Lost and found: 160 years of Lepidoptera observations in Wuppertal (Germany)

In the light of the current discussion on reduced insect biomass and species decline, we would like to draw attention to the work of amateur entomologists who have been observing the moth and butterfly fauna for decades. Actually, the recording of butterflies and moths has a long tradition in Wuppertal and its surroundings (Germany, North Rhine-Westfalia, Bergisches Land). Therefore, we have access to rather detailed data of the local macrolepidoptera fauna collected over the last 160 years and are able to comment on the trends of moth and butterfly populations during this rather long period. We review historical and current data and provide a comprehensive abundance list of all macrolepidoptera species observed in the study region. We found that, from the mid-twentieth century onwards, the species richness of butterfly and moths species decreased considerably. In terms of the number of species evaluated (537), we see that 27% decreased within the last 160 years while 15% have already been lost. Additionally, 24% are apparently stable at a low level. Particularly affected are highly specialised species of heath, moor, grassland, scrub, coppice and orchard habitats. However, 15% of the evaluated species are observed more frequently. Some of these newly colonised the study region (2.4%). Since Wuppertal is a city that profited from the industrial revolution from the middle of the nineteenth century onwards, we think that our results could serve as a representative example of the loss of species richness due to industrialisation, urbanisation, intensive agriculture and forestry. Implications for insect conservation If we intend to increase species richness of butterflies and moths again, the focus must be on protecting, restoring and promoting low-nutrient open landscape habitats rather than forests.

Automated summary

This study highlights the decline in butterfly and moth species richness in the Wuppertal region over the past 160 years, with a particular impact on specialized habitat species. Factors such as industrialization, urbanization, intensive agriculture, and forestry are seen as contributing to this trend.