Various evolutionary avenues of Nematoda to parasitism in Gastropoda

Abstract

The various associations between nematodes and gastropods, which range from random transportation to endophoresis, necromeny, larval parasitism and an entire parasitic or parasitoidic life-style with and without intermediate or paratenic hosts, are discussed in an evolutionary context. Ten to eleven lineages have accomplished the transition to a life at the expense of gastropods, three via a detour of parasitism in vertebrates (Metastrongyloidea, Nemhelix and within Cosmocercoides). In the lineage to Agfa the sequence endophoretic, necromenic, parasitic in the intestine to parasitic in salivary glands of gastropods is reconstructed.

Keywords

• necromeny
• parasitoidism
• larval parasitism
• paratenic host
• host switch