Figs: Friends and Foes

A young fig wasp is lured by the fragrance of a cluster fig tree. She hurriedly flies to it to lay her eggs. The fig welcomes her like a good host. It knows she is a pollinator, and like a good guest, she is bringing pollen from another fig. Thus begins the story of a mutually beneficial friendship in nature.

We know that there is a lot of interdependence in nature and this is just one of the relationships that you can spot if you look around. Trees provide shelter to birds. Flowers give their nectar to bees. In return, the birds and bees spread the pollen and help make new trees and plants.

We call these relationships between species and organisms ecological interactions or symbiotic relationships. This simply means their relationship affects one another. When two species benefit and help each other, we call it mutualism. When this relationship causes harm to the other, we say it is predatorial or competitive. The fig plant can be found in both types of relationship.

Figs as friends

A beautiful story of friendship (or mutualism) in nature is that of the fig wasp and the fig tree. A cluster fig tree is an unusual tree. The figs grow directly on the trunk. Even stranger, the flowers and seeds are inside the “fruit,” which is called a syconium or an inflorescence. So, how do the flowers get pollinated? This is where the fig wasp comes in. A fig wasp is not just any other wasp but a wasp that is made just for the fig tree!

The fig has a little opening in it called an ostiole. The female flowers inside it give out a fragrance that attracts pregnant fig wasps. The fig wasp burrows into the ostiole to reach the flower. While entering, she loses her wings—which means she cannot fly out. No matter: she has found a nice, safe space to lay her eggs and feed. When she enters the syconium, she also brings with her pollen from another fig. Thus, her arrival leads to the fertilisation of the fig tree’s female flowers—so the wasp’s visit ensures the future of both wasp and fig.

The lifespan of a fig wasp is less than two days. She will die after laying her eggs, but new wasps will soon emerge from the eggs she has left behind. The male wasps hatch first. They grow fast and break the eggs of the female wasps and mate with them. The males make holes in the fig, but they never leave. However, the female wasps develop delicate wings that enable them to emerge from these holes. After this, they have a very, very short time to find another hospitable fig where they can lay their own eggs. And so, the cycle continues.

You may ask, what happens to the dead female and the dead male wasps inside? Simple. The fig digests them—but sometimes, if you break open a cluster fig, you can actually see black specks. These are the remains of the wasps. (These types of figs are usually eaten by birds and monkeys. The commercial figs that humans eat don’t need to be pollinated by the fig wasps.

It is unlikely that the figs that you buy and eat from the market contain dead wasps in them.) You may also wonder what happens if the female fig wasp does not bring pollen with her for the female flowers of the fig? It is simple: the tree just drops that fig. This means the fig wasp’s eggs die and don’t get the protection they need to hatch. The tree helps the wasp only if the wasp helps the tree.

The relationship between the fig tree and the fig wasp is important for our ecosystem, but it has been negatively impacted by climate change. Hotter temperatures make it difficult for female fig wasps to survive as long, which means that they have even less time to pollinate a fig and lay their eggs. This is bad news for both species as they could slowly die out.

Figs as foes

Figs are not always friendly. Sometimes they are involved in relationships that are predatory or parasitic. Have you seen a strangler fig? It sounds scary, doesn’t it? It is called a ‘strangler’ because it literally strangles the host tree. An example of a strangler fig is the banyan tree.

Strangler figs are also called hemiepiphytes. An epiphyte is any plant that grows on another plant. A hemiepiphyte is a plant that starts its life in this way, but eventually grows such long roots that it makes contact with the ground.

When birds and monkeys eat figs, they may happily perch on random trees while enjoying their little treat. If they are messy eaters, seeds from the fruit can drop onto the tree, allowing these hemiepiphytes to establish themselves on their host. Over time, they flourish, developing aerial roots that grow down to the ground and anchor the fig tree. Initially, the fig offers protection to the host tree during storms, but,
slowly, the host tree withers until nothing is left but a hollow trunk. However, even in this state, it continues to support the ecosystem by providing a home to small animals and birds. Pay close attention and you will see many such friendships and enmities, even right in your own backyard!

This article is from issue

CC Kids 17

2023 Dec