UBC Theses and Dissertations
The effects of atmospheric ionization on insects measured with a stationary flight apparatus Hildebrandt, Jacob
In recent years a number of publications have shown a renewed interest in the possible effects of atmospheric electricity on biological systems. The work here presented is an attempt to measure the changes in the behaviour, or the power output, of certain insects during stationary flight in a unipolar atmosphere. Since several published references indicate the existence of a "weather sense" in insects, which has been attributed to sensitivity to atmospheric space charge fluctuations, various species of flies were chosen for this study. Various studies have been carried out on insect flight endurance with flight mills. For this work a new type of closed insect flight, apparatus has been developed, in which environmental conditions can be altered, and the pull and wing beat frequency of the fly under test recorded simultaneously. Insects were attached to a mechano-electrical transducer either directly or indirectly. The transducer output was resolved into an AC component, whose frequency corresponds to the wing beat frequency, and a DC component whose magnitude corresponds to the force exerted by the insect in flight. Both components were traced on graphical recorders. In a modified apparatus two transducers were used for measuring the pull and wing beat frequency independently. Even under identical physical conditions insects were found to behave in an erratic manner, so that possible small effects due to variations of the ion concentration were difficult to establish. The spiracles of some flies were dilated by increasing the ambient CO₂ concentration up to 15% causing various changes in the flight patterns without rendering them more regular. From a statistical analysis of the energies produced, some evidence can be obtained that individuals of Muscina stabulans and Lucilia sericata under a negative ionization excess display greater activity than those under normal conditions or under positive ion excess. More tests will be necessary to substantiate the results. The use of the apparatus as an entomological olfactometer or for the test of other insect responses is suggested; several insect repellents were tested on the same apparatus.
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