Environmental DNA (eDNA) analyses have become invaluable for detecting and monitoring aquatic and terrestrial species and assessing site biodiversity within aquatic environments or soil. Recent studies have extended these techniques by using eDNA to identify the presence of aboveground terrestrial arthropods directly from aboveground substrates. However, while the dynamics of eDNA state, transport, and fate (its ‘ecology’) have been explored within aquatic environments and soil, they have yet to be explored within aboveground terrestrial systems. Here we explore the ecology of terrestrial eDNA deposited by fluid-feeding arthropods on leaf surfaces. We carried out a series of experiments to evaluate the optimal filter pore size for intracellular eDNA collection, how eDNA is affected by rain events, and its degradation rate under different solar radiation conditions. We found that the captured concentration of intracellular eDNA was not significantly affected by an increase in filter pore size, suggesting a wide range of viable pore size options exist for targeting intracellular eDNA. We also found extracellular eDNA from fluid excrement degrades more rapidly than intracellular when exposed to solar radiation, indicating the latter is a more viable target for collection. Finally, we identified that rainfall or mist will remove most terrestrial eDNA present on vegetation surfaces. We provide researchers and environmental managers key insights into successfully designing and carrying out terrestrial arthropod eDNA surveys that maximize detection probability.

Environmental DNA (eDNA) analysis has become a valuable tool for detecting aquatic and terrestrial species for monitoring efforts and site biodiversity assessments. However, if aboveground terrestrial eDNA surveys are to be widely adopted, it is necessary to first understand how terrestrial conditions affect the state, transport, and ultimate fate (or ‘ecology’) of terrestrially deposited eDNA. Many of the processes that affect the state, transport, and fate of eDNA in aquatic environments may not be applicable in aboveground systems, warranting an exploration of the terrestrial processes that likely do affect eDNA. Here we explore the ecology of aboveground terrestrial eDNA through a series of experiments evaluating the optimal filter pore size for intracellular eDNA collection, how eDNA is affected by rain events, and its degradation rate under different solar radiation conditions. We found that the captured concentration of intracellular eDNA was not significantly affected by an increase in filter pore size, suggesting there is a wide range of viable pore size options for targeting intracellular eDNA. We also found extracellular eDNA degrades more rapidly than intracellular forms when exposed to solar radiation, indicating the latter is a more viable target for collection. Finally, we identified that rainfall or mist will remove most terrestrial eDNA present on vegetation substrate. This study provides researchers and managers key insights into successfully designing and carrying out terrestrial eDNA surveys that maximize detection probability and minimize false positive results.

Environmental DNA (eDNA) has become a valuable tool for monitoring species of concern or site biodiversity, including expanded use of surveys designed to detect fully terrestrial species. However, if aboveground terrestrial eDNA surveys are to be widely adopted, it is necessary to first understand how terrestrial conditions affect the state, transport, and ultimate fate (or ‘ecology’) of terrestrially deposited eDNA. Many of the processes that affect eDNA’s state, transport, and fate in aquatic environments may not be applicable in aboveground systems, warranting an exploration of the terrestrial processes that likely do affect eDNA. Here we explore ecology terrestrial eDNA through a series of experiments exploring the optimal filter pore size for eDNA collection, how eDNA is affected by rain events, and its degradation rate under different solar radiation conditions. We found that the capture concentration of intracellular eDNA was not significantly affected by an increase in filter pore size, suggesting there is a wide range of viable pore size options for targeting intracellular eDNA. We also found extracellular eDNA degrades more rapidly than intracellular forms when exposed to solar radiation, indicating the latter is a more viable target for collection. Finally, we identified that rainfall or mist will remove most terrestrial eDNA present on vegetation substrate. This study provides researchers and managers key insights into successfully designing and carrying out terrestrial eDNA surveys that maximize detection probability and reduce production of false positive survey results.