Physical assessments of termites (Termitidae) under 2.45 GHz microwave irradiation

Abstract

Demands for chemical-free treatments for controlling insect pests are increasing worldwide. One such treatment is microwave heating; however, two critical issues arise when using microwaves as a heat source: intensive labor and excessive energy-consumption. Optimization is thus required to reduce energy consumption while effectively killing insects. Currently, the lethal effect of microwaves on insects is considered to be due to the temperature of the irradiated materials. This study examines how the conditions of irradiation, such as resonance or traveling mode, changed the conversion of electromagnetic energy into heat when 2.45 GHz microwaves penetrated the body of the termite, C. formosanus. Our results indicated that it is possible to heat and kill termites with microwaves under resonance condition. Termites were however found to be very tolerant to microwave irradiation as the permittivity of the insect was low compared with other reported insects and plants. Electron spin resonance revealed that termites contained several paramagnetic substances in their bodies, such as fe 3+ , cu 2+ , Mn 2+ , and organic radicals. Interestingly, irradiation with traveling microwaves hardly produced heat, but increased the organic radicals in termite bodies indicating non-thermal effects of microwaves.

Impact of 2.45 GHz Microwave Irradiation on the Fruit Fly, Drosophila melanogaster

“…The microwave system was a solid-state amplifier (R&K GA0827-4754-R) at Kyoto University. This is an analysis and development system for advanced materials and consists of a waveguide cavity with a microwave oscillator (Agilent, MXG wave generator, N5183A), a 3-stub, and a short plunger (Device 1, Supplementary Figure S1 ) [ 7 ]. Microwaves with a frequency of 2.45 GHz are focused by an iris and form a TE103 mode in this cavity.…”

“…D. melanogaster , these insects were exposed to travelling microwaves to determine the influence of ordinal microwave irradiation. The microwave irradiation system was a solid-state amplifier (R&K GA0827-4754-R) at Kyoto University; it consisted of a waveguide cavity with a microwave oscillator (Agilent, MXG wave generator, N5183A) and a dummy load [ 7 ]. The 2.45 GHz microwaves irradiate the cavity.…”

“…A microwave irradiation system (Sunny Engineering Co., Ltd., MTS03(S), Osaka, Japan) consisting of a semiconductor microwave oscillator and an applicator was used for microwave irradiation. The semiconductor oscillator generates microwave outputs at 10 W, with a single, sharp frequency spectrum at 2.45 GHz (Device 3, Supplementary Figure S3 ) [ 7 ]. This device does not include sensors to monitor inflow/outflow power; instead, it can monitor the temperature inside the applicator and petri dish (DC 3.5 cm) with a thermistor.…”

“…UV sterilization is also employed in the laboratory clean bench. EMFs such as microwaves used in the industry are strong; thermal and non-thermal effects play an important role in pest control [ 6 , 7 , 8 , 9 ]. However, it is not easy to investigate the non-thermal effects on living organisms because the significant damage caused by thermal effects can obscure those caused by non-thermal effects, thus preventing the investigation of non-thermal effects.…”

Non-chemical signatures of biological materials: Radio signals from Covid19?

“…) and find a strong microwave absorption peak on WSSV at a frequency (6:5 � 1) GHz. Termite (Termiditiae) control has been demonstrated with 2.45 GHz microwave radiation (Yanagawa et al 2020).…”