The insect visual system is energetically demanding because photoreceptors require energy for phototransduction, maintenance of membrane potential and restoration of ionic gradients. The aim of this BSc thesis was to compare oxygen consumption in butterflies across different body preparations and light conditions, and to interpret the results in the context of published data on oxygen consumption in fly eyes. Eight adult butterflies of Papilio xuthus and Morpho peleides were used. Oxygen consumption was measured with a FireSting-O2 optical oxygen meter in darkness and under blue-light illumination. Whole butterflies, heads with the chitinous head wall preserved, heads after removal of the chitinous wall, and bodies without heads were analysed. In whole butterflies, oxygen consumption was significantly higher in darkness than under blue light (0.090 ± 0.007 vs. 0.073 ± 0.006 % O₂/min; p = 0.0014). A significant difference was also observed in heads with the chitinous wall preserved, whereas no significant differences were found in heads without the chitinous wall or bodies without heads. The results did not confirm the expected light-induced increase in oxygen consumption, but they demonstrate the usefulness of the method and identify important limitations for future studies.
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