Mimicry is a very widespread phenomenon in Nature, where some species imitate the morphological and chromatic patterns of others, benefiting from some kind of protection due to this similarity to the model. The later usually has some physical or biochemical characteristic that makes it ‘hated’ by predators. In the case of butterflies, it is usually the presence of toxic (most often alkaloids) and/or unpalatable substances in the body of the models.
In the Americas there is an endemic tribe of the Danainae subfamily of Nymphalidae: the Ithomiini butterflies comprising about 350 species – many of them popularly called ‘glasswings’ or ‘clearwings’ due to the transparency of much of the surface of their wings – where most participate in mimetic rings between themselves and with other lepidopterans, including the subfamily Heliconiinae and some diurnal moths.
In most cases. the chemical compounds involved in toxic or “bad tasting” (unpalatable) butterflies are incorporated during the larva stage from feeding on their food plants. In the case of glasswings the plants used by the larvae are partly Apocynaceae (a source shared with the Danaiini tribe) but the majority feed on Solanaceae, a botanical family which includes popular vegetables such as tomatoes, potatoes, eggplant and ‘jiló’. However, many species sequester these alkaloid compounds already in adulthood; especially the males which suck alkaloids from the flowers and roots of shrubs, lianas or weeds of the Asteraceae family or decaying dry leaves of Boraginaceae.
During the tour of one of the butterfly monitoring transects (a section of the Yellow Trail) recently cleared for maintenance, I was able to observe over the course of a week how groups of various species of glasswings congregated on the roots of an Eupatorium shrub (Asteraceae) – especially in the early morning and afternoon – as exemplified by the photo below. The species observed sequestering alkaloids from these exposed roots were the following: Episcada striposis, Episcada sylvo, Hypothiris ninonia daeta, Hypothiris euclea lapria, Ithomia agnosia zikani, Ithomia drymo and Pseudocada erruca.
© Jorge Bizarro
