Lichens as material for Lepidoptera's housing: A molecular approach to a widespread and highly selective interaction

Interactions between lichens and invertebrates are widespread and have evolved independently in several orders of invertebrates. Lichens participate as food, shelter, background for mimicry, or as camouflage for animals to wear. For this study, we discovered caterpillars of the moth family Psychidae living inside bags made from silk and lichens. We used molecular techniques to identify the lichens present and analyzed caterpillar selectivity for lichen species. We selected 13 bags and recovered the ITS genetic marker for every visually different lichen fragment. Obtained sequences were compared against a newly created ITS database from lichens of the study area. Caterpillars only used eight out of the 300 lichen species present showing a strong selection tendency for microfoliose lichens containing sekikaic acid. Our results suggest that caterpillars select lichen species at a higher rate than what is expected based on their local abundances. We provide an accessible way to study these widespread interactions in future projects.