Abstract:
The ability of subterranean termites to digest lignocellulose relies not only
on their digestive tract physiology, but also on the symbiotic relationships
established with flagellate protists and bacteria. The objective of this work
was to test the possible effect of different cellulose-based diets on the community
structure (species richness and other diversity metrics) of the flagellate
protists of the subterranean termite Reticulitermes grassei. Termites
belonging to the same colony were subjected to six different diets (natural
diet, maritime pine wood, European beech, thermally modified European
beech, cellulose powder and starvation), and their flagellate protist community
was evaluated after the trials.
All non-treated sound woods produced similar flagellate protist communities
that were more diverse and of high evenness (low dominance).
On the contrary, flagellate protist communities from cellulose-fed termites
and starving termites were considered to be significantly different from all
non-treated woods; they were less diverse and some morphotypes became
dominant as a consequence of flagellate protist communities having suffered
major adaptations to these diets. The flagellate protist communities
of untreated beech and thermally modified beech-fed termites were considered
to be significantly different in terms of abundance and morphotype
diversity. This may be caused by a decrease in lignocellulose quality
available for termites and from an interference of thermally treated wood
with the chemical stability of the termite hindgut.
Our study suggests that as a consequence of the strong division of
labour among these protists to accomplish the intricate process of lignocellulose
digestion, termite symbiotic flagellate protist communities are a
dynamic assemblage able to adapt to different conditions and diets. This
study is important for the community-level alteration approach, and it is
the first study to investigate the effects of thermally modified wood on the
flagellate protist communities of subterranean termites.