The battle against invasive species has found an unlikely ally in one of nature’s most organised workforces: ants. Recent research has uncovered that these industrious insects can serve as remarkably effective biological collectors of environmental DNA (eDNA). Specifically, ants are proving instrumental in detecting one of North America’s most damaging invasive pests: the spotted lanternfly (SLF). This discovery is not merely a curious scientific finding; it offers a transformative approach to early detection and control, providing real hope in a battle often defined by costly management and reactive solutions.
The Promise of Environmental DNA
Environmental DNA has already profoundly reshaped our understanding of biodiversity. Every organism, as it interacts with its surroundings, leaves behind traces of its genetic material. This eDNA can be sampled from the environment, enabling scientists to detect species without the need for direct observation.
In aquatic habitats, this technique has become invaluable. Water, by its very nature, gathers and disperses DNA effectively, making it comparatively straightforward to analyse. However, on land, eDNA monitoring faces considerable difficulties. Unlike the uniform distribution found in rivers and lakes, terrestrial landscapes scatter genetic traces unpredictably. This complexity means identifying exactly where and how to sample becomes a significant challenge.
The spotted lanternfly case perfectly illustrates both the problem and the opportunity. Previous eDNA detection methods for this invasive species included spray aggregation (rinsing vegetation surfaces) and tree rolling (using paint rollers to collect DNA from tree trunks and branches). While effective, these approaches require specialised equipment, extensive labour, and complex preservation procedures.
The Hidden Potential of Ants as eDNA Collectors
Ants naturally and routinely engage with their environment in a way that offers a surprising advantage for eDNA sampling.
Targeted Foraging Behaviour: Ants actively seek carbohydrate-rich resources, including honeydew from sap-sucking insects. This behaviour means they directly interact with spotted lanternfly excretions, which contain detectable DNA. Unlike passive sampling methods, ants actively aggregate eDNA through their natural foraging activities.
Extended Retention and Distribution: Worker ants can retain liquid food in their digestive systems for extended periods, later sharing it with nestmates through trophallaxis. This biological storage system effectively concentrates and preserves eDNA within the ant colony network, creating mobile reservoirs of genetic material.
Extensive Coverage Areas: Ants do not just forage randomly—they systematically cover large territories. Some species, like Camponotus ants, found in this study, forage 10-30 meters from their nests. Their polydomous nature, where colonies spread across multiple spatially separated nests, further extends this coverage area. This natural surveillance network can detect spotted lanternfly presence even in low-density populations where the insects might otherwise go unnoticed.
Ecological Dominance and Accessibility: Ants’ ecological dominance means they are present across diverse habitats where invasive species monitoring is needed. Unlike specialised equipment or trained personnel, ants are already deployed across the landscape, working around the clock.
Conducting the Groundbreaking Study
Researchers tested this novel concept by conducting carefully controlled experiments at six sites across Virginia, USA—four sites were known to harbour spotted lanternfly populations, while two were free from infestation. At each infested location, the research team collected ants directly from affected trees as well as from points five metres away in several directions. The goal was simple yet crucial: to determine if ants could reliably detect SLF DNA in areas of varying infestation intensity.
To ensure scientific rigour, the researchers also collected other insects, such as ladybirds and leafhoppers, which do not usually feed on lanternfly honeydew. This control group was essential to rule out the possibility that positive results arose simply from environmental contamination rather than targeted ingestion.
Collected samples underwent cleaning to ensure that any genetic material detected came solely from what ants had ingested. The researchers employed two highly precise molecular techniques, endpoint PCR and quantitative PCR, targeting genetic sequences unique to the spotted lanternfly.
Results: Reliable, Specific, and Convincing
The results surpassed expectations.
High Detection Rates: Ant samples from infested sites showed remarkable detection success: 60-100% using endpoint PCR and 80-100% using qPCR. This consistency across different molecular methods demonstrates the reliability of ants as eDNA samplers.
Perfect Specificity: Perhaps more importantly, zero ant samples from non-infested control sites tested positive for spotted lanternfly DNA using either detection method. This specificity eliminates concerns about false positives that could lead to unnecessary management interventions.
Superior Performance: When compared to non-ant insects, ants consistently showed higher spotted lanternfly DNA concentrations. While some non-ant insects showed occasional positive signals in qPCR assays, these likely resulted from technical artefacts rather than genuine biological uptake.
Why the Spotted Lanternfly Demands Urgent Attention
Originally native to parts of Asia, the spotted lanternfly has rapidly become one of North America’s most pressing agricultural and ecological threats. First identified in Pennsylvania in 2014, it has since spread swiftly, primarily due to inadvertent human-assisted transport and its adaptability to numerous plant hosts.
This pest severely impacts agriculture, particularly orchards and vineyards, by extracting large quantities of sap and depositing sticky honeydew, which fosters mould growth. Such damage significantly reduces fruit yield and quality, threatening livelihoods and regional economies dependent on horticulture. SLF infestations also weaken native trees, undermine forest health, and disrupt local ecosystems.
The public nuisance aspect of lanternfly swarms cannot be underestimated, as large numbers congregate in urban areas, creating unpleasant conditions and increasing pressure on public resources.
Broad Implications for Conservation and Pest Management
The significant advantage of ant-based eDNA sampling lies in its potential for early detection. Invasive species, including the spotted lanternfly, are most manageable when their populations remain small and localised. Ants, with their extensive foraging ranges and inherent sensitivity to insect-produced honeydew, offer a remarkably early warning system, detecting pests long before conventional methods might notice their presence.
Beyond managing the spotted lanternfly, this research suggests broader possibilities. Many invasive insects produce detectable genetic markers through their excretions. Thus, the general principle—using insects’ natural behaviours to sample eDNA—might be adaptable to monitor other pest species effectively.
More profoundly, this method aligns with the emerging ethos of conservation technologies that work alongside natural processes, leveraging existing ecological relationships rather than imposing artificial, resource-intensive interventions.
Future Refinements and Directions
While the initial findings are compelling, further research will enhance the practicality and effectiveness of ant-based eDNA sampling.
Sensitivity Testing: Future studies should evaluate detection sensitivity when spotted lanternfly populations are extremely low, determining the minimum density thresholds for reliable detection.
Automated Collection Methods: Transitioning from manual collection using aspirators to automated lure-based systems could enable continuous monitoring across large geographic areas without constant human intervention.
Temporal and Environmental Variables: Understanding how seasonal variations, weather patterns, and local ecological conditions affect ant foraging behaviour and eDNA retention will be crucial for developing standardised monitoring protocols.
A Quiet but Profound Transformation
This innovative use of ants represents more than a quirky scientific insight; it embodies a fundamental shift towards harnessing ecological relationships for environmental management. By collaborating with a common yet overlooked ally, researchers have devised an efficient, cost-effective, and elegant solution to one of conservation’s perennial challenges: detecting invasive species early enough to act decisively.
In the broader battle against invasive species, this quiet revolution demonstrates the immense potential of working with nature rather than against it. Through such partnerships, we might indeed find our strongest allies in the smallest of creatures.
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