Resting potentials in Apis mellifera and Drosophila melanogaster flight mus
cles decrease with falling temperatures. When resting potentials fall to be
tween -37 and -45 mV they activate a final burst of spontaneous muscle acti
on potentials (MAPs). This final burst of MAPs marks the beginning of chill
-coma for each species. The temperature at which the final burst occurs for
D. melanogaster (7.0+/-0.9 degrees C) is significantly lower than that of
A. mellifera workers (10.6+/-1.2 degrees C), queens (10.2+/-0.8 degrees C),
and drones (12.8+/-0.8 degrees C). Prior to chill-coma, MAP amplitudes dec
rease and durations increase with falling temperatures in both A. mellifera
and D. melanogaster. The rate of these changes and the temperatures at whi
ch they occur appear to be related to the rate of decline in each species'
resting potential. These results suggest that insect chill-coma varies with
a species' ability to maintain its resting potential at low temperatures.
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