Land-cover and climate factors contribute to the prevalence of the ectoparasitic fungus Laboulbenia formicarum in its invasive ant host Lasius neglectus

Jérôme M.W Gippet,Nathalie Mondy,Adeline Dumet,Bernard Kaufmann,Fiona Winkler,Simon Tragust,Julien Grangier,Théotime Colin,Marjorie Haond

doi:10.1016/j.funeco.2021.101045

Abstract

Understanding the distribution of parasites is crucial for biodiversity conservation. Here, we studied the distribution of the ectoparasitic fungus Laboulbenia formicarum in native and invasive Lasius ants in a 2000 km 2 area. We screened over 16,000 ant workers in 478 colonies of five different species. We found that Lab. formicarum was rare in native Lasius species but infected 58% of the colonies of the invasive species Las. neglectus . At landscape scale, Lab. formicarum presence could not be explained by geographic and genetic distances between Las. neglectus colonies but was associated with hotter and dryer climatic conditions and its prevalence in colonies increased with urbanization. Within infected colonies, fungal prevalence varied from 0 to 100 percent within meters and was negatively correlated with impervious ground cover. In a changing world, our findings emphasize the importance of land-use and climatic factors in shaping the distribution and prevalence of fungal parasites.

Highlights

Parasites and pathogens are major, albeit understudied, components of ecosystems which often impose tremendous costs to human societies (Carlson et al, 2017; Frainer et al, 2018; Gomez and Nichols, 2013; Rocha et al, 2016; Torgerson, 2013)
Large-scale climatic variations affect the probability of infection of the ant Myrmica scabrinodis by the laboulbenian fungus Rickia wasmanni (Szentivanyi et al, 2019), but it is not known whether landscape- and localscale environmental conditions, such as elevation and land cover type, affect the distribution or infection success of the Laboulbeniales that parasitize ants
To understand what determines Laboulbeniales’ spatial distribution at landscape- and local-scale, we studied the ectoparasitic fungus Laboulbenia formicarum, that parasitizes Lasius ants, including one of the most widespread invasive ant species in Europe, Lasius neglectus

Summary

Introduction

Parasites and pathogens are major, albeit understudied, components of ecosystems which often impose tremendous costs to human societies (Carlson et al, 2017; Frainer et al, 2018; Gomez and Nichols, 2013; Rocha et al, 2016; Torgerson, 2013). Understanding the spatial distribution of parasites is essential to the conservation of species and ecosystems (Frainer et al, 2018; Rocha et al, 2016; Weldon et al, 2004), to the control of invasive species and agricultural pests (Hall and Papierok, 1982; Meikle et al, 2015; Vega et al, 2009) and to human health (Thompson et al, 2010; Torgerson, 2013). Six Laboulbeniales species are known to parasitize 43 ant species from ten genera (Santamaria and Espadaler, 2015). Large-scale climatic variations affect the probability of infection of the ant Myrmica scabrinodis by the laboulbenian fungus Rickia wasmanni (Szentivanyi et al, 2019), but it is not known whether landscape- and localscale environmental conditions, such as elevation and land cover type, affect the distribution or infection success of the Laboulbeniales that parasitize ants

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