Dispersion of nematodes (Rhabditida) in the guts of slugs and snails

Abstract

A survey was carried out to find non-parasitic nematodes associated with slugs and snails in order to elucidate the initial phase of endophoresis and necromeny in gastropods. 78 % of the specimens of the 12 terrestrial gastropod species surveyed carried nematodes. A total of 23 nematode species were detected alive and propagable in gastropod faeces, with 16 different species found in Arion rufus alone. Most were saprobiontic rhabditids, with species of Caenorhabditis, Oscheius and Panagrolaimus appearing with some regularity. The nematodes were accidentally ingested with food and survived the passage through the digestive tract, allowing them to be transported to suitable microhabitats such as decaying fruits or fungi. The intestines of snails and slugs taken from hibernation or aestivation were free of nematodes. Seven gastropod species were experimentally infected with eight rhabditid species, all of which were able to persist uninjured in the intestines of the gastropods for two to five days before being excreted with the faeces. A list of nematode species accidentally associated with gastropods is compiled from the literature for comparison. The role of gastropods in spreading nematodes and other small animals (a few observations on rotifers and mites are mentioned) deserves more attention.

Keywords

• rhabditids
• accidental phoresis
• endophoresis | necromeny
• dispersal
• phasmarhabditis