Effect of a permanent magnetic field on wing size parameters in Drosophila melanogaster.

The width and length variability of both D. melanogaster wings were measured in samples of flies after two and six generations under a permanent magnetic field of 35 mT. While in earlier generations under exposure sexes differ in the size response, later they both show a decrease in the wing size under the magnetic field exposure if compared to the control. The bilateral asymmetry in wings as a potential indicator of developmental instability does not increase significantly under exposure. The ecological and adaptive implications of the change of the magnetic intensity as an environmental factor generating stress in populations is discussed.