The state of our insect fauna

Dusky large blue (Phengaris nausithous)
Dusky large blue (Phengaris nausithous)Image: Sophie Giriens

Introduction: Insects in distress

Insect populations are undoubtedly in danger - various factors such as degradation or even loss of habitats, climate change, light pollution or environmental toxins are exerting pressures on insects everywhere. Also indisputable is the fact that insects are hugely important, and that their continued and accelerated endangerment hence has serious consequences. Insects play central roles in diverse ecological contexts, and are vital to many other organisms, including humans, who depend heavily on their pollinator activity.

In recent years scientific studies have increasingly focused on the worrying developments affecting many insect populations, bringing the issue of insect decline into the spotlight (see e.g. recent Hotspot issue on insects1). In addition to declines and even local extinctions, shifts in the local composition of species can also be observed (e.g. towards heat-loving versus cold-loving species where temperatures are rising). The body of scientific evidence on the causes and consequences of insect decline is becoming increasingly convincing (see, for example, the analysis including concrete recommendations for countermeasures in the forthcoming Swiss Academies Report2), yet equally impressive are the personal accounts of entomologists. Based on their long experience of encountering insects in the wild, these individual stories on different facets of the insect fauna contain similar warnings: Our insects are in danger and we urgently need to do something about it.

Here we have collected the personal statements of various entomologists (see list with links below, statements in their original language). These statements represent reviews of lives with insects, and underline various important aspects. For example, the importance of basic ecological knowledge is emphasised, as we need to know more about target species if we want to protect them effectively. In their statements, the authors describe the development of the insect fauna in various areas of Switzerland from a very personal perspective. Reading these pieces, it quickly becomes apparent that negative effects on insects are noticeable throughout various landscapes of Switzerland. In many areas, marked declines can be observed concerning both the number of individuals and species diversity. The loss of insect habitats across all altitudes should therefore be stopped at all costs.

Another key point that emerges several times when reading these statements is that is not only rarer species that are in danger. Formerly very common insects have also become rare - Hansruedi Wildermuth emphasises, for example, that even previously common species are in decline. This should really give us pause for thought: after all, it is not just a few isolated rarities that could disappear in the near future, many more common and familiar insects are also in distress.

I wish you an interesting read!

Oliver Y. Martin

President of the SES

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1Forum Biodiversität Schweiz, Hrsg. (2019) Insekten im Fokus der Forschung. Hotspot - Zeitschrift des Forum Biodiversität Schweiz, 40/2019, 32 S.

2Widmer I., Mühlethaler R., Baur B., Gonseth Y., Guntern J., Klaus G., Knop E., Lachat T., Moretti M., Pauli D., Pellissier L., Sattler T. & Altermatt F. (2021) Insektenvielfalt in der Schweiz: Bedeutung, Trends, Handlungsoptionen. Swiss Academies Report Nr. X/2021.

Brown-banded carder bee (Bombus humilis)
Brown-banded carder bee (Bombus humilis)Image: Sophie Giriens

Personal statements of entomologists:

Hannes Baur: Entwicklung der Heuschrecken in der Schweiz

Hansruedi Wildermuth: Wo sind die Libellen?

Hans-Peter Wymann: Sterben die Schmetterlinge?

(alphabetical order; more to come)

Dead butterfly (Lasiommata megera)
Dead butterfly (Lasiommata megera)Image: Sophie Giriens