Animal societies use nestmate recognition to protect against social
cheaters and parasites. In most social insect societies individuals
recognize and exclude any non-nestmates and the roles of cuticular
hydrocarbons as recognition cues are well documented. Some ambrosia
beetles live in cooperatively breeding societies with farmed fungus
cultures that are challenging to establish, but of very high value once
established. Hence, social cheaters that sneak into a nest without
paying the costs of nest foundation may be selected. Therefore, nestmate
recognition is also expected to exist in ambrosia beetles, but so far
nobody has investigated this behavior and its underlying mechanisms.
Here we studied the ability for nestmate recognition in the
cooperatively breeding ambrosia beetle Xyleborinus saxesenii, combining
behavioural observations and cuticular hydrocarbon analyses. Laboratory
nests of X. saxesenii were exposed to foreign adult females from the
same population, another population and another species. Survival as
well as behaviours of the foreign female were observed. Behaviours of
the receiving individuals were also observed. We expected that
increasing genetic distance would cause increasing distance in chemical
profiles and increasing levels of behavioural exclusion and possibly
mortality. Chemical profiles differed between populations and appeared
as variable as in other highly social insects. However, we found only
very little evidence for behavioural exclusion of foreign individuals.
Interpopulation donors left nests at a higher rate than control donors,
but neither their behaviours nor the behaviours of receiver individuals
within the nest showed any response to the foreign individual in either
of the treatments. These results suggest that cuticular hydrocarbon
profiles might be used for communication and nestmate recognition, but
that behavioural exclusion of non-nestmates is either absent in X.
saxesenii or agonistic encounters are so rare or subtle that they could
not be detected by our method. Additional studies are needed to
investigate this further.