Abstract
Low-productive open landscapes, once prevalent in Western Europe, have significantly declined due to land reclamation and afforestation. Despite protection under the European Union Habitats Directive, remaining heathlands face degradation from various factors, including nitrogen deposition, climate change, and altered land use. Using laboratory and field experiments we examined the habitat requirements and causes of decline for two large heathland bush-crickets, Ephippiger diurnus Dufour, 1841 and Gampsocleis glabra (Herbst , 1786) , focusing on the availability of bare mineral soil for egg-deposition. Our study revealed a strong preference for bare sand over moss-covered soil for oviposition for both species. Eggs deposited in bare sand showed higher survival rates, better development, and increased hatching success compared to those in moss-covered soil. The decline of these bush-cricket species is linked to the reduction of bare soil due to moss encroachment, exacerbated by nitrogen deposition. Implications for insect conservation: Our results show that loss of bare soil patches is an important bottleneck in the life cycle of large heathland bush-crickets. Conservation efforts therefore must prioritize maintaining bare soil patches through anthropogenic disturbances and reducing nitrogen deposition to support bush-cricket reproduction and sustain their populations in Northwestern Europe.