Data/hora: 09/06/2024 20:38:32

Biblioteca(s): 	Embrapa Florestas.	
Data corrente: 	18/09/2008	
Data da última atualização: 	18/09/2008	
Autoria: 	BENITO, N. P.; BROSSARD, M.; JOST, C.; FOURCASSIE, V.; CAMARGO, A.	
Título: 	In vitro tunnel network construction by Cornitermes cumulans (Isoptera: Termitidae) and resulting soil structures.	
Ano de publicação: 	2008	
Fonte/Imprenta: 	In: 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.	
Idioma: 	Português	
Conteúdo: 	With 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.	
Categoria do assunto: 	--	
Registro original: 	Embrapa Florestas (CNPF)	
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