An exploratory survey of common and unexpected insect associates of Arnica montana L. capitula in the French Pyrenees

Although arthropods inhabiting Arnica montana capitula may affect both plant reproductive success and the quantity and quality of flower heads harvested for medicinal use, little is known about the composition of this assemblage. We used morphological sorting and COI DNA barcoding to identify arthropods collected from 115 capitula in a natural population managed under sustainable harvesting, with insects being the only group found. A total of 473 larvae, exuviae and adults were recovered, revealing a community largely dominated by the florivorous tephritid Tephritis arnicae , together with a smaller number of additional dipteran, hymenopteran, and hemipteran taxa. Molecular identification confirmed several previously reported associations and documented new capitulum-associated taxa, including Lasiomma sp. (Diptera: Anthomyiidae) and Melanostoma sp. (Diptera: Syrphidae). Preliminary results also suggested a reduced T. arnicae infestation in late-flowering capitula and in those from plants growing in open areas.