Search

Plants protect themselves against various stresses by using volatile terpenes, which are also key precursors of climate‐relevant constituents in the atmosphere. Conifers store terpenes in storage pools, which serve as emission sources. However, how leaf terpene contents influence the quantity and composition of emissions is uncertain. Here, we examined whether they explain the profile of terpene emissions by using the measurements of 6 monoterpenes and 2 diterpenes stored in and emitted from the same branches of 10 local populations in Japanese cedar (Cryptomeria japonica), a common conifer in Japan. We estimated partial pressures of terpenes from leaf terpene contents by using a thermodynamic algorithm. The estimates correlated well with emissions of monoterpenes, suggesting the release of monoterpenes from the storage pools. High tree‐to‐tree variations in emissions of individual terpenes did not correlate with variations in concentrations of corresponding terpenes in leaves. Diterpenes (ent‐kaurene and phyllocladene) were emitted in most cases when individual trees held corresponding diterpenes, suggesting a linkage between emissions and storage pools, but the emissions were not explained by the algorithm owing to their low vapor pressure. [ABSTRACT FROM AUTHOR]

Cantharidin is produced by beetles of only two families, the Meloidae and the Oedemeridae. This substance is a defensive terpenoid that is toxic to the enemies of the beetles. Cantharidin also attracts other groups of insects and has been used as a bait to trap them. Cantharidin-baited traps deployed in central Japan captured coleopterans (Anthicidae, Endomychidae, Pyrochroidae, and Scarabaeidae), dipterans (Ceratopogonidae), hymenopterans (Formicidae), and harvestmen (Podoctidae). The seasonal occurrences of these arthropods, their sex ratios, known feeding choices, and mating habits suggest three possible underlying reasons for the attractancy of cantharidin: (i) it is accumulated as a defense against enemies and sometimes for transfer from males to females as a nuptial gift; (ii) it is used as a chemical cue in food searching; and (iii) it is used as an aggregation pheromone by mature arthropod individuals. The group of canthariphilous arthropods we describe represents a cryptic ecological assemblage with rare chemical networking among apparently unrelated species. [ABSTRACT FROM AUTHOR]