Meranoplus, The Shield Ant
Meranoplus is a genus of ant in the subfamily Myrmicinae. They are distributed mainly in Australia (most of the existing species), South Asia, Madagascar, Central and South Africa.
They are characterised for being small, extremely hairy, slow-moving and highly armoured ants, thus also known as “Shield Ants”. Most of the Meranoplus species have a heart shaped gaster very similar to Crematogaster.
Meranoplus workers can vary between 2 to 6mm, the largest being M.mucronatus, and queens vary between 8 and 10mm.
The species is monogyne, nonetheless related new queens might be kept together during founding stage, but not advisable as unrelated queens will fight each other.
In the wild, Meranoplus prefer to nest on the ground, near the edges of roads, or clear pathways. Their nests, although small, can be easily spotted because of the characteristic loose soil mound that surrounds the entrance.
The nests are relatively shallow and concentrated around a 20cm diameter area and around 30cm deep.
They live surrounded by other ant species, such as Camponotus, Diacamma, Anoplolepis, Oecophylla, Paratrechina, Solenopsis, etc (in Asia). I have seen ants disputing territory, sometimes gaining, sometimes losing ground to other species. But Meranoplus doesn’t seem to be engaged actively in territorial disputes. Even between other Meranoplus neighboring colonies. There are areas were the distance from one nest to the other can be less than 2 meters, still there is no sign of active confrontation.
With respect to diet, most species are omnivores and facultative granivores, while others, including the whole M.diversus species group, are specialist granivores. Meranoplus species are active both day and night, and can recruit via pheromone trails laid from the base of the sting using secretions from their extremely large Dufour glands. Foraging is performed primarily on the ground or in the leaf litter whereas only very few species may additionally climb up trees or shrubs.
In the wild I have never seen them hunt, capturing a live prey and killing it. I believe the reason why they nest near the road edges is mainly because the street lamps always attract a lot of flying insects at night, which end up dying from exhaustion and falling on the ground, thus becoming easy food source for the Meranoplus. In captivity, whenever I feed them any freshly crushed insect the recruitment period is very fast, and the colony will mobilize in mass to handle the prey. The larger the prey the bigger the mobilization. They will dismember the prey outside, and bring it, piece by piece, inside the nest.
In Asia they can have nuptial flights from early May until end of September, depending on the region, humidity, etc.
The most intriguing thing found regarding these ants' nuptial flights is that there are two types of flights. The active flights, where you will see male and queen alates running out from the nest and flying, just like any other species. And the passive flights, where there are no male alates whatsoever, and already de-alate queens also rush out the nest in search of their new home.
If you dig a nest during nuptial flight season, it will be common to dig out a nest with many de-alate queens, thus making you believe that the species is polyginous. When in reality, it’s a bunch of new queens (mated or not) waiting for their chance to escape. New de-alate queens that remain in the mother nest, will not lay eggs, and will do the work just like any other worker.
From past experience, it is advisable to feed your queens a good drop of sugar water and tube them individually. Tubing them together might prevent them from laying eggs, due to the presence of other queen pheromones.
Regarding defense mechanisms they have three main mechanisms. First, the amount of hairs present, deter other ants from getting close, secondly, the chemical defenses employed, also stop the most aggressive species to come in close contact with them. Lastly, when disturbed, will display thanatosis (is the process by which an animal feigns death in order to evade unwelcome attention) enhanced by crypsis (it is the ability of an animal to avoid observation or detection by other animals), i.e., individuals will accumulate dirt in their pilosity and retract their antennae into the scrobes, tuck their legs under the promesonotal shield and remain motionless.
It is said that because of their slow pace, their zen ways and their potent repellent make them a great species for communal nests. We decided to put this myth to the test, and have joined together some Meranoplus bicolor workers together with the highly aggressive Solenopsis invicta major workers.
Once introduced, the S.invicta workers immediately started to roam the small enclosure and when they encountered the M.bicolor workers they would stop, open their mandibles, sense them with their antennae for a few moments, and then try to aggressively engage the M.bicolor. M.bicolor on the other hand, as soon as they detected any slightest touch, they would turn their gasters towards their aggressors and start to show their stinger.
S.invicta would unsuccessfully try to bite and sting M.bicolor, but to no avail. With so many hairs S.invicta isn’t able to bite any part of M.bicolor, and it does seem to prevent them from being able to sting them effectively.
M.bicolor sensing the aggressor getting even closer would retract slightly and start accumulating a droplet of liquid on the tip of the gaster.
Note: I am not sure if there are chemicals being sprayed, from what I could see there were none. There was one occasion where S.invicta touched the droplet and the reaction was to quickly run away and spent the next moments cleaning herself frantically. There was no occasion where I was able to see a M.bicolor being stung or bitten, and after 10 minutes of constant engagement, S.invicta major workers lost interest.
No M.bicolor workers died, and they were all safely returned to their nest.
Who would say such a small ant could stop S.invicta? For this and so many other reasons, there are many ant keepers who are keen in having a colony of them communally housed with other species.
This practice/information doesn’t seem to have much dispersal on overall western ant keeping community except for German and Austrian ant keepers who seem to be more exposed and prone to do it.
If you want more information we advise you to search German/Austrian forums and site. You would be able to find the most comprehensive information and photo record about communal ant enclosures with M.bicolor together with ponerines, camponotus, crematogaster and other species.