DNA metabarcoding of faecal samples reveals life-history traits in the critically endangered bush-cricket

Abstract Understanding the diet composition of herbivorous insects is crucial for the conservation of threatened species and their habitats. This study investigated the diet of the critically endangered Bei-Bienko’s Plump Bush-cricket ( Isophya beybienkoi ) using DNA metabarcoding of faecal samples collected from 49 individuals. A total of 28 families and 52 genera of plants were identified, with an average of 9.0 (± 2.77) plant taxa per sample. The diet consisted exclusively of dicotyledonous plant species, dominated by herbaceous flowering plants, which accounted for 76.5% of all the species identified. The most abundant families were Fabaceae (34.9%), Apiaceae (19.8%) and Rosaceae (16.9%). Key species included Securigera varia (26%; Fabaceae), Peucedanum cervaria (16%; Apiaceae) and Prunus spinosa (11%; Rosaceae). A complementary vegetation survey recorded 178 vascular plant species—primarily herbaceous plants—in the bush-cricket’s habitat. Of these, 31 taxa were found in both the faecal samples and vegetation plots. Notably, several plant families, including Fabaceae and Orobanchaceae, were significantly more prevalent in faecal samples than in vegetation plots. This study showed the selection of nitrogen-rich herbs with higher water content, indicating the insect’s life-history traits and nutritional needs in the extreme environment of the Slovak Karst National Park. Overall, this study provides critical insights into the bush-cricket’s ecological requirements and underscores the importance of specific habitat types and plant species for its conservation.