Dragonflies move to the city

Insect declines and extinctions are accelerating in many parts of the world. With this comes the disappearance of irreplaceable services to humans, the consequences of which are unpredictable.

A group of scientists from across the globe, including Prof. Frank Suhling from the Institute of Geoecology at Technische Universität Braunschweig, has united to warn humanity of such dangers.

Humanity is pushing many ecosystems beyond recovery. As a consequence, unquantified and unquantifiable insect extinctions are happening every day.

Two scientific papers by 30 experts from around the world discuss both the perils and ways to avoid further extinctions, intending to contribute towards a necessary change of attitude for humanity’s own sake. In addition to mitigating climate change, an important aspect of the solution involves setting aside high-quality and manageable portions of land for conservation, and transforming global agricultural practices to promote species co-existence.

“It is surprising how little we know about biodiversity at a global level, when only about 10 to 20 per cent of insect and other invertebrate species have been described and named. And of those with a name, we know little more than a brief morphological description, maybe a part of the genetic code and a single site where it was seen some time ago,” says the biologist Pedro Cardoso, from the Finnish Museum of Natural History, University of Helsinki, and leading author of the paper „Scientists’ warning to humanity on insect extinctions“.

Dragonflies: Species richness in the cities

Scientists from the working group Landscape Ecology and Environmental Systems Analysis at the Institute of Geoecology at TU Braunschweig have found that land use makes a significant contribution to the diversity of aquatic insects such as dragonflies.

“Agricultural landscapes are currently the least suitable for preserving a high species diversity,” says Professor Frank Suhling. In contrast, there is a considerable potential in cities. In the 30 cities that were studied, a high species richness could be found.

In Braunschweig, 70 percent of the dragonfly species found in Germany were detected. “One reason is probably that the outskirts of the cities are more likely to be used for recreational purposes and are therefore managed in a more environmentally friendly way than the surrounding agricultural areas,” explains Professor Suhling.

“There are more natural landscape elements and less use of pesticides.” In addition, dragonflies find ideal conditions by renaturing running waters or creating ponds.

Species that benefit from climate change seem to be particularly at home in cities. Such species were rather rare in the past. “We believe that their abundance may have a negative impact on other species.”

No healthy ecosystem without insects

Habitat loss, pollution – including harmful agricultural practices, invasive species that do not encounter borders, climate change, overexploitation and extinction of dependent species all variably contribute to documented insect population declines and species extinctions.

“With species loss, we lose not only another piece of the complex puzzle that is our living world, but also biomass, essential for example to feed other animals in the living chain, unique genes and substances that might one day contribute to cure diseases, and ecosystem functions on which humanity depends,” confirms Cardoso.

The ecosystem functions he mentions include pollination, as most crops depend on insects to survive. Additionally, decomposition, as they contribute to nutrient cycling, as well as many other functions for which we have no technological or other replacement.

Practical solutions

The researchers also suggest possible practical solutions based on existing evidence gathered from around the world, which would help to avoid further insect population loss and species extinctions. These include actions such as setting aside high-quality and manageable portions of land for conservation, transforming global agricultural practices to promote species co-existence, and mitigating climate change.

Above all, communicating and engaging with civil society and policy makers is essential for the future and mutual well-being both of people and insects, the scientists emphasize.

“While small groups of people can impact insect conservation locally, collective consciousness and a globally coordinated effort for species inventorying, monitoring and conservation is required for large-scale recovery” says Michael Samways, Distinguished Professor at Stellenbosch University, South Africa.

Ideas to help insects

1. Avoid mowing your garden frequently; let nature grow and feed insects.
2. Plant native plants; many insects need only these to survive.
3. Avoid pesticides; go organic, at least for your own backyard.
4. Leave old trees, stumps and dead leaves alone; they are home to countless species.
5. Build an insect hotel with small horizontal holes that can become their nests.
6. Reduce your carbon footprint; this affects insects as much as other organisms.
7. Support and volunteer in conservation organizations.
8. Do not import or release living animals or plants into the wild that could harm native species.
9. Be more aware of tiny creatures; always look on the small side of life.

Prof. Dr. Frank Suhling
Technische Universität Braunschweig
Institute of Geoecology
Landscape Ecology and Environmental Systems Analysis
Langer Kamp 19c
38106 Braunschweig
Phone: +49 531 391-5915
Email: f.suhling@tu-braunschweig.de

www.tu-braunschweig.de/en/geooekologie

Scientists’ warning to humanity on insect extinctions. Biological Conservation. DOI: https:/doi.org/1016/j.biocon.2020.108426

Solutions for humanity on how to conserve insects. Biological Conservation. DOI: https:/doi.org/10.1016/j.biocon.2020.108427