Lasius japonicus

Mizuno et al. (2018) studied interactions between this ant and the myrmecophytic butterly Lampides argyrognomon.

Distribution based on Regional Taxon Lists
Palaearctic Region: China, Democratic Peoples Republic of Korea, Japan, Republic of Korea, Russian Federation.

Biology
Mizuno et al (2018) - Myrmecophilous lycaenid caterpillars have close relationships with their ant hosts by means of various myrmecophilous organs, most of which are usually lost after pupation. However, some lycaenid species, including Lycaeides argyrognomon, maintain such relationships at the pupal stage and go so far as to pupate in ant nests. This invokes the hypothesis that these myrmecophilous lycaenid pupae might have alternative tactics to retain myrmecophilous interactions without ant attacks. Camponotus japonicus, Formica japonica, and Lasius japonicus exhibited distinctive aggressive behaviors against ant cuticular hydrocarbons (CHCs) from different colonies of the same species but few attacks against the crude extract of L. argyrognomon pupae. GC-MS analysis revealed that the pupal cuticular lipids contain not only CHCs but also several long-chained aliphatic aldehydes, including 1-octacosanal and 1-triacontanal, which are absent from larval cuticular lipids. With the addition of synthesized 1-octacosanal and 1-triacontanal to ant CHCs from different colonies of the same species, the aggressive behavior decreased in C. japonicus, and the duration of physical contact shortened in C. japonicus and F. japonica. However, the behavior of L. japonicus remained unaffected after the addition of those aldehydes. These results suggest that the pupae-specific cuticular aldehydes of L. argyrognomon suppress ant aggression even after the loss of certain myrmecophilous organs, though the effects varied depending on the attending ant species. Since L. argyrognomon occasionally pupate in the nests of C. japonicus in the field, the lycaenids might be better adapted to associations with C. japonicus than with the other two ant species studied.

Watanabe et al. (2019) conducted an observational study of the aphid species Macrosiphoniella yomogicola (Matsumura) and the ants that tended their colonies. This aphid has been found to be an obligate ant mutualist. Nine aphid colonies were monitored in Sapporo, Japan over a multi-week period in August and September. Lasius japonicus, Tetramorium tsushimae and Pheidole fervida were found attending the aphids, with each ant species exclusively tending the aphid colony where each was observed. The only aphid colonies to survive through the monitoring period were those tended by Lasius japonicus. This suggests, but the he number of observed colonies was not sufficient to conclude, this ant species is a mutualist with these aphids while the other ants are only opportunistically gathering honeydew and possible preying upon the aphids.

Nomenclature

 *  japonicus. Lasius (Lasius) emarginatus var. japonicus Santschi, 1941: 277 (w.q.) JAPAN. Junior synonym of niger: Wilson, 1955a: 60; Yamauchi, 1979: 152. Revived from synonymy and raised to species: Seifert, 1992b: 30.