As a consequence of intensive industrialization, artificial magnetic fields are common in the living environment. This study should contribute to a better understanding of the sepecies-specific responses in variable environmental conditions.
The pupae (0-24 hours old) were randomly divided into three groups: 1.) control group (Tenebrio obscurus (n=8), Tenebrio molitor (n=12)), 5 m distance from the magnet; 2.) exposure close to the north pole of the magnet (N-group) (T. obscurus (n=6), T. molitor (n=11)) and 3.) exposure close to the south pole of the magnet (S-group) (T. obscurus (n=8), T. molitor (n=11)). The pupa-adult development was recorded daily.
After eclosion, every single insect was put into a dish containing food and then returned to the north or south magnetic pole for another 24 hours. Afterwards, the beetles were placed into a petri dish where its behavior was recorded for 15 minutes.
|magnetic flux density||50 mT||-||measured||-||± 5 mT|
No significant differences in the pupae-adult development were found among the groups.
Regarding the locomotor activity, no significant changes in the behavior of T. obscurus were observed between the S-group, the N-group and the control group. However, significant changes in the locomotor activity of T. molitor occurred when compared to the control: In the N-group, the covered distance and the average speed increased while the immobility time decreased. In the S-group, the covered distance was decreased.
The authors conclude that a static magnetic field (50 mT) could be considered as a possible stress factor that does not have any influence on pupa-adult development dynamic, but could induce changes in the locomotor activity of T. molitor .