Nematodes in the heads of ants associated with sap flux and rotten wood

Abstract

Ants from samples from ten sap fluxes and rotten wood accumulations were examined for the presence of nematodes. The arboreal ant, Lasius brunneus, was found in seven of the ten samples. In the heads of L. brunneus five nematode species were detected: Koerneria histophora, Diploscapter sp., Oscheius dolichurus, Diplogasteroides spengelii and Halicephalobus similigaster, the latter two species for the first time in ants. The occurrence of Koerneria histophora more frequently than described in the literature can be explained by its strong preference for sap fluxes and rotten wood. It is hypothesised that only ants which come into contact with sap flux or rotten wood carry K. histophora. Waving dauer juveniles of Diploscapter sp. and H. similigaster successfully infested not only ants, but also beetles (Tenebrio molitor) in controlled experiments. In two of 11 cases, a transfer of dauer juveniles between ant specimens by trophallaxis was observed. Diploscapter sp. and H. similigaster left infested ants when they were stored in a wet environment.