Using eDNA to detect the distribution and density of invasive crayfish in the Honghe-Hani rice terrace World Heritage site

Environmental DNA (eDNA) analysis emerges as a highly sensitive tool for detecting invasive crayfish (Procambarus clarkii) in the UNESCO World Heritage site of Honghe-Hani rice terraces, offering potential to revolutionize pest management strategies. The study found that eDNA sampling from paddy water could reliably detect even low-density crayfish populations—outperforming traditional bottle traps—which missed 32% of infested paddies. Real-time qPCR analysis confirmed the presence of crayfish in all observed cases (100% accuracy) and none in uninfested ones, with eDNA concentrations correlating positively with crayfish counts. While not perfect (one false negative), repeated eDNA sampling proved feasible for tracking invasion fronts and monitoring geographic spread, addressing critical gaps in current farmer-led pesticide applications. This approach could enhance regional control efforts by enabling early detection of small, cryptic populations before they cause structural damage to terraces or rice yields.

Cai, W., Ma, Z., Yang, C., Wang, L., Wang, W., Zhao, G., Geng, Y., & Yu, D. W. (2017). Using eDNA to detect the distribution and density of invasive crayfish in the Honghe-Hani rice terrace World Heritage site. Plos One, 12(5), e0177724. https://doi.org/10.1371/journal.pone.0177724