The Double-Crossing Ants to Whom Friendship Means Nothing | Deep Look

by Super User, 8 years ago
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The Peruvian Amazon is a dangerous place when you're small. So the young Inga tree hires ants as bodyguards to protect its vulnerable leaves. Their pay: delicious nectar served up in tiny ant-sized dishes. But will the ants keep up their end of the bargain?

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For some, ants are welcome guests. In the Amazon rainforest of Peru, a type of tree called the Inga actively encourages ants to stick around.

The tree, which is related to plants that produce beans and other legumes, grows tiny structures near the base of its leaves, called nectaries, that secrete a sugary fluid to feed to the ants. In turn, the ants serve as bodyguards, protecting the Inga and its nectaries from invading herbivores.

“Plants have all kinds of defenses, but because Inga leaves are not as toxic as many other plants,” says Suzanne Koptur, a professor of biology at Florida International University, “they’re good food for herbivores of all sizes and shapes, from big mammals like sloths and monkeys to little invertebrates like caterpillars.“

The rainforest is especially dangerous for young trees. The branches and leaves of mature trees merge together high in the air forming a canopy. Young trees on the forest floor struggle to get enough light. Young trees also have fewer leaves, and losing even a few to herbivores can threaten their survival.

They may be small, but few species want to tangle with the aggressive and territorial big-headed ants.

"Ants have powers in numbers, especially if they bite and sting," says Koptur.

The ants keep most herbivores, especially hungry caterpillars, away from the young trees. Simply put, the trees provide nectar to the ants in exchange for protection.

--- What is mutualism?

In biology, mutualism refers to a relationship between two organisms that benefits both of parties. Mutualism is one type of symbiotic relationship.

--- What are caterpillars?

Caterpillars are the larvae of butterflies and caterpillars. Young caterpillars hatch out of eggs, eat, grow and molt. They eventually pupate inside their cocoons and then emerge as winged adults.

--- What is plant nectar?

Nectar is a sugary liquid secreted by plants through structures called nectaries. Nectaries are commonly found in flowers to attract pollinators. Some plants also have extra-floral nectaries located outside of the flowers. To attract animals including ants and predatory wasps that protect the plant from herbivores.

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Interactions Among Inga, Herbivores, Ants, and Insect Visitors to Foliar Nectaries

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