Tag: ant colony

New ant species from Borneo explodes to defend its colony

Minor worker of the new species in a defensive pose.
Minor worker of the new species in a defensive pose.

Amongst the countless fascinating plants and animals inhabiting the tropical rainforests of Southeast Asia, there are the spectacular “exploding ants”, a group of arboreal, canopy dwelling ants nicknamed for their unique defensive behaviour.

When threatened by other insects, minor workers can actively rupture their body wall. Apart from leading to the ants’ imminent death, the “explosion” releases a sticky, toxic liquid from their enlarged glands, in order to either kill or hold off the enemy.

Three 'exploding' ants of the new species grasping onto a weaver ant.
Three ‘exploding’ ants of the new species grasping onto a weaver ant.

Curiously enough, while these ants’ peculiar behaviour was first mentioned in distant 1916, no new species have been formally described since 1935, due to insufficient evidence. Instead, scientists used to simply refer to them as the members of a remarkable species group – Colobopsis cylindrica, better known as “the exploding ants”.

That was until an interdisciplinary research team from Austria, Thailand and Brunei came together led by their shared fascination with these insects and their extraordinary mechanism of self-sacrifice (also called autothysis) in 2014. Thus, entomologists, botanists, microbiologists, and chemists from the Natural History Museum Vienna, Technical University Vienna, IFA Tulln and Universiti Brunei Darussalam together identified roughly 15 separate species of exploding ants, with one of them now described as new to science in the open access journal ZooKeys.

Aptly named Colobopsis explodens, previously nicknamed “Yellow Goo” for its bright yellow gland secretion, the new species has been picked as the model species of the group, after the scientists deemed it to be “particularly prone to self-sacrifice when threatened by enemy arthropods, as well as intruding researchers”.

The new species grasping onto a larger unidentified 'exploding' ant.
The new species grasping onto a larger unidentified ‘exploding’ ant.

Being a “model species” means that the ant will serve as an important navigation point in future studies on exploding ants. Publications regarding their behaviour, chemical profile, microbiology, anatomy and evolution are currently in preparation, say the authors. In addition, there are several more new species expected to be described in the near future.

While minor workers exhibit the ability to “explode”, the other castes have specialities of their own. For example, major workers (also called “doorkeepers”) have big, plug-shaped heads used to physically barricade the nest entrances against intruders.

Major worker of the new species ('doorkeeper') with characteristically enlarged head.
Major worker of the new species (‘doorkeeper’) with characteristically enlarged head.

During a sampling trip to Brunei in 2015, project members Alexey Kopchinskiy and Alice Laciny even managed to observe queens and males on a mating flight. They sampled the first males of these ants ever to be seen.

The same expedition was used to record the ants’ activity schedule and conduct the first experiments on food preferences and exploding behaviour.

While the exploding ants play a dominant role in rainforests, their biology still holds a number of secrets. The observations and experiments conducted on the newly described species have laid important groundwork for future research that will uncover even more details about these enigmatic explosive insects.

Watch this video to observe the behaviour of the exploding ants in various settings.

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Learn more about the ‘Exploding ants’ project at: http://explodingants.com/

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Original source:

Laciny A, Zettel H, Kopchinskiy A, Pretzer C, Pal A, Salim KA, Rahimi MJ, Hoenigsberger M, Lim L, Jaitrong W, Druzhinina IS (2018) Colobopsis explodens sp. n., model species for studies on “exploding ants” (Hymenoptera, Formicidae), with biological notes and first illustrations of males of the Colobopsis cylindrica group. ZooKeys 751: 1-40. https://doi.org/10.3897/zookeys.751.22661

 

Trapped in a nuclear weapon bunker wood ants survive for years in Poland

Having built their nest over the vertical ventilation pipe of an old nuclear weapon bunker in Poland, every year a large number of wood ants fall down the pipe to never return back to their colony.

Curiously, although trapped in extremely severe conditions underground, the ants have already upped their numbers to these of big, mature natural colonies, while also carrying on with their basic activities of nest maintenance, constructing and moulding. This unique population is described in the open access Journal of Hymenoptera Research by the team of Polish scientist Wojciech Czechowski, Polish Academy of Science.

The studied colony is still unique, despite the fact that there are previously known similar cases, such as a black garden ant colony that found a home in a chassis of an immobilised car, where the insects had built their nest from mud and dry plant remnants stuck to the underbody. Another wood ant colony is known to have lived in almost complete darkness within a cubic wooden box with no openings apart from a narrow slit at the bottom of one side. Yet, unlike the ants from the bunker, they have all had access to the outside world, having deliberately made their own choice to settle in such extraordinary locations.

Thanks to an yearly campaign set to count the hibernating in the same bunker bats, the ant population was discovered in 2013. Interestingly, when the ants were checked on in 2015, the researchers not only found the population still surviving, but even increasing its numbers.9096_image2

According to the estimates, they counted at least several hundred thousand workers, arguably close to a million. Moreover, when the researchers went back to the bunker in 2016, they found the mound’s damage, caused on their previous visit, repaired, which showed the population still managed to maintain their nest almost as if they were leading a normal life.

The ant ‘colony’ was found to have built an earthen mound in a small 2.3 m high room with a base area of 3 m x 1.2 m. Normally, such wood ants settle exclusively on large forested islands, where they can forage enough food to answer the high energy demand of the colony.

However, the confined space within the bunker has not been the only obstacle the ants have been facing in their underground trap. Beside the lacking food and light, the ‘colony’ had to also deal with the low temperatures between the one-metre thick ferroconcrete walls. All year long it was no more than 10 °C.

Understandably, the severe conditions within the bunker made reproduction effectively impossible. Although the scientists did undertake a special search for larvae, pupae, empty cocoons or queens, they found nothing. Nor did they find signs of male offspring.

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Looking for an answer why the population was still seemingly thriving, the scientists deducted that there was a constant influx of newly fallen ants. The metal plate that once covered the pipe outlet had obviously rusted so much that it has been collapsing under a big wood ant colony’s mound built right over the pipe. In fact, the mortality in the bunker is quite high, but the regular ‘newcomers’ turn out to be overcompensating for the dead ants.

“To conclude, the wood ant ‘colony’ described here – although superficially looking like a functioning colony with workers teeming on the surface of the mound – is rather an example of survival of a large amount of workers trapped within a hostile environment in total darkness, with constantly low temperatures and no ample supply of food,” say the authors.

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Original source:

Czechowski W, Rutkowski T, Stephan W, Vepsäläinen K (2016) Living beyond the limits of survival: wood ants trapped in a gigantic pitfall. Journal of Hymenoptera Research 51: 227-239. doi: 10.3897/jhr.51.9096