LYCAENID BUTTERFLIES AND PLANTS - IS MYRMECOPHILY ASSOCIATED WITH PARTICULAR HOSTPLANT PREFERENCES

Life-history data on 1050 phytophagous species of the butterfly subfamily Lycaeninae were used to examine previously suggested correlations between hostplant use and myrmecophily. Myrmecophily is an ancestral character of the Lycaeninae, which has been reduced independently in a number of lineages (secondary myrmecoxenes). Members of the order Fabales (''legumes'') are the most widespread, and probably the ancestral, hostplants of Lycaeninae caterpillars. At subfamily level, myrmecophily is more common among legume feeders than in species utilizing non-legume hosts. A different pattern emerges on tribal level; Theclini show much a lower affinity to Fabales as hostplants, whereas Polyommatini have a high incidence of myrmecophily even if not feeding on legumes. A number of non-legume hostplant families support a proportion of myrmecophiles comparable to that found in legume-feeders (>90%), notably the families Crassulaceae, Proteaceae, Myrtaceae, Melastomataceae, Combretaceae, Anacardiaceae, Sapindaceae, Rhamnaceae (all in the subclass Rosidae) and others. In contrast, plant families such as Polygonaceae, Fagaceae, or Ericaceae support distinctly fewer myrmecophiles. Roughly half of all myrmecophilous species are not known to feed on legumes, and less than 1/3 of the myrmecophiles are specialized legume feeders. Furthermore, there is no stronger preference for legumes among obligate myrmecophiles in comparison to facultatively ant-associated lycaenids, and various highly myrmecophilous clades show a very low affinity to legumes. These findings weaken the idea that nutritive requirements caused by myrmecophily have selected for the utilization of nitrogen-fixing leguminous hostplants. There is also no support for the hypotheses that nitrogen-fixing hostplants other than legumes, or parasitic plants of the order Santalales, support an increased proportion of myrmecophiles. Lycaeninae caterpillars predominantly feed on plant families rich in polyphenolics or tannins, especially in the subclass Rosidae, but more rarely utilize hostplant taxa with advanced chemical defenses such as cardenolides, alkaloids, or iridoids. Overall, members of at least 149 plant families are utilized. Taxonomic idiosyncrasies in hostplant relationships are common in Lycaeninae butterflies. Plant chemistry (secondary metabolites), therefore, appears to be more important in shaping lycaenid hostplant utilization patterns than is myrmecophily. The most distinct relations between hostplant associations and interactions with ants occur in secondarily myrmecoxenous species which mostly have restricted host-ranges and rarely feed on legumes. The findings suggest that, instead of selection for nitrogen-fixing hostplants in myrmecophilous species, selection against myrmecophily has occurred in certain lineages that have switched to ''aberrant'' hostplants.