Abstract
A wide variety of arthropods and members of other phyla have elevated concentrations of Zn, Mn, other heavy metals and halogens in their jaws, leg claws, and other "tools" for interacting with the environment. While measured Zn concentrations reach 25% of dry mass in scorpion stings, concentrations are often lower than this and the enriched structures are not heavily biomineralized like vertebrate teeth and the radula of mollusks. For this reason, the degree to which the inorganic components of these structures modify their mechanical properties is in question. Here we address this problem by measuring hardness during the development of Zn accumulations in ant mandibles. We found that Zn is incorporated into the mandibular teeth of leaf-cutter ants during early adult life, reaching concentrations of about 16% of dry mass. We show that the hardness of the mandibular teeth increases nearly three-fold as the adults age and that hardness correlates with Zn content (r=0.91). We suggest that young adults rarely cut leaves partly because their mandibles are not yet rich in Zn. Zinc enrichment (along with enrichment by other heavy metals and halogens) may play an unrecognized role in the behavioral ecology and evolution of a wide variety of invertebrates.
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References
Andersen SO, Peter MG, Roepstorff P (1996) Cuticular sclerotization in insects. Comp Biochem Physiol 113B:689–705
Edwards AJ, Fawke JD, McClements JG, Smith SA, Wyeth P (1993) Correlation of zinc distribution and enhanced hardness in the mandibular cuticle of the leaf-cutting ant Atta sexdens rubropilosa. Cell Biol Int 17:697–698
Grime GW, Palsgard E, Garman EF, Ugarte M, Pottage D, Wyeth P (1999) Recent biomedical applications of the Oxford scanning proton microprobe. Int J PIXE 9:199–216
Hillerton JE, Vincent JFV (1982) The specific location of zinc in insect mandibles. J Exp Biol 101:333–336
Hillerton JE, Reynolds SE, Vincent JFV (1982) On the indentation hardness of insect cuticle. J Exp Biol 96:45–52
Hopkins TL, Kramer KJ (1992) Insect cuticle sclerotization. Annu Rev Entomol 37:237–302
McClements JG, Smith SA, Wyeth P (1993) Chemical and physical characterization of zinc-replete biocomposites. In: Welch AJ, Chapman SK (eds) The chemistry of the copper and zinc triads. Royal Society of Chemistry, Cambridge, pp 58–61
Nichols-Orians CM, Schultz JC (1989) Leaf toughness affects leaf harvesting by the leafcutter ant, Atta cephalotes (L.) (Hymenoptera: Formicidae). Biotropica 21:1 80–83
Roces F, Lighton JRB (1995) Larger bites of leafcutting ants. Nature 373:392–293
Schofield RMS (1990) X-ray microanalytic concentration measurements in unsectioned specimens: a technique and its application to Zn, Mn and Fe enriched mechanical structures of organisms from three phyla. PhD dissertation, University of Oregon, Eugene, USA
Schofield RMS (2001) Metals in cuticular structures. In: Brownell P, Polis, G (eds) Scorpion biology and research. Oxford University Press, Oxford, pp 234–256
Schofield RMS, Nesson MH, Richardson KA, Wyeth P (2003) Zinc is incorporated into cuticular "tools" after ecdysis: the time course of the zinc distribution in "tools" and whole bodies of an ant and a scorpion. J Insect Physiol 49
Wilson EO (1980) Caste and division of labor in leaf-cutter ants (Hymenoptera: Formicidae: Atta). I.The overall pattern in A. sexdens. Behav Ecol Sociobiol 7:143–156
Acknowledgements
We thank Chris Jackson, University of Southampton, for providing specimens. This research was supported by NSF grant IBN 9817206.
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Schofield, R.M.S., Nesson, M.H. & Richardson, K.A. Tooth hardness increases with zinc-content in mandibles of young adult leaf-cutter ants. Naturwissenschaften 89, 579–583 (2002). https://doi.org/10.1007/s00114-002-0381-4
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DOI: https://doi.org/10.1007/s00114-002-0381-4