Infected Ixodes ricinus ticks are attracted by electromagnetic radiation of 900 MHz
Authors: Blažena Vargová
Roman Cimbala
Łukasz Jankowiak
Igor Majláth
Martyna Frątczak
Juraj Kurimský
Leszek Jerzak
Zsolt Conka
Piotr Tryjanowski
Viktória Majláthová
Journal: Ticks and Tick-borne Diseases (2020)
Discipline: MICROBIOLOGY
Keywords: Borrelia; EMF; Electromagnetic sense; Prevention; Rickettsia.
Affiliations: Institute of Zoology, Poznań University of Life Sciences, Wojska Polskiego 71C, 60-625 Poznań, Poland., Centre of Applied Science, University of Veterinary Medicine and Pharmacy, Komenského 73, Košice, Slovakia., Institute of Biology and Ecology, Pavol Jozef Safarik University in Kosice, Srobarova 2, 041 80 Kosice, Slovakia., Faculty of Biological Sciences, University of Zielona Góra, Prof. Z. Szafrana St. 1, 65-516 Zielona Góra, Poland., Department of Electrical Power Engineering, Faculty of Electrical Engineering and Informatics, Technical University of Kosice, Masiarska 74, 041 20 Kosice, Slovakia., Department of Vertebrate Anatomy and Zoology, University of Szczecin, Wąska 13, 71-412 Szczecin, Poland., Institute of Biology and Ecology, Pavol Jozef Safarik University in Kosice, Srobarova 2, 041 80 Kosice, Slovakia. Electronic address: .

Abstract:  The electromagnetic field (EMF) is known to influence functions of the nervous, cardiovascular and reproductive systems of many animals, including ticks. The aim of this study was to test the behavior of ticks in the presence of radio-frequency EMF. For testing, 160 adult male and 140 adult female unfed Ixodes ricinus ticks were used. Individuals were exposed to 900 MHz EMF in the Radiation-Shielded Tube (RST). Ticks were attracted to the irradiated area. This effect was significantly stronger for ticks infected with Rickettsia spp., suggesting that pathogens can alter the ticks' response to environmental stimuli. These results lead to the question of whether man-made EMF may have an impact on I. ricinus activity and, as such, be a contributing factor to the ongoing changes in the distribution of the tick and its pathogens currently observed in Europe and elsewhere. 

Retracted: No

PubPeer comments:
 I have several concerns about this study on the effect of electromagnetic radiation on *Ixodes ricinus* ticks behaviour. Ticks were placed into tubes submitted to electromagnetic radiations. Tubes were covered by copper on half of the length (shielded) to stop the electromagnetic field in this part of the tube. - First, on 160 males *Ixodes ricinus* ticks, the authors report that 104 moved toward the exposed part of the tubes, and 46 to the shielded part of the tube. Perhaps there is a mistake. Otherwise, I wonder where are the ten missing ticks gone? - With a simple chiu00b2 test on the results for females, for which 81 moved to the exposed side and 69 to the shielded side, I found a p-value of 0.327. It is difficult to interpret this result as an evidence of a sensibility to electromagnetic fields in female ticks. - The authors stated that  the mean (u00b1 SE) probability of *Rickettsia* infected ticks moving toward the EMF was 0.766u00b10.060 and toward the shielded part 0.594u00b10.034. It is a bit embarrassing that there is a probability of 1.36u00b10.091 for a tick to be somewhere. - The infectious statute of Borrelia burgdorferi s.l. and *R*. spp. have been summed as a continuous variable. There is no or little justification for this approach. - The difference in proportion of ticks in each side of the tubes between infected and un-infected ticks are about five and ten percent over 92 and 49 ticks for respectively *B*. *burgdorferi* s.l. and *R*. spp. infected ticks. That is quite different from the 52% increased claimed by the authors. Unfortunately, the data on infections presented by the authors are only proportions of ticks in both sides of the tubes for infected un-infected females males, that did not allow to re-analyse the data further. - Ticks were placed in tubes of 3 cm diameter. Tick body length is about 3 mm. It seems difficult to put them all exactly at the middle of the tubes. Additionally, despite the experiment is done in the absence of light, the counting is not. Because it seems difficult to count ticks in the 30 tubes at the same time, ticks could had moved at the time of counting. Furthermore, the counting was not performed in a blind fashon. - In another study using the same protocol with the ticks species *Dermacentor reticulatus*, it is reported that over 220 ticks, 70% moved toward the shielded side (Vargovu00e1 et al. 2018). However, it happened in the control group, demonstrating that this kind of deviation from expected (u00b150%) is quite frequent (by the way, there is no negative control in the experiment). It demonstrates the existence of potential bias or at least the lack of statistical power. For instance, there is some evidence of tick aggregation driven by pheromones in ticks, including *I*. *ricinus* male aggregation (Healy Bourk 2004). In this case, each tube should be considered as a single statistical individual, reducing the sample size to 30. The authors did not discuss this problem at all. Actually, there is nothing in the discussion about the limitation of the experiment. - The authors discuss the implications of electromagnetic sensibility of ticks. However, *I*. *ricinus* ticks move only small distances by themselves generally less then 10 m (Perret et al. 2003). The changes in electromagnetic fields at this scale is so small that the utility of this ability seems limited for their orientation. The utility to find a host seems also very limited, since roe deer electromagnetic field is very low and these hosts rarely carry electromagnetic devices (excepted GPS collared ones). In summary, the results are weak. Conclusions are not supported by the results. Results of more controlled experiments are needed before drawing conclusions (better designed experiment without subjective measurement: a single tick per tubes with automated video recording, more statistical power, replicating the experiment several times). The implications of these finding need stronger support, that is a functional study of electromagnetic sensing by ticks and evidence of usefulness in the wild. I hope the authors can clarify all these points and the editors will encourage the authors to do so as well. References: - Vargovu00e1 et al. 2018 Electromagnetic radiation and behavioural response of ticks an experimental test. Experimental Applied Acarology, 75(1), 85-95. - Perret et al. 2003 Darkness induces mobility, and saturation deficit limits questing duration, in the tick *Ixodes ricinus*. Journal of Experimental Biology, 206(11), 1809-1815. - Healy Bourk 2004 Field evidence for aggregating behaviour in the tick *Ixodes ricinus* L.. Acarologia, 44(1-2), 3-14. ,