An impostor among termites: the fly that 'changes' species to survive

BarcelonaIn nature there are several examples of animals impostors They manage to fool their predators thanks to their physical appearance. As their names indicate, the bee fly and the ant spider pretend to be what they are not in order to survive: the first earns respect with its colors and the second appears to be harmless. However, research confirms that one of the queens of mimicry would be the blue fly. According to a study led by the Institute of Evolutionary Biology (IBE), the larvae of this insect are capable of developing a "mask" and a characteristic smell to coexist with termites.

Specifically, on the back of their body, these larvae have a kind of head with antennae very similar to those of a large harvester termite, with two false eyes that, in reality, are their respiratory holes. In addition, they have chemically evolved to emit an odor identical to that of theirstepsistersto avoid being killed. Their adaptation is so detailed that they even manage to get termites to take care of them.

The Botanical Institute of Barcelona (IBB) and the IBE, which is a joint centre of the Spanish National Research Council (CSIC) and the Pompeu Fabra University (UPF), have discovered that a species of blue fly, Rhyncomya, can live and actively participate in colonies of harvester termites thanks to a morphological and chemical disguise. That is, it looks similar both on the outside (although larger) and on the inside. A discovery of natural evolution that was accidental in the Anti-Atlas mountain range, in southern Morocco.

According to this research, which has been published in the journal Current Biology, The deceptive ability of these flies is sophisticated. Most termites live meters deep and, although they do not have visual perception, they do have a kind of functional eyes to collect grass. According to the IBE researcher, Roger Vila, they have observed that larvae of Rhyncomya They use their spiracles (breathing holes) to simulate having these eyes.

In addition, these flies have unusual "tentacles" around their bodies that mimic termite antennae in astonishing detail; they look so similar that researchers have only been able to identify the differences with scanning electron microscopy. "The numerous tentacles surrounding the larvae's body facilitate simultaneous communication with several termites," they explain.

Since everything is dark inside the nest and the termites recognize each other through their antennae, with which they detect the shape and smell of their sisters, this chemical ability is extremely important. "All members of the nest share this scent, and soldier termites attack and dismember any intruder from another colony. The larvae of this fly, however, have also managed to imitate the distinctive smell of their hosts," they point out in the study. In fact, their smell is identical to that of the termites in the colony. "This is key to interacting with the termites and benefiting from their community life; it is a chemical disguise," Vila stresses.

One of the proofs of the coexistence between these insects is that the blue fly larvae occupy the cameras The termites are kept in the nest where food is stored and receive constant "attention" from the termites. For example, they clean the food with their mouthparts. Now, the researchers also want to find out whether, as it seems, the termites transmit food from mouth to mouth in the larvae. "The larva is not only tolerated, but constantly communicates with the termites by contact with their antenna-like tentacles and even appears to be fed," concludes Vila.

Elements that cannot be reproduced by science

The relationship between these bluebottle larvae and termites seems to be a form of social parasitism or symbiosis. The most similar case is found in humpback flies, although the adult specimens are the ones that imitate the termites. "The common ancestor between bluebottles and humpback flies dates back more than 150 million years, much longer than the time that separates humans from mice. Therefore, we can say that we have discovered a new case of the evolution of social integration," explains Vila.

However, he admits that the Rhyncomya It must be an extremely rare species. "We have made three other expeditions in this area and, despite lifting hundreds of stones, we have only found two other flies, together, in another termite mound," he says. In addition, their adult form remains a mystery.

The international team highlights the difficulty of caring for these insects in the laboratory, since it involves maintaining colonies of termites native to the desert, which live in very special conditions. All the larvae studied ended up dying without reaching metamorphosis, so there could be elements of the nest and the symbiotic relationship between termites and flies that could not be reproduced scientifically.

"This discovery invites us to reconsider the limits and potential of symbiotic relationships and social parasitism in nature. But, above all, to become aware of everything we still do not know about the vast diversity and specialization of insects, which are essential organisms in ecosystems," he concludes.