Magnetite biomineralization in termites

Abstract

Experimental evidence exists for magnetoreception in termites, a major component of the soil macrofauna in many tropical countries. This preliminary study identi¢es, probably for the ¢rst time, the presence of biogenic ferrimagnets (magnetite?) in two species of termite (Nasutitermes exitiosus and Amitermes meridionalis), based on magnetic measurements of whole termite specimens and individual body sections, and analysis by electron microscopy of magnetically extracted grains. The magnetic measurements indicate the presence of very small concentrations of magnetic material, with more magnetic grains in the thorax and abdomen region compared with the head. Magnetic interaction, due to clustering of grains, is also identi¢ed by the measurements. Analysis of magnetic extracts by transmission electron microscopy identi¢es the presence of uniquely ultra¢ne (10 nm) and unidimensional grains of ferrimagnetic material, unequivocally distinct from any possible extraneous magnetite sources, such as ingested soil. Hence, this provides ¢rm evidence for biogenic formation of this magnetic material by these two termite species. Such ultra¢ne grains would be superparamagnetic, i.e. incapable of carrying a permanent magnetic moment, unless they were sited in clusters of interacting grains, when some remanence-carrying abilityöand hence magnetotaxisöwould be possible.

Magnetoreception in eusocial insects: an update

“…The search for a magnetoreceptor system has been extended to two termite species (N. exitiosus and A. meridionalis) fed only on cellulose for at least 3 days to clear their guts of any ingested detrital material. The study was based on magnetic measurements of their body parts and TEM analysis of magnetically extracted grains (Maher 1998). Clusters of ultrafine electron-dense material were found in the extracts, and results from the termite extraction were compared with inorganic magnetite of Rendzina soil profile from the UK instead of particles found in the soil where these insects were collected.…”

“…Looking for low concentrations of magnetic particles dispersed in an insect body is still a needle-in-the-haystack task (Kirschvink et al 1997;Maher 1998). At least an indication of which body part contains magnetic material is necessary.…”

Static electric field detection and behavioural avoidance in cockroaches

“…For example, magnetite (Fe 3 O 4 ) is deposited in specific regions of certain insects and birds, allowing them to detect magnetic fields (Maher, 1998;Wiltschko and Wiltschko, 2006). Likewise, some aquatic animals can perceive the Earth's magnetic field using specific structures, such as the ampullary organs (Kalmijn, 1971;Kalmijn, 1982).…”

Physiological origin of biogenic magnetic nanoparticles in health and disease: from bacteria to humans

“…[4][5][6][7]9,[32][33][34][35][36][37][38][39][40] However, as already mentioned, for the first time BMNPs have been revealed in MTB that are characterized by the ability to "taxi" or navigate under a geomagnetic field. That is why historically the idea of magnetotaxis was transformed into an 59 dolphins, whales, 60 and humans.…”