Thursday, December 08, 2005

Figgy stories:

Almost every species of fig (almost over 900 of them) rely on its own species of wasp to pollinate them. The fig genus contains other trees like the rubber tree, banyan tree, and the Bo tree (Buddha's tree of enlightment).



Life cycle of a fig wasp:

1.Each egg is found curled up in each of the base of each of the female flower.
2.It hatches and feeds on the developing seed, growing into an adult and emerging into the fig interior.
3.The males hatches first and actually seek out the unborn females. He chews through the capsule of the flower and the ovule to mate with the unborn virgin.
4.The female is born. She looks for the male flowers flowers which are often found near the entrance of the fig. Using custom-made pollen-brushes on her front leg, she sweeps the pollen into special pollen pockets in her breast.
5.This is interesting because most pollinating do not have special equipment to carry pollen and are often just dusted with pollen in a random way from the flowers. Bees do have pollen baskets to carry pollen but it is to feed their larvae. Fig wasps seem to do so purely to pollinate the fig plant.
6.In some species, the female then just crawls through the hole to fly to another fig plant. However, in other species, the males work together to bite a hole for the female to escape.
7.The question is that why doesn't one of the male sit back and leave it to other males to make the holes, where then he can save his energy to fertilise other females? One possible reason is that these males are all brothers and they share copies of the same genes. By contributing to the digging of the hole, they are assisting in the release of the females that their brothers have mated with.
8.After the female flys out to another fig plant of the same species and at the particular period where the female flowers are ripe.
9.There she squeeze through the hole, often losing her wings. From the fig's point of view, it probably helps to keep out other unwanted insects. This process also helps to wipe the female wasps clean of dirt. More importantly, she does not need her wings again.
10.Once inside the fig, the female wasps proceed to pollinate the ALL the flowers, and she does so deliberately using the pollen brushes of her front leg. Again, this is unlike other pollinating insects which just accidentally brushes off the pollen on their body.
11.The female also proceeds to lay eggs in some of the female flowers in the fig. If she laid eggs in all of the flowers, the fig would have failed to reproduce as all the seeds would have been eaten by the wasp grubs. Is this altruistic restraint on the part of the wasp?
12.Some species of fig ensure that the female does not lay eggs in all the flowers by having different lengths for the style of the flowers. The ovipositor of the female wasp can only reach the bottom of the shorter-style female flowers and she lays an egg.
13.In other species of fig, the plant can detect if the fig has been overexploited by the wasps – that is all the flowers have eggs lying in them. The fig plant can cause the overexploited fig to drop to the ground where all the eggs of the wasps then perish.

Here is a good video:http://www.figweb.org/Interaction/Video/index.htm
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