6 colonies of Myrmica sabuleti ants were used to study the effects of exposure to the electromagnetic field by comparing their behavior before (control) and during/after exposure. These ants had been used in a previous study by the authors (Cammaerts et al. 2012) and had already been exposed to electromagnetic fields there. To ensure their suitability for the present study, their behavior was compared with ants never experimentally exposed to electromagnetic fields prior to exposure. Only slight differences were found and the colonies were deemed adequate.
The exposure consisted of 3 periods of 60 h (12 hours prior to and 2 days during each experiments on pheromone response) and one period of 18 h (12 hours prior to and 6 hours during the test on food collection) with a delay of 3 days between each period.
A pheromone is a chemical factor for information transfer between members of the same species.
|Distance between exposed object and exposure source||1 m|
|Setup||a vector signal generator with two channels produced the signal; each channel delivered horizontally polarized electromagnetic waves to three nests over an antenna ; the manufacturer stipulated that the radiation pattern was unidirectional; electrical field pattern over the ants was uniform|
The responses to the pheromone trail, area-marking pheromone and alarm pheromone as well as the ability for social food collection were significantly deteriorated in exposed ants compared to before the exposure. Exposed ants followed marked trails for only short distances, did not recognize marked areas, no longer orientated themselves to a source of alarm pheromone and became unable to return to their nest during food collection and recruit helpers.
The authors conclude that exposure to a 900 MHz electromagnetic field might impair pheromone response and social food collection behavior in ants.