Metal composition as a natural marker in anthomyiid flyDelia radicum (L.)

Graphite furnace and flame atomic absorption spectroscopy were used to make quantitative determinations of a range of metallic cation contents of wet-ashed female individuals ofDelia radicum (L.) from a laboratory culture reared under controlled conditions and freeze-dried upon emergence. Analyses were done for seven elements: Fe, Zn, Cu, Pb, AI, Mg, and K. The quantities of K and Mg present were positively related to the dry weight of individual flies, while the others showed an exponential decrease in concentration with increasing fly weight. This difference is attributed to the different roles of surface adsorption of metals with higher oxidation states and the high absorption efficiencies of those existing as oxidation states 1 and 2. The weight of the insect is therefore a major factor in determining the individual's chemoprint. The implications of this observation for other studies are discussed.