DNA barcodes of 38 plant species

Grasshoppers are integral to grassland ecosystems, influencing vegetation structure and productivity, and participating in energy flow and material cycling. However, increased stocking rates can alter the composition and structure of plant communities, thereby impacting the food resources and trophic niche of grasshoppers. Currently, significant gaps exist in research on how the trophic niche of grasshoppers changes under different stocking rates. Therefore, we conducted a field experiment in the Inner Mongolian desert steppe with four stocking rate treatments: no grazing, light, moderate, and heavy stocking rate grazing. We utilized stable carbon isotopes (δ13C) and nitrogen isotopes (δ15N) to analyze the trophic positions of three dominantgrasshopper species. Additionally, we assessed dietary diversity through high-throughput gut content DNA barcoding sequencing. Our results showed that moderate to heavy grazing significantly altered the isotopic ratios of grasshoppers, and affected their trophic niche and dietary preferences. The trophic niche of Oedaleus asiaticuswas the broadest under no grazing, whereas the trophic niche of Myrmeleotettix palpalis and Calliptamus abbreviatus increased with stocking rates. Dietary diversity decreased with stocking rates but then increased under heavy stocking rates, and was positively correlated with plant species richness, diversity, and biomass. These changes may affect the survival of grasshoppers and ecosystem functions. These findings highlight the impact of stocking rate on the dietary diversity of three grasshopper species and provide a new perspective for understanding how herbivorous insects respond to environmental changes.