Aquatic Invasions (2014) Volume 9, Issue 1: 47–58 doi: http://dx.doi.org/10.3391/ai.2014.9.1.04 © 2014 The Author(s). Journal compilation © 2014 REABIC Open Access 47 Research Article First evidence of microfungal “extra oomph” in the invasive red swamp crayfish Procambarus clarkii Laura Garzoli 1 *, Daniele Paganelli 2 , Marinella Rodolfi 1 , Dario Savini 2 , Mattia Moretto 2 , Anna Occhipinti-Ambrogi 2 and Anna Maria Picco 1 1 Lab. of Mycology, DSTA-Department of Earth and Environmental Sciences, University of Pavia, Via S. Epifanio 14, 27100 Pavia, Italy 2 Lab. of Ecology, DSTA-Department of Earth and Environmental Sciences, University of Pavia, Via S. Epifanio 14, 27100 Pavia, Italy E-mail: laura.garzoli01@gmail.com (LG), daniele.paganelli@unipv.it (DP), marinella.rodolfi@unipv.it (MR), dario.savini@unipv.it (DS), mattia.moretto01@universitadipavia.it (MM), anna.occhipinti@unipv.it (AOA), annamaria.picco@unipv.it (AP) *Corresponding author Received: 17 July 2013 / Accepted: 10 January 2014 / Published online: 3 February 2014 Handling editor: Chris Chucholl Abstract This paper represents the first attempt to study the microfungal flora contained in the digestive system of the most widespread aquatic invasive invertebrate in the world: Procambarus clarkii (Cambaridae, Decapoda). Understanding its bioinvasion, in terms of ecological risk and environmental impact, requires a multidisciplinary approach that considers consequences on all levels, from macroscopic to microscopic. In this study, we investigated both the population dynamics and the dietary habits of the red swamp crayfish captured within a natural biotope in Northern Italy. The diet was mainly based on plant detritus. The analysis of microfungal flora in the crayfish stomach revealed a fairly constant composition, unrelated to season and diet. Since most of the fungi were associated with detritus and some species were particularly frequent, we formulate the hypothesis that the fungi may be selected to decompose plant material in the digestive tract, thus providing a source of energy to the crayfish. Procambarus clarkii is also shown to be a potential vector of plant diseases as some of the 45 isolated fungal taxa are potentially phytopathogenic. Key words: population study, diet, microfungi, digestive system, wet woodland biotopes, Northern Italy Introduction The red swamp crayfish Procambarus clarkii (Girard, 1852) is one of the top 27 alien species of animals to have been introduced into Europe for aquaculture (Savini et al. 2010), and is considered to be one of the most dangerous species in terms of ecological risk and environ- mental impact (Geiger et al. 2005; Gherardi and Acquistapace 2007; Tricarico et al. 2010). Although P. clarkii is a North American native species (Huner 1988), due to its outstanding performances in aquaculture productivity, it was legally introduced into southern Spain in 1973, and later illegally introduced into most other European countries between 1970 and 1990 (Souty- Grosset et al. 2006). Many biological traits, such as the capability to live out of water for long periods (Gherardi and Barbaresi 2007), a high reproductive potential (Aquiloni et al. 2010; Barbaresi and Gherardi 2006; Savini 2007), and tolerance to environmental pollution (Aquiloni et al. 2011), are responsible for the rapid spread of crayfish in the wild. High motility and burrowing behaviour make this species one of the most successful fugitives from aquaculture facilities (Gherardi 2006). Nowadays, P. clarkii is widespread in Western Europe, Africa, Asia and North America; the only continents where the crayfish has never been recorded are Australia and Antarctica (Gherardi 2006). In Italy, Procambarus clarkii appeared in the wild for the first time in 1989 in the river Banna, a tributary of the Po river, after escaping from an experimental farm (Delmastro 1992); its distribution currently includes the majority of the northern and central regions, as well as the