# Varroa Control by Means of a Hyperthermic Device
## 1 Introduction
In 2006, the Thermovar was developed in Greece; this device performs heat treatment by gradually heating the air inside the system and distributing it among the combs of the hive. However, long treatment times are required to effectively affect varroa in both the reproductive and phoretic phases [8]. The Thermovar, like the other devices described, heats the colony by feeding heat from outside into the hive, failing to consistently heat the brood due to the ventilation carried out by adult bees. The next step in the evolution of thermotherapy was the development of devices capable of heating hives directly from the inside; in the United States, the Mite Zapper was developed, the first device able to do so. It is made up of a male brood comb with heating elements incorporated in the wax that generate heat when connected to a source of electricity [13]. The device has shown high efficacy, but treating only male brood does not allow a low level of parasite infestation to be maintained throughout the season, as bees no longer raise male brood towards the end of the summer. In order to maintain a low infestation as long as possible throughout the season with thermotherapy, heat must be applied to worker brood also. In Switzerland, starting in 2015, a technique was developed to heat the hive from the inside by treating only the female brood using an electrically powered device called the Vatorex, which consists of a thermal comb with an electrical heating element built into the wax. The electrical resistance is connected to a distributor (control unit) that regulates the flow of current to the connected combs. The method involves heating one comb at a time at a temperature of 42 \({}^{\circ}\)C for 3 h [14]. The limitations of this device are the heating element, which covers only the central area of the comb, as well as the treatment time, as only one comb is heated at a time. In 2015, independently from Swiss developments, a device called Bee Ethic was marketed in Italy, equipped, like the Vatorex system, with a thermal comb. This solution differs from the previous ones in terms of its electrical resistance, which is incorporated in the foundation; the electrical resistance is distributed over the entire surface of the comb and not only in its central part, and all the brood combs are equipped with resistance and heated simultaneously. The efficacy and functionality of the Bee Ethic system were preliminarily tested in 2014, 2015 and 2016 in Umbria (central Italy) on a hundred colonies to define the best ways of using this technology (unpublished results). Subsequently, in the years 2018, 2020 and 2021, further research was carried out in Piedmont (north-western Italy) to further investigate the effects of hyperthermia on bees and varroa. Based on the information collected in the apiary, simulations were then carried out with a well-known mathematical model of the hive that was suitably modified for the specific conditions of hyperthermia. The present work reports the experimental results obtained in Piedmont and what emerged from the simulations developed using the mathematical model.