Mapping specific habitat requirements as a base for conservation measures for two strongly endangered burnet moth species in Southern France: Zygaena brizae and Zygaena cynarae (Lepidoptera, Zygaenidae)

Abstract Zygaena species are sensitive indicators of ecological changes and habitat destruction. Here, field results on the ecology of two highly endangered species, Zygaena brizae and Zygaena cynarae, from optimal habitats near Col d'Araud in Hautes-Alpes, France are reported. Both species have faced severe population decline in the last decades in Southwest France, probably due to habitat deterioration. During May and June 2022, larvae, imagines and egg batches were mapped in carefully characterized habitat patches. In total, 713 imagines, 67 larvae and 20 egg batches of Zygaena cynarae (which was the most common burnet moth in the area in 2022) and 23 imagines, 84 larvae, 2 pupae and 18 egg batches of Zygaena brizae were observed. While Zygaena brizae occurs both on mesophile and on semi-dry slopes (only north-and west-facing), supported by increasing numbers of the larval food plant (Cirsium tuberosum), larval habitats of Zygaena cynarae are characterized by the common occurrence of the larval food plant (Peucedanum cervaria) and by (optimally) 10-30% tree cover. Most colonized patches are south-facing and flat; open habitat patches with many larval food plants are not inhabited. All inhabited patches are extensively grazed by sheep, goats, cattle or horses-the specifics do not seem to matter. Details of grazing schedule, sunshine duration, slope exposure and other habitat parameters are reported and evaluated to support conservation measures of these burnet moth species. Implications for insect conservation: Our results provide robust data about the specific habitat requirements of these two strongly endangered burnet moth species.