The ant associates of Lycaenidae butterfly caterpillars – revisited

Based on a global compilation of data on ant associates of 523 Lycaenidae species, a synthesis is attempted as to which ants participate in these interactions. Ants from 63 genera have thus far been observed as visitors of facultative myrmecophiles or as hosts of obligate myrmecophiles among the Lycaenidae. Over 98% of records come from nectarivorous and trophobiotic ants in just three subfamilies, viz. Formicinae, Myrmicinae and Dolichoderinae, with the genera Crematogaster and Camponotus occupying the top ranks. Accumulation analysis suggests that rather few ant genera remain to be added to the list of associates. The representation of ant genera as attendants of lycaenid immatures is related to their global species richness, but with some notable exceptions. Ants that form ecologically dominant, large, long-lived colonies are over-represented as hosts of obligate myrmecophiles. The taxonomic diversity of lycaenid-ant associations is highest in the Oriental and Australian region, and lowest in the Neotropical and Afrotropical region. Among tropical African lycaenids, this is due to two butterfly lineages (genus Lepidochrysops and subfamily Aphnaeinae) that have massively radiated in the Neogene, but mostly maintaining their general affiliations with either Camponotus or Crematogaster ants, respectively. Many tropical and subtropical lycaenids nowadays form associations also with invasive alien tramp ants, giving rise to novel mutualistic interactions.

Do mutualistic interactions last longer than antagonistic interactions?

Species interactions are crucial and ubiquitous across organisms. However, it remains unclear how long these interactions last over macroevolutionary timescales, and whether the nature of these interactions (mutualistic versus antagonistic) helps predict how long they persist. Here, we estimated the ages of diverse species interactions, based on phylogenies from 60 studies spanning the Tree of Life. We then tested if mutualistic interactions persist longer than antagonistic interactions. We found that the oldest mutualisms were significantly older than the oldest antagonisms across all organisms, and within plants, fungi, bacteria and protists. Surprisingly, this pattern was reversed in animals, with the oldest mutualisms significantly younger than the oldest antagonisms. We also found that many mutualisms were maintained for hundreds of millions of years (some greater than 1 billion years), providing strong evidence for the long-term stability of mutualisms and for niche conservatism in species interactions.

Resource exchange and partner recognition mediate mutualistic interactions between prey and their would-be predators

Animals may develop mutualistic associations with other species, whereby prey offer resources or services in exchange for protection from predators. Alternatively, prey may offer resources or services directly to their would-be predators in exchange for their lives. The latter may be the case of hemipterans that engage in mutualistic interactions with ants by offering a honeydew reward. We test the extent to which a honeydew offering versus partner recognition may play a role as proximate mechanisms deterring ants from predating upon their hemipteran partners. We showed that, when presented with a choice between a hemipteran partner and an alternative prey type, mutualist ants were less likely to attack and more likely to remain probing their hemipteran partners. This occurred even in the absence of an immediate sugary reward, suggesting either an evolved or learned partner recognition response. To a similar extent, however, ants were also less likely to attack the alternative prey type when laced with honey as a proxy for a honeydew reward. This was the case even after the honey had been depleted, suggesting an ability of ants to recognize new potential sources of sugars. Either possibility suggests a degree of innate or learned partner recognition.

First Report on the Acrobat Ant Crematogaster scutellaris Storing Live Aphids in Its Oak-Gall Nests

This study provides new data about the role of ants in mutualistic interactions with aphids mediated by galls. We focused our investigation on galls induced by the cynipid Andricus kollari by conducting a survey and a subsequent experiment in an Italian oak forest. The ants Crematogaster scutellaris, Colobopsis truncata and Temnothorax italicus frequently used the galls as nests: Crematogaster scutellaris occupied galls which were located higher on the oak trees, while C. truncata and T. italicus were located at lower positions. In addition, galls occupied by C. scutellaris showed varied internal architecture in relation to the colony composition. Importantly, field surveys revealed for the first time that C. scutellaris nest galls also contained live individuals of the non-galligenous aphid Panaphis juglandis. Field experiments suggested that the ants actively seek, collect and stock live aphids. No signs of predation and injuries were detected on the stored aphids, which were probably kept for safe overwintering, though we cannot exclude a possible occasional use as food. This report reveals a possible novel relationship which could have important consequences on the phenology and presence of aphids on the host plant.

Endosymbionts associated with Diaphorina citri, vector of Candidatus Liberibacter asiaticus

iaphorina citri is considered the most dangerous citrus pest because it transmits Candidatus Liberibacter asiaticus, the causal agent of Huanglongbing (HLB). Like other hemiptera insects, D. citri has developed mutualistic interactions with prokaryotic organisms known as endosymbionts. This symbiosis can be obligatory, when the interaction occurs with a primary endosymbiont, or facultative, when it is a secondary endosymbiont. Symbiosis is essential for various physiological functions, but some endosymbionts can adversely affect the psyllid's abilities. D. citri is associated with a great diversity of endosymbionts, with Candidatus Carsonella ruddii, Candidatus Profftella armatura, Candidatus Wolbachia spp. and Candidatus Liberibacter spp standing out. The aim o symbiotic relationship, prokaryotes, Candidatus Wolbachia, transmission of Candidatus Liberibacter asiaticus.