FAQs

Insects are hexapod invertebrate animals of the class Insecta within the phylum Arthropoda. An insect stands out from the rest of the arthropods because of its three-part body (head, thorax and abdomen). Its body is covered with a chitinous exoskeleton which both supports and protects the insect. On the head, the eyes, the mouthparts and a pair of antennae of the insect can be found. On the thorax of adult insects there are three pairs of legs (six in total - that is why they are called “Hexapoda”) and one or two pairs of wings. The abdomen contains the reproductive, digestive and excretory organs. Insects have a wide range of habitats and feeding habits and many of them are considered plant pests, vectors of diseases, pollinators, parasites etc.

The biological cycle of an insect includes a lot of molts because the chitinous exoskeleton cannot grow with the insect’s body. Depending on the stages of the metamorphosis, insects are divided into three categories: ametabolous (slight or no metamorphosis), hemimetabolous (no complete metamorphosis) and holometabolous (complete metamorphosis). The immature stages of an insect (egg, larva, nymph, pupa) differ from the adults morphologically as to habit and habitat.

Most of the insects are solitary but some of them, such as honeybees, ants, termites, are social, meaning that they build colonies in which every member has a specific and discrete role.

The number of studies that investigate RF-EMF exposure of insects are very limited in comparison to the available literature for vertebrates. In particular, at frequencies above 6 GHz there is currently a lack of studies that have investigated (the effects of) RF-EMF exposure of insects. Consequently, there is uncertainty on the potential outcomes of RF-EMF exposure of these organisms.

What we know for sure is that, for insects, telecommunication networks are the dominant source of RF-EMF exposure. There are also some technologies such as wireless monitoring, insect telemetry, and entomological radar that cause RF-EMF exposure, but these are not widely spread at the moment.

Telecommunication networks evolve over time and this brings about technological changes in these networks. One of the expected technological changes in these networks is the use of additional frequency bands in the RF-EMF spectrum, for example between 24-28 GHz. It has been shown with numerical simulations that insects will absorb RF-EMFs more efficiently at these frequencies than at the currently used frequencies below 6 GHz. However, this still needs to be confirmed experimentally.

Dielectric heating of insects due to RF-EMF exposure has been demonstrated for a variety of species and a variety of life stages. This effect is used in industry to disinfect certain perishable goods from insect pests. This heating can cause internal temperature increases in organisms, which in its turn has a variety of biological effects. Consequently, there is always a level of RF-EMF exposure that will cause biological effects in any insect. The thresholds for such effects are frequency- and species-dependent, but are currently unknown.

ETAIN aims to determine how much RF-EMF power is absorbed in an insect when it is exposed to a given level of RF-EMFs. This is important because this absorbed power is directly proportional to a potential dielectric heating of the insect. We also aim to determine how this absorbed power is distributed over an insect’s body. How it varies from one species to another and whether it depends on the developmental stage of the insect. ETAIN studies this using the creation of 3D EM insect models. These are 3D representations of insects, which can be used in numerical EM solvers to calculate EM fields inside and around an insect under a given exposure condition. The fields inside of an insect can be linked to RF absorption within an insect. These calculations require knowledge on insects’ dielectric properties. These are measured using dielectric characterization test equipment on (parts of) deceased insects.

Second, ETAIN aims to investigate insect development under RF-EMF exposure. It is known that insects’ development can be influenced by temperature. Since dielectric heating is one of the established outcomes of RF-EMF exposure, ETAIN aims at studying whether dielectric heating due to RF-EMF exposure can have developmental effects. This is done by exposing flies in immature stages to controlled RF-EMF fields and looking at their further development. Additionally, ETAIN also investigates whether the levels of RF-EMF exposure that one can expect in the environment, whether they are thermal or non-thermal is currently unknown, can lead to developmental effects. This is studied using the same flies, but also using bee colonies and the trapping of wild bees in nest-traps.

Finally, ETAIN is investigating whether RF-EMFs can have effects in insect biodiversity, in particular the diversity of insect pollinators. This is done in a longitudinal study where insect trapping is repeated over time in an area that is longitudinally exposed to RF-EMFs. ETAIN also looks into whether underlying effects such as avoidance or changes in foraging might (or not) play a role in this.

A material’s dielectric properties determine how this material interacts with electromagnetic fields. These properties determine the velocity and magnitude of these fields inside of the material, how much gain or loss the fields experience in the material, and how much fields are transmitted into and reflected from such a material when fields are incident on such a material. Dielectric properties are tied to the properties of the atoms and molecules that make up the material and how these are electromagnetically and physically arranged.

In ETAIN we study the honey bees (Apis mellifera), which are the most common taxa and the only one producing honey, in Europe. Honey bees in Europe are mainly domesticated and kept in hives, thus called honey bee colonies as they consist of thousands of individuals.

We also study another bee, a solitary insect, the Osmia bicornis, which lives in horizontal hollow nests, and it is one of the greatest pollinators of orchards. Solitary bees construct one tube nest by female, and they live in congregation so many nests can be found in very close vicinity, next to the other. This is one species that can also be reared commercially, thus increasing the number for adequate pollination early in spring.

Pollination refers to the transfer of pollen from one plant to the other or from the male parts to the female parts of a flower. Pollination is a service provided by wind or insects to the plants and shows the ancestral connection and co-existence between plants and insects. Some plants can not produce fruits if they are not pollinated, and insects, mainly bees, are the most valuable vectors of pollination.

Pollinators are the insects (mainly) or the mammals transferring the pollen. Therefore they constitute the essential means for plant reproduction. Honey bees, other bees (solitary bees and bumblebees), butterflies, lady birds, ants, flies, wasps, bats, are considered the main pollinators, with bees being the most important and valuable.

Apiculture and beekeeping refer to the keeping and producing honey bees and their products. Beekeeping has been a profession since ancient times. Apiculture, however, can also mean the science behind beekeeping, and not only the practice of keeping bees.

Beekeepers keep their bees in ‘colonies’. A colony is a family of bees, led by one special female, the queen, and several thousands of other females, the worker bees. The ‘houses’ of the bees are called ‘hives’. Therefore, a ‘colony’ is a bee family while a ‘hive’ is the box housing the bee family.

Four different insect traps are used in ETAIN: Pitfall, Malaise, yellow sticky and pan traps.

Pitfall traps are used for the sampling of ground-dwelling insects and other arthropods, such as mites, spiders etc. A pitfall trap consists of a container which is buried into the soil so that insects walking on the surface of the ground fall in and become trapped there.

The Malaise trap is a tent-like structure which is used for the collection mainly of flying insects. This trap has two short end walls, one central wall and a roof, all made of a mesh material. Through a large opening at the bottom, the insects fly into the trap and the tall central wall directs them into a container with ethanol, which both kills and preserves them. Combining these two kinds of traps ensures the capture of both flying and walking arthropods for the study of biodiversity.

Yellow sticky traps are paper traps with a sticky substance that are usually hung on trees. The flying insects are attracted to the yellow color and they stick on the trap due to glue. In some cases, food attractants or sex pheromones are used additionally on the traps to ensure the attraction of the insects.

Last but not least, pan traps are used for the sampling of many insects, especially pollinators. The structure of this trap includes small colored pans or bowls filled with water and detergent. Every insect which will be attracted by the color, it will surface to the water and then collected.

The bees and other pollinators usually fly a long way searching for food. Thus, they come in contact with electromagnetic radiation, even if their nests/ hives are far away. They also fly well above the ground, visiting the flowers of even the tallest trees.

Bees have a very delicate biological cycle, including a long period of immature stages of development. Their nervous system is very sensitive as well. Furthermore, they possess this unique ability to communicate with each other, as well as to navigate, to learn and memorize the landscape, the colors and the odors. If their nervous system, or their development is disrupted their behavior might change, which could even lead to loss of survival. Specific behaviors, observed only on honey bees for example, such as aggressivity, guarding, swarming, queen replacement, and hygienic behavior are important for their survival and wellbeing.

Bees’s vision is unique! Although they have the same function with humans they operate differently! But unlike humans—whose color vision is based on red, blue, and green—the vision of a honeybee is based on blue, green, and ultraviolet light. Ultraviolet is generally invisible to the human eye. They can not see all colors, but can see reddish wavelengths like yellow and orange. Their eyes contain three photoreceptors, so they are trichromatic. A bee’s eye can detect from 300 to 650 nanometers, while humans can detect from 390 to 750 nanometers of the light spectrum. That means that bees are not able to see the red color but they can see the ultraviolet. Still they can see red flowers!

The bees can also detect polarized light patterns and they use this to navigate back to their colony even where there is no sunlight. Because they have other three little eyes, the ocelli, they can also detect the intensity of light. This helps some of them that they are nocturnal to see also during night. In addition to some unique mechanisms in honey bees’ eyes, they also detect electromagnetic fields, which they use to locate adequate food sources.