Entomopathogenic nematodes in Italy: Occurrence and use in microbial control strategies

Abstract

The first data of entomopathogenic nematodes (EPNs) population isolation in Italy goes back to the end of the Second World War with the discovery of some specimens of Temnorhinus mendicus Gyll. (Coleoptera: Curculionidae), infested with nematodes, which were described as Neoaplectana menozii Travassos, currently an inquirenda species. The first samplings, performed in Emilia Romagna, in order to ensure the dissemination of entomopathogenic nematodes in the soil were carried out in 1983 by Deseö, Grassi, Foschi, and Rovesti (1984) and some years later they published the first data on the presence of Heterorhabditidae and Steinernematidae in Italian agricultural land (Deseö, Fantoni, Lazzari, 1988). Subsequent surveys conducted in the recent decades (Clausi, Longo, Rappazzo, Tarasco, Vinciguerra, 2011; Clausi Vinciguerra, 2005, 2007, 2008; Rappazzo et al., 2011; Rappazzo, Clausi, Vinciguerra, 2005; Susurluk, Tarasco, Triggiani, Ehlers, 2007; Tarasco et al., 2009; Tarasco, Mráček, Nguyen, Triggiani, 2008; Tarasco Triggiani, 1997, 2005, 2007; Triggiani, Mráček, Reid, 2004; Triggiani Tarasco, 2000) have contributed to the discovery of new species. The discovery and knowledge of indigenous EPN populations in Italy has gone on with the increase for their use in agricultural and forest biological practices. Surveys on the occurrence and distribution of EPNs have been carried out in several Italian regions following a large–scale biogeographic approach with respect to different vegetation levels and habitats (Tarasco et al., 2014) in order to create a comprehensive map of the Italian EPN biodiversity. Currently the EPNs isolated from different habitats are almost 140 indigenous populations belonging to 12 species: Heterorhabditis bacteriophora Poinar (Rhabditida: Heterorhabditidae), Heterorhabditis downesi Stock, Griffin Burnell (Rhabditida: Heterorhabditidae), Heterorhabditis megidis Poinar, Jackson Klein (Rhabditida: Heterorhabditidae), Steinernema feltiae (Filipjev) (Rhabditida: Steinernematidae), Steinernema affine (Bovien) (Rhabditida: Steinernematidae), Steinernema kraussei (Steiner) (Rhabditida: Steinernematidae), Steinernema apuliae Triggiani, Mràcek Reid (Rhabditida: Steinernematidae), Steinernema ichnusae Tarasco, Mràcek, Nguyen Triggiani (Rhabditida: Steinernematidae), Steinernema carpocapsae (Weiser) (Rhabditida: Steinernematidae), Steinernema vulcanicum Clausi, Longo, Rappazzo, Tarasco Vinciguerra (Rhabditida: Steinernematidae), Steinernema “isolate S.sp.MY7” of “S. intermedium group” and Steinernema arenarium (Artyukhovsky) (Rhabditida: Steinernematidae). Steinernematids are more widespread and biodiverse than heterorhabditids and S. feltiae and H. bacteriophora are the most commonly encountered species (Tarasco et al.). EPN populations and species are mainly found in natural sites rather than in cultivated soil (Tarasco et al., 2014; Tarasco Triggiani, 1997). Steinernema kraussei, H. downesi and H. megidis were collected only in Sicily, whereas two of the species recently described – S. apuliae and S. vulcanicum – are known only from Italy and seem to be endemic (Tarasco et al., 2014). The high EPN biodiversity found in Italy could be related to the unique geographic diversity of the country, which provides different vegetation habitats plus the unique island fauna. In addition to the native populations, there are several commercial EPN products used in Italian agro–forest ecosystems which will be discussed later. Herein, we will describe the peculiarities of our native EPN fauna and their contribution to the biological control of insect pest for major crops.