Chemical‐Free Pest Control by Dielectric Heating with Radio Waves and Microwaves: Thermal Effects

Abstract

Thermal pest control with hot air is widely accepted as an alternative to chemical methods. However, it requires relatively long treatment times owing to the low thermal conductivity of wood. Direct dielectric heating that applies radio waves or microwaves has the advantage of more homogeneous heating. However, sound experimental data on this technique are currently rare. Therefore, the thermal treatment of wood-destroying insects with radio waves and microwaves was studied with two model pests, Anobium punctatum and Hylotrupes bajulus, and with Tenebrio molitor as a reference. The secure elimination of pests was achieved, and the corresponding treatment time was in the range of a few minutes. Temperature profiles were more homogeneous when applying radio waves.

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

“…During the last decade, several studies have supported the efficiency of microwave heating of wood [18][19][20][21][22][23][24][25] and wood-invading insects 7,10,11,26 . However, some other studies reported reduced or no lethal impact on pests 24,27,28 . According to Nakai et al 27 , direct exposure of the termite body to microwave radiation did not show a lethal effect.…”

Chemical‐Free Pest Control by Means of Dielectric Heating with Radio Waves: Selective Heating

“…Mortality tests were carried out analogously to the studies described in previous papers , with mealworm beetle larvae as a reference for wood‐destroying pests.…”

“…For the RF heating experiments, a similar generator system to that employed for the tests described in a previous publication and elsewhere was used (fixed working frequency of 13.56 MHz, PFG 1000 RF generator with matching network PFM 3000A, both water‐cooled, from Trumpf Hüttinger, Freiburg/Brsg., Germany). The RF voltage was measured with a high‐voltage probe (P6015A, from Tektronix Inc., Plano, USA) in combination with a potential divider (1:1000) and an oscilloscope (RTO 1024, 2 GHz, 10 GSa s −1 , Rohde & Schwarz, Neu‐Isenburg, Germany).…”

“…Since then, many studies have been carried out on the disinfection of a large number of materials that can be attacked by pests. The disinfection of stored grain , insect management in fruits , as well as in textiles , , and pest control in timber (as reported in the first part of this study) are described in the literature. A detailed overview of these studies and the main results are given in the Supporting Information.…”

“…Nevertheless, deviations from mechanisms related to the mean temperature of the matrix material were discussed even in early publications, and the discussion continues to this day. In a previous study we demonstrated the potential of dielectric heating for chemical‐free pest control and excluded a lethal effect of the electrical field alone, at least for field strengths typical of microwave (MW) and radio‐frequency (RF) heating.…”