New research demonstrates that an introduced European species of damselfly offers only a little threat to native British damselflies and dragonflies.
The little red-eyed damselfly has expanded its range northward from the Mediterranean as temperatures rise. In 1999, it was first seen in the UK, and since then it has spread throughout the country.
The new research examined data from the British Dragonfly Society to determine whether or not this has led to a decrease in native damselflies and dragonflies in the UK. This article is in the latest issue of Insect Conservation and Diversity.
The little red-eyed damselfly was found to have increased or maintained its population in regions where native dragonflies and damselflies were already present.
However, further research is required to determine the extent of the impact on two species of damselflies.
With range-shifting globally growing, researchers need to understand what influence newly arrived species have on ecosystems according to Dr. Regan Early, of the Centre for Ecology and Conservation at Exeter’s Penryn Campus in Cornwall.
Small red-eyed damselflies appear to have successfully established a population in the UK without negatively affecting native populations. It may be doing well in locations with favorable environments, and in the future, these biologically rich areas may be crucial for the expansion of range-expanding species.
Dr. Early differentiated between invading species and range-shifters, the latter of which come naturally from neighboring places. Existing native species have usually come into contact with range-shifters before, as these species have evolved in comparable habitats.
Human-transported invasive species can introduce harmful behaviors and illnesses to local ecosystems (e.g., gray squirrels in the UK).
This new study analyzed data from the British Dragonfly Society’s database of over 50,000 site visits between 2000 and 2015 to identify the locations where each of 17 native UK dragonflies and damselflies was sighted during those years. The impact of the introduction of little red-eyed damselflies on these native species was then evaluated by the research team.
Dr. Jamie Cranston, also from the University of Exeter, explained that their technique permits fast evaluation of how range-shifters are harming local animals. It demonstrates the power of citizen research, in this case by serving as a ‘early warning system’ for potential risks to UK species.
Two other species of damselfly have declined in areas where little red-eyed damselflies have become established, and one of them is closely related to the newcomer. Dr. Early hypothesizes that the little red-eyed damselfly might out-compete its sister species because of their shared habitat preferences and flying season.
However, due to their varied diet, damselflies shouldn’t face much competition for food unless there are significant shortages. In addition, there may be “empty niches” for new arrivals to exploit because the UK has a smaller diversity of these species than the rest of Europe.
Cranston, J., Isaac, N.J.B. & Early, R. (2023) Associations between a range-shifting damselfly (Erythromma viridulum) and the UK’s resident Odonata suggest habitat sharing is more important than antagonism. Insect Conservation and Diversity, 1– 11. Available from: https://doi.org/10.1111/icad.12630