Study type: Medical/biological study (experimental study)

The influence of static magnetic field (50 mT) on development and motor behaviour of Tenebrio (Insecta, Coleoptera). med./bio.

Published in: Int J Radiat Biol 2013; 89 (1): 44-50

Aim of study (acc. to author)

To examine the influence of a static magnetic field on the development from the pupae to the adult and motor behaviour in two mealworm beetle species.

Background/further details

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.

Endpoint

Exposure

Exposure Parameters
Exposure 1:
Exposure duration: during development from pupa to eclosion and 24 h after eclosion

General information

Pupae were divided into the following three groups: i) control (kept at a distance of 5 m from the magnet) ii) nearer to the magnetic south pole iii) nearer to the magnetic north pole

Exposure 1

Main characteristics
Frequency
Type
Exposure duration during development from pupa to eclosion and 24 h after eclosion
Exposure setup
Exposure source
Distance between exposed object and exposure source 2 mm
Setup 37 mm high cylindrical magnet with a diameter of 45 mm positioned above the cell plate dish; pupae placed into the cell plate dish with the head towards the magnetic pole (head 2 mm from the magnetic pole)
Parameters
Measurand Value Type Method Mass Remarks
magnetic flux density 50 mT - measured - ± 5 mT

Exposed system:

Methods Endpoint/measurement parameters/methodology

Investigated system:
Time of investigation:
  • during exposure
  • after exposure

Main outcome of study (acc. to author)

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 .

Study character:

Study funded by

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