Mealworm chitin content?

[spooky]

As my frogs both feed from my hand, I decided that the best approach re. calcium powder would be to handfeed a dusted mealworm to each frog (white's tree frogs) a couple of times a week. In the box of mealworms I have, I noticed that a few of them are white and softer looking. Am I right in thinking that they are mealworms shedding their exo skeletons, and therefore lower in chitin?

[John]

Actually, no they're not lower in chitin, just their new exoskeleton hasn't hardened yet.

[Malduroque]

Actually, no they're not lower in chitin, just their new exoskeleton hasn't hardened yet.

Perhaps. Perhaps not.

"However, newly molted mealworms, which are white in color, are soft, have weak mouthparts and lower chitin levels." - Frank Indiviglio from his blog

[Tropicok]

Being from the South (sort of) and with my brain still not firing on all its neurons, I misread the topic and thought it said "mealworm chitlin'". What? Chitlin? It's not possible? and then the next thought was "it's the dried carcasses of the mealworm when they shed the outer shell. So I read on and discovered the real content of the question. Whew! Just glad the next topic is not "mealworm grits."

[John]

Perhaps. Perhaps not.

"However, newly molted mealworms, which are white in color, are soft, have weak mouthparts and lower chitin levels." - Frank Indiviglio from his blog

Far be it from me to disagree with Frank but I am going to stick by what I said. Case in point, ever notice how your finger nails get softer if you take a shower (or particularly a bath)? Does that mean that the amount of keratin in your finger nails changes when you have a wash? (Keratin is another structural protein, just as chitin is a structural protein in insects)

[Socrates]

John is correct. Chitin is a polysacharacide that has proteins incorporated into them. These amino acids make up a secondary B structure, creating B-bends which allow for tight packing giving an extremely dense, strong, flexible, but not elastic covering. After an arthropod molts, the B sheets have not fully formed, i.e. covalent bounds of Cysteine haven't formed yet to add structural rigidity. So the amount of chitin is the same, just the arrangement is slightly different, which allows easier digestion by gastric juices/enzymes to break down the chitin. this is because hydrophobic bounds haven't not been maximized (along with a few covalent bounds) which are as I stated before give chitin is structural rigidity.

P.S. I would strongly suggest staying away from meal worms, they can destroy the endothelium (internal lining of the lumen) of your amphibians, because the meal worms can still retain their ability to use those sharp mandibles.

[spooky]

Ahh ok! Makes sense! Also, I generally don't feed mealworms. I just bought some last week to try and persuade my frog to eat as he had quite a big op. I'll stick to locusts, crickets and the occasional wax worm! Thanks for the replies

[Malduroque]

John is correct. Chitin is a polysacharacide that has proteins incorporated into them. These amino acids make up a secondary B structure, creating B-bends which allow for tight packing giving an extremely dense, strong, flexible, but not elastic covering. After an arthropod molts, the B sheets have not fully formed, i.e. covalent bounds of Cysteine haven't formed yet to add structural rigidity. So the amount of chitin is the same, just the arrangement is slightly different, which allows easier digestion by gastric juices/enzymes to break down the chitin. this is because hydrophobic bounds haven't not been maximized (along with a few covalent bounds) which are as I stated before give chitin is structural rigidity.

P.S. I would strongly suggest staying away from meal worms, they can destroy the endothelium (internal lining of the lumen) of your amphibians, because the meal worms can still retain their ability to use those sharp mandibles.

Interesting. This though begs the question of why we limit chitin intake. Is it because it taxes the digestive system, which would then mean a recently molted one (mandibles aside) is ok, or is there something intrinsically negative in the substance itself that we should limit its intake under any circumstances?

I rarely use mealworms myself but this question would pertain to any heavily chitinous food item.

[Socrates]

Chitin lacks any real significant nutritional value. It's a structural molecule and as such is very low in nutritional value. It's similar to keratin you find in mammalian nails or hair. Not very nutritional if one was to eat those. Overall there isn't anything overtly negative about chitin. It's just a structural compound (it's an arthropods skeletal system). That's why when we as hobbyist are feeding our amphibians or reptiles it is important to not give them to large of insects to eat. It would be equivalent to a human eating only the skin of a fruit. This is mostly fiber, which many types are insoluble and thus non-digestible by mammalian enzymes. That's why when you look at a Herp's fecal matter you can see the exoskeleton of the cricket, roach etc of what it ate. This is also why insects with more chitinous exoskeletons have an unfavorable inverse Ca:P ratio. Phosphorus is extremely important in structural molecules and more will be present with an older insect (because the body is producing more P to create this durable exoskeleton). The only organisms that can readily digest chitin is some species of fungi and bacteria (such as those found in ruminants - such as cows) who can produce enzymes to break down chitin and lignin (another structural polysaccharide). Hope that explains it haha.