Conservation on the edge: unravelling critical drivers behind the decline of a mountain grasshopper’s marginal populations

Abstract The ongoing decline of insects highlights the global biodiversity crisis, with orthopterans among the most threatened terrestrial invertebrates in Europe. A mountain grasshopper, Arcyptera fusca , is experiencing declines throughout its range, particularly in Central Europe. Over recent decades, only eight marginal populations remained in Hungary. This study aimed to identify key factors contributing to the decline of A. fusca , intending to elaborate conservation measures to support its long-term regional survival. Field studies were conducted in Hungary’s two largest populations in 2021 and 2023 with nymphs and adults. We compared habitat characteristics (vegetation height, cover, Poaceae ratio) between occupied and unoccupied microhabitats recorded along line transects and used mark-recapture method to assess dispersal ability. Laboratory experiments tested nymph and adult acceptance of 18 plant species, and the reproductive capacity of adult females. Our research indicated that A. fusca relies on microhabitats with short, sparse vegetation and bare patches for egg-laying, essential for its local survival. The daily dispersal rate from release points was 0.2–0.7 m/day for nymphs and 4.4–4.8 m/day for adults, showing low mobility. A. fusca proved to be polyphagous, feeding on both monocots and dicots. Collected females averaged 21 ovarioles and laid about 17 eggs per pod. Implications for insect conservation: Our results highlight the importance of traditional extensive habitat management (grazing, mowing) and leaving uncut refuges to maintain the biodiversity of mountain meadows. Establishing new populations through translocation events into properly managed habitats may also promote the long-term regional persistence of endangered species.