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Report

Teaser, summary, work performed and final results

Periodic Reporting for period 1 - ElectroBee (Mechanisms of electroreception in bees and other terrestrial animals)

Teaser

Summary

The project aims at generating transformative information on the sense of electroreception in terrestrial arthropods. The project will identify the how and why of electroreception in honeybees and bumblebees, and establish the importance of this new sense in the sensory ecology of these animals. Beyond bees, the project is investigating aerial electroreception in other arthropod species, namely beetles, treehoppers and spiders.
The importance of this project resides in the fact that aerial electroreception, as a new sense, might be more present in animals than we have previously surmised. Our work has established that electroreception is possible outside the aquatic environment, where it has been scientifically studied for more than half a century. The project will contribute to evaluate whether the electric ecology of natural environment is affected or not by human activity. The world, under human influence has become very electrically-laden, and this change may generate alterations in the physical and sensory ecologies of organisms, including humans. Studying an evolved sense, and describing and characterising it in its natural condition will help appreciate the changes and potential disruption, or their absence, for the health of ecosystems and their organisms. The overall objective is to delineate a framework that can be used to predict and evaluate the conditions presiding to electroreception in air, providing a tool to measure deviations or alterations form it.

Work performed

\"We have initiated work on several work packages. In particular, the part dedicated to further instrumentation development has yielded some valuable outcomes. For example, we have been able to break a length scale barrier with a new laser Doppler vibrometer, allowing us to measure electromechanical actuation with unprecedented spatial accuracy. Using our state of the art low-noise laboratories at the University of Bristol (Robert lab), the resolution obtained in the magnitude of vibration is ground-breaking. We have been able to measure deflection of bulk sensory insect material as low as 8 picometres. To facilitate perspective these pico metres are to a metre what the stone of a cherry is to the earth. Such resolution allows us to establish that very weak electric fields have an effect on selected structure. Whilst we have not yet fully developed the electrophysiological tests, the putative sensors are being now identified. Another piece of progress is the development of techniques to \"\"make electric visible\"\". How do we know about the existence of electric field arising between a flower and a pollinator such as a bee? How do we know about the field between an insect sitting on the surface of a leaf, the leaf, and the predatory wasp searching for its prey? These questions necessitate the characterisation of electric fields, in magnitude, dynamics and structure. For this objective we now have prototype dual electrometers that can report on electric field at the length scale required to leaves in the order of 5-10 cm. For smaller scale, more development is needed for the probes involved, accompanied by computer modelling. We have also made progress on the plant side of the question, establishing that contrary to prediction, the electro-activity of plants within an atmospheric electric gradient depends very much on its surface chemistry. This is this chemistry that will also interact with the insect, hence we are paying attention to this aspect. Finally, we have complete the first stage of understanding the direct role of atmospheric potential gradient on the ballooning behaviour of spiders. Since Darwin and Faraday, the suspicion was that both mild wind and electrostatic interactions were important to the ballooning behaviour of spiders, in which they cast thin strands of silk to create a \"\"silk sail\"\". We have demonstrated that the electric potential present in the atmosphere on fair weather days is sufficient to create enough force to make the spiders airborne. This answers the question asked by Darwin, and also established a general mechanism by which trillions of insects and arachnids can be found flying in the atmosphere up to 5km altitude, even if they do not have wings. The biomass of airborne insects, and how it can move over large distances, between continents, is important to the spread of species in novel environments. In view of a changing climate, new territories become fertile for species to invade. it may be useful to be able to predict the spread of species and the reason how they can do so in the near future.\"

Final results

The results with the new laser technology, although it has suffered teething problems, is beyond state of the art. in general, as electroreception and mesoscale electric field imaging is not very well known and still faces instrumentation development, we consider our activities as rather innovative. Fortunately, we have excellent contacts with experts in the UK, and in the EU, that contribute to our progress. In return we do communicate our progress with them as much as we can and inasmuch it is useful to our partners. We expect to be able to contribute broadly and specifically to a further and deeper and broader appreciation of the role of weak electric fields and triboelectrification in animals, plants and their possible role in adapted behavioural strategies.