Co-occurrence of three Aristolochia-feeding Papilionids (Archon apollinus, Zerynthia polyxena and Zerynthia cerisy) in Greek Thrace

Comparative studies of co-occurring species using overlapping resources may help in understanding the mechanisms supporting biotic diversity in species-rich regions, such as the Mediterranean region of Europe. Three Papilionidae butterflies, Archon apollinus, Zerynthia cerisy and Zerynthia polyxena, develop on Aristolochia plants and co-occur in Greek Thrace. We used mark-recapture to describe adult demography and dispersal, and searched for eggs and larvae to assess host plants and microhabitat preferences. Adult flight timing followed a sequence from earliest A.apollinus, through Z.polyxena to late Z.cerisy; this was more prominent in 2010 (warm early spring) than in 2011 (cold delayed spring). Population densities were highest for A.apollinus and lowest for Z.cerisy, whereas dispersal ability followed a reverse pattern. Adults of all three species crossed distances >3km and used all habitat types present. Four Aristolochia host plants were used at the study locality: small Aristolochiapallida, intermediate Aristolochiarotunda and Aristolochiahirta, and bulky, late-sprouting Aristolochiaclematitis. Both A.apollinus and Z.polyxena used all four Aristolochia species, the former preferring Aristolochiarotunda and Aristolochiahirta, the latter Aristolochiarotunda and Aristolochiapallida. Zerynthia cerisy did not use the early-growing Aristolochiapallida while frequently using the late-growing Aristolochiaclematitis. Further parameters affecting oviposition were biotope and canopy closure: early A.apollinus tolerated shady sites but late Z.cerisy avoided them. The simultaneous use of several host plants differing in phenology and habitat requirements, combined with rather high dispersal ability, arguably buffers the butterflies' population dynamics against yearly variation in weather, while allowing efficient occupation of the diverse Mediterranean landscapes. The regional habitat diversity, created during millennia of human activity, is currently threatened by land abandonment, which may diminish the resource base for the studied butterflies.