03893naa a2200169 a 450000100080000000500110000800800410001910000180006024501190007826000090019752031310020670000170333770000130335470000190336770000160338677303210340213148712008-09-18       2008    bl uuuu     u00u1 u    #d1 aBENITO, N. P.  aIn vitro tunnel network construction by Cornitermes cumulans (IsopterabTermitidae) and resulting soil structures.  c2008  aWith the exception of arboreal nesting species, termite activities can be classified into foraging, building, tunneling, and feeding in and on the soil. In particular the construction of subterranean galleries and chambers is a very common activity. The microped structure (soil micromorphological description) revealed a possible biotic origin of a part of the ovoid and spherical microaggregates which are observed in most ferrasols in inter-tropical area. Therefore, the aim of this work was to observe the tunneling and construction activity under controlled conditions and, in a second step, compare the new structures to others observed from the field. We focused in particular on Cornitermes cumulans, a common species in South America, and observed its tunneling and building activity in a terrarium. The termites (workers) were collected in a pasture area. The terrarium consists of a thin layer (2mm) of soil, placed between two horizontal glass plates. The total area was 900cm2 (30cm x 30cm). The soil used (clayey yellow red Ferralsol) was collected down to a depth of 20cm in the same area where termites were collected. The soil was air dried and sieved to 1mm. We made a full factorial experimental design with three different soil water contents (25, 50 and 100%) and three different worker densities (90, 180 and 360 individuals). Three terrarium replicates were done for each condition and each excavation experiment lasted five days. The excavation process carried out by the termites presented the following schedule: the first day several starting points were marked; on the second and third day tunnels were excavated from one or two of these points; on the fourth and fifth days the activity decreased because of a high worker mortality. The excavated area showed a direct relationship with the number of termites. Part of the excavated soil was transported out of the mesocosm, forming landfills that contained also dead individuals. The other part is used internally to form more dense tunnel walls or to be transported to already excavated areas, forming internal landfills which are also more dense. The construction of the structures occured in two distinct ways: a) soil aggregates were manipulated by mandibles and embedded in the walls of the tunnels or landfills with cute made by the head in order to increase individual pressure against the wall; b) the aggregates were deposited on feces left on the wall under construction. Tunneling termites occupied up to 20% of the terrarium area within five days. This corresponds to an excavation capacity of approximately 0.06 to 0.15 cm2/individual. The soil water content was positively correlated with excavation activity. The number of individuals was also correlated with excavated area, but it did not affect the number of tunnels. Similar excavation studies with other species of the Cerrado (Brazilian savannah bioma) are planned and will lead to a more precise picture of the dynamic interactions between termite and soil processes in order to better appreciate the contribution of this group of insects to the Cerrado soil characteristics.1 aBROSSARD, M.1 aJOST, C.1 aFOURCASSIE, V.1 aCAMARGO, A.  tIn: INTERNATIONAL COLLOQUIUM ON SOIL ZOOLOGY, 15; INTERNATIONAL COLLOQUIUM ON APTERYGOTA, 12., 2008, Curitiba. Biodiversity, conservation and sustainabele management of soil animal: abstracts. Colombo: Embrapa Florestas. Editors: George Gardner Brown; Klaus Dieter Sautter; Renato Marques; Amarildo Pasini. 1 CD-ROM.