The system of underground passages in Macrotermes subhyalinus and comparison of laboratory bioassays to field evidence of intraspecific encounters in M-subhyalinus and M-bellicosus (Isoptera, Termitidae)

The system of underground passages and storage pits used in foraging have been excavated in two nests of the termite Macrotermes subhyalinus in West Africa (Ivory Coast). A detailed qualitative description of the morphology and the dimensions of the passage network is given. Three types of passages could be distinguished: radial passages, big cross passages and small cross passages, These varied in their dimensions and their functional significance. Density values for the different types of passages and the storage pits in various zones of the two mounds were calculated. Density of total passages varied between 1.46 m/m(2) and 1.80 m/m(2) being in the order of other Macrotermes species with a comparable foraging behaviour. In the second part of the study intraspecific behavioural tests between pairs of colonies of M. subhyalinus and M. bellicosus were performed in neutral arenas and the zones of contact between the corresponding colonies were then excavated. Hints of agonism such as cemeteries with dry head capsules of termites, passage blockings and phenomena of horizontal or vertical passage segregation were found. Generally colonies displaying strong reaction in behavioural tests reacted in the natural context: upon contact with deadly conflicts. On the other hand, colonies with a weak behavioural reaction withdrew and blocked the passages without deadly conflicts. For the first time results of laboratory bioassays were connected to unmanipulated field evidence of termite agonism.