Iridoids and volatile pheromones of Tapinoma darioi ants: chemical differences to the closely related species Tapinoma magnum

Thermally Induced Actinidine Production in Biological Samples

“…melanocephalum workers, was clarified by GC–MS and 1 H and 13 C NMR analyses (Figure S1–S3). It was identical to the mass spectrum and NMR spectra of actinidine found in the literature. , For unheated samples, the dominant components were monoterpenes including the six isomers of iridodials and 6-methyl-5-hepten-2-one in T. melanocephalum and I.…”

“…Synthetic iridodials [(1 R , 2 S , 5 R , 8 R )-iridodial as the major isomer] were provided by Dr. Kamal Chauhan, Invasive Insect Biocontrol & Behavior Laboratory, USDA-ARS, Beltsville, MD. When standards were not available, identification would be based on comparison with the mass spectra in the literature , and the computer library (NIST 12 library).…”

“…Chemical shifts (δ H and δ C ) are quoted as downfield from TMS. The identification would be based on comparison with the NMR spectra in the literature. , …”

“…Actinidine, a methylcyclopentane pyridine monoterpenoid alkaloid, was first reported in the silver vine, Actinidia polygama Maxim (Ericales: Actinidiaceae), in 1959 and was named after this plant . For the past six decades, actinidine has been studied in many plants in the families Actinidiaceae, Bignoniaceae, Caprifoliaceae, Loganiaceae, Pandanaceae, and Valerianaceae, − more likely because it is a feline attractant. − In addition, it has also been found in many insect species (i.e., ants, sawflies, rove beetles, and stick insects) and presumably functions as a defensive chemical. − Recently, it was reported as a biosynthetic compound in two Tapinoma ant species and used in chemotaxonomy …”

“…Actinidine and methylcyclopentane monoterpenoid iridoids often co-occur in biological samples. For example, silver vine plants are rich not only in actinidine but also in iridodiols and matatabilactones, such as neomatatabiol, iridomyrmecin, isoiridomyrmecin, neonepetalactone, dihydronepetalactone, and isodihydronepetalactone. ,− , Iridodial and its stereoisomers are key intermediates in the biosynthesis of many iridoids in plants. − Actinidine, iridodials, and some other iridoid lactones such as iridomyrmecin, isoiridomyrmecin, nepetalactone, dihydronepetalactone, and isodihydronepetalactone also co-occur in the pygidial glands of ants in the subfamily Dolichoderinae. − ,− Traces of actinidine, five iridoid dialdehydes, and three iridoid lactones coexist in the larvae of several species of Chrysomelid beetles . Iridodials have been reported as defensive chemicals and pheromones in ants in the subfamily Dolichoderinae and other insects. − , Although the fact that actinidine is not a biosynthetic compound in insects has been suspected, , it has never been experimentally demonstrated.…”