X-Message-Number: 27835
Date: Mon, 10 Apr 2006 19:53:11 -0700 (PDT)
From: Doug Skrecky <>
Subject: 222'nd update on fly longevity experiments
This is the 222'nd update of my fly longevity experiments. Average
temperature was 23.6 C during this run. Estimated maximal longevity using
the formula (363 - T*11.2) is 99 days.
In run #221 the addition of hydrated sugars modestly, but
consistently increased longevity. This might be explained by a sugar
induced antibacterial effect, or alternatively by dilution of a toxin
added to the fly food by the manufacturer. If starches fail to increase
longevity then the antibacteria hypothesis is confirmed. If starches also
increase longevity then it is the toxin hypothesis that is confirmed.
In this run, 1/2 tsp of extra water was added for every extra 1 tsp
of starch to prevent dehydration stress. Unlike sugars, only a slight
increase in the wetness of the surface of the fly food was noticed in the
8 tsp bottles in which corn starch, Jiao Dasheen starch, and rice flour
were used. Probably due to a greater hydration ability, the surface of
the 8 tsp potato starch bottle was not wet.
Judging by the day 80 census the addition of starches was universally
beneficial, with no great differences between dosages. There was also
evidence of a slight increase in maximum lifespan in the Jiao Dasheen
starch, and rice flour bottles.
The antibacterial hypothesis is refuted, while the toxin hypothesis
is supported by the present results. The top suspect for this toxin is
the mold inhibitor p-hydroxy benzoate.
The additional slight benefit on maximum longevity of Jiao Dasheen
starch and rice flour requires further testing to confirm.
Run #222 Percent Survival on Day
supplement 13 22 33 44 54 64 71 80 94 109 116
______________________________________________________
control one 78 91 87 70 48 30 13 9 4 0 -
control two 76 72 66 59 31 28 10 0 - - -
corn starch 2 tsp 72 66 63 63 56 44 28 22 6 0 -
" 4 tsp 80 52 52 48 48 44 36 24 8 0 -
" 8 tsp 83 67 63 63 60 53 50 33 17 0 -
Jiao Dasheen 2 tsp 83 58 58 50 50 42 42 33 33 4 0
(starch) 4 tsp 82 64 64 57 50 50 36 32 25 0 -
" 8 tsp 76 65 51 49 41 41 30 27 16 3 0
potato starch 2 tsp 89 61 54 46 39 32 29 25 7 0 -
" 4 tsp 88 71 65 59 56 35 29 18 6 0 -
" 8 tsp 79 68 57 57 46 46 46 36 18 0 -
rice flour 2 tsp 59 56 56 56 48 41 33 33 11 7 0
" 4 tsp 71 71 68 64 57 50 50 39 32 4 0
" 8 tsp 60 39 35 35 32 32 27 16 11 3 0
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