Active aggregation sampling for eDNA outperforms visual surveys for early detection of a terrestrial insect, spotted lanternfly

Recently, eDNA has begun to be used in terrestrial systems to survey for insect pests, but little is known about how detection rates compare with conventional surveys. One protocol was designed for spotted lanternfly (SLF; Lycorma delicatula). Originally from China, this true bug is a significant pest of forested and agricultural systems, especially grapes. We conducted field sampling within 48 plots at 12 vineyards to compare the detection of SLF using eDNA and visual surveying in Fall 2019. Multimethod occupancy analysis revealed the probability of detecting SLF was nearly three times more likely with eDNA (86%) compared to visual surveys (35%). In September sampling, eDNA found lanternfly at five plots within three vineyards in contrast to one plot at a single vineyard via visual survey. In October, eDNA detected this pest in 12 plots within six vineyards compared with six plots in two vineyards for visual surveys. The higher detection rates of SLF in October corresponded with SLF migrating from adjacent forests, allowing us to evaluate the methods under different densities. Occupancy and detection rates indicate that fewer plots need to be examined to detect SLF with 95% confidence using eDNA (12 plots in Sept. and 5 in Oct.) compared to visual surveys (30 and 15 plots, respectively). Thus, we provide some of the first evidence to support the enhanced sensitivity of eDNA over conventional methods in a terrestrial system. eDNA enhances efforts to combat this invasive species, especially by delimiting invasion fronts, identifying satellite populations, and confirming eradications.