Pilot study of a new methodology to study the development of the blue bottle fly (Calliphora vomitoria) under exposure to radio-frequency electromagnetic fields at 5.4 GHz

Abstract

Purpose Exposure of insects to radio-frequency electromagnetic fields (RF-EMFs) can have developmental effects. However, there is currently no clear understanding of the exposure level that can lead to such effects. Therefore, the goal of this study was to, for the first time, study the development of the Blue Bottle Fly (Calliphora vomitoria, CV) under exposure to RF-EMFs at 5.4 GHz, using both numerical RF-EMF dosimetry with anatomically accurate 3 D models of insects and an RF-EMF exposure experiment. Materials and Methods CV was chosen as a model organism in this study because CV’s development can be influenced thermally and CV’s pupal stage presents a window of several days in which immobile pupae can be exposed to RF-EMFs. The 5.4 GHz frequency was used because it allowed us the license-free operation of the exposure setup. Numerical, EM simulations with 3 D anatomically accurate models of CV, obtained using micro-CT scanning, were used in this study. These simulations enable the estimation of the absorbed power and the whole-body averaged specific absorption rate in CV during RF exposure experiments. An experiment with three exposure conditions was designed and executed in which 400 pupae were split into an exposed group that was placed inside the TEM cell for 48 h and concurrent control. Two exposure conditions used RF-EMF input power into the TEM cell at 5.4 GHz on two different levels. One exposure condition was sham exposure. Electric field strength measurements were used to validate the proper functioning of the exposure setups and to quantify the RF-EMF exposure of the control groups. Results and conclusions All studied groups of pupae – exposed to RF-EMFs, sham, and control groups- showed similar (evolutions of) masses, lengths and diameters during their development. The total rate of pupal emergence was reduced in one of the studied RF-EMF exposures in comparison to its concurrent control, while the other RF-EMF exposure and the sham exposure did not alter the total rate of pupal emergence. The sham exposure and the lowest of the two studied RF-EMF exposure conditions (19.4 V/m) caused a median delay in pupal emergence of 4 and 8 hours, respectively, in comparison to concurrent control groups. The higher studied exposure of 55 V/m caused a median relative acceleration in the development of 8 h.