Insects and arachnids

It is known that bees can perceive the Earth’s static magnetic field and orientate themselves according to it. They have a magnetite-based receptor that reacts to the polarity of the magnetic field ^[1]. Bees can also perceive low-frequency magnetic fields at particularly low frequencies and higher flux densities ^[2].

A combined field and laboratory study showed that bees can use static magnetic fields above 26 µT (approx. 50% of the Earth’s magnetic field) when foraging. Experience and learning play a considerable role in this. Other perceptions – such as colour – have a stronger effect than the magnetic field ^[3].

In a study, it was shown that low-frequency magnetic fields, as they occur under AC power lines, negatively influence the learning ability, flight behaviour, and foraging behaviour of bees. The threshold value was 20–100 µT. Long-term memory was not affected ^[4]. A follow-up study then showed that above 100 µT, the learning ability of bees was impaired, and aggression was increased ^[5]. Another study has shown that low doses of insecticides, which are toxic to bees, do not further increase the effects of magnetic fields and in some cases even show an opposite effect ^[6]. Although there is no synergistic effect, both environmental stressors affect bee populations.

Two field studies ^{[7, 8]} investigated the effects of pesticides, magnetic fields near power lines, and the combination of these on several enzymatic biomarkers in bees. Both exposures individually had partly opposite effects; a synergistic effect was not shown. However, the vital parameters and survival rate of the hives were worst at the site with combined exposure.

Bees also perceive static electric fields and use the electrostatic charge of flowers and conspecifics for communication and orientation ^[9]. Electrostatic fields are also involved in the transfer of pollen by bees ^[10]. Bumblebees also perceive static electric fields; they can orientate themselves according to them and even gauge how much nectar a flower contains ^[11].

An older study ^[12] investigated the effect of low-frequency electric fields on bee behaviour and vital parameters (weight, honey quantity, brood) in hives below power lines. At an electric field of 7 kV/m (above the limits valid today), relatively strong electric currents were generated inside the hives. These caused contact currents and electric shocks that were perceived by bees and considerably disturbed their behaviour. In the end, this led to the lower weight of the affected colonies and high losses of colonies over the winter.

Because bees can be exposed near power lines above the limits applicable to humans, it is possible that their behaviour is also affected there. This applies equally to DC and AC power lines.

Spiders can perceive electric fields. Young spiders spread by gliding through the air on their threads. In addition to the wind, they also use the forces of natural electric fields ^[13]. Here, too, it cannot be ruled out that artificial static electric fields such as those from DC power lines influence this behaviour.

References

[1] Lambinet V, Hayden ME, Reid C, Gries G (2017). Honey bees possess a polarity-sensitive magnetoreceptor. J Comp Physiol A Neuroethol Sens Neural Behav Physiol.

[2] Kirschwink JL, Padmanabha S, Boyce CK, Ogelsby J (1997) Measurement of the threshold sensitivity of honeybees to weak, extremely low-frequency magnetic fields. J. Exp. Bio. 200(Pt9): 1363 - 1368.

[3] Chicas-Mosier, AM, Radi, M, Lafferrandre, J, O'Hara, JF, Vora, HD, Abramson, CI (2020). Low strength magnetic fields serve as a cue for foraging honey bees but prior experience is more indicative of choice. Bioelectromagnetics 41(6): 458-470.

[4] Shepherd S, Lima MAP, Oliveira EE, Sharkh SM, Jackson CW, Newland PL (2018). Extremely Low Frequency Electromagnetic Fields impair the Cognitive and Motor Abilities of Honey Bees. Sci Rep 8(1): 7932.

[5] Shepherd, S, Hollands, G, Godley, VC, Sharkh, SM, Jackson, CW, Newland, PL (2019). Increased aggression and reduced aversive learning in honey bees exposed to extremely low frequency electromagnetic fields. PLoS One 14(10): e0223614.

[6] Shepherd S, Lima MAP, Oliveira EE, Sharkh SM, Aonuma H, Jackson CW, Newland PL (2021) Sublethal neonicotinoid exposure attenuates the effects of electromagnetic fields on honey bee flight and learning. Environmental Advances 4: 100051.

[7] Lupi D, Tremolada P, Colombo M, Giacchini R, Benocci R, Parenti P, Parolini M, Zambon G, Vighi M (2020) Effects of pesticides and electromagnetic fields on honeybees: A field study using biomarkers. International Journal of Environmental Research 14(1): 107-122

[8] Lupi D, Palamara Mesiano M, Adani A, Benocci R, Giacchini R, Parenti P, Zambon G, Lavazza A, Boniotti MB, Bassi S, Colombo M, Tremolada P (2021) Combined effects of pesticides and electromagnetic-fields on honeybees: Multi-stress exposure. Insects 12(8).

[9] Greggers, U, Koch, G, Schmidt, V, Durr, A, Floriou-Servou, A, Piepenbrock, D, Gopfert, MC, Menzel, R (2013). Reception and learning of electric fields in bees. Proc Biol Sci 280(1759): 20130528.

[10] Clarke D, Morley E, Robert D (2017). The bee, the flower, and the electric field: electric ecology and aerial electroreception. J Comp Physiol A Neuroethol Sens Neural Behav Physiol.

[11] Clarke D, Whitney H, Sutton G, Robert D (2013) Detection and learning of floral electric fields by bumblebees. Science 340(6128): 66-69.

[12] Greenberg B, Bindokas VP, Frazier MJ, Gauger JR (1981) Response of honey bees, apis mellifera l., to high-voltage transmission lines 1. Environmental Entomology 10(5): 600-610.

[13] Morley EL, Robert D (2018). Electric Fields Elicit Ballooning in Spiders. Curr Biol 28(14): 2324-2330.