Where Have All the Spiders Gone? Observations of a Dramatic Population Density Decline in the Once Very Abundant Garden Spider, Araneus diadematus (Araneae : Araneidae), in the Swiss Midland

Aerial web-spinning spiders (including large orb-weavers), as a group, depend almost entirely on flying insects as a food source. The recent widespread loss of flying insects across large parts of western Europe, in terms of both diversity and biomass, can therefore be anticipated to have a drastic negative impact on the survival and abundance of this type of spider. To test the putative importance of such a hitherto neglected trophic cascade, a survey of population densities of the European garden spider Araneus diadematus-a large orb-weaving species-was conducted in the late summer of 2019 at twenty sites in the Swiss midland. The data from this survey were compared with published population densities for this species from the previous century. The study verified the above-mentioned hypothesis that this spider's present-day overall mean population density has declined alarmingly to densities much lower than can be expected from normal population fluctuations (0.7% of the historical values). Review of other available records suggested that this pattern is widespread and not restricted to this region. In conclusion, the decline of this once so abundant spider in the Swiss midland is evidently revealing a bottom-up trophic cascade in response to the widespread loss of flying insect prey in recent decades.

Medienart:

E-Artikel

Erscheinungsjahr:

2020

Erschienen:

2020

Enthalten in:

Zur Gesamtaufnahme - volume:11

Enthalten in:

Insects - 11(2020), 4 vom: 15. Apr.

Sprache:

Englisch

Beteiligte Personen:

Nyffeler, Martin [VerfasserIn]
Bonte, Dries [VerfasserIn]

Links:

Volltext

Themen:

Bottom-up trophic cascade
Journal Article
Low abundance
Orb-weaving spiders
Prey scarcity
Western European landscape

Anmerkungen:

Date Revised 28.09.2020

published: Electronic

Citation Status PubMed-not-MEDLINE

doi:

10.3390/insects11040248

funding:

Förderinstitution / Projekttitel:

PPN (Katalog-ID):

NLM309108373