Magnetic orientation in the mealworm beetle Tenebrio and the effect of light.

There is evidence for both light-dependent and light-independent mechanisms of magnetoreception of terrestrial animals. One example of a light-independent mechanism frequently cited is the magnetic compass of the mealworm beetle (Tenebrio molitor). We found that magnetoreception of the mealworm beetle per se is a replicable phenomenon but that, in contrast to earlier findings, Tenebrio only exhibited consistent magnetic compass orientation when light was present. The problem of whether the loss of orientation is due to a light-dependent magnetoreception mechanism or is instead an effect of motivation change is discussed.