The mechanisms of electroreception in bees

The ecological partnership between flowers and bees is profound; flowers evolved spectacular displays of colours and fragrant volatiles to attract pollinators, in particular bees, to secure pollen transfer and fertilisation. Many flowers include nutritious nectar as a special reward. Both bee and flower benefit from this remarkable example of cooperation. Thus, bees can see and smell flowers, but is that all? Our research changed its path when we marveled at the fact that a flower's pollen is capable of jumping towards an approaching bee and sticking to it. Driven by electrostatic forces, the pollen is transported from flower to flower. But is this the only way electricity can enhance pollination? Following these observations, a simple question came to our minds: does the bee know anything about the presence of this electrostatic field?

Recently, we reported that bumblebees (Bombus terrestris) can detect and learn about floral electric fields. These fields are in fact floral cues, complementing colour, scent, temperature, humidity and shape. Floral fields are affected by the visit of bees, which are also electrically charged. Like visual cues, floral electric fields exhibit variations in pattern and structure, which can be discriminated by bumblebees. We also showed that electric field information can improve a pollinator's memory of floral rewards. Because floral electric fields can change within seconds, their detection may facilitate rapid communication between flowers and their pollinators. Yet, how bees detect floral electric fields remains unknown.

The goal of the proposed research is to identify the sensory mechanisms by which a bee detects electric fields. Do bees have a dedicated electric sensory organ, like many animals have dedicated ears to detect sounds? We hypothesise that bees use the fine hairs on their bodies to sense the presence of floral electrostatic fields. This is similar to the sensation we experience from the hairs on our arm rising in front of an old television set. We will measure the deflection of bee hair and record the activity of sensory neurones at their base. We will also train bees to recognise different electric fields and, after impairing the bending of these hairs, evaluate their recognition ability. Using mathematical modelling and laser vibration technology, we will also establish the kind of electric fields that bees are in effect sensitive to. Are they only sensitive to floral fields?

This work will describe an entirely novel sense. The role this electrical sense plays in the life of bees including their mutualism with flowers, is still poorly understood. Do other important pollinators, such as flies, beetles and moths also sense floral electric fields?

Our work will also change the way we understand our environment and its complexity, adding an electric component. Currently we are blind to this electrical ecology; yet this research project aims at providing ways to visualise this thus far elusive part of the natural world. Potentially, novel electrical measurement techniques, perhaps bio-inspired, will emerge from our investigations on detection of weak and local electric fields. As such, the interest of technologists may also be important to the long term continuation and diversification of our research and its impacts.

Also, our research will enable further questions to be asked about the possible negative or positive, but currently unknown, impacts of man-made electric fields on pollinators, and other organisms, including plants, and the environment. As bees provide important and valuable pollination services for many crops consumed by humans, it may be very timely to better understand the biology of bees, and ensure they can remain safe and healthy in a rapidly changing and uncertain environment.

We recently discovered that bumblebees (Bombus terrestris) can detect and learn about floral electric fields. Our discovery establishes the existence of a formerly unknown sensory modality in terrestrial animals. Bees use several senses to detect flowers, sensing floral cues such as colors, shapes, patterns, fragrant volatiles and humidity. Weak electric fields can also act as floral cues. Like visual cues, floral electric fields exhibit variations in pattern, which bees can discriminate. We established that such electric field information improves the bee's memory of floral rewards. Bees can remember to associate food rewards with a particular electric field. This is evidence of a well-developed sensory system.
Our central objective is to establish how bees detect floral electrical fields.
The goal of the proposed research is to identify the sensory mechanisms by which bee detect electric fields. We will establish whether bees have dedicated electric sensory organs. We hypothesise that bees use the fine hairs on their body to sense electrostatic fields. We know that such hair can be deflected by incident weak electric fields. To test this hypothesis, we will measure the mechanical deflection of bee hair and record the activity of sensory neurones at their base. We will extend this test to the bee's antennae. We will train bees to recognise different electric fields and, after impairing hairs motion (or antennae), evaluate their recognition ability. Using mathematical modeling, we will establish the electric parameter space that bees are sensitive to in nature.
The planned work will change our appreciation of the environment by adding an electric component. Humans are apparently not sensitive to an electrical ecology, only visible to bees. Our research aims at providing novel ways to visualise and understand this elusive part of the natural world, where man-made electric fields may impact positively or negatively on the life of pollinators and other organisms.

The planned research will benefit those in the field of sensory biology. Several other disciplines related to the studies of atmospheric physics and chemistry will be interested by our approach and research rationale aimed at both large and small scale measurements. Scientists in the fields of physics, chemistry and biology are interested, and more specifically those working on atmospheric physics, methods for local weather predictions. Because bees provide extremely important ecological services, we expect impact to also reach researchers and policy-maker in the areas of research in the sustainability of food production.

Our discovery of a new sensory modality, through its first reporting in the journal Science, has generated broad interest in the scientific community. Through the emails we received we know that the curiosity of a wide range of scientists of all trades, from astrophysics, atmosphere and climate scientists, and weather forecasters.

In the past hundred years, the world has become electrical, with a vast network of wires, and more recently electromagnetic waves constantly percolating through our living habitats. Our research is expected to impact on our fundamental understanding of electric ecology, a part of the natural world we know very little about. This research has direct impact on how scientists will understand ecosystems and key species -pollinators- that are underpinning food webs and providing globally important ecosystem services. Our work has direct relevance to national and global food security.

The outcomes of the research planned will also appeal to a broad cross-section of the public as part of an increasing awareness of the beauty and complexity of the natural world. Our findings will highlight and inform individual and societal responsibilities to monitor and guarantee sustainability of this natural world. As detailed in our Pathways to Impact document we will directly engage with the media, science festival, environmental charities and other organisations. The public will thus actively benefit from our activities through the electronic media (web pages, twitter, YouTube channel), but also through activities in science festivals, contributions to the general press, and television and radio interviews.

In conducting this programme of research, the team (especially the PDRAs) will gain further training and experience in project and personnel management, as well as developing strong communication skills through public engagement and industry and policy-driven knowledge exchange activities. Importantly, we will ensure that training is delivered to our entire team, and that of volunteers, enhancing the educational value of impact, and generating increased opportunities for science to engage with the public and policy makers, teachers, school children, industrial partners and fellow academic researchers.