By Elton Gomes
Scientists working in northeastern Brazil have discovered a collection of termite mounds that cover an area as large as Britain. The gigantic complex is said to contain nearly 200 million termite mounds, with some mounds being up to 4,000 years old.
Stephen Martin, from the School of Environment and Life Sciences at the University of Salford, Manchester, had previously travelled to the Brazilian forest in search of honeybees.
Martin failed to notice the mounds at first as they were only visible once the road cut through the trees to reveal the mounds’ gumdrop shape. Local residents told Martin that these were termite mounds. The locals were correct, as Martin found out when he returned.
Martin, along with three other researchers, published their findings in Current Biology. The researchers note that some of the conical mounds rise up to 10 feet high, but most remain largely hidden from view at ground level due to the semi-arid, thorny-scrub forests.
“These mounds were formed by a single termite species that excavated a massive network of tunnels to allow them to access dead leaves to eat safely and directly from the forest floor,” Martin said in a press release.
He added, “The amount of soil excavated is over 10 cubic kilometers, equivalent to 4,000 great pyramids of Giza, and represents one of the biggest structures built by a single insect species.”
Co-author Roy Funch, from the Universidade Estadual de Feira de Santana in Brazil, termed this “the world’s most extensive bioengineering effort by a single insect species”. He added, “Perhaps most exciting of all — the mounds are extremely old — up to 4,000 years, similar to the ages of the pyramids,” as per the official statement.
What did the researchers find?
The researchers collected samples from the centres of 11 mounds. They then measured radiation in the mineral grains, and determined that the oldest mound tested is about 3,800 years old.
The researchers surmise that other mounds could be older. On the basis of satellite images and spot checks across thousands of kilometres, they estimate that there could be around 200 million mounds across the landscape.
Martin said that if the forest cover disappeared, and consequently the mounds were to be be exposed, the place would be celebrated as a natural “wonder of the Earth”.
The mounds are not nests
Martin and his team found that the mounds were not nests. Instead, they were the result of the termites’ slow and steady excavation of a network of interconnected underground tunnels. Since the termites were digging tunnels underground, waste began building up in cones on the surface.
The researchers said that the vast tunnel network allows safe access to a sporadic food supply. Such a network is similar to one created by naked mole rats, which also live in arid regions and construct extensive burrow networks to obtain food.
Pattern of the mounds
The researchers investigated whether the strangely regular spatial pattern of the mounds was due to competition among termites from neighbouring mounds. However, the researchers’ behavioral tests found little aggression among the termites at the mound level.
The findings led the team to suggest that the over-dispersed spatial mound pattern is not generated by aggressive interactions. But the pattern is a result of self-organisational processes that were facilitated by the increased connectivity of the tunnel network and driven by episodic leaf-fall in the dry forest.
They said that a pheromone map could help the termites to reduce their travel time from any location in the colony to the nearest mound.
What do we know about the termites?
The mounds have been built by an unknown number of termites, all of which belong to the same species, Syntermes dirus.
The termites of this species are one of the largest in the world, and are often used as food by local tribes in the Amazon. They are known to live underground, and feed on dead leaves at night. Similar to most termites, these insects are blind, but they are very aggressive and can draw blood when they bite humans.
The researchers say there are many questions left to pursue. For instance, it remains unclear as to how these termite colonies are physically structured because a queen chamber of the species has never been found. A queen chamber is a room where the colony’s queen resides, and a queen mating with one or several males marks the beginning of a colony.
Elton Gomes is a staff writer at Qrius.
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