I was flipping through a German book -- Karnivoren, (The Curious World of Carnivorous Plants : A Review) -- the other night (in a very successful effort to get drowsy), which had a table listing the various chemical components necessary for carnivorous plants to digest their prey; and there was a listing of various genera with the necessary enzymes they had, or, in some cases, lacked altogether.
There was amylase, chitinase, esterase, lipase, peroxidase, phosphatase, protease, and ribonuclease as the most frequent-appearing enzymes.
The clear "winner" among genera, was Nepenthes, whose digestive fluids produced all of the above enzymes, while Brocchinia, Catopsis, Roridula, and Heliamphora produced none and are dependent upon bacterial action for "digestion" of prey.
Others produced most of the enzymes (Dionaea and Pinguicula lacking only lipase and peroxidase, for example), while some possessed a small assortment, such as Genlisea with three, or Darlingtonia with only one (amylase).
Under the oh, so poetical heading of "Nährwert der Beute," or "Nutritional Value of Prey," the authors went on to illustrate the efficiency among carnivores in absorbing nitrogen, potassium, calcium, among other elements. In dried insects, the proportion of the six most important nutrients are as follows: 10.5% nitrogen, 3.2% potassium, 2.3% calcium, 0.6% phosphorus, 0.09% magnesium, and 0.02% iron.
Strangely (especially with all the endless talk of nitrogen-poor soils), it turns out that Sarracenia only absorb magnesium and iron in any real quantity from their insect prey -- and the rates and percentages of nitrogen intake varies greatly, even among species. Dionaea and Nepenthes mirabilis utilzes or receives 75% of the available Stickstoff (uh, nitrogen), while Darlingtonia and Cephalotus only utilize 25%. In rosetted Drosera, the nitrogen uptake was 20%, while upright and filiform species utilized upwards of 50%.
Just something to consider while watering those creepy Fleischfressender Pflanzen in the morning . . .