Distribution of Metals in the Termite Tumulitermes tumuli (Froggatt): Two Types of Malpighian Tubule Concretion Host Zn and Ca Mutually Exclusively

Abstract

The aim of this study was to determine specific distribution of metals in the termite Tumulitermes tumuli (Froggatt) and identify specific organs within the termite that host elevated metals and therefore play an important role in the regulation and transfer of these back into the environment. Like other insects, termites bio-accumulate essential metals to reinforce cuticular structures and utilize storage detoxification for other metals including Ca, P, Mg and K. Previously, Mn and Zn have been found concentrated in mandible tips and are associated with increased hardness whereas Ca, P, Mg and K are accumulated in Malpighian tubules. Using high resolution Particle Induced X-Ray Emission (PIXE) mapping of whole termites and Scanning Electron Microscope (SEM) Energy Dispersive X-ray (EDX) spot analysis, localised accumulations of metals in the termite T. tumuli were identified. Tumulitermes tumuli was found to have proportionally high Mn concentrations in mandible tips. Malpighian tubules had significant enrichment of Zn (1.6%), Mg (4.9%), P (6.8%), Ca (2.7%) and K (2.4%). Synchrotron scanning X-ray Fluorescence Microprobe (XFM) mapping demonstrated two different concretion types defined by the mutually exclusive presence of Ca and Zn. In-situ SEM EDX realisation of these concretions is problematic due to the excitation volume caused by operating conditions required to detect minor amounts of Zn in the presence of significant amounts of Na. For this reason, previous researchers have not demonstrated this surprising finding.

The Coptotermes gestroi aldo–keto reductase: a multipurpose enzyme for biorefinery applications

“…2c). To the best of our knowledge, some PAD enzymes, such as cytochrome oxidase [36], a candidate enzyme involved in enzymatic detoxification and lignin degradation in termites [34, 37], are expressed in the malpighian tubules.…”

Physicochemical conditions and metal ion profiles in the gut of the fungus-growing termite Odontotermes formosanus

“…From the current investigation, it is clear that O. formosanus selectively accumulates several metal ions at a high concentration in its gut system, as well as the cultivated fungal combs. These metal ions may potentially correlate with the wood deconstruction process and the functions of some endosymbiotic and exosymbiotic microbes (Mills et al, 2009;Stewart et al, 2011;Yoshimura et al, 2002).…”

A review of metal transfer mechanisms through transported cover with emphasis on the vadose zone within the Australian regolith

“…Analysis by Particle Induced X-ray Emission (PIXE) spectroscopy and synchrotron μXRF spectroscopy has been used to map mandibles of termites and ants (Ohmura et al, 2007;Stewart et al, 2011). The aim of this work was to determine specific distribution of metals in the termite T. tumuli (Froggatt) and identify specific organs within the termite that host elevated metals and therefore play an important role in the regulation and transfer of these back into the environment.…”

“…Whole body PIXE imaging of termites over a VMS deposit in Western Australia reveal local concentrations of Fe, Zn, Cu, Ca and Mn ( Fig. 10; Stewart et al, 2011). Iron is found throughout the termite with local high concentration spots predominantly in the antennae, head and lower abdomen.…”

“…Ca, Na, Mg, S and Zn) occur within nests compared to the surrounding soil. Elements accumulated in the nest are likely to occur in highly soluble forms, allowing rapid leaching and a consequent halo around individual nests (Stewart et al, 2011).…”