Facultative associations of two sympatric lycaenid butterflies with Camponotus compressus – field study and larval surface ultrastructure

The present study focused on the associations of two sympatric lycaenid species, Chilades pandava Horsfield, 1829 and Euchrysops cnejus Fabricius, 1798 with their respective host plants and the lycaenid tending Camponotus compressus Fabricius, 1787 ants by conduction of field studies and by examination of the ultrastructure of the larval myrmecophilous organs. The study revealed two facultative association complexes: ants - the defoliating Cl. pandava larvae - Cycas revoluta (Thunb.) plants and ants - the pod-boring E. cnejus larvae - cowpea plant, Vigna unguiculata (L.) Walp. The association of Cl. pandava was strongly synchronized with its host plant phenology and relatively less strongly with its late-arriving ant partner since the young, curled up leaves provided resources only to the caterpillars. The provision of resources to both the ants and the lycaenids by the cowpea plants contributed to the synchronization of E. cnejus association with the early arriving ants as well as the host plant. Presence of a single type of setae in Cl. pandava and of two types of setae in E. cnejus larvae indicates their facultative adaptations for resisting attack by their host ants. Ultrastructural similarity in the dorsal nectary, pore cupola and tentacle organs suggest that the basic myrmecophilous organs are conserved in these two lycaenid species.