Weak radiofrequency fields affect the insect circadian clock. Author: Bartos P1, Netusil R1, Slaby P1, Dolezel D2,3, Ritz T4, Vacha M1 Affiliation: <sup>1</sup>Department of Experimental Biology, Section of Animal Physiology and Immunology, Faculty of Science, Masaryk University, Czech Republic. <sup>2</sup>Biology Centre of the Czech Academy of Sciences, Institute of Entomology, Branisovska 31, Ceske Budejovice, Czech Republic. <sup>3</sup>Department of Molecular Biology and Genetics, Faculty of Science, Branisovska 31, Ceske Budejovice, Czech Republic. <sup>4</sup>Department of Physics and Astronomy, University of California Irvine, Irvine, CA, USA. Conference/Journal: J R Soc Interface. Date published: 2019 Sep 27 Other: Volume ID: 16 , Issue ID: 158 , Pages: 20190285 , Special Notes: doi: 10.1098/rsif.2019.0285. Epub 2019 Sep 18. , Word Count: 148 It is known that the circadian clock in Drosophila can be sensitive to static magnetic fields (MFs). Man-made radiofrequency (RF) electromagnetic fields have been shown to have effects on animal orientation responses at remarkably weak intensities in the nanotesla range. Here, we tested if weak broadband RF fields also affect the circadian rhythm of the German cockroach (Blatella germanica). We observed that static MFs slow down the cockroach clock rhythm under dim UV light, consistent with results on the Drosophila circadian clock. Remarkably, 300 times weaker RF fields likewise slowed down the cockroach clock in a near-zero static magnetic field. This demonstrates that the internal clock of organisms can be sensitive to weak RF fields, consequently opening the possibility of an influence of man-made RF fields on many clock-dependent events in living systems. KEYWORDS: circadian clock; free-running rhythm; insects; magnetic field; magnetoreception; radiofrequency field nano scale PMID: 31530135 DOI: 10.1098/rsif.2019.0285