Data and code for: Terrestrial eDNA survey outperforms conventional approach for detecting an invasive pest insect within an agricultural ecosystem

Recent methodological advances permit surveys for terrestrial insects from
the direct collection of environmental DNA (eDNA) deposited on vegetation
or other surfaces. However, in contrast to well-studied aquatic
applications, little is known about how detection rates for such
terrestrial eDNA-based surveys compare with conventional survey methods.
Lycorma delicatula, the spotted lanternfly, is an emerging invasive insect
in eastern North America, and a significant ecological and economic pest
of forested and agricultural systems, especially grapes. During fall 2019
we conducted two rounds of paired eDNA and visual surveys for spotted
lanternflies within 48 plots at 12 vineyards in New Jersey, USA. We
compared detection probabilities within a multimethod occupancy modeling
framework and used the results to extrapolate and inform survey design.
The probability of detecting spotted lanternflies given presence in a plot
was over two times higher for eDNA (84%) versus visual surveys (36%). In
mid-September, lanternfly eDNA was detected at five plots in three
vineyards while visual surveys revealed only a single individual in one
plot. In early October, after dispersal of lanternflies into vineyards,
lanternfly eDNA was detected in 12 plots within six vineyards compared
with visual detections in six plots in two vineyards. Extrapolations based
on detection and local-scale occupancy rates indicate that only five and
12 plots would have been needed to positively detect lanternfly presence
with 95% confidence using eDNA in contrast to 14 and 29 plots with visual
surveys alone, respective to survey rounds. Log-linear models revealed
that visual counts of lanternflies were positively related to eDNA
concentrations (R2 = 71%). We provide some of the first quantitative
evidence to support the enhanced sensitivity of terrestrial eDNA
approaches compared with conventional methods. Such methods can augment
efforts to combat invasive species through improved ability to delimit
invasion fronts, identify satellite populations, and confirm local
eradications.

近年来方法学的进展使得可通过直接采集附着于植被或其他表面的环境DNA（environmental DNA）来开展陆生昆虫调查。然而，与研究较为充分的水生应用场景相比，学界对这类基于eDNA的陆生昆虫调查的检出率与传统调查方法的对比情况仍知之甚少。斑衣蜡蝉（spotted lanternfly，学名*Lycorma delicatula*）是北美东部地区的新兴入侵昆虫，也是森林与农业生态系统中极具危害性的生态与经济害虫，尤其对葡萄产业造成严重影响。2019年秋季，我们在美国新泽西州的12座葡萄园中共设置48个样地，针对斑衣蜡蝉开展了两轮配对eDNA采样与目视调查。我们采用多方法占有模型框架对比了两种调查方式的检出概率，并基于结果进行外推以指导调查方案设计。当样地内存在斑衣蜡蝉时，eDNA调查的检出概率（84%）较目视调查（36%）高出两倍以上。9月中旬，我们在3座葡萄园的5个样地中检测到斑衣蜡蝉eDNA，而同期目视调查仅在1个样地中发现1头成虫。10月初，在斑衣蜡蝉扩散至葡萄园后，我们在6座葡萄园的12个样地中检测到eDNA，而目视调查仅在2座葡萄园的6个样地中发现成虫。基于检出率与局域占有率的外推结果显示，两轮调查中，若要以95%的置信度确证斑衣蜡蝉的存在，采用eDNA调查仅需设置5和12个样地，而仅采用目视调查则分别需要14和29个样地。对数线性模型分析结果表明，斑衣蜡蝉的目视计数与eDNA浓度呈显著正相关（决定系数R²=71%）。本研究提供了首批定量证据之一，证实相较于传统调查方法，陆生eDNA调查方法具有更高的灵敏度。此类方法可通过优化入侵边界划定、卫星种群识别以及本地根除效果确认等能力，助力入侵物种防控工作。