calcio nel pastone droso

pashetti · 29-10-2008, 20:02

qui sotto copoincollo quello che scrive ajcs nella sua virtual frogroom

tirando 2 somme è assurdo aggiungere il calcio al pastone tanto loro non ne assumono neanche un goccio

Can you turn fruit flies into calcium pills?

A while ago, I wrote about Why do frogs need vitamins:

Animals also need a range of minerals, one of the main ones being calcium (for bones and the nervous system). Insects don't have bones, and compared with vertebrates, they have a reversed calcium:phosphorus ratio, i.e. they contain more phosphorus than calcium, whereas in animals, it's the other way round. Most insects are therefore a poor source of calcium, although soil arthropods such as springtails and woodlice may contain reasonable amounts.

On Frognet recently, Ed Kowalski pointed at an interesting scientific paper I hadn't seen before, in which scientists kept Drosophila melanogaster on low and high calcium diets to see if this increased the calcium content of the flies. To cut a long story short, the answer is no:

Flies were raised on the standard calcium diet and then transferred to either the high calcium or low calcium diet within 24 h of emergence. Calcium contents of whole flies and tubules were measured for 10 days after transfer, and calcium contents of whole flies of the resulting F1 generation were determined at intervals for 15 days after emergence. The flies maintained a calcium content of ~4.4 nmol/fly for 10 days after emergence; there was no increase in calcium content with time after transfer to high calcium diet.

However, they did find that:

Although larvae weighed 2X as much as adult flies, they contained 3–4X as much calcium.

Unfortunately, these amount of calcium are low, probably not enough to satisfy frog's needs. When the levels of calcium are high enough to ensure a positive calcium to phosphorus ratio of at least 1:1 and ideally closer to 1.5 to 1, the mortality of the insects increases rapidly. So we still need to supplement feeder insects with calcium (and other minerals and vitamins).