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)

Abstract

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.

Cuticular hydrocarbons in a termite: phenotypes and a neighbour–stranger effect

“…2). The lack of aggression between workers from different colonies foraging in the open field apparently is a contradiction to the large number of dead soldiers found near the contact zones between neighbouring colonies (Jmhasly & Leuthold, 1999a). Such graveyards' are found at the ends of underground passages which, by connecting to those of other colonies, would join the nests of different colonies.…”

“…Darlington, 1982;Lys & Leuthold, 1991;Dangerfield & Mosugelo, 1997;Jmhasly & Leuthold, 1999a). Others used behavioural observations to describe the dynamics of aggression within and between termite colonies (e.g.…”

Communication and Social Regulation in Termites

“…Intercolonial interactions can involve thousands of individuals and may wipe out entire colonies (Levings and Adams 1984;Leponce et al 1996) or, more often, lead to the spatial separation of territories. Territory boundaries are dynamic and defined by repeated encounters between neighboring colonies, and the former zones of contact are lined with dead bodies generated by past conflicts (Darlington 1982;Levings and Adams 1984;Jmhasly and Leuthold 1999b). When two colonies interact, whether more or less aggressively and with or without ensuing mortality, intensive building activities often follow.…”

Vibrational long-distance communication in the termitesMacrotermes natalensisandOdontotermessp.

“…The galleries of neighbouring Macrotermes colonies can overlap and Macrotermes displays a strong aggressive reaction towards nonnestmates (Jmhasly and Leuthold, 1999). Hence, drumming signals could be used for communication with neighbouring colonies to prevent expensive aggressive interactions at the boundaries of their territories.…”

“…These gallery systems can spread over an area of up to 2000m 2 . The galleries are constructed underground; mounds consist of thick, massive walls (Jmhasly and Leuthold, 1999;Lys and Leuthold, 1991). This impressive architectural structure is probably the most promising way to avoid predation.…”