The complex and diverse life of anthills

Anthills are complex social structures of a multitude of insects and not just their owners, the ants. The biodiversity of these colonies is overwhelming compared to that of other eusocial insects such as bees.

This has been verified in the latest study by professors Miguel Gaju and Rafael Molero from the Department of Zoology of the University of Córdoba in Spain, in which they synthesize more than 30 years of research on the fauna of Zygentoma insects, known as myrmecophiles, which They live associated with anthills in the Mediterranean region. A work in which an identification guide for these insects is provided and distribution maps of the 35 species found in said region are provided, based on a database of more than 1600 records.

Among all the myrmecophiles, they have focused on the insects of the order Zygentoma, to which the well-known silverfish that are frequently found in our homes and the goldfish, in wild anthills, belong. Why and how anthills “squat” these insects has occupied the research group “Terrestrial and edaphic fauna” of the University of Córdoba for decades. Time in which, in addition to describing new species of Spanish wildlife, they have concluded that some species visit anthills occasionally, while others (the majority) develop their entire lives in said anthills, where they find food and shelter.

The diversity is not only in the species, but also in the way of behaving and relating to the anthills. Thus, it has been shown that there are generalist myrmecophiles, which associate with many classes of ants, while others have specialized in specific types. It is also known that there are insects that manage to blend in with the colony in order to go unnoticed. This is done mainly by insects from the lepismatid family, which have small compound eyes and which, by chemical mimicry, rub against the body of the ants to acquire the colony’s own odor, escaping their attack with quick movements. Some specialists are even capable of generating their own mimetic cuticular hydrocarbons without rubbing, since they produce them in the absence of ants after molting their exoskeleton (Zygentoma molt throughout their lives, unlike winged insects, that stop moulting after metamorphosis). In addition, a more “daring” behavior was detected in the specialist silverfish when approaching the ants from the front, while the generalists preferred to approach their hosts from behind.

Ants. (Photo: Amazings/NCYT)

In the study, which is also co-authored by Jairo Robla, from the Doñana Experimental Station of the Higher Council for Scientific Research (CSIC) in Spain, a methodology is also offered for the identification of these insects with the aim of avoiding errors in records both of scientific platforms such as citizen science. In this sense, Molero and Gaju emphasize that “the problem is that it is not possible to identify these insects at the species level (and, in many cases, not at the genus level) by means of a photograph taken in their habitat, no matter how clear and of good quality, but requires microscopic examination, so many photo-based IDs are at least dubious.”

In their study, Gaju, Molero and Robla use the taxonomic characters that are really appropriate for their diagnosis, and update the knowledge about their true geographic distribution, after evaluating the reliability of the records that exist on these species. With this, an attempt is made to disseminate valuable information among the scientific community so that future ecological and genetic research carried out on these species is based on correct identifications.

Thus, as explained by Gaju and Molero, “it has been possible to offer an identification key that covers all the species known up to now in the Mediterranean region, and distribution maps of all of them in said geographical area and its environment, prepared from from a database of more than 1600 records. 35 myrmecophilous Zygentoma species have been recorded in the Mediterranean region, of which more than half are present in Spain”. In this sense, they warn that “the high proportion of Iberian species does not necessarily mean that Spain is the area with the greatest diversity in the Mediterranean for these insects. Although the Iberian diversity is high, it is very likely that these results are a reflection of the poor knowledge of these insects in the eastern Mediterranean and North Africa”.

The study is titled “Assessing the Diversity of Ant-Associated Silverfish (Insecta: Zygentoma) in Mediterranean Countries: The Most Important Hotspot for Lepismatidae in Western Palaearctic.” And it has been published in the academic journal Diversity. (Source: University of Córdoba)