Orbis Insecta

In 2017 it became world news and led to a real media storm: German-Dutch research – published in Plos One – showed that in nature reserves in Germany that in the past 30 years more than three-quarters of flying insects (biomass) have disappeared.

Since 1989, German entomologists from the Entomological society Krefeld have been monitoring flying insects in 63 protected natural areas. A globally unique collection of insect data has been collected over many years.

Professor Hans de Kroon, PhD candidate Caspar Hallman of Radboud University in Nijmegen, analyzed this data and showed a 75 percent drop in flying insect biomass over 27 years. An alarming outcome!

The cause of deterioration is probably a complex of factors such as intensification of agriculture, nitrogen deposition, use of plant protection products (especially insecticides) and fragmentation of habitats, as a result of which new areas can be reached badly or not by insects.

Researchers speak of the onset of a sixth mass extinction. Insects are essential for the proper functioning of all ecosystems. They play an indispensable role in the cycle, processing organic material so that the soil remains healthy. This also allows plants and trees to grow better. In addition, they are important for the pollination of wild plants and the vast majority of them – eighty percent – largely dependent on insects. Three-quarters of all crops grown by humans are pollinated by insects. Insects are also a great source of food for many other animal species. About 60 percent of all bird species depend on insects as food.  In the Netherlands, analysis of data from 2 long-term studies also showed a similar result in insect decline as in Germany.

Commissioned by National Geographic Magazine NL & BE, science journalist Gemma Venhuizen (text) and I (photography) have worked in 2019 on an article about the decline of insects. In no less than 24 pages National Geographic has given ample attention to this important story. In the coming years, Edwin will work on his project ‘Orbis Insecta‘ to give more attention to these small and wonderful animals that are so important to our ecosystem.

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From 1989 the Entomolische society in Krefeld/Germany coordinated a long-term research, which shows the large insect decline of 75 percent in biomass. The collaboration with Prof. dr. Hans de Kroon and his team from Radboud University in Nijmegen resulted in the PLOS ONE publication and led to a worldwide media storm with attention for the enormous insect decline. Nature organizations and other parties saw all this publication as the time to go ahead and this was rolled out in the ‘Delta Plan for Biodiversity Restoration’.

The best researched nature area (450 hectares) in the Netherlands you can find Southwest of the city of Tilburg: ‘De Kaaistoep’. For more then 25 years, flora and fauna have been permanently explored in this 400-hectare area by a group of enthusiastic volunteers. The result is an unprecedented number of data and data. Also in this Dutch nature area the insect decline is clearly visible: the number of moths had decreased by more than half. The number of beetles and sleeve damselfly even decreased by more than 60 percent.

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The importance of bees is well know: fruit growers hire beekeepers to improve pollination / fertilization with their bee colonies. Beekeeper Willem Verstijnen is one such beekeeper. He has 60 bee colonies, part of which are used annually by fruit growers in spring time in the Netherlands.

Since 1959, ground beetles have been caught weekly in ground traps in National Park Dwingelderveld, and since 1963 also in the nature area Mantingerveld: home of one of the rarest ground beetles (Carabus Nitens). The researchers now have the longest running continuous research data of ground beetles in the world. Analysis of this data showed that the number of ground beetle had plummeted by 72 percent in the past 22 years.

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At the BioScience park – at Leiden University – 36 experimental trial locks – called the Living Lab – have been installed for research and education. A unique facility in Europe where exchange and growth of animals and plants is possible. Here Professor Martina Vijver and PhD candidate Henrik Barmentlo are researching the effects of the agricultural poison thiacloprid: a ‘neonicotinoid. They discovered that small amounts of thiacloprid gain much harder in real life than in the lab. Animals in the ditch proved to be up to 2500 times more sensitive to the insecticide when exposed to it for a long time than in the lab. The latest research from the Living Lab (published in journal of Applied Ecology 7/2019) shows that the poison also strongly influences the most common dragonfly species (Ischnura elegans). 

Nick Hofland (PhD student Animal Ecology and Physiology Radboud University and co-author PLOS ONE publication) is conducting PhD research into the influence of pesticides on the population dynamics of insectivorous birds (barn swallows and starlings) and the availability of insects in agricultural areas.

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