From: Doug Skrecky (oberon@vcn.bc.ca)
Date: Wed Sep 12 2001 - 13:54:08 MDT
This is the 47'th update of my fly longevity experiments. All bottles
except those with vinegar contain 1/4 tsp citric acid as a standard
additive. Here I examine elderberry juice again, as well it's major
components such as apple and grape juice. Balsalmic vinegar is made from
grape juice.
Back in Run #36 freeze concentrated elderberry juice greatly increased
average longevity from 40 days (control) to about 80 days. Maximum
survival increased from 73 days (control) to a record 118 days. The
current experiment was done in the summer, and average temperature had
increased to about 25.5 C. Higher temperatures are known to accelerate
motor neuron disease in flies, but also may greatly increase the
confounding effect of viral infections.
Balsalmic vinegar turned out to be a dud this time, but my failure to
add extra potassium to counter the potassium depleting effect of acetic
acid may have biased the result.
Few flies in my recent experiments lost the ability to fly before
perishing. In is interesting that at the day 49 census the surviving 32%
of flies in the freeze concentrated elderberry juice bottle had ALL lost
their ability to fly. This strongly suggested that this concentrated juice
was successful in blocking many of the pathogen associated deaths. At the
day 54 census the surviving 21% had even lost the ability to walk. These
extremely decrepit flies could barely move even when the bottle was
greatly agitated. Under magnification they exhibited only slight signs of
movement. They were literally on their last legs.
I am reluctant to make freeze concentrated elderberry juice a standard
additive to all my bottles because the colour it imparts to the fly food
makes a census difficult. Therfore I will continue to look for other
additives that are effective in allowing flies to live long enough to die
of motor neuron diease. In my next experiment I look at the effect of
removing all dead fly corpses from bottles at each census.
Note: Below FC means freeze concentrated.
Run #47 Percent Survival on Day
supplement 7 12 16 21 26 31 38 43 49 54 59
__________________________________________________________
control 85 85 75 70 60 55 20 20 0 - -
apple Okanagan FC 100 96 78 78 65 48 39 17 4 0 -
elderberry 100 80 77 73 73 70 33 20 7 0 -
elderberry FC 100 89 84 84 68 58 47 47 32 21 0
grape 89 84 84 84 79 53 37 16 11 5 0
grape FC 93 87 80 73 73 60 47 40 13 0 -
vineger, balsalmic 1 tbl 93 73 67 47 40 40 20 7 0 - -
vinegar, balsalmic 2 tbl 100 64 45 36 27 9 9 9 0 - -
vinegar, balsalmic 3 tbl 100 95 84 58 42 26 5 0 - - -
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