Magnetoreception in eusocial insects: an update

Abstract

Behavioural 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 along 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 eusocial insects, obtained by magnetic techniques and electron microscopy, are reviewed. Different magnetic oxide nanoparticles, ranging from superparamagnetic to multi-domain particles, were observed in all body parts, but greater relative concentrations in the abdomens and antennae of honeybees and ants have focused attention on these segments. Theoretical models for how these specific magnetosensory apparatuses 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 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 suggests 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.

Honeybees as a Model for the Study of Visually Guided Flight, Navigation, and Biologically Inspired Robotics

“…Recent research on certain insects, notably Drosophila, is revealing the presence of an additional magnetoreceptive mechanism, which is light dependent and based on cryptochrome photopigments (84,85,185,274), but its presence in the honeybee is yet to be investigated.…”

The depth of the honeybee's backup sun-compass systems

“…Honeybees have a magnetic compass (DeJong, 1982;Collett and Baron, 1994;Schmitt and Esch, 1993;Frier et al, 1996;Walker, 1997;Wajnberg et al, 2010), a celestial compass based on the sun and sun-linked patterns of color and polarization in the blue sky (von Frisch, 1967;Wehner, 1994;Wehner, 1997), and a backup celestial compass for cloudy days, the latter based on a memory of the celestial rotation over time in relation to the landscape (Dyer and Gould, 1981;Dyer, 1987). The celestial compasses based on direct views of the sun and skylight polarization patterns might best be considered distinct, as the sun itself and the skylight polarization patterns are detected separately, and the polarization compass dominates when it is made to conflict with direct views of the sun, at least in ants (Wehner and Müller, 2006).…”

“…Orientation cues that can provide directional information on an earthwide scale are called compass cues, and there are two general types (Able, 2001;Wiltschko and Wiltschko, 2009): magnetic cues, based on the earth's magnetic field (Wiltschko and Wiltschko, 2005;Walker, 1997;Wajnberg et al, 2010); and celestial cues, based on the stars, sun, moon, and skylight patterns associated with the sun and moon (Wiltschko and Wiltschko, 2009;Wehner, 1994;Wehner, 1997;Wehner and Müller, 2006;Kraft et al, 2011;Ugolini et al, 2009;Warrant and Dacke, 2011;Dacke et al, 2011;Dacke et al, 2013). To use celestial cues as a compass, animals must account for the cues' movements across the sky, for which they use their innate circadian and other physiological rhythms (Wiltschko and Wiltschko, 2003;von Frisch, 1967;Reppert et al, 2010;Ugolini et al, 2007;Meschini et al, 2008).…”

Magnetoreception

“…Wajnberg et al (2010) review magnetoreception studies in a polyphyletic group of eusocial insects, such as ants, some bees and wasps, as well as termites. After giving an overview of magnetic alignment behaviour as well as untrained and trained orientation responses in these insects, the authors focus on the detection of iron-bearing minerals in body parts or tissue samples, based on magnetometry, electron paramagnetic resonance/ferromagnetic resonance absorption and electron microscopical techniques.…”