X-Message-Number: 27792
Date: Sun, 2 Apr 2006 23:23:54 -0700 (PDT)
From: Doug Skrecky <>
Subject: 221'st update on fly longevity experiments
This is the 221'st update of my fly longevity experiments. Average
temperature was 23.5 C during this run. Estimated maximal longevity using
the formula (363 - T*11.2) is 100 days.
The addition of sugars to fly food has modestly increased longevity
in some previous runs. However this beneficial effect does not always
occur, possibly because of variable amounts of dessication stress. This
run added an extra 1/2 tsp of water to each 1 tsp of extra carbohydrate
so as to prevent this stress. However after seeing that the surface of
the 8 tsp fructose bottle was wet, this extra ration of water was halved
for all of the other 8 tsp bottles. These all proved to have wet surfaces
as well! It appears that adding too much sugar inhibits the gelling of
the fly food.
Judging by the day 65 census, 4 tsp of any sugar was more beneficial
than the 2 tsp dosage. High doses of the sugar alcohol maltitol proved to
be toxic.
I have two hypotheses to account for the longevity benefit of sugars.
Inhibition of bacterial growth by sugars is one idea, which will be
tested by adding starchy carbohydrates in run #222. Another idea is the
dilution of some hypothetical toxin in the fly food. Since sugar
additions will not dilute calories, this toxin must be something added to
the food. Carolina Biological Supply Company provides a 4 page material
safety data sheet for its fly formula 4-24. However virtually all of this
is just meaningless legalese dealing with (for example) firefighting
procedures in case the fly food ignites. (Dilbert cartoons could use this
material!) Nowhere is the full list of ingrediants of the fly food
disclosed, presumably so the ingrediants can be changed without notice.
The only food item admitted to be included was sucrose! However my top
suspect for the added toxin is the mold inhibitor methyl p-hydroxy
benzoate. My own addition of the mold inhibitor potassium sorbate in run
#200 proved to exert a longevity shortening effect, which was potentiated
by the further addition of citric acid. If the addition of starches in
run #222 increases longevity, then it is the dilution of the mold
inhibitor which may be responsible for this.
Run #221 Percent Survival on Day
supplement 12 24 33 44 55 65 75 82 91 97 105 120
_____________________________________________________
control one 86 73 64 41 27 18 5 5 5 5 0 -
control two 83 52 52 17 9 0 - - - - - -
fructose 2 tsp 90 60 45 35 5 5 5 0 - - - -
" 4 tsp 90 80 75 60 50 40 5 5 5 0 - -
" 8 tsp 84 68 72 56 52 28 20 16 8 8 0 -
glucose 2 tsp 91 70 70 57 44 30 17 17 13 4 0 -
" 4 tsp 96 88 80 64 52 44 40 24 8 4 4 0
" 8 tsp 75 40 35 30 25 25 20 20 10 0 - -
honey 2 tsp 91 57 52 33 29 14 10 0 - - - -
" 4 tsp 83 75 71 58 46 38 29 4 0 - - -
" 8 tsp 67 57 48 43 33 33 24 19 10 14 10 0
maltitol 2 tsp 87 60 67 47 33 20 13 7 7 7 0 -
" 4 tsp 86 86 67 48 29 10 0 - - - - -
" 8 tsp 67 47 47 20 7 0 - - - - - -
sucrose 2 tsp 83 83 63 38 21 13 8 4 4 4 4 0
" 4 tsp 82 64 64 64 50 27 9 9 0 - - -
" 8 tsp 63 53 53 21 11 5 5 5 0 - - -
Rate This Message: http://www.cryonet.org/cgi-bin/rate.cgi?msg=27792