Hexamermis sp. an entomopathogenous nematode associated with the European stink bug

The nematodes of the Mermithidae family are a large and important group obligatory parasite of arthropods, principally insects, and are almost always lethal to their hosts. They are usually specific to a single species or to one or two families of them. A mermithid of the genus Hexamermis Steiner, was found parasiting the stink bug Rhaphigaster nebulosa Poda (Hemiptera: Pentatomidae), present on hazelnut plants in the Piedmont region. The bug feeds on various broadleaved woody plant and is considered a serious pest for Mermithidae in Italy. Considerations regarding the taxonomy of the Hexamermis genus are reported. From the taxonomic point of view is very difficult to describe the different species of Hexamermis. Morphologically they are similar but the biology and the ecology of all these species is almost unknown. For this reason it is difficult to identify with a certain degree of precision the species. The specimen found, from the morphological data, is probably H. albicans. This findings is particularly interesting as there is restricted literature about the mermithids which attack Rhynchota. Moreover there are few mermithids of this genus reported from Hemiptera. Further investigations are necessary to better understand the taxonomy and biology of this mermithid and to know its role as a biological agent in controlling this or other bugs of hazelnuts.