Hello ,

We hear daily about invasive species and the negative impact that they have on our local biodiversity. But how do these exotic species take over and cause damage? Let us investigate some of the invasive species of ants within South Africa to try and solve this puzzle.

Over the last two weeks I have observed the strangest behaviour in some of my larger ant colonies. Specifically in multi-queen colonies they exhibited very strange and yet interesting behaviour.

My one multi-queen Big-Headed ant (Pheidole sp.) colony has steadily been growing in number and they are looking very good. Although, over the entire winter they refused to use two test tubes within the same nest, even though their numbers outgrew a single test tube. They seemed to prefer the cramped space and being in close contact with one another inside the nest.

This, however, all changed as the temperature started rising. They started being restless, splitting the queens into different test tubes. The colony also figured out how to escape, and instead of just vanishing like a colony usually do, they invaded another nest and killed the occupant, taking hold of the nest and moving a single queen to the new nest. The very interesting part, however, is that the ants keep on moving between the nests continuously.

Prof. SH Skaife wrote that he witnessed the same behaviour with the extremely invasive Argintine ants (Linepithema humile) in the Western Cape. The colonies over winter would consist of multiple queens and then when the temperature starts rising in spring the colonies would split into single queen colonies with continuous movement between the new and old colonies.

This enables a species like this, to not only survive through the cold of winter, but also increases the territory that the colony occupies.

The genus Anoplolepis (crazy or pugnacious ants) that contains the Yellow Crazy ants (Anoplolepis gracilipes) are also known to have multiple queens in the colony.

This mechanism, of merging and separating a colony seasonally, that these ant genera thus exhibit enables them to quickly establish and defend a territory at the start of every season. Along with the aggression of these ants they have been able to not only successfully spread across the globe, but also to invade and conquer vast land masses outside of their original distribution.

Have you ever encountered angry ants that wanted you out of their territory or tried to evict you from your home?

If you would like to send me a message with your answers, feel free to do so on Instagram @abugmanslife or via email to [email protected].

Weekly Top Shot: The Pugnacious Ant