Unexpected sensitivity of the highly invasive spider Mermessus trilobatus to soil disturbance in grasslands

Nijat Narimanov,Martin H Entling,Mark Van Kleunen,Anne Kempel

doi:10.1007/s10530-020-02348-9

Abstract

The dwarf spider Mermessus trilobatus (Araneae: Linyphiidae), native to North America, has expanded its range over large parts of Europe within less than fifty years. It is notable for occurring in a wide range of mostly agricultural habitats, while most other invasive spiders in Europe are associated with human buildings. As in other invasive invertebrates and plants, the tremendous colonisation success of Mermessus trilobatus might be related to anthropogenic habitat disturbance. Here we aim to test if the invasion success of Mermessus trilobatus in Europe is associated with high tolerance towards soil disturbance. We sampled spiders from eight grasslands experimentally disturbed with superficial soil tillage and eight undisturbed grasslands without tillage. Opposite to our expectation, Mermessus trilobatus densities decrease sharply with soil disturbance. This is in contrast to several native species such as Oedothorax apicatus, which becomes more abundant in the fields after superficial soil tillage. Our study suggests that invasion success of Mermessus trilobatus is not connected to a ruderal strategy. The ecological and evolutionary processes behind colonisation success of Mermessus trilobatus need to be further investigated.

Highlights

Despite their essential role in ecosystems (Michalko et al 2019; Nyffeler and Birkhofer 2017), invasions by spiders have only recently started to receive scientific attention (Nentwig 2015)
Its occurrence in agricultural lands suggests that the invasion success of M. trilobatus could be based on a ruderal strategy, whereby it would benefit from reduced competition with native species in disturbed habitats (Elton 1958)
Our results suggest that the highly invasive spider M. trilobatus is more sensitive to soil disturbance than sympatric native European species

Summary

Introduction

Despite their essential role in ecosystems (Michalko et al 2019; Nyffeler and Birkhofer 2017), invasions by spiders have only recently started to receive scientific attention (Nentwig 2015). One of the most widespread alien spider species in Europe is the North American dwarf spider Mermessus trilobatus (Araneae: Linyphiidae), formerly known as Eperigone trilobata (Millidge 1987; Nentwig 2015; Nentwig and Kobelt 2010; Schmidt et al 2008). The species has undergone a largely concentric range expansion and has been recorded in numerous other countries since 1990, such as Austria, Belgium, Croatia, Czech Republic, France, Great Britain, Hungary, Italy, the Netherlands, Poland, Slovakia, Slovenia, Switzerland, and Ukraine (Hirna 2017) To our knowledge, this rapid spread makes M. trilobatus currently the most invasive (sensu Richardson et al 2000) spider in Europe. M. trilobatus might benefit from post-disturbance resource influxes to the habitat (e.g. from decomposing plant material), or from altered structure and habitat opening (Lear et al 2020)

Objectives

Methods

Results

Conclusion