Two centimeters of grass

The protagonist of this entry is a small blue butterfly called Phengaris rebeli, (previously under the genre Maculinea) also acquaintance like “hormiguera of spots“. Lepidopterous tiny East is well-known for many decades on the part of the entomologists due to a few very curious peculiarities of his vital cycle. It belongs to the family of the licénidos, a few small butterflies and of delicate and discreet beauty that passions raise between certain photographers. Many licénidos larvae show some type of mutualism with the ants, being common that these defend in his nutritional insects plants theirs predators in exchange for molasses that exudan for a few glands of his cuticle. Nevertheless the species that occupies us became famous precisely for going a step further away and to complete the last phase of his metamorphosis inside an anthill. Apparently it was in 1956 when a British investigator saw by chance how a larva in last stadium of the Phengaris "was" "dropped" of the gentian that had fed it and how a working ant of the species Myrmica nausithous was taking it to his anthill.

The entomólgo in question had just spun what happened and announced the curious phenomenon: the larva had to suffer his last change as such in the anthill, being thus the chrysalis sure and protected under ground, emerging like adult in the suitable moment. The discovery of this singularity attracted the attention on this species of butterfly that was taking a time in frank regression and by the end of 50s it was practically extinguished in Great Britain. In 1960, like desperate measurement, the entomological shift society bought the area where there was living the last English population of Phengaris rebeli and the valló as last attempt of avoiding his disappearance. Let's make here a fully deserved comment about the well-intentioned intervention of these Englishmen. I do not know how many previous examples would be of protection measurements of a species of invertebrate, but I do not believe that they were great. Unfortunately, a few years later, this butterfly disappeared definitely of this shore of the English Channel. A decade later, the relative near Phengaris arion (=Maculinea arion), continued for the same way and became extinct in the whole country.

The history continues in the continental Europe, where the knowledge was extended on the biology of the hormiguera of spots. There ended up by being unraveled, for example, the biochemical trick that allows him to share cockpit with the jealous ants: a few porous glands secrete an attractive substance for the ants, while the called "tentacles" are in charge of producing the pheromone that identifies this larva as ant, avoiding to be devoured by his rent matrons. This does that the life of the larva depends completely on the correct functioning of these deceitful glands of the cuticle and turns the moment of the change into critic. Since you know, all the arthropods change his cuticle and this butterfly is not an exception. Newly gone out of the chrysalis, the new cuticle of the adult lacks the glands swindlers that we were mentioning and any ant that detects it will not hesitate to attack it. It is for it that the adult butterfly flees of the night anthill, while the ants are inactive, like an inverse thief: going out of the house with evening hours and secretiveness.

The new investigations met the same way on the possible cause of the extinction of the British population, since the biochemical relation of these butterflies was quite narrow with a species of ant (I remember: Myrmica nausithous), but not with others. Apparently, to the vallarse the area where the last butterflies population was living, the cattle stopped feeding in the area and the grassland did a few centimeters to itself higher. This was enough so that the average temperature of the soil was lowering of temperature a pair of grades, and this cooling of the soil was sufficient so that Myrmica nausithous was displaced by another species of very similar ant, M. scabridonis, not capable of being cheated by the glands of the larvae of the butterfly, which were turning out to be unable to complete his cycle.

Ironies of the life, the measurement driven to despair to protect the English Phengaris population with the whole good intention of the world was the one that provoked his extinction in the island. A marvelous example that demonstrates that the intricate relations between the living beings can be very surprising and that to realize works of conservation of fauna and flora it is not necessary to get tired of investigating and to study in depth the biology of the species, is not going to be that we end up by tying it up for things so dumb as two centimeters of grass.

The history of the butterflies hormigueras would give to speak very much: there are larvae that end up by being carnivorous and feed on eggs and larvae of the ants that lodge them; recently they have discovered that in addition to the chemical tricks, the ants larvae express also sonorous tricks to be identified like ants, and insurance that you find fascinating knowledge that there are wasps icneumónidas (these cabronas that put eggs in the larvae of other insects so that they are eating up them live inside showing the God's immense love) that they settle in the entry of the anthill and are capable of "hearing" if there is inside a butterfly larva hormiguera before risking to enter and put the "alien". Nevertheless I believe that it is worth finishing with good news. Last year was publishing in Science a few good results in the reintroduction of P. arion Swedes in the British islands: the populations were increasing thank you, between other things, to the correct diagnosis of the problem. Precisely there where the cattle was grazing again according to the traditional use of the area, the populations of the butterfly were prospering again demonstrating that the knowledge and the investigation are the key for the design of good strategies for the conservation of the threatened flora and fauna, and that once again the abandonment of the traditional uses of the area is a probable cause of the extinction of many species.

In north half of Spain there live four species of the genre Phengaris, including P. rebeli. The last one is considered to be according to the Red Book of the Invertebrates of Spain a vulnerable species. His principal threats are, as it was of waiting, the abandonment of the bovine and sheep pasture of his habitat and the proliferation of the tracks of ski along with some of his Aragonese populations.