A preliminary behavioral assay was performed using the common cutworm (Spodoptera litura) to examine the magnetoreceptive behavior during exposure to an extremely low frequency magnetic field.
After an acclimatization period of several days, larvae (caterpillar) were placed in a round plastic Petri dish as a group (n=16 sham exposed, n=16 exposed) or as individuals (n=16 sham exposed, n=30 exposed).
|Exposure 1: 60 Hz||
|Chamber||larvae were exposed in round plastic petri dishes (groups: diameter of 100 mm, individuals: diameter of 35 mm) which were put at the center of the testing arena (13 cm wide Œ 13 cm deep Œ 15 cm high) in the middle of the exposure system|
|Setup||self-made exposure system (28 cm long Œ 28 cm deep Œ 30 cm high) was composed of open acrylic frames with three bundles (2000 turns per bundle) of copper wires (0.5 mm diameter) aligned parallel 20 cm apart and was connected to a locally supplied voltage transformer; temperature inside the exposure system was regulated (25°C ± 0.1°C)|
|Sham exposure||A sham exposure was conducted.|
|magnetic flux density||0.2 mT||-||measured||-||-|
Exposed larvae (group and individual) showed a significantly increased motor activity in comparison to the sham exposed larvae. The magnetic field-induced movement was significantly longer and had an earlier onset when compared to the sham exposure. In the exposed groups of larvae the onset time of movement was earlier than in the exposed individuals, maybe because of physical contact to other larvae, suggesting that the individual test is more favorable.
The authors conclude that investigating the motor behavior of the common cutworm (Spodoptera litura) while exposed to an extremely low frequency field represents a suitable model system in some areas of magnetoreceptive neurological behavioral research.