Rungtip Wonglersak (picture above centre) gave a talk about her PhD research work at the Natural History Museum in London. She is studying the response in terms of body size of British Odonata to latitude and temperature changes. She has carried out detailed measurements on specimens from known locations to see what changes there might be. The general expectation for mammals and birds is set out in Bergmann’s Law which says that body size will increase for populations located further north. Her work has suggested, in contrast, that Damselflies show an effect which is the reverse of this with more northerly populations of a species tending to have a smaller body size, whereas dragonflies show either no change or a small increase in body size with increasing latitude.
After lunch, Ellie Colver, BDS Conservation Officer, gave an update on her work and particularly on some of our projects and our plans for 2019. She showed the results of Clubtail Count for 2018 and highlighted the full roll out of the White-legged Damselfly Project in 2019. We are still monitoring the range expansion of Willow Emerald and she noted the new site for Southern Emerald that was found in 2018. Already in 2019 there have been a fair number of reports of Vagrant Emperors and it was suggested that these have been associated with winds that have been blowing up from North Africa recently. It was noted that the recent warm weather had already resulted in some early reports of damselflies.
Dr Huai-Ti Lin, from Imperial College, gave a talk on dragonfly wings. This was an innovation for us as he was unable to attend in person and gave his talk via an internet connection. This worked without any technical problems. There were mixed views as to whether people would have preferred to see the speaker in person but the talk was very informative and it came as a surprise to most in the audience that the wings have a network of neurons to act as sensors rather than being simply passive structures. The leading edges of a dragonfly’s wings are serrated and we learnt that there is a neuron in the tip of each tooth. The wings have nodules and bristles on the surface which also include neurons and research is leading to the conclusion that the network of neurons act as sensors help the insect to control the movement of its wings. Computational Fluid Dynamics (CFD) analysis has indicated that the bristles tend to be located where airflow may separate from the wings in flight, which tends to reinforce the view that they are acting as sensors. Follow the project on Twitter and Instagram.
The final talk was about the Wrexham Industrial Estate Living Landscape Scheme managed by the North Wales Wildlife Trust. Adrian Jones (pictured below) told us about the project which provides a good example of what is achievable in the way of landscape scale improvements to habitat in an industrial area. The aim has been to work with the companies on the estate and others to improve it by creating flower meadows, planting hedges, digging ponds, managing verges and improving connectivity. The aim has also been to create footpaths and cycle routes for access and improve the well being of those working on the site. One of the key messages to the businesses on site is that grounds which are neat and tidy are also sterile and most businesses have been very supportive of the project. Surveys have been carried out to establish the distribution of species on the site and particular efforts have been made to create habitat for the likes of Grizzled Skipper butterflies and Great Crested Newts. Dragonflies have benefitted for the project and Clubtail Dragonfly has been recorded on the site; the river Dee runs along the southern boundary.