Wednesday, 3 December 2014

Flying like an Ant!

Fresh after meeting the doyen of Indian Myrmecology at Bangalore Prof. T.M.Mustak Ali, I returned home to face a question which has now become very common, whenever I say to people I study ants.

 "Can ants fly?" "When do ants get wings?" "My granny told me that good ants get wings and become angles, is it true?" "Are winged ants similar to termites?" and such questions go on and on and on...

One very interesting statement that I heard an old village shepherd in Tamil Nadu say to me last year was "ants are better managers of population than us, when ants grow old they no longer want to be a burden to the younger generation and hence develop wings to leave the nest in search of acquiring moksha flying towards the heaven. The deserving and true souls reach heaven while the undeserving falls dead to the ground". He further went ahead linking this to the "ancient practice of Indian's going to sanyas after completing all their worldly duties".

Good managers of population? Yes indeed they are but the presence of winged ants is a different ball game and let me welcome you to the world of Queens and Kings of Ant society.

Ants are highly social creatures and have reached the pinnacle of social evolution.  They are so specialized in their social behaviour that they are called “eusocial” animals. One of the characters of a eusocial being is that there is a division of labour, which means every individual is assigned a particular task at any given stage of life and they will do that and that alone in general.

So a typical ant colony has casts according to which there is a division of labour. There is a "queen" whose work is only to lay eggs and "workers" who perform all the other duties of the colony like searching for food, defending the colony and looking after the young larvae and pupae. In general, the ants that we see are invariably always workers, since the queen hardly ever comes out of the nest.

Inside the nest, the queen lays eggs. These eggs then develop undergoing the larval and pupae stages from which three casts of adult ants develop- “Daughter” Queens, “Son” Drones and “Daughter” Workers (who are sterile and can’t mate/reproduce).
Out of these three casts, only the “daughter” queens and the “son” drones develop wings as they grow up. 

Camponotus irritans (Smith, 1857) "daughter"queen (female) with wings

Aphaenogaster beccarii (Emery, 1887) "son" drone (male) with wings

The maturity period of the “daughter” queens and “son” drones will invariably coincide with the rainfall patterns. Just after the first showers of monsoon, these “daughter” queens and “son” drones automatically get ready and on a moist and humid evening, when there is very little wind outside they fly out of their parent nest in an exodus which is called the "Mating Swarm". During this, thousands of “daughter” queens and “son” drones emerge out of the several nests in the area and undertake an aerial dance during which the “daughter” queen will mate with several of the “son” drones. Upon mating, the daughter queens (who have become queens with their own rights) descend to the ground and start looking for an ideal place to establish their own nest. Once they have found this ideal spot, they will make a small hole (in case of ground nesting ants) and seal themselves inside. Once they have occupied this hole, they will shed their wings since they will no longer need them and will lay the first batch of their eggs. When the eggs develop into larvae, to feed them the new queen will dissolve her flight muscles (since she will no longer need them) using special enzymes and use this to feed her larvae (talk about mother's love!). When the larvae develop, the queen will have the first batch of her daughter workers, who will now make the nest bigger, will acquire food for the colony and will take care of all the future larvae and pupae.

Newly mated Camponotus sericeus (Fabricius, 1798) queen, excavating a hole to lay her first batch of eggs.

After setting up her own nest, the queen will keep producing only worker daughters till a certain time, who will help in expanding the colony and developing it. When the queen senses that the colony is mature and stable, she will produce eggs which will give rise to the next generation of “daughter” queens and “son” drones. This cycle goes on and on…

So all the ants that we see commonly running around or walking in a trail are females! In that case what happened to the "son" drones (males) who flew with the daughter queens?

"They are dead"

Strange as it may sound, ant society gives least importance to males. Males are treated just like an entity for gene transfer. The work of the male ant (drone) is to mate with the “daughter” queen and pass on their genes to the next generation. Once their task is complete, they fall to the ground exhausted and are invariably devoured by the many predators that wait for them to fall down.

So how is it that one distinguishes the queen or drone from the regular workers?
Its simple, the queens are usually bigger and bulkier than the normal workers. They might sometimes be very different morphologically from their daughters and sisters. The queen will also have sutures on its thorax from where the wings have been shed.

Monomorium pharaonis (Linnaeus, 1758) "daughter" queen accompanied by worker sisters. Note the difference in the size of queen and workers.

Morphological difference between worker and queen of Oecophylla smaragdina (Fabricius, 1775)

Sutures in the thorax of this Camponotus sericeus (Fabricius, 1798) queen where the wings were attached prior to shedding is clearly visible.

The male on the other hand will look completely different from his mother or sisters and it often is extremely difficult to associate a male to any given species, unless we find them in their parent colony. 

So in conclusion, the answers to the many questions I had mentioned above are:
1. Yes, ants can fly but only reproductive ants can fly and just once in their life time.
2. Yes, ants’ develop wings, but only the reproductive casts get them.
3. No, all ants don't develop wings and certainly they are not angels.
4. No winged ants are not termites.
5. I am not sure if ants have the concept of "moksha" in their society.

I am certain, that this post would have created more questions in your mind than you originally had and I expect that to happen, since ants really are such amazing creatures. Do let me know what your questions are and I will be more than happy to try to answer to them.

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