/J(s) the magnetic particle sizes are estimated. The J(s) and the FMR spectral absorption areas yield 23+/-3%, 45+/-5%, 15+/-2% and 19+/-4% magnetic material contributions of head, pair of antennae, thorax and abdomen, respectively, similar to those observed in the migratory ant Pachycondyla marginata. This result is discussed in light of the hypothesis of antennae as a magnetosensor structure.