There are numerous popular articles claiming that the wasp Apocrypta Westwoodi Grandi features an ovipositor tipped with zinc. You can find such an article here. You can watch an impressive video here. Beyond that, I have found information on the genus to be sparse.
Yet my question is, how metallic tissue can be formed. The popular article claims actual zinc was detected. It seems unlikely to me, these creatures consistently find a source of zinc to feed from, so as to deposit zinc in their tissue. Even so, I don't understand how this zinc can be made to deposit at a specific point. The article clarifies:
With an x-ray detector and the electron microscope, they discovered the presence of zinc. It was only on the tips of the parasitic fig wasp’s ovipositors. Gundiah said, “We see it very consistently only at the tip and not anywhere else.”
I am no biologist, but, to my feeble understanding the only alternative is that the so called zinc is actually synthesised by the body as a protein normally is. Surely no atomic reactions could take place in the wasp! :-p Even teeth are mostly Ca5(PO4)3 OH, Calcium is found in plenty of our foods. Phosphorus is present in meats. But zinc? I totally don't understand it!
Answer
First and foremost, it looks like the original article is slightly less dramatic:
Parasitoid ovipositor tips have a higher content of the transition metal zinc compared with the cuticle elsewhere on the ovipositor
So a 'higher concentration' isn't quite the same as 'tipped with'. It looks like they are describing a higher numbers of metal ions, rather than pure metal:
The presence of transition metals in insect cuticle and mandible is hypothesized to increase material hardness to permit cutting through hard substrates with minimal wear
There are many examples of organisms using inorganic chemistry to make materials. The overall topic is called biomineralization and you even mention teeth - which is hydroxyapatite (not really organic chemistry!).
However, a pure metal like zinc is unusual, I think. There are examples such as the snail that has an iron pyrite 'armor' or even the iron nanocrystals in ferritin.
More spectacular examples include the bacteria that produce gold particles
As a result, Au detoxification is mediated by a combination of efflux, reduction, and possibly methylation of Au-complexes, leading to the formation of Au(I)-C-compounds and nanoparticulate Au0.
Where Au0 is pure gold. I don't know of any other examples of pure zinc in organisms, but there is a nice review here of zinc biochemistry.
When you say 'synthesise' I assume that you mean 'deposit'.
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