Not only human societies are full of imposters, they also exist in nature, especially among insects. Some species play the dismissal, such as the bee fly or the ant spider, to take advantage of others they mimic. But never before the researchers had found a blue fly more than impudence than the talented Mr Ripley.
This species, family of the Caliphóridos, makes their larvae part of the colonies of the harvesting termites thanks to a unique disguise: a mask with false eyes and antennas, which also carry in the tail, and a smell that mimics that of their hosts
This fake insect has been discovered by an international team led by the Institute of Evolutionary Biology (IBE), a mixed center of the CSIC and the Pompeu Fabra University (UPF), with the participation of the Botanical Institute of Barcelona (IBB, CSIC-CMCNB). The scientists found him in the Anti-Atlas mountain range to the south of Morocco.
«It is a casual finding. In our research group we mainly study butterflies and ants. As it had rained a lot and the butterflies did not fly, we dedicated ourselves to looking for ants. When we lift a stone we found a termiter with three fly larvae that we had never seen. The water had probably flooded the deepest layers of the nest and the larvae emerged to the surface, ”says Roger Vila, an IBE researcher who has led the study. “It must be an extremely rare species, because we have made three more expeditions in that area and, despite raising hundreds of stones, we only find two more flies, together in another termiter.”
Blue fly larva surrounded by harvesting termites in the laboratory
Vlad Dunca
A mask in the tail
The team has described in the magazine ‘Curren Biology’ The unique morphological and chemical adaptations of the blue fly to infiltrate the termites. On the back of its body, the larva shows a “termite mask”: a “head” – non -functional – with antennas and palpos the size of a large harvester termite. In addition, it has two fake eyes, which are actually the respiratory holes of the larva.
«Most termites live meters deep and have no visual perception. However, the harvesting termites go out at sunset to collect grass, so they have functional eyes that the larva manages to imitate with their spiracles, ”says Vila.
In addition, the larvae have unusual “tentacles” around the body that mimic the antennas of the termites in great detail, something that the equipment has been able to show by means of scanning electronic microscopy. The numerous tentacles surrounding the body of the larvae facilitate simultaneous communication with several termites.
Within the nest everything is dark, so the termites are recognized between them through the antennas, with which they detect the shape and smell of their sisters. All the members of the nest share this aroma, and the soldier termites attack and dismembered any intruder of another colony. The larvae of this fly, however, have also managed to imitate the distinctive smell of their hosts.
«We quantify the chemical composition of these larvae and the result is surprising: they cannot be distinguished from the termites of the colony where they live, they smell exactly the same. In addition, the larvae and termites of each colony have slight differences in their chemical profile that differentiate them from the other termiters. This smell is key to relating to termites and benefiting from their community life, it is a chemical disguise ».
Back of the blue fly larva where the “Termita mask” can be seen, with false eyes and antennas
Vlad Dunca
Groomed by termites
When the team found the larvae in Morocco, they occupied the food cameras of the Termitero. Once in the laboratory, they were able to observe that the fly larvae used to be located in the most populated areas of the nest, where they received constant attention from the termites, which groomed them with their oral pieces.
Although the team failed to reveal its diet, it was able to observe behaviors similar to trofalaxis: the termites seemed to transmit mouth food to the larvae. “The larva is not only tolerated, but constantly communicates with the termites by contact with its tentacles similar to antennas and even seem to feed it, although this has not yet been demonstrated,” says Vila.
The team highlights the difficulty of caring for these insects in the laboratory, since it implies maintaining colonies of termites from the desert, which live in very special conditions. «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 we fail to move to the laboratory. Its diet is unknown to date, and its adult form remains a mystery, ”adds Vila.
Evolutionary jump
The relationship between blue fly larvae and termites seems to be a form of social parasitism or symbiosis. The most similar case is found in humpback flies. However, in humpback flies are adults, and not the larvae, those who mimic the termites, representing a case of independent evolution of seatophilia (relationship with termites).
«The common ancestor between the blue and humpback flies dates back to more than 150 million years ago, much more than separates the human beings from the mice. Therefore, we can affirm that we have discovered a new case of evolution of social integration, ”explains Vila.
The team has demonstrated through phylogenomic studies that the discovered fly belongs to the genus Rhyncomyya. Since none of the known species of this genus share the unusual way of life or the incredible morphology of the discovered fly, the study suggests that the new species must have evolved very quickly.
«This discovery invites us to reconsider the limits and the 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, essential organisms of ecosystems, ”concludes Vila.
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