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Food Insect Nutritional Value

Discussion in 'Tarantula Questions & Discussions' started by Predacons5, Jul 17, 2019.

  1. Predacons5

    Predacons5 Arachnopeon

    I have been reading on Arachnoboards how some people are saying that fruit flies are devoid of nutritional value. That got me wondering if this is actually true. I wanted to know if there was any scientific basis for this claim. I was also curious about the nutritional value of other food insects that are regularly used to feed reptiles, amphibians, and our pet invertebrates (in our case, for many of us here on Arachnoboards, it would be tarantulas).

    In my search, I came across a blog that briefly talks about the nutritional values of some of these food insects: http://www.geckotime.com/nutritional-value-of-commercially-raised-insects/

    This blog seems credible because there were some reference sources mentioned that are peer reviewed, this is a link to one of those peer reviewed journals: https://onlinelibrary.wiley.com/doi/abs/10.1002/zoo.10031?cookieSet=1

    After reading the blog, I am wondering where the claim that fruit flies did not have nutritional value comes from because according to the table in this blog, they sure do have significant enough nutritional value to warrant its usage. I'm wondering if anybody can comment further or provide evidence that supports the claim that fruit flies are nutritionally void.
    • Informative Informative x 1
  2. korg

    korg Arachnobaron

    Some good discussion and evidence regarding of the nutritional value (or lack thereof) of fruit flies in this thread from last year: http://arachnoboards.com/threads/mass-sling-death.307446/

    If you follow some of the links in that discussion you'll see there is hard evidence suggesting fruit flies are not ideal feeders for spiders, but it's not like they are nutritionally "void." Seems to depend on how the flies themselves are raised.
  3. viper69

    viper69 ArachnoGod Old Timer

    They don’t have a lot of value compared to high fat insects
    • Agree Agree x 1
  4. cold blood

    cold blood Moderator Staff Member

    Arachnologist Sam Marshall describes fruit flies as "nutritionally deficient", citing that slings fed too long on fruit flies alone develop curled legs and have molting problems.
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  5. mack1855

    mack1855 Arachnobaron Arachnosupporter

    I have no intension of making my hobby harder than it has to be.Tap the container of FF,to keep
    them from escaping.Then pour a few out into a small vial,all the while tapping the original container,
    to keep the FF from escaping,while tapping the small vial to keep those FF from escaping,and keepin an
    eye on my tiny slings,while I tap the original container,trying to keep the FF from escaping,....while
    trying to secure lids on all the containers!!!:inpain::rage:

    OH NO,baby!!!!cut up some mealworms.Much easier,and real substance to them.
    Last edited: Jul 17, 2019
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  6. EtienneN

    EtienneN Arachnonovelist-musician-artist Arachnosupporter

    Sorry if this sounds like a fairly stupid question but is the reason they are nutritionally deficient because there just isn't any real 'substance' to them??? Like if they were fed 'fruit fly steroids' (joking for the sake of making my point, of course) would they be nutritionally acceptable? Or is it something about the actual chemical composition of their bodies?
    • Agree Agree x 1
  7. cold blood

    cold blood Moderator Staff Member

    Yeah, diced mealworms are 100 times easier and more nutritional. And you can feed infrequently and still maintain max growth rates.

    Sure, but to me that's like feeding kids twinkies that were injected with vitamins...lol.....and it doesn't mitigate the PITA factor.
    Last edited: Jul 17, 2019
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  8. Predacons5

    Predacons5 Arachnopeon

    I see...

    So it isn't that tarantulas shouldn't be fed fruit flies at all, but that if they are being fed fruit flies, then supplementation with other prey items is needed.

    I guess I can do the diced mealworms to mix things up a bit and for cost efficiency and ease too. They're definitely cheaper than fly maggots!

    I get fruit flies mainly for my dart frogs. For me, all that tapping of the cups is habit.

    Do I have to wave the diced mealworms in front of the tarantulas or can I drop the pieces into the containers and the spiders will find them?
    Last edited: Jul 17, 2019
  9. krequiem

    krequiem Arachnopeon Active Member

    You can just drop the pieces in the container and the slings will scavenge then. No waving required.
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  10. cold blood

    cold blood Moderator Staff Member

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  11. Gogyeng

    Gogyeng Arachnobaron Active Member

    If you absolutely want to stick to flies, black Soldier fly larvae (calcigrubs/nutrigrubs) are closest in fat to mealworms.
    Last edited by a moderator: Jul 18, 2019
  12. Not sure how to do columns and rows so I'll wing it, fruit fly vs mealworm, mean +/- SD:

    Water %: FF 67.2 +/- 4.3, MW 62.9 +/- 3.6
    Protein % of dry matter: FF 56.3 +/- 0.8, MW 51.8 +/- 5.3
    Fat % of dry matter: FF 16.7 +/- 2.1, MW 31.1 +/- 3.9
    Carbohydrate % of dry matter: FF ?, MW 12.8
    Total ash % of dry matter: FF 3.1 +/- 0.8, MW 4.3 +/- 3.7
    Ca: FF 0.2 +/- 0.02, MW 0.1 +/- 0.1
    Mg: FF 0.1 +/- 0.03, MW 0.3 +/- 0.02
    Cu: FF 7.3 +/- 3.6, MW 17.7 +/- 4.7
    Fe: FF 473 +/- 41, MW 39.7 +/- 19.2
    Mn: FF 16.1 +/- 2.7, MW 6.8 +/- 4.2
    Zn: FF 158 +/- 82, MW 131 +/- 7
    Vitamin A IU/kg DM: FF 0, MW 811 +/- 324
    Vitamin E IU/kg DM: FF 16 +/- 7, MW 30 +/- 3

    Data from Dierenfeld and Barker, 1995.
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  13. Predacons5

    Predacons5 Arachnopeon

    The reason I use fruit flies is for cost efficiency and ease of acquiring size appropriate food items when I already use them for the purposes of feeding dart frogs without resorting to the trouble of breeding the feeders and gut loading them and having to constantly worry that if I leave the prey items in the container that they will kill my pets.

    Pinhead crickets are nearly impossible to find here unless I breed crickets myself.

    Fruit flies have no biting mandibles. They regurgitate digestive enzymes onto the food they eat and they suck it up. I can leave them in there if the spiders will not go after them immediately. It allows them to hunt down the prey on their own time.

    Drosophila melanogaster are easily sourced even in places like Petco. If I run out of the big 32 oz container full of flies I get from places like Josh's Frogs and I have to get some in an emergency, I can go to my nearest Petco and buy some.

    Drosophila hydei I can also get in an emergency pretty easily at one of my local general pet stores.

    Drosophila melanogaster are size appropriate for slings that are 1/8" - 3/4".

    Drosophila hydei are size appropriate for slings that are 1/2" - 1.25".

    I'm not really too worried about any of my stock that are 1.25" and up. Food sources for them are far more abundantly available.

    Drosophila melanogaster and Drosophila hydei are both relatively inexpensive for the amount of flies I can get in one purchase.

    The more reasonable solution is to use the diced mealworms, because those are extremely easy to get and they are pretty inexpensive too. I can get them from anywhere, including places like Petco.

    They can be sized appropriately for a wider variety of sizes of animals, including my larger juveniles that are 1.5" - 2.5" DLS and a few of the adult dwarf species at 3" DLS.

    I can drop them in without any worries of the feeder biting back (unless I use it whole).

    Calciworms are expensive here. There aren't a lot of Soldier Fly larvae per container. They're not popular feeders and are harder to get because they are not sold in large quantities locally. If I had an emergency where I ran out and could not get them by shipping them in fast enough, it is difficult to find a consistent source from Petco.

    The adult flies do not have biting parts, but I'm unsure as to what the larvae can do.

    I also find that Soldier Fly larvae pupate too fast.

    I was using House Fly larvae for my Wahlberg's Spiny Mantis (Pseudocreobotra wahlbergii) and the slings that were 3/4" - 1" DLS to see what they were like as feeders. I've only attempted using them two or three times, and I can say, they're too expensive and each container does not contain a whole lot of larvae. If I bought 200 larvae, only 75 would be usable larvae. The rest are unusable pupae. I find the adult flies rather repulsive. I don't think I will continue purchasing these anymore (although, I may not have to now that I have enough adults to start my own culture indefinitely).
    Last edited: Jul 20, 2019