This website uses cookies

We use cookies to personalize content and ads, and to analyze our traffic and improve our service.

Cookies that the site cannot function properly without. The information they store is not sent anywhere.
Statistic cookies help us understand how visitors interact with websites by collecting and reporting information anonymously.
Marketing cookies are used to track visitors across websites. The intention is to display ads that are relevant and engaging for the individual user and thereby more valuable for publishers and third party advertisers.

Global warming changing insect fauna in Switzerland

Declining insect populations are being reported worldwide. The INSECT project has investigated how the distribution of 390 insect species in Switzerland has changed over the past 40 years – and the role of climate change and land-use changes in this process.

published on:
written by:
An extensively managed grassland which provides important habitat for diverse insect communities in agriculturally dominated landscapes

An extensively managed grassland, which provides important habitat for diverse insect communities in agriculturally dominated landscapes. Image: © Agroscope, INSECT project

Various studies in Switzerland and abroad give cause for concern that insect populations are suffering significantly due to climate change and land-use changes. In response, the research institutes Agroscope, WSL, FiBL, along with the Swiss Ornithological Institute in Sempach and the Swiss Information Centre for Fauna «info fauna », have launched the INSECT project. This research initiative aims to analyze why and how insect distribution in Switzerland has changed over recent decades. 

Changes in the distribution of 390 insect species 

To investigate these trends, we analyzed 1.5 million species records collected by amateur and professional entomologists since 1980. These records document the occurrence of butterflies, grasshoppers, and dragonflies across Switzerland. We were able to reconstruct distribution changes over the past 40 years for 215 butterfly species, 103 grasshopper species, and 72 dragonfly species. The results show both winners and losers among the studied species. The species that expanded the most increased their habitat range by over 70% on average, while those in the strongest decline lost nearly 60% of their distribution area. However, this study does not provide insights into the total insect biomass. 

Agroscope researchers on their weekly emptying round of pitfall traps with which ground beetle and spider communities are sampled

Agroscope researchers on their weekly emptying round of pitfall traps, with which ground beetle and spider communities are sampled. Image: © Agroscope, INSECT project

Rare species are declining further 

The distribution of specialized, cold-adapted species from the alpine and pre-alpine regions has declined most. Examples include the shepherd's fritillary (Boloria pales) and the two-spotted groundhopper (Tetrix bipunctata), both of which are found at mid to high elevations. Alpine species and habitats need therefore special protection. Meanwhile, warmth-loving species from lower elevations have maintained or even expanded their ranges, such as the Scarlet dragonfly (Crocothemis erythraea) and the mallow skipper (Carcharodus alceae). As a result, rare species have become even rarer, while already widespread species expanded their range. The findings also suggest a turning point: while habitat loss and land-use changes were historically the main drivers of local insect species extinctions, climate change has now become a major factor influencing insect populations in Switzerland. 

Winners and losers

The willow emerald damselfly Chalcolestes viridis a common dragonfly species on the Central Plateau has spread slightly at higher altitudes

The willow emerald damselfly (Chalcolestes viridis), a common dragonfly species on the Central Plateau, has spread slightly at higher altitudes. Image: © Felix Neff

The shepherds fritillary Boloria pales is a cold adapted butterfly whose distribution has declined in the last 40 years

The shepherd's fritillary (Boloria pales) is a cold-adapted butterfly whose distribution has declined in the last 40 years. Image: © Felix Neff 

The very common meadow grasshopper Pseudochorthippus parallelus has been able to further expand its distribution area over the last 40 years

The very common meadow grasshopper (Pseudochorthippus parallelus) has been able to further expand its distribution area over the last 40 years. Image: © Felix Neff

In Switzerland the scarce copper Lycaena virgaureae is mainly found in the mountains and has declined slightly in the last 40 years

In Switzerland, the scarce copper (Lycaena virgaureae) is mainly found in the mountains and has declined slightly in the last 40 years. Image: © Felix Neff 

The beautiful demoiselle Calopteryx virgo a species typical of watercourses has spread rapidly over the last 40 years

The beautiful demoiselle (Calopteryx virgo), a species typical of watercourses, has spread rapidly over the last 40 years. Image: © Felix Neff 

The Adonis blue Lysandra bellargus has spread in the last 40 years especially at higher altitudes

The Adonis blue (Lysandra bellargus) has spread in the last 40 years, especially at higher altitudes. Image: © Felix Neff

The distribution of the two spotted grasshopper Tetrix bipunctata a species that tends to be found in the middle and higher altitudes has declined over the last 40 years

The distribution of the two-spotted grasshopper (Tetrix bipunctata), a species that tends to be found in the middle and higher altitudes, has declined over the last 40 years. Image: © Felix Neff

The green hairstreak Callophrys rubi a species that can be found at various altitudes has experienced a slight decline over the past 40 years

The green hairstreak (Callophrys rubi), a species that can be found at various altitudes, has experienced a slight decline over the past 40 years. Image: © Felix Neff

The mallow skipper Carcharodus alceae a warmth loving species that has spread over the past 40 years is often found in wildflower fallows perennial areas or strips of arable land sown with native wild herbs to increase biodiversity

The mallow skipper (Carcharodus alceae), a warmth-loving species that has spread over the past 40 years, is often found in wildflower fallows (perennial areas or strips of arable land sown with native wild herbs to increase biodiversity). Image: Felix Neff

Global warming as the key driver of change 

The combination of two factors – climate change and land-use changes – can be particularly detrimental to insect populations, and we found numerous indicators supporting this. For example, the intensification of grassland management appears to have a particularly negative impact on insects when coupled with increasing summer droughts. Such interactions could also lead to unpredictable future developments in insect distributions. Statistically, over the past 40 years, it is mainly global warming – increase in mean temperature of nearly 2°C over the analyzed period – that can be linked to the observed long-term changes in Switzerland’s insect fauna. As climate change progresses, we expect insect populations to continue changing on a large scale. 

Further research planned 

These analyses provide an initial insight into changes affecting the studied insect species over recent decades. However, knowledge gaps remain regarding the overall state of insect populations in Switzerland. Major shifts in agricultural land use, for example, had already taken place before 1980. In the next phase of our research, we aim to reconstruct long-term distribution changes for selected insect species over an extended period. Additionally, we plan to examine other insect groups, as experience shows that different taxa respond differently to climate and land-use changes.

References

Neff F et al. 2022. Different roles of concurring climate and regional land-use changes in past 40 years' insect trends. Nat Commun 13;7611. https://doi.org/10.1038/s41467-022-35223-3

The author

Felix Neff

Dr. Felix Neff

Agroscope

Reach us