Fruit Fly myth

BobGrill

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I read somewhere that feeding a tarantula fruit flies too often can cause molting issues due to amino acids or lack of. Is there any truth at all to this or is this another one of those myths like the whole thing about not feeding them mice due to calcium? Just wondering because I occasionally have to use them on my tiny slings when I run out of crickets. It seems to me that there's no real evidence to support this from what I've read.
 

Hanska

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Can't confirm or deny the myth on Ts, but I have raised a few small slings with fruit flies untill they've been big enough to take other feeders.
I did however read an older thread about Ancylometes(wandering spider). There were atleast two experienced keepers that had similar experiences that when they rised Ancylometes slings with only fff most/all died very young either molting or right after molting and changing their diet fixed this issue. So it seems that there is some truth about this "myth".
I've raised wolf spider slings and running crab spider slings with fff with no signifigant issues.

EDIT: Found the thread.

I had 5 Slings dead so far, got them 2 months ago. 3 of the deaths were due to bad molt, the other 2 were to no apparent reason. The 3 losses due to bad molt were to my idea caused by malnutrition. Cause of the very tiny size the slings had when i got them, i fed them fruit-flies. For 2 molts everything worked out fine, then the trouble started. I was fortune to stumble across a paper dealing with the effects of mono-type diets on the growth and survival of Lycosids. The author stated, that his findings may be equal applied to most other families as well.

The exclusive feeding of fruit-flies seems to be a bad idea, some substances needed by spiders for growing are not built in Drosophilas. The experiment he carried out brought some devastating results, the group fed only with Drosos and later with crickets had a 75% higher mortality-rate than the group fed with a bigger variety of prey items...
 
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cold blood

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I've read this in a few places, one is Barron's "Tarantulas and other Arachnids":

"A culture of vestigial-winged fruit flies is very handy for starting hatchling tarantulas. Unfortunately, fruit flies are deficient in amino acids (such as linoleic acid) so they are not suitable to feed as more than half the diet of a growing tarantula. You can add linoleic acid to the fly culture medium, which helps, but the usefulness of fruit flies is unfortunately limited. Spiders fed too long on fruit flies alone develop molting problems and curly legs, which is too bad as fruit flies are so easy to raise once you have the rearing medium."

It did not cite where this information was derived from. The Author is Samuel D. Marshall. This particular publication is about 10 years old by now.
 

tweakz

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I have trouble believing something that has evolved as such an opportunistic feeder, allowing it to sustain long periods of time without food eating whatever it can get its fangs on, would have all these dietary requirements. They're simple animals, very low on the evolutionary ladder. People stress about gutloading feeders and not feeding certain things to their T's and its just not necessary. The research just isn't there, whatever we've heard about chemical requirements in the diet of our spiders is just speculation and conjecture.
 

Hanska

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This topic coming up again, and the fact that I use fff as feeders for my smaller spiders and dart frogs, peaked my interest and I did some digging around the web(no pun intended).
This is what I came up with(most studies were made with wolf spiders):
A monotype diet of Drosophila can indeed lead to even a 100% mortality rate before maturing, BUT more important than the spider eating only ff is what the ff larvae eat. The nutritional values of Drosophila melanogaster varies greatly depending on the nutrients of the medium they are cultivated in(more so than other feeders, irregardless of wether they have food in their digestive tract or not) and ff from cultures of good nutritional values and proper micronutrients can alone be used to raise healthy spiders. How well the ff larvae eat(or how good and varied the diet otherwise is) affects the spiders growth, mortality rate, resistance to toxins and even behaviour.

I have trouble believing something that has evolved as such an opportunistic feeder, allowing it to sustain long periods of time without food eating whatever it can get its fangs on, would have all these dietary requirements. They're simple animals, very low on the evolutionary ladder. People stress about gutloading feeders and not feeding certain things to their T's and its just not necessary. The research just isn't there, whatever we've heard about chemical requirements in the diet of our spiders is just speculation and conjecture.
But there is alot of studies regarding spiders and their food.

Spiders in the wild are never restricted by having just one type of prey eating one type of food. It also seems that spiders in the wild seek different prey depending on their nutritional needs if they can(so it seems even spiders can have gravings).

I have just scratched the tip of the iceberg it seems and I'll have something to search and read for months.

And as someone's gonna ask anyway, I started with "Arachnid physiology and behavior (Advances in Insect Physiology)" by Stephen Simpson and searched for the many papers referenced there.
 

MadMauC

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This topic coming up again, and the fact that I use fff as feeders for my smaller spiders and dart frogs, peaked my interest and I did some digging around the web(no pun intended).
This is what I came up with(most studies were made with wolf spiders):
A monotype diet of Drosophila can indeed lead to even a 100% mortality rate before maturing, BUT more important than the spider eating only ff is what the ff larvae eat. The nutritional values of Drosophila melanogaster varies greatly depending on the nutrients of the medium they are cultivated in(more so than other feeders, irregardless of wether they have food in their digestive tract or not) and ff from cultures of good nutritional values and proper micronutrients can alone be used to raise healthy spiders. How well the ff larvae eat(or how good and varied the diet otherwise is) affects the spiders growth, mortality rate, resistance to toxins and even behaviour.


But there is alot of studies regarding spiders and their food.

Spiders in the wild are never restricted by having just one type of prey eating one type of food. It also seems that spiders in the wild seek different prey depending on their nutritional needs if they can(so it seems even spiders can have gravings).

I have just scratched the tip of the iceberg it seems and I'll have something to search and read for months.

And as someone's gonna ask anyway, I started with "Arachnid physiology and behavior (Advances in Insect Physiology)" by Stephen Simpson and searched for the many papers referenced there.
Great information & learning. There's a NGC news report relating to this selective diet - and am intending to get Stephen Simpson's book - thank you Hanska.

http://news.nationalgeographic.com/news/2005/01/0106_050106_spider_diet.html
 

BobGrill

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I read this in the book that cold blood mentioned which is what made me want to ask about it on here.
 

viper69

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I've read this in a few places, one is Barron's "Tarantulas and other Arachnids":

"A culture of vestigial-winged fruit flies is very handy for starting hatchling tarantulas. Unfortunately, fruit flies are deficient in amino acids (such as linoleic acid) so they are not suitable to feed as more than half the diet of a growing tarantula. You can add linoleic acid to the fly culture medium, which helps, but the usefulness of fruit flies is unfortunately limited. Spiders fed too long on fruit flies alone develop molting problems and curly legs, which is too bad as fruit flies are so easy to raise once you have the rearing medium."

It did not cite where this information was derived from. The Author is Samuel D. Marshall. This particular publication is about 10 years old by now.
I hate to be the bringer of bad news, but linoleic acid is definitely NOT an amino acid; it's a polyunsaturated omega-6 fatty acid. As a result of this post, I may have to review all your others and verify them. Until then, they are all suspect! ;)

http://www.biology.arizona.edu/biochemistry/problem_sets/aa/aa.html


I think people tend to forget that in captivity many pets only get one food source, eg crickets, whereas in wild they eat a variety of prey items. These prey items have themselves eaten many different things collectively. You are what you eat is very appropriate it.

When an owner limits their pet to only 1 food item, there is potential for harm. For example, I owned chameleons, and while they will definitely eat wax worms and butterworms, it's a bad idea to feed them these exclusively because these larvae are HIGH in fat.
 
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MrDave

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The wikipedia article for linoleic acid says "It is abundant in many vegetable oils, comprising over half (by weight) of poppy seed, safflower, sunflower, corn, and soybean oils." So, I wonder if adding a some oil to your fruit fly culture recipe would be a good idea. My extensive research (5 minutes with google) didn't find any fruit fly culture recipes with oil in them.

I'd try this, but the few slings I have are doing well with crickets.
 

Poec54

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I've read this in a few places, one is Barron's "Tarantulas and other Arachnids":

"A culture of vestigial-winged fruit flies is very handy for starting hatchling tarantulas. Unfortunately, fruit flies are deficient in amino acids (such as linoleic acid) so they are not suitable to feed as more than half the diet of a growing tarantula. You can add linoleic acid to the fly culture medium, which helps, but the usefulness of fruit flies is unfortunately limited. Spiders fed too long on fruit flies alone develop molting problems and curly legs, which is too bad as fruit flies are so easy to raise once you have the rearing medium."

It did not cite where this information was derived from. The Author is Samuel D. Marshall. This particular publication is about 10 years old by now.
I've known Sam Marshall for decades. He's a profession arachnologist, works at universities, so he knows his stuff. Met as college students in the mid 1970's, at the 'Spider Museum' in Powhatan, VA. I worked there during a summer and he was passing thru, collecting true spiders across the country. His dad was the actor E. G. Marshall.
 

Bill Myers

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I've known Sam Marshall for decades. He's a profession arachnologist, works at universities, so he knows his stuff. Met as college students in the mid 1970's, at the 'Spider Museum' in Powhatan, VA. I worked there during a summer and he was passing thru, collecting true spiders across the country. His dad was the actor E. G. Marshall.
LOL! E.G. Marshall is the guy in the movie Creepshow where the cockroaches invade his house and then come pouring out of his mouth. Just thought it was kinda' coincidentally funny, since we are talking about insect food sources for T's.

Cheers
 

Poec54

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LOL! E.G. Marshall is the guy in the movie Creepshow where the cockroaches invade his house and then come pouring out of his mouth. Just thought it was kinda' coincidentally funny, since we are talking about insect food sources for T's.
Yes, oddly enough. He probably was conditioned to inverts with all his son had brought home for years. E.G. Marshall was in a lot of movies, well-respected actor. He supported Sam's decision to be an arachnologist. Sam also went to Guyana a few times and studied/collected T blondi there.
 

Bill Myers

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Yes, oddly enough. He probably was conditioned to inverts with all his son had brought home for years. E.G. Marshall was in a lot of movies, well-respected actor. He supported Sam's decision to be an arachnologist. Sam also went to Guyana a few times and studied/collected T blondi there.
Makes a lot of sense.

Cheers
 
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viper69

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I've known Sam Marshall for decades. He's a profession arachnologist, works at universities, so he knows his stuff. Met as college students in the mid 1970's, at the 'Spider Museum' in Powhatan, VA. I worked there during a summer and he was passing thru, collecting true spiders across the country. His dad was the actor E. G. Marshall.
Now this is a cool fact Poec, didn't know you knew Sam Marshall. Didn't know he was the son of that actor. He was in a lot of movies, good actor.
 

BobGrill

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LOL! E.G. Marshall is the guy in the movie Creepshow where the cockroaches invade his house and then come pouring out of his mouth. Just thought it was kinda' coincidentally funny, since we are talking about insect food sources for T's.

Cheers
Creepshow is a great film. I especially love that particular segment "They're Creeping Up on You." The roaches deserved Oscars for their performances as well.

In this same book, the author claims to put H.macs in the fridge for a few minutes prior to rehousing them. Which seems extremely unnecessary to me.
 

Poec54

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In this same book, the author claims to put H.macs in the fridge for a few minutes prior to rehousing them. Which seems extremely unnecessary to me.
He's an professional arachnologist, so he knows more about spiders than any one of us.
 

Poec54

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So I think it's safe to say that Sam knows infinitely more about spiders than we do, and therefore it is not a 'myth' that fruit flies can cause problems for spiderlings.
 

Wadew

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This is also not a myth. Variety in the diet is directly related to "Good health". Static diet can be as harmful as poor quality diet!

-Wade
 
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