ARS | Publication request: Magnetoreception in Eusocial Insects: An Update

Submitted to: Journal of the Royal Society Interface
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: January 5, 2010
Publication Date: January 27, 2010
Repository URL: http://hdl.handle.net/10113/43928
Citation: Wajnberg, E., Acosta-Avalos, D., Cambraia Alves, O., Oliveira, J., Srygley, R.B., Esquivel, D.M. 2010. Magnetoreception in Eusocial Insects: An Update. Journal Royal Society Interface. 7(2): S207-S225.

Interpretive Summary: Many ants, bees, wasps, and termites are beneficial to ecosystem function and control agricultural pests, whereas some are also harmful pests. Understanding how these eusocial insects orient spatially will help us to make use of their beneficial attributes and control their harmful ones. This paper integrates studies on the magnetic compass in eusocial insects from the biological and physical sciences. Ants and bees use the geomagnetic field to orient and navigate in areas around their nests and in migratory paths. Although termites and wasps orient their nests to the geomagnetic field, it is not known whether they use it as a spatial orientation cue. Bees sense small changes in the geomagnetic field including changes in the vertical direction of the field. Drawing from knowledge of magnetotactic bacteria, researchers hypothesize that iron oxide particles are a component of the magnetic compass in eusocial insects. Magnetic oxide nanoparticles have been observed in all body parts of termites. They are concentrated in the head with antennae in all species sampled except for in the honeybee where they are concentrated in the abdomen and the termites, where they are concentrated in the thorax and abdomen combined. Electron microscopy and high resolution magnetometry have yielded promising results, and theorists have modeled the magnetosensory function in tissues of the abdomen of honeybees and antennae of ants. With these concentrated efforts, we are closer to identifying a magnetoreceptor but much work remains to be done.

Technical Abstract: Behavioral experiments for magnetoreception in eusocial insects in the last decade are reviewed. Ants and bees use the geomagnetic field to orient and navigate in areas around their nests and in migratory paths. Bees show sensitivity to small changes in magnetic fields in conditioning experiments and when exiting the hive. For the first time, the magnetic properties of the nanoparticles found in these insects, obtained by magnetic techniques and electron microscopy, are reviewed. Different magnetic oxide nanoparticles, ranging from superparamagnetic to multidomain particles, were observed in all body parts, but relative concentrations in these segments has focused attention on honeybee and ant abdomens and antennae, with different distributions in these parts. Theoretical models for how these specific magnetosensory apparati function have been proposed. Neuron-rich ant antennae may be the most amenable to discovering a magnetosensor that will greatly assist research into higher-order processing of the magnetic information. The ferromagnetic hypothesis is believed to apply to eusocial insects but interest in a light-sensitive mechanism is growing. The diversity of compass mechanisms in animals makes evident that multiple compasses may function in insect orientation and navigation. The search for magnetic compasses will continue even after a magnetosensor is discovered in eusocial insects.