Amazon invertebrates

Leaf-cutter ants, Devil’s gardens and other Amazon bug stories

 / ©: WWF-Canon / Juan PRATGINESTOS
Coleoptera Black beetle, Jaú National Park, Amazonas, Brazil
© WWF-Canon / Juan PRATGINESTOS
Amazon invertebrates come in an incredible range of sizes, features and degrees of annoyance.
Random snapshots of this huge group of species will reveal the fiery rhinoceros beetle, the beautiful morpho butterfly and one of the world’s largest cockroaches.

Invertebrates, including insects, represent a disproportionately large share of species found in the Amazon - and more are being discovered all the time.

Some scientists estimate that 30% of the animal biomass of the Amazon Basin is made up of ants1. Ants can easily outweigh in mass all other vertebrates in a parcel of lowland rainforest. In fact, just the total arthropod species richness of the tropical canopy may be as high as 20 million2.

Leaf-cutter ants (Atta species)

With their massive jaws, strong enough to pierce human skin, leaf-cutter ants are well equipped to tear away at vegetation. Not surprisingly, they have the distinction of being the primary consumer of vegetation in the Amazon rainforests, where their actions remove 15% of leaf production3.

Leaf-cutter ants live in massive colonies – sometimes reaching three million – and build gigantic hills for their homes. These are equivalent to huge housing complexes, often reaching more than 9 m across and more than 6 m deep, with multiple entrances.4
Some of the most complex social systems seen in organized societies are found in these colonies. Leaf-cutter ants form female societies, where the males’ main function is reproduction. Females (referred to as workers) are daughters of the same queen, who emits chemical that keep them infertile.

The size, appearance and function of new adults (their caste) depends on how much fungus they are fed when they are at the larval stage. In some leaf-cutter species, societies include a type of ant that can reach gigantic proportions on the ant scale. The primary function of these giant ants is to retaliate in case of an attack.5

Leaf-cutter ants do not actually feed on the leaves they are so adept at destroying. While it has been thought that the fungus cultivated by leaf-cutting ants digests cellulose, which forms the major part of plant cell walls, recent research puts into doubt that ability.6

 / ©: WWF-Canon / Martin HARVEY
Leaf-cutter ant, Atta sp. carrying cut leaves. Distribution Central & South America
© WWF-Canon / Martin HARVEY

Lemon ants

Lemon ants cultivate areas called devil's gardens, named after lore, which holds that these gardens are home to an evil spirit called the Chuyachaqui. Devil’s gardens are monocultures – just one tree species is found – because the ants get rid of every single other plant. Some of the gardens are at least 800 years old.

For this task, lemon ants use formic acid, which is used by humans to preserve foods.7

Termites

These species occur in rainforests, savannas and mangroves, where they build conspicuous nests. Some termites form castes, which include a worker, soldier and queen.

Termite nests are made of a material called “carton”, which is a mix of digested wood and faecal matter. Their stomachs are adapted to processing wood, although some plant species resist termites. Termite-building abilities are impressive, and they can quickly fix a damaged nest, or termitarium.

Occasionally, termites must share their termitaria with birds such as parakeets, which also use them as nests. Why these birds will also settle in termitaria inhabited by both termites and aggressive biting ants (Dolichoderus species) is still not clear. These ants may be protecting the birds' nests by attacking predators or by providing a sort of “odour camouflage”.8

Cockroaches

Most of the world's 4,000-plus cockroach species live in the tropics. Despite their poor reputation, they carry no diseases, and they do not bite nor sting.

The giant cockroach (Blaberus giganteus) is one of the largest cockroach species on the planet, with a full-grown individual filling the palm of an adult human's hand. It lives in hollow trees and other reclusive places.

Cockroaches are particularly fond of bat guano (faecal matter), and are hence often found in bat caves.

Rhinoceros beetle (Megasoma elephas)

Males are instantly recognized by a long, curved horn, and their hairy body. The horn is used to fight with other males. It is now considered a rare species, because of habitat loss.

Morpho butterflies (genus Morpho)

Wide, brilliant and deep blue wings combine to make these species one of the most spectacular of Amazon butterflies. They are common around streams and places that receive plenty of light, and they feed on a variety of plant species.



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1Mongabay.com. Amazon insects. http://rainforests.mongabay.com/amazon/insects.html. Accessed: 06/10/05
2Wilson, 1992 in Kricher, 1997
3Moffett, M. 1995 (July). Leafcutters: Gardeners of the Ant World. National Geographic Magazine.
4ThinkQuest. Animals of the Amazon. http://library.thinkquest.org/04oct/02004/pages/ant.htm. Accessed: 06/10/05
5Mark Moffett. Leafcutters: Gardeners of the Ant World. National Geographic Magazine. July 1995.
6Adriana B. A. et al. 2002. Evidence that the fungus cultured by leaf-cutting ants does not metabolize cellulose. Ecology Letters. 5 (3) p. 325.
7National Geographic. Ants Use Acid to Make "Gardens" in Amazon, Study Says (September 21, 2005). http://news.nationalgeographic.com/news/2005/09/
0921_050921_amazon_ant.html
. Accessed 06/10/2005
8Brightsmith, D. 2000. Use of arboreal termitaria by nesting birds in the Peruvian Amazon. The Condor, 102 (3), pp: 529-538

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