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Monday, April 19, 2010

Oecophylla Smaragdina

Oecophylla smaragdina is a common red tree dwelling weaver ant. The color is not definitive of the species as there are also those which are green. Oecophylla smaragdina are group hunters and individual ants are mostly ineffective against live prey except very small ones.

This arboreal or tree dwelling ant is the only species of ant that has been used by mankind as an effective biological control agent against agricultural pest. In parts of South East Asia the grubs (larvae and pupae) of the female reproductives are also collected and sold in markets as a local delicacy.

The name smaragdina which means emerald comes from the green color of this ant species found in Australia. Over here in South Asia the local species is red in color (the workers).

Oecophylla smaragdina nests can be quite extensive covering several trees over a few acres. These nests are made of leaves woven together with ants' silk secreted by the larvae. Some workers pulled leaves together while other workers each with a larva in its mandibles 'glue' the leaves together, with the ant silk secreted by these larvae, to formed a shelter where the brood are housed.

A typical colony may commonly have several of these leaves cluster nests spread over several trees. A large colony may have a foraging area of over a hundred meters with nests all along the trees (and shrubs-) that lined their foraging route.

Oecophylla smaragdina workers are dimorphic. It is among a few species of ants that practice true caste separation where the much smaller minor workers strictly tend to the nest while the foraging and hunting activities are carried out by the major workers.

This ant both bite and “sting” (by squirting formic acid from it gaster) reversing its abdomen upwards and forwards towards its head instead of down and forward. It can also squirt droplets of formic acid from the end of its abdomen which is mostly aimed at the eyes and noses of browsing cattle and goats. Oecophylla smaragdina like most species of the Formicinae subfamily do not have a 'functional' sting like other stinging ants.

Even as the hunting and foraging are carried almost extensively by the major worker, both major and minor workers of Oecophylla smaragdina tend to the brood as well as in nest defense. However only the major worker undertake territorial defense of their pathway and trees where they nest or harvest  nectar and honey dew. The minor workers also undertake the collection of honey dew and plant nectar in the vicinity of their nests.

Like many tree dwelling ants, Oecophyla smaragdina establishes mutualistic relationship with many sap sucking insects and also with the caterpillar of some butterfly species. Some parasitic caterpillar species that feed on their brood are also harbored by Oecophylla smaragdina.


Oecophylla workers 'weaving' a new nest
Oecophylla workers 'weaving' a new nest. This is a fairly young nest and the workers have not attained to the full size of a mature nest.

A sub nest of Oecophylla smaragdina on a low hanging branch.


On sensing my movement as I focused to shoot a photo, all the workers rush out to the end of the leaf formed sub nest. This I suspect is a respond against cows and goats.


Oecophylla smaragdina workers collecting the sweet secretions of this leaf eating caterpillar
Oecophylla workers collecting the sweet secretions of this leaf eating caterpillar of Hypolycaena erylus. This is a mutualistic relationship. The caterpillar gets protection from predators and reward the ants for the protection with a sweet sugary secretion.


Workers of Oecophylla attacking a bee mimicking moth.


Male alate of Oecophylla smaragdina.


An female alate of Oecophylla smaragdina.


Workers of Oecophylla smaragdina in a ritual feeding (trophallaxis).


major and minor workers of Oecophylla smaragdina
The major and minor workers of Oecophylla smaragdina tending to the brood.

A normal major worker of Oecophylla smaragdina (above and below).




A minor worker of Oecophylla smaragdina grooming a major worker
A minor worker of Oecophylla smaragdina grooming a major worker. 


Minor workers of Oecophylla smaragdina are about half the size of the major workers.


A major worker of Oecophylla smaragdina holding a pupa.

Above and below workers of Oecophylla smaragdina tending the pupae. Unlike the larvae and eggs, pupae of Oecophylla smaragdina are not 'sticky' and are held together by the workers covering over them.

A minor worker of Oecophylla smaragdina with a pupa.


The baby looking minor worker of Oecophylla smaragdina.

Photo above and below shows the minor workers. 


The queen or gyne of Oecophylla smaragdina viewed from top.


Lateral view of a queen or gyne of Oecophylla smaragdina.

Frontal view. The gyne is 17 millimeters long.


 Oecophylla smaragdina gyne tending to her first clutch of eggs. Both the eggs and larvae of Oecophylla smaragdina are sticky and adhere to leaves' surfaces but not the pupae. Typically a newly mated alate gyne will make her way up a tree looking for a suitable leaf that have a concave curve to begin her new nest. Through instinct she will chose a fairly young leaf that has reached its full size. This leaf is typically near (but not at) the tip of the branch-lets. She typically chooses a leaf that is slightly curving downwards creating some sort of a concave hollow. She then settles on the underside of the leaf where she immediately lays her first clutch of some over twenty eggs. Within two days she would have laid slightly over thirty eggs. Oecophylla eggs hatching in four to five days is one of the fastest among mid size ants.  The larvae growth rate is likewise quite fast (for ants of that size range) and they begin to pupate within a week to ten days and typically eclose around 25 to 26 days. The new queen uses the larvae to spin a nest of ant's silk as a tent to cover the whole area over where she is brooding. This nest 'tent' covering is crucial as the pupae is non 'sticky' and will not adhere to the brood clutch and would be easily blown off the nest by even a light breeze.

An Oecophylla smaragdina queen with her first clutch of eggs.

Whenever she detect motion the Oecophylla founding queen will try to make herself inconspicuous. Like most big to large ants especially those that are arboreal foragers, Oecophylla smaragdina are alert to movement within their proximity.

The Oecophylla smaragdina founding queen tending to her first brood.

Queen of Oecophylla smaragdina and her partially completed tent
 Three days after the first batch of larvae hatched, the Oecophyalla smaragdina queen begins building her protective tent. Around 7 to 8 days after laying the first egg which takes around 4 (or more) days to hatch, the queen with her first batch of larvae begin weaving her tent of ant silk, a process that takes several days.

Queen of Oecophylla smaragdina and her partially completed tent
Following chemical cues from the larvae the queen select one that is ready to produce silk and began the construction of her protective tent.

Queen of Oecophylla smaragdina and her partially completed tent
 The 'tent' building works usually takes several days.

Queen of Oecophylla smaragdina and her partially completed tent
Once a larva is momentary 'depleted' the queen will return her to the brood and picks up another larvae to continue the 'tent' building until she has thoroughly weave a water proof tent.

Oecophyla smaragdina queen and brood
How the ant communicate with the larva in spinning the silk should be of particular interest.  A genetic intelligence expressed is the larvae communicates with the ant possibly using chemical signals as the ant appeared to know which larva is ready to use and when to stop and switch to another larva.

The Oecophylla queen hiding under her tent. Oecophylla queens are semi-claustral. She will leave a small opening in her silken tent allowing her to venture out to get moisture.

The larvae soon transform into pupae.

Oecophyla smaragdina queen with her brood under her tent
Oecophyla smaragdina queen with her brood under her tent. Here the photo shows how critical it was for the queen to have her silken tent done as the pupa does not stick to the clutch or to surfaces.

The Oecohylla queen with her first worker. On the left there can be observed a small opening in the tent that allows the queen to venture forth for moisture.

The first batch of Oechophylla smaragdina workers
The workers eclosed in 25 to 26 days. Typical of most ants the first few batches of workers are much smaller than those in mature nests.

Oecophylla smaragdina workers feeding on a piece of cooked chicken. By the 30th day the workers are actively foraging for food.



Around a month after the first batch of workers begins foraging and dependent on availability of food, the first full size worker eclosed. Image above show the size difference between the first batch and the full size worker.

The gyne is very protective of the brood and sits directly over them. Here only a larva is seen. Unlike nest of subterranean ants that are safely hidden in the underground craven or tunnel, all that stands between the brood and a predator of Oecophylla smaragdina is the gyne guarding them during the founding stage before the first larvae hatch and the first brood of workers eclose.

Sometimes for the first few months, new nests are found on the underside of leaves as there are insufficient larvae  (and also workers to fold leaves) to weave together a proper nest (when the first leaf on which the queen established the tent nest dried out and drop from the tree) as the food gathering activities of the first batch of workers maybe unable to sustain the food requirement of the queen to produce a large enough quantity of eggs and the corresponding larvae to weave together new leaves for their nest. Minor workers do not appear until some three to six months later.

Eggs, and larvae of the weaver ant Oecophylla smaragdina in various stages of growth
Eggs, and larvae of the weaver ant Oecophylla smaragdina in various stages of growth.

Close up of two young larvae of Oecophylla smaragdina
Close up of two young larvae.

A larva of Oecophylla smaragdina ceased feeding as it gets ready to pupate
A larva of Oecophylla smaragdina ceased feeding as it gets ready to pupate.

A larva of Oecophylla smaragdina at the peak of its growth
A larva of Oecophylla smaragdina at the peak of its growth.

The pupa of Oecophylla smaragdina
The pupa of Oecophylla smaragdina.


The nest of Oecophylla smaragdina is made by weaving leaves together with ant silk secreted by the larvae.


The nuptial flights. The nuptial flights take place from early morning after the sun is fully up to around noon depending on the weather. Nuptials are released all year round but peaked during the raining season.

Taxonomy:
Kingdom: Animalia
Phylum - Arthropoda
Subphylum - Hexapoda
Class - Insecta
Subclass - Pterygota
Infraclass - Neoptera 
Order - Hymenoptera 7399
Suborder - Apocrita 7400
Infraorder - Aculeata 7434
Superfamily - Vespoidea 34725
Family: Formicidae 36668
Subfamily: Formicinae 7479
Tribe: Oecophyllini 84545
Genus: Oecophylla 84546
Species: smaragdina 84561


Last updated: 2014 04 30
First Posted: 2010 04 19

© 2010 - 2014 Quah. All rights reserved.

6 comments:

  1. Excellent work!!!!

    ReplyDelete
  2. Fantastic job! Very interesting! Perfectly described / documented.

    ReplyDelete
  3. Magic!, did you qurantine the new queen (just after nuptial flight) inside a petri dish?

    ReplyDelete
    Replies
    1. No quarantine, just use that as the media for the queen to lay eggs and as the foundation for her founding nest. Once the larvae hatched she started to build a silk nest over them.

      Delete
  4. in quarantine queen in glass media prenatal food worker ants are given to the queen, if only there was fried chicken or other nutrients

    ReplyDelete

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